burning

Net Primary Production Data: Konza-Kruger Fire-Grazing Project (2006-2009)

Abstract: 

The distribution, structure and function of mesic savanna grasslands are strongly driven by fire regimes, grazing by large herbivores, and their interactions. This research addresses a general question about our understanding of savanna grasslands globally: Is our knowledge of fire and grazing sufficiently general to enable us to make accurate predictions of how these ecosystems will respond to changes in these drivers over time? Some evidence suggests that fire and grazing influence savanna grassland structure and function differently in South Africa (SA) compared to North America (NA). These differences have been attributed to the contingent factors of greater biome age, longer evolutionary history with fire and grazing, reduced soil fertility, and greater diversity of plants and large herbivores in SA. An alternative hypothesis is that differences in methods and approaches used to study these systems have led to differing perspectives on the role of these drivers. If the impacts of shared ecosystem drivers truly differ between NA and SA, this calls into question the generality of our understanding of these ecosystems and our ability to forecast how changes in key drivers will affect savanna grasslands globally. Since 2006, an explicitly comparative research program has been conducted to determine the degree of convergence in ecosystem (productivity, N and C cycling) and plant community (composition, diversity, dynamics) responses to fire and grazing in SA and NA.

Thus far, initial support has been found for convergence at the ecosystem level and divergence at the community level in response to alterations in both fire regimes and grazing. However, there have also been two unexpected findings (1) the ways in which fire and grazing interact differed between NA and SA, and (2) the rate of change in communities when grazers were removed was much greater in NA than in SA. These unexpected findings raise a number of important new questions: (Q1) Will exclusion of grazing eventually affect community structure and composition across all fire regimes in SA? (Q2) Will these effects differ from those observed in NA? (Q3) What are the determinants of the different rates of community change? (Q4) How will these determinants influence future trajectories of change? (Q5) Will the different rates and trajectories of community change be mirrored by responses in ecosystem function over time? This project is based on a large herbivore exclusion study established within the context of long-term (25-50+ yr) experimental manipulations of fire frequency at the Konza Prairie Biological Station (KPBS) in NA and the Kruger National Park (KNP) in SA. The suite of core studies and measurements include plant community composition, ANPP, and herbivore abundance and distribution at both study sites to answer these research questions.

This data set was added to the Sevilleta LTER archive at the request of the SEV Principal Investigator Scott Collins.

Core Areas: 

Data set ID: 

272

Keywords: 

Purpose: 

Data are collected twice each year at each site. Sample periods are equivalent to spring and late summer at each study site (December/January and March/April in South Africa, May and September in North America.

Where the Data were Collected: 

Ukulinga Research Farm, Pietermaritzburg, South Africa; Satara Region of Kruger National Park, South Africa; Konza Prairie Biological Station, North America

Additional Geographic Metadata:  

Ukulinga Research Farm (URF), South Africa. The URF of the University of KwaZulu-Natal is located in Pietermaritzburg, in southeastern South Africa (30o 24’ S, 29o 24’ E). The site is dominated by native perennial C4 grasses, such as Themeda triandra and Heteropogon contortus, that account for much of the herbaceous aboveground net primary production (ANPP). Mean annual precipitation is 790 mm, coming mostly as convective storms during summer (Oct-Apr). Summers are warm with a mean monthly maximum of 26.4oC in February, and winters are mild with occasional frost. Soils are fine-textured and derived from shales. There has been no grazing at this site for >60 years. Long-term experimental plots were established at URF in 1950 with the objective of determining the optimal fire and/or summer cutting regime to maximize hay production. The experiment is a randomized block (three replicates) split-plot design with four whole-plot haying treatments and 11 subplot fire or mowing treatments. Subplot sizes are 13.7 x 18.3 m. 

Kruger National Park (KNP), South Africa. The KNP is a 2 million ha protected area of savanna grassland that includes many of the large herbivores common to southern Africa (22º 25' to 25º 2 32' S, 30º 50' to 32º 2' E). The extant abundance and grazing intensity of herbivores in KNP is considered moderate for regional savanna grasslands. In the south-central region of KNP where our research takes place, average rainfall is 537 mm with most falling during the growing season (Oct-Apr). The dormant season is mild, dry and frost free, and summers are warm with mean monthly maximum air temperature of 28.9oC in January. Because of the importance of fire in savanna grassland ecosystems, the Experimental Burn Plot (EBP) experiment was initiated in 1954 to examine the effects of fire frequency (control-no fire, 1-, 2-, 3-, 4- and 6-yr return interval) and season [early spring (Aug), spring (Oct), mid-summer (Dec), late summer (Feb), and fall (Apr)] on vegetation communities in the park. Four blocks of 12 plots (two were later split for the 4- and 6-yr trts), each ~7 ha (370 x 180 m) in size, were established in four primary vegetation types covering the two major soil types (granites and basalts) and spanning the precipitation gradient in the park. Each plot has 50+ years of known fire history, and native herbivores have had unrestricted access, thus fire and grazing effects are combined. This research focuses on the EBPs located near Satara where precipitation, soil type, and the mix of herbaceous and woody plants are similar to KPBS. Vegetation on the blocks is co-dominated by C4 grasses, such as Bothriochloa radicans, Panicum coloratum and Digiteria eriantha, and woody plants, such as Acacia nigrescens and Sclerocarya birrea.  Soils are fine-textured and derived from basalts. Adjacent to one of the Satara blocks is the Cape buffalo enclosure, erected in 2000 for veterinary purposes. The 200 ha permanent enclosure contains 65-80 animals and is divided into 4 blocks burned on a rotational basis. The grazing intensity inside is comparable to the moderate levels imposed in the park and at KPBS. Two blocks are burned annually while others are burned infrequently (approximately once every 4-yr). 

Konza Prairie Biological Station (KPBS), North America. The KPBS is a 3,487 ha savanna grassland in northeastern Kansas, USA (39o 05’ N, 96o 35’ W) dominated by native perennial C4 grasses such as Andropogon gerardii and Sorghastrum nutans that account for the majority of ANPP. Scattered shrub and tree species include Cornus drummondii, Gleditsia triacanthos, and Prunus spp. Numerous sub-dominant grasses and forbs contribute to the floristic diversity of the site. The climate is continental, with mean July air temperature of 27°C. Annual precipitation is ca. 820 mm/year, with 75% falling as rain during the Apr-Oct growing season. Soils are fine textured, silty clay loams derived from limestone and shales. KPBS includes fully replicated watershed-level fire and fire/grazing treatments, in place since 1977 and 1987, respectively.  Replicate watersheds (mean size ~60ha) are burned at 1-, 2-, 4-, 10- and 20-yr intervals, mainly in April, to encompass a range of likely natural fire frequencies and management practices. A subset of watersheds has not been grazed for more than 30 years. To address the role of native grazers and fire/grazing interactions, bison (~260 individuals) were reintroduced to KPBS in a 1000-ha fenced area that includes replicate watersheds burned in the spring at 1-, 2-, 4- and 20-year intervals. The overall grazing intensity is considered moderate.

Study Area 1:  

Study Area Name:  Ukulinga Research Farm

Study Area Location: Near Pietermaritzburg, South Africa 

Elevation: 840 m above sea level

Landform: Colluvium fan

Geology: Marine shales and dolerite colluvium

Soils: Dystric leptosols, Chromic luvisols, Haplic plinthisols

Vegetation: Native grassland

Climate: Mean annual precipitation is 844 mm, Mean annual temperature 17.6C

Site history: Ungrazed since 1950

Single Point: 29o 40’ S / 30o 20’ E

Study Area 2:  Kruger National Park, South Africa

Study Area Name: Satara Experimental Burn Plots and Cape Buffalo Exclosure

Study Area Location: Near Satara rest camp

Elevation:  240-320 meters above sea level

Landform:  Level Upland

Geology: Basalts

Soils: Rhodic nitisols, Haplic luvisols, Leptic phaeozems

Vegetation: Native grassland

Climate: Mean annual precipitation 544 mm; mean annual temperature 21.2–23.3C

Site history: Grazed by native herbivores

Single Point: 23–25o S /30-31o E

   

Study Area 3:  Konza Prairie Biological Station

Study Area Name: Konza Prairie

Study Area Location: Watersheds N20B, N4D, N1B, N4B; 1D, 4F, 20B

Elevation: 320-444 meters above sea level

Landform: Alluvial terrace

Geology: Cherty limestone and shale

Soils: Udic argiustolls

Vegetation: Native grassland

Climate: Mean annual precipitation 835 mm; mean annual temperature 12.7C

Site history: Ungrazed watersheds (since 1971), watersheds grazed by native herbivores (since 1987)

Single Point: 39o 05.48’ N / 96o 34.12’ W

Data sources: 

sev272_Biomass_KNZ-KNP_ 2006-2009.txt

Methods: 

We used comparable experimental designs and sampling procedures at both URF and KPBS. At URF we used three replicate plots (not hayed or mowed) that have been burned every 1 and 3 years in the spring, and those left unburned (N=9 plots). At KPBS, we established replicate plots in experimental watersheds burned every 1 and 4 years in the spring, and those left unburned (N=9 plots). Thus, the only difference in design between NA and SA was the intermediate burn frequency. In 2005 at both sites we established four 2x2m areas in each replicate of the 1-yr, 3-4 yr burned, and unburned plots (N=36 subplots). We then randomly selected two of the subplots for the fertilization treatment and the other two subplots served as controls (Fig. 1). Starting in 2006 at KPBS and 2007 at URF, we began adding 10 gN/m2/yr as NH4+NO3- to assess the interactive effects of fire frequency and nitrogen limitation on plant community composition, structure and dynamics.

Fig. 1. Experimental design and sampling for the proposed studies: A) the role of long-term fire regimes (without megaherbivores), B) the importance of grazing and grazing/fire interactions, and C) the role of megaherbivore diversity. Moveable exclosures (3/plot) will be used to estimate ANPP in the grazed plots.  N addition subplots (2 x 2 m) will be divided into 4 1 x 1 plots, with two designated for plant species composition sampling and the other two for destructive sampling. Soil samples will be collected from areas not designated for ANPP or plant composition sampling. Note that the same annually and infrequently burned plots at Kruger and Konza will be used in (B) and (C). In addition, similar plots will be established minus the N addition subplots in the 1-yr and 4-yr burned blocks of the Buffalo enclosure for (C). 

Each of the 2x2m subplots was divided into four 1x1m quadrats. Annually since 2005 (prior to nitrogen addition) canopy cover of each species rooted in each quadrat was visually estimated twice during the growing season to sample early and late season species. As a surrogate for aboveground production, we measured light availability at the end of the growing season above the canopy at the ground surface in each quadrat (N=4 per subplot) using a Decagon ceptometer. 

Net primary production measurements: Prior to the 2005 growing season we established plots (13.7 m by 18.3 m) in ungrazed areas burned annually, at 3–4-year intervals, and unburned (n  = 3 per fire treatment) at both KBPS and URF. Areas with trees or large shrubs were avoided as our main goal was to evaluate responses in the herbaceous plant community. ANPP was estimated from end-of-season harvests starting in 2005 (September for KBPS, April for URF). In 10, 0.1-m2 (20 cm by 50 cm) quadrats randomly located in each plot (n  = 30/treatment/site), we harvested the vegetation at ground level and separated it into grass, forb, and previous year’s dead biomass. Samples were dried at 60C to a constant weight. For annually burned plots, total biomass harvested represents ANPP. For the intermediate and unburned sites, we calculated ANPP by summing all but the previous year’s dead component.

To assess the impacts of fire on ANPP in grazed areas, we established herbivore exclusion treatments in KBPS in North America and KNP in South Africa. Herbivore exclosures in grazed areas in KPBS and KNP were erected prior to the 2006 growing season. The exclosures were 7 m in diameter, 2 m tall, and constructed of diamond mesh (5-cm diameter). Seven exclosures were established in each of three blocks of the three fire treatments— annually burned, intermediate burn (3- years for KNP or 4-years for KPBS), and unburned (n = 21 exclosures/treatment/site). As our focus was on ANPP responses of the herbaceous layer, exclosures were not located beneath trees or where dense shrub patches were present. Additionally, in the Satara region of KNP is a 900-ha permanent enclosure containing 80–90 adult African buffalo (S. caffer). This enclosure was erected in 2000 and was divided into six areas (100–200 ha each), with these burned on a rotational basis including plots burned annually and plots that were unburned. We used the unburned and annually burned areas in the buffalo enclosure to provide a direct comparison for determining the effects of a single-species large grazer in KNP and KPBS, and to assess the effects of large herbivore diversity at adjacent sites in KNP. Similar exclosures were built in the African buffalo enclosure at KNP. We placed 7 exclosures in the three blocks of each fire treatment (annually burned and unburned) resulting in 21 exclosures/treatment. We sampled ANPP by harvesting plant biomass from three 0.1 m2 quadrats per herbivore exclosure at the end of the growing season starting in 2006. 

Ukulinga Species Composition: Fire by Nitrogen Project

Abstract: 

The distribution, structure and function of mesic savanna grasslands are strongly driven by fire regimes, grazing by large herbivores, and their interactions. This research addresses a general question about our understanding of savanna grasslands globally: Is our knowledge of fire and grazing sufficiently general to enable us to make accurate predictions of how these ecosystems will respond to changes in these drivers over time? Some evidence suggests that fire and grazing influence savanna grassland structure and function differently in South Africa (SA) compared to North America (NA). These differences have been attributed to the contingent factors of greater biome age, longer evolutionary history with fire and grazing, reduced soil fertility, and greater diversity of plants and large herbivores in SA. An alternative hypothesis is that differences in methods and approaches used to study these systems have led to differing perspectives on the role of these drivers. If the impacts of shared ecosystem drivers truly differ between NA and SA, this calls into question the generality of our understanding of these ecosystems and our ability to forecast how changes in key drivers will affect savanna grasslands globally. Since 2006, an explicitly comparative research program has been conducted to determine the degree of convergence in ecosystem (productivity, N and C cycling) and plant community (composition, diversity, dynamics) responses to fire and grazing in SA and NA.

Thus far, initial support has been found for convergence at the ecosystem level and divergence at the community level in response to alterations in both fire regimes and grazing. However, there have also been two unexpected findings (1) the ways in which fire and grazing interact differed between NA and SA, and (2) the rate of change in communities when grazers were removed was much greater in NA than in SA. These unexpected findings raise a number of important new questions: (Q1) Will exclusion of grazing eventually affect community structure and composition across all fire regimes in SA? (Q2) Will these effects differ from those observed in NA? (Q3) What are the determinants of the different rates of community change? (Q4) How will these determinants influence future trajectories of change? (Q5) Will the different rates and trajectories of community change be mirrored by responses in ecosystem function over time? This project is based on a large herbivore exclusion study established within the context of long-term (25-50+ yr) experimental manipulations of fire frequency at the Konza Prairie Biological Station (KPBS) in NA and the Kruger National Park (KNP) in SA. The suite of core studies and measurements include plant community composition, ANPP, and herbivore abundance and distribution at both study sites to answer these research questions.

Data set ID: 

263

Core Areas: 

Keywords: 

Methods: 

Konza-Ukulinga fire by nitrogen project: We used comparable experimental designs and sampling procedures at both URF and KPBS (Figure 1). At URF we used three replicate plots (not hayed or mowed) that have been burned every 1 and 3 years in the spring, and those left unburned (N=9 plots). At KPBS, we established replicate plots in experimental watersheds burned every 1 and 4 years in the spring, and those left unburned (N=9 plots). Thus, the only difference in design between NA and SA was the intermediate burn frequency. In 2005 at both sites we established four 2x2m areas in each replicate of the 1-yr, 3-4 yr burned, and unburned plots (N=36 subplots). We then randomly selected two of the subplots for the fertilization treatment and the other two subplots served as controls (Fig. 1). Starting in 2006 at KPBS and 2007 at URF, we began adding 10 gN/m2/yr as NH4+NO3- to assess the interactive effects of fire frequency and nitrogen limitation on plant community composition, structure and dynamics.

Fig. 1. Experimental design and sampling for the proposed studies: A) the role of long-term fire regimes (without megaherbivores), B) the importance of grazing and grazing/fire interactions, and C) the role of megaherbivore diversity. Moveable exclosures (3/plot) will be used to estimate ANPP in the grazed plots.  N addition subplots (2 x 2 m) will be divided into 4 1 x 1 plots, with two designated for plant species composition sampling and the other two for destructive sampling. Soil samples will be collected from areas not designated for ANPP or plant composition sampling. Note that the same annually and infrequently burned plots at Kruger and Konza will be used in (B) and (C). In addition, similar plots will be established minus the N addition subplots in the 1-yr and 4-yr burned blocks of the Buffalo enclosure for (C). 

Each of the 2x2m subplots was divided into four 1x1m quadrats. Annually since 2005 (prior to nitrogen addition) canopy cover of each species rooted in each quadrat was visually estimated twice during the growing season to sample early and late season species. As a surrogate for aboveground production, we measured light availability at the end of the growing season above the canopy at the ground surface in each quadrat (N=4 per subplot) using a Decagon ceptometer. 

Konza-Kruger fire by grazing project: For this study, we are utilizing the long-term experiments at KPBS and KNP in which native megaherbivore grazers are present and fire frequency is directly manipulated. To assess the effects of grazing and fire-grazing interactions, we constructed seven sets of permanent exclosures and adjacent control plots in three blocks at both sites. The exclosures and matching paired open plots were established in 2005 in the Satara EBPs that are burned every 1 and 3 years in the spring or left unburned and at KPBS in watersheds that are burned every 1 and 4 years or left unburned. (N=63 exclosures/site; Fig. 1). Within each exclosure and paired open plot, we sample plant community composition and light availability in permanent 2x2 m subplots. We collect ANPP at the end of each growing season from each exclosure, and throughout the growing season in grazed areas adjacent to the unexclosed plots using 1x1 m moveable exclosures (Fig. 1).

Net primary production measurements: Prior to the 2005 growing season we established plots (13.7 m by 18.3 m) in ungrazed areas burned annually, at 3–4-year intervals, and unburned (n  = 3 per fire treatment) at both KBPS and URF. Areas with trees or large shrubs were avoided as our main goal was to evaluate responses in the herbaceous plant community. ANPP was estimated from end-of-season harvests starting in 2005 (September for KBPS, April for URF). In 10, 0.1-m2 (20 cm by 50 cm) quadrats randomly located in each plot (n  = 30/treatment/site), we harvested the vegetation at ground level and separated it into grass, forb, and previous year’s dead biomass. Samples were dried at 60C to a constant weight. For annually burned plots, total biomass harvested represents ANPP. For the intermediate and unburned sites, we calculated ANPP by summing all but the previous year’s dead component.

To assess the impacts of fire on ANPP in grazed areas, we established herbivore exclusion treatments in KBPS in North America and KNP in South Africa. Herbivore exclosures in grazed areas in KPBS and KNP were erected prior to the 2006 growing season. The exclosures were 7 m in diameter, 2 m tall, and constructed of diamond mesh (5-cm diameter). Seven exclosures were established in each of three blocks of the three fire treatments— annually burned, intermediate burn (3- years for KNP or 4-years for KPBS), and unburned (n = 21 exclosures/treatment/site). As our focus was on ANPP responses of the herbaceous layer, exclosures were not located beneath trees or where dense shrub patches were present. Additionally, in the Satara region of KNP is a 900-ha permanent enclosure containing 80–90 adult African buffalo (S. caffer). This enclosure was erected in 2000 and was divided into six areas (100–200 ha each), with these burned on a rotational basis including plots burned annually and plots that were unburned. We used the unburned and annually burned areas in the buffalo enclosure to provide a direct comparison for determining the effects of a single-species large grazer in KNP and KPBS, and to assess the effects of large herbivore diversity at adjacent sites in KNP. Similar exclosures were built in the African buffalo enclosure at KNP. We placed 7 exclosures in the three blocks of each fire treatment (annually burned and unburned) resulting in 21 exclosures/treatment. We sampled ANPP by harvesting plant biomass from three 0.1 m2 quadrats per herbivore exclosure at the end of the growing season starting in 2006. 

Additional information: 

Data are collected twice each year at each site. Sample periods are equivalent to spring and late summer at each study site (December/January and March/April in South Africa, May and September in North America.

Where the Data were Collected: 

Ukulinga Research Farm, Pietermaritzburg, South Africa; Satara Region of Kruger National Park, South Africa; Konza Prairie Biological Station, North America

Additional Geographic Metadata:  

Ukulinga Research Farm (URF), South Africa. The URF of the University of KwaZulu-Natal is located in Pietermaritzburg, in southeastern South Africa (30o 24’ S, 29o 24’ E). The site is dominated by native perennial C4 grasses, such as Themeda triandra and Heteropogon contortus, that account for much of the herbaceous aboveground net primary production (ANPP). Mean annual precipitation is 790 mm, coming mostly as convective storms during summer (Oct-Apr). Summers are warm with a mean monthly maximum of 26.4oC in February, and winters are mild with occasional frost. Soils are fine-textured and derived from shales. There has been no grazing at this site for >60 years. Long-term experimental plots were established at URF in 1950 with the objective of determining the optimal fire and/or summer cutting regime to maximize hay production. The experiment is a randomized block (three replicates) split-plot design with four whole-plot haying treatments and 11 subplot fire or mowing treatments. Subplot sizes are 13.7 x 18.3 m. 

Kruger National Park (KNP), South Africa. The KNP is a 2 million ha protected area of savanna grassland that includes many of the large herbivores common to southern Africa (22º 25' to 25º 2 32' S, 30º 50' to 32º 2' E). The extant abundance and grazing intensity of herbivores in KNP is considered moderate for regional savanna grasslands. In the south-central region of KNP where our research takes place, average rainfall is 537 mm with most falling during the growing season (Oct-Apr). The dormant season is mild, dry and frost free, and summers are warm with mean monthly maximum air temperature of 28.9oC in January. Because of the importance of fire in savanna grassland ecosystems, the Experimental Burn Plot (EBP) experiment was initiated in 1954 to examine the effects of fire frequency (control-no fire, 1-, 2-, 3-, 4- and 6-yr return interval) and season [early spring (Aug), spring (Oct), mid-summer (Dec), late summer (Feb), and fall (Apr)] on vegetation communities in the park. Four blocks of 12 plots (two were later split for the 4- and 6-yr trts), each ~7 ha (370 x 180 m) in size, were established in four primary vegetation types covering the two major soil types (granites and basalts) and spanning the precipitation gradient in the park. Each plot has 50+ years of known fire history, and native herbivores have had unrestricted access, thus fire and grazing effects are combined. This research focuses on the EBPs located near Satara where precipitation, soil type, and the mix of herbaceous and woody plants are similar to KPBS. Vegetation on the blocks is co-dominated by C4 grasses, such as Bothriochloa radicans, Panicum coloratum and Digiteria eriantha, and woody plants, such as Acacia nigrescens and Sclerocarya birrea.  Soils are fine-textured and derived from basalts. Adjacent to one of the Satara blocks is the Cape buffalo enclosure, erected in 2000 for veterinary purposes. The 200 ha permanent enclosure contains 65-80 animals and is divided into 4 blocks burned on a rotational basis. The grazing intensity inside is comparable to the moderate levels imposed in the park and at KPBS. Two blocks are burned annually while others are burned infrequently (approximately once every 4-yr). 

Konza Prairie Biological Station (KPBS), North America. The KPBS is a 3,487 ha savanna grassland in northeastern Kansas, USA (39o 05’ N, 96o 35’ W) dominated by native perennial C4 grasses such as Andropogon gerardii and Sorghastrum nutans that account for the majority of ANPP. Scattered shrub and tree species include Cornus drummondii, Gleditsia triacanthos, and Prunus spp. Numerous sub-dominant grasses and forbs contribute to the floristic diversity of the site. The climate is continental, with mean July air temperature of 27°C. Annual precipitation is ca. 820 mm/year, with 75% falling as rain during the Apr-Oct growing season. Soils are fine textured, silty clay loams derived from limestone and shales. KPBS includes fully replicated watershed-level fire and fire/grazing treatments, in place since 1977 and 1987, respectively.  Replicate watersheds (mean size ~60ha) are burned at 1-, 2-, 4-, 10- and 20-yr intervals, mainly in April, to encompass a range of likely natural fire frequencies and management practices. A subset of watersheds has not been grazed for more than 30 years. To address the role of native grazers and fire/grazing interactions, bison (~260 individuals) were reintroduced to KPBS in a 1000-ha fenced area that includes replicate watersheds burned in the spring at 1-, 2-, 4- and 20-year intervals. The overall grazing intensity is considered moderate.

Study Area 1:  

Study Area Name:  Ukulinga Research Farm

Study Area Location: Near Pietermaritzburg, South Africa 

Elevation: 840 m above sea level

Landform: Colluvium fan

Geology: Marine shales and dolerite colluvium

Soils: Dystric leptosols, Chromic luvisols, Haplic plinthisols

Vegetation: Native grassland

Climate: Mean annual precipitation is 844 mm, Mean annual temperature 17.6C

Site history: Ungrazed since 1950

Single Point: 29o 40’ S / 30o 20’ E

Study Area 2:  Kruger National Park, South Africa

Study Area Name: Satara Experimental Burn Plots and Cape Buffalo Exclosure

Study Area Location: Near Satara rest camp

Elevation:  240-320 meters above sea level

Landform:  Level Upland

Geology: Basalts

Soils: Rhodic nitisols, Haplic luvisols, Leptic phaeozems

Vegetation: Native grassland

Climate: Mean annual precipitation 544 mm; mean annual temperature 21.2–23.3C

Site history: Grazed by native herbivores

Single Point: 23–25o S /30-31o E

   

Study Area 3:  Konza Prairie Biological Station

Study Area Name: Konza Prairie

Study Area Location: Watersheds N20B, N4D, N1B, N4B; 1D, 4F, 20B

Elevation: 320-444 meters above sea level

Landform: Alluvial terrace

Geology: Cherty limestone and shale

Soils: Udic argiustolls

Vegetation: Native grassland

Climate: Mean annual precipitation 835 mm; mean annual temperature 12.7C

Site history: Ungrazed watersheds (since 1971), watersheds grazed by native herbivores (since 1987)

Single Point: 39o 05.48’ N / 96o 34.12’ W

Burn Exclosure Rodent Population Study at the Sevilleta National Wildlife Refuge, New Mexico (1991-1993)

Abstract: 

Small mammal densities were estimated from small mammal recapture data in burned and unburned grassland.

Data set ID: 

15

Additional Project roles: 

53

Core Areas: 

Keywords: 

Methods: 

Web trapping design:

Experimental units were established in a 4 x 4 grid as part of a burn and antelope exclosure experiment. Small mammals were trapped in fireblocks 1, 2, 3, and 4. Each fireblock contains four webs, for a total of 16 webs. Small mammal densities are estimated from recapture data.

Within each location four webs were established. Each web contains twelve 100m transects radiating from a central point in a spoke like fashion. Four "Sherman" traps were placed around this central point. Twelve traps are placed along each of the radiating lines, the first four are placed at 5m intervals, and the remaining eight placed at 10m intervals. Rebar were used to mark the location of trap placement. Each rebar was tagged with a number from 1 to 145, with trap number 1 at the north facing spoke and radiating out to trap number 12, with each spoke following with successive numbers increasing in a clockwise fashion. Trap number 145 includes the four traps placed in the center of the web. Traps were placed adjacent to rebar unless a shaded area could be found within a meter or so along an arc of equal radius from the center. The webs are separated by distances from approx. 100m to 600m. Within each fireblock, each web is marked with a number from 1-4.

Trapping times:

Each summer was divided into two periods: period 1 and period 2.
Mammals were trapped as follows:

1991: period 1: NA
         period 2: September 4 - October 4
1992: period 1: April 15 - May 8
         period 2: August 4 - September 17
1993: period 1: April 6 - 29
         period 2: September ??

Each location was trapped in the same order for each period.
The order is as follows:

1. Fireblock 1
2. Fireblock 2
3. Fireblock 3
4. Fireblock 4

Each trapping session consisted of placing and baiting traps on Monday, then checking the traps at dawn on both Tuesday (night 1), Wednesday (night 2), and Thursday (night 3). The traps were collected on Thursday after being checked for animals. A small handful of rolled oats was placed into each trap, with small amounts placed outside trap door. Animals were removed form closed traps with the aid of plastic bags. They were then identified to species. Weight was determined to the nearest gram using a pesola scale. Body, tail, foot, and ear measurements were taken for Peromyscus. Body and tail measurements were taken for Onychomys, Perognathus, and Reithrodomtomys. All measurments were taken to the nearest millimeter using a plastic ruler. Reproductive status was determined by examination of the genitalia. The animal was also sexed, aged, and marked. Marking was done to each animal on the first nights capture for each individual animal.

Data sources: 

sev015_burnxrodentpop_10191995.txt

Maintenance: 

File created by Susan McKelvey 3/29/93. File supplemented by Rosemary Vigil 24 June 1993. Checked Oct 20, 1995; James Brunt

Quality Assurance: 

Data Entry

1. Data were entered at Biology Annex using data entry program "mammal-entry"
2. Data were checked for errors by comparing original data sheets with the
data entered into the computer.
3. After all errors were corrected, a dbf file was created using a Sun machine.
(/research/local/mammal/bin/SASmam2dbf filename > filename.dbf) This
modifies the comments, leaving out comments noted as "na".
4. A rdb file was then created using "arc2rdb filename.dbf > filename.rdb".
5. The rdb file was then checked for errors using "check < filename.rdb".
6. After errors were corrected, the rdb file was sorted using "sort
filename | uniq -c | page" to check that every entry was unique.
7. Duplications were investigated and corrected.
8. Dbf and rdb files were then copied to /research/archive/dbwork/vertebrate/
mammal/burnplot
9. From sevilleta, at burnplot>, the rdb file was run through a program called
webDist to create an input file as such: " webDist filename.rdb location
period > conventional input name. (naming conventions: site-season-year.in)
10.Input file was copied into /research/archive/dbwork/vertebrate/mammal/
burnplot
11.From a PC, the input file was run through a distance program in order to
get densities. (from dos: L:, cd distance, dist i=L:\burnplot/filename.in
o=L:\burnplot\filename.out)
12.Densities were cbtained from the output file and put into /mammal/data/
density-data/mammal_densities.data.burn which is a table containing the
following: year season location web n density stderr cv lcl ucl.
13.At this point, nothing further has been done.

2003 Prescribed Burn Effect on Chihuahuan Desert Grasses and Shrubs at the Sevilleta National Wildlife Refuge, New Mexico: Shrub Recovery Study (2003-2009)

Abstract: 

Disturbance from fire can affect the abundance and distribution of shrubs and grasses in arid ecosystems. In particular, fire may increase grass and forb production while hindering shrub encroachment. Therefore, prescribed fires are a common management tool for maintaining grassland habitats in the southwest. However, Bouteloua eriopoda (black grama), a dominant species in Chihuahuan Desert grassland, is highly susceptible to fire resulting in death followed by slow recovery rates. A prescribed fire on the Sevilleta National Wildlife refuge in central New Mexico in 2003 provided the opportunity to study the effects of infrequent fires on shrub invasion in this region. This study was conducted along a transition zone where creosote bushes (Larrea tridentata) are encroaching on a black grama grassland.

Core Areas: 

Data set ID: 

164

Keywords: 

Purpose: 

To study the effects of infrequent fires on shrub invasion in Chihuahuan desert grassland.

Methods: 

Contact Burt Pendleton at the email address below for the methods/protocol for this study.

bpendleton01@fs.fed.us

Plots Definition:

Plots are a replicate and treatment from the previous study. The following codes define the plots listed in this study:  3 B-O and 4 B-O=burned open, 3 B-F and 4 B-F=burned fenced, 3 C-F and 4 C-F=control fenced, 3 C-O and 4 C-O=control open

Quads  Definition:

Quads are 3m by 4m and values range from 3099-3191. 

***2003 data were collected before the prescribed fire. All data from subsequent years were collected after the fire.

Data sources: 

sev164_burnxshrubs_20131203.txt

Instrumentation: 

Contact Burt Pendleton at the email address below for the methods/protocol for this study.

bpendleton01@fs.fed.us bpendleton01@fs.fed.us

Quality Assurance: 

Data were visually assessed for obvious errors.

Burn Study Sites Quadrat Data for the Net Primary Production Study at the Sevilleta National Wildlife Refuge, New Mexico (2004-present)

Abstract: 

In 2003, the U.S. Fish and Wildlife Service conducted a prescribed burn over a large part of the northeastern corner of the Sevilleta National Wildlife Refuge. Following this burn, a study was designed to look at the effect of fire on above-ground net primary productivity (ANPP) (i.e., the change in plant biomass, represented by stems, flowers, fruit and foliage, over time) within three different vegetation types: mixed grass (MG), mixed shrub (MS) and black grama (G). Forty permanent 1m x 1m plots were installed in both burned and unburned (i.e., control) sections of each habitat type. The core black grama site included in SEV129 is used as a G control site for analyses and does not appear in this dataset. The MG control site caught fire unexpectedly in the fall of 2009 and some plots were subsequently moved to the south. For details of how the fire affected plot placement, see Methods below. In spring 2010, sampling of plots 16-25 was discontinued at the MG (burned and control) and G (burned treatment only) sites, reducing the number of sampled plots to 30 at each.

To measure ANPP (i.e., the change in plant biomass, represented by stems, flowers, fruit and foliage, over time), the vegetation variables in this dataset, including species composition and the cover and height of individuals, are sampled twice yearly (spring and fall) at each plot. The data from these plots is used to build regressions correlating biomass and volume via weights of select harvested species obtained in SEV157, "Net Primary Productivity (NPP) Weight Data." This biomass data is included in SEV185, "Burn Study Sites Seasonal Biomass and Seasonal and Annual NPP Data."

Core Areas: 

Data set ID: 

156

Additional Project roles: 

438
439
440
441

Keywords: 

Data sources: 

sev156_nppburnquadrat_20161214.csv

Methods: 

Collecting the Data:

Net primary production data is collected three times each year, winter, spring, and fall, for all burn sites. Spring measurements are taken in April or May when shrubs and spring annuals have reached peak biomass. Fall measurements are taken in either September or October when summer annuals have reached peak biomass but prior to killing frosts. Winter measurements are taken in February before the onset of spring growth and only creosote is measured.

Vegetation data is collected on a palm top computer. A 1-m2 PVC-frame is placed over the fiberglass stakes that mark the diagonal corners of each quadrat. When measuring cover it is important to stay centered over the vegetation in the quadrat to prevent errors caused by angle of view (parallax). Each PVC-frame is divided into 100 squares with nylon string. The dimensions of each square are 10cm x 10cm and represent 1 percent of the total area.

The cover (area) and height of each individual live (green) vegetative unit that falls within the one square meter quadrat is measured. A vegetative unit consists of an individual size class (as defined by a unique cover and height) of a particular species within a quadrat. Cover is quantified by counting the number of 10cm x 10cm squares filled by each vegetative unit. It is possible to obtain a total percent cover greater than 100% for a given quadrat because vegetative units for different species often overlap.

Niners and plexidecs are additional tools that can help accurately determine the cover a vegetative unit. A niner is a small, hand-held PVC frame that can be used to measure canopies. Like the larger PVC frame it is divided into 10cm x 10cm squares, each square representing 1% of the total cover. However, there are only nine squares within the frame, hence the name “niner.” A plexidec can help determine the cover of vegetative units with covers less than 1%. Plexidecs are clear plastic squares that are held above vegetation. Each plexidec represents a cover of 0.5% and has smaller dimensions etched onto the surface that correspond to 0.01%, 0.05%, 0.1%, and 0.25% cover.

It is extremely important that cover and height measurements remain consistent over time to ensure that regressions based on this data remain valid. Field crew members should calibrate with each other to ensure that observer bias does not influence data collection

Cover Measurements:

Grasses-To determine the cover of a grass clump, envision a perimeter around the central mass or densest portion of the plant, excluding individual long leaves, wispy ends, or more open upper regions of the plant. Live foliage is frequently mixed with dead foliage in grass clumps and this must be kept in mind during measurement as our goal is to measure only plant biomass for the current season. In general, recently dead foliage is yellow and dead foliage is gray. Within reason, try to include only yellow or green portions of the plant in cover measurement while excluding portions of the plant that are gray. This is particularly important for measurements made in the winter when there is little or no green foliage present. In winter, sometimes measurements will be based mainly on yellow foliage. Stoloniferous stems of grasses that are not rooted should be ignored. If a stem is rooted it should be recorded as a separate observation from the parent plant.

Forbs, shrubs and sub-shrubs (non-creosote)-The cover of forbs, shrubs and sub-shrubs is measured as the horizontal area of the plant. If the species is an annual it is acceptable to include the inflorescence in this measurement if it increases cover. If the species is a perennial, do not include the inflorescence as part of the cover measurement. Measure all foliage that was produced during the current season, including any recently dead (yellow) foliage. Avoid measuring gray foliage that died in a previous season.

Cacti-For cacti that consist of a series of pads or jointed stems (Opuntia phaecantha, Opuntia imbricata) measure the length and width of each pad to the nearest centimeter instead of cover and height. Cacti that occur as a dense ball/clump of stems (Opuntia leptocaulis) are measured using the same protocol as shrubs. Pincushion or hedgehog cacti (Escobaria vivipara, Schlerocactus intertextus, Echinocereus fendleri) that occur as single (or clustered) cylindrical stems are measured as a single cover.

Yuccas-Make separate observations for the leaves and caudex (thick basal stem). Break the observations into sections of leaves that are approximately the same height and record the cover as the perimeter around this group of leaf blades. The caudex is measured as a single cover. The thick leaves of yuccas make it difficult to make a cover measurement by centering yourself over the caudex of the plant. The cover of the caudex may be estimated by holding a niner next to it or using a tape measure to measure to approximate the area.

Height Measurements:

Height is recorded as a whole number in centimeters. All heights are vertical heights but they are not necessarily perpendicular to the ground if the ground is sloping.

Annual grasses and all forbs-Measure the height from the base of the plant to the top of the inflorescence (if present). Otherwise, measure to the top of the green foliage.

Perennial grasses-Measure the height from the base of the plant to the top of the live green foliage. Do not include the inflorescence in the height measurement. The presence of live green foliage may be difficult to see in the winter. Check carefully at the base of the plant for the presence of green foliage. If none is found it may be necessary to pull the leaf sheaths off of several plants outside the quadrat. From this you may be able to make some observations about where green foliage is likely to occur.

Perennial shrub and sub-shrubs (non-creosote)-Measure the height from the base of the green foliage to the top of the green foliage, ignoring all bare stems. Do not measure to the ground unless the foliage reaches the ground.

Plants rooted outside but hanging into a quadrat-Do not measure the height from the ground. Measure only the height of the portion of the plant that is within the quadrat.

Creosote Measurements till 2013:

To measure creosote (i.e., Larrea tridenta) break the observations into two categories:

1.) Small, individual clusters of foliage on a branch (i.e., branch systems): Measure the horizontal cover of each live (i.e., green) foliage cluster, ignoring small open spaces (keeping in mind the 15% guideline stated above). Then measure the vertical "height" of each cluster from the top of the foliage to a plane created by extending a line horizontally from the bottom of the foliage. Each individual foliage cluster within a bush is considered a separate observation.

2.) Stems: Measure the length of each stem from the base to the beginning of live (i.e., green) foliage. Calculate the cumulative total of all stem measurements. This value is entered under "height" with the species as "stem" for each quadrat containing creosote. All other variable receive a default entry of "1" for creosote stem measurements.

Do not measure dead stems or areas of dead foliage. If in doubt about whether a stem is alive, scrape the stem with your fingernail and check for the presence of green cambium.

Creosote Measurements 2013 and after:

Each creosote is only measured as one total cover. Each quad that contains creosote will have one cover observation for each creosote canopy in quad.

Recording the Data:

Excel spreadsheets are used for data entry and file names should begin with the overall study (npp), followed by the date (mm.dd.yy) and the initials of the recorder (.abc). Finally, the site abbreviation should be added (i.e., mg, ms, or g). The final format should be as follows: npp_burn.mm.dd.yy.abc.xls. File names should be in lowercase.

August 2009 Burn:

On August 4, 2009, a lightning-initiated fire began on the Sevilleta National Wildlife Refuge.  The fire reached the Mixed-Grass Unburned plots on August 5, 2009, consuming them in their entirety.  As a result, in the spring of 2010, the Mixed-Grass (MG) unburned plots were moved to a different area within Deep Well, southwest of the Warming site. 

Also, on August 4, 2009, some of the webs and quadrats within the unburned Black Grama (G) site were impacted by the fire.  Thus, webs 2 and 3 were abandoned and extra plots added to areas within webs 1, 4, and 5 that were not burned.  Changes were as follows:

Webs 1, 4, and 5: A plot was added to the northeast to compensate for the loss of all plots at webs 2 and 3.

Web 4: A plot was added to the northwest to compensate for the northern plot, which was burned.

Maintenance: 

01/13/2011-Burn NPP quad data was QA/QC'd and put in Navicat. Matadata updated and compiled from 2004-2010. The mixed-grass unburned plot was moved to the south after the original plot burned unexpectedly in the fire of August 2009. (JMM) 11/28/2009-Burn NPP quad data was QA/QC'd and put in Navicat. Metadata updated and complied from 2004-2009. Mixed-grass unburned data (Fall 2009) was not collected due to unexpected fire at Sevilleta LTER in Aug 2009. (YX) 01/14/09-Metadata updated and compiled from 2004-2008 data. As of 2007, winter measurements are longer being taken. (YX) 12/20/2008-This data was QAQC'd in MySQL. I checked for duplicates and missing quads. (YX)

Additional information: 

Other researchers involved with collecting samples/data: Chandra Tucker (CAT; 04/2014-present), Megan McClung (MAM; 04/2013-present), Stephanie Baker (SRB; 09/2010-present), John Mulhouse (JMM; 08/2010-04/2013), Amaris Swann (ALS; 08/2008-01/2013), Maya Kapoor (MLK; 08/2003-01/2005, 05/2010-03/2011), Terri Koontz (TLK; 02/2000-08/2003, 08/2006-08/2010), Yang Xia (YX; 01/2005-03/2010), Karen Wetherill (KRW; 02/2000-08/2009); Michell Thomey (MLT; 09/2005-08/2008); Seth Munson (SMM; 09/2002-06/2004), Jay McLeod (JRM; 01/2006-08/2006); Caleb Hickman (CRH; 09/2002-11/2004), Charity Hall (CLH; 01/2005-01/2006); Tessa Edelen (MTE, 08/2004-08/2005).Data updated 08/18/15: MOSQ changed to MUSQ3; ARPUP6 changed to ARPU9; SPWR changed to SPPO6; a single entry BOER changed to BOER4.

Below-Ground Net Primary Production (BNPP): Root Ingrowth Donuts in Chihuahuan Desert Grassland and Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico (2005-present)

Abstract: 

In 2005, annually harvested root ingrowth donut structures were co-located with previously established mini-rhizotron tubes established at four sites on McKenzie Flats located on the east side of Sevilleta NWR: 10 replicate structures in both burned and unburned blue and black grama dominated grassland plots at Deep Well, 10 replicates each on nitrogen fertilization plots and respective control plots on McKenzie Flats(20 total), 10 replicates in creosote dominated shrubland at the Five Points Creosote Core site and in 2011, 13 structures were put in the Monsoon site. Roots and soil are harvested annually in late fall after the growing season, and structures are reestablished in situ for consecutive harvests each year. Each structure allows roots to be harvested at two depths (0-15 and 15-30 cm) to estimate root production, or below ground net primary productivity. In order to compare estimates of root production from two methods, root ingrowth donuts were collocated with mini-rhizotron tubes at all localities except for the burned grassland plot at Deep Well.

Core Areas: 

Data set ID: 

175

Additional Project roles: 

311
312
313
314
316

Keywords: 

Data sources: 

sev175_rootingrowth_20160127.txt

Methods: 

Experimental Design
Annually harvested root ingrowth donut structures are co-located with previously established mini-rhizotron tubes established at four sites on the McKenzie Flats on the east side of Sevilleta NWR: 10 replicate structures in both burned and unburned blue and black grama dominated grassland plots at Deep Well, 10 replicates each on nitrogen fertilization plots and respective control plots on McKenzie Flats (20 total), and 10 replicates in creosote dominated shrubland at the Five Points Creosote Core site. Methods were adapted from Milchunas et al (2005). We use a formidable 10 diameter soil core to create cylindrical holes in the ground to a depth of 30cm without disturbing soil profile at the cylinder walls. The soil core was inserted with a slide hammer and had to be removed each time with a come-along mounted on a steel-pipe tripod. Walls were subsequently lined with plastic cross-stitch craft work canvas (macram mesh) which supports cylinder walls through time but allows roots to pass through. Two pieces of 6 diameter PVC were placed in the center of the larger cylindrical hole, set in place with bags filled with sand that act as ballasts. The two pieces of PVC were beveled on opposite ends to fit together and prevent movement of the donut center. The top cylinder went to a depth of 15 cm and the bottom piece went to a depth of 30 cm, representing 0-15 and 15-30 cm in the soil profile when stacked upon one another. Finally, sifted soil from the location was used to fill the space between the plastic canvas lining the hole wall and the PVC pipe placed in the center. It is this soil which is harvested annually at two depths. A PVC cap was placed on top of the PVC to eliminate water infiltration from rain through the donut center and to keep sunlight from disintegrating the sand bag ballast. All root ingrowth donuts were GPSed.

Sample Harvest
Root donuts are harvested annually in November after the growing season. Roots are harvested by first removing the sand bags from the top cylinder and placing a bowl into the center of the cylinder. The top cylinder is then removed. Soil and roots are cut away from the cylinder wall and collected. This harvest procedure is then repeated for the lower half of the donut structure. Soil and roots collected are placed in a separate plastic bag for each depth. Once the soil and roots are harvested, the root ingrowth structure is rebuilt. After harvest, soil and root samples are stored in a chest freezer until they can be processed.

Sample Processing
The total volume of soil from each sample is measured and recorded. Soils are filtered through a series of sieves in which to harvest the roots present in the sample. The roots are then repeatedly rinsed to remove all the soil from the sample, dried at 60 degrees C, and then weighed.

Maintenance: 

23 Jan 2009All data sets (2005-2008) were combined and checked for errors in excel and exported into Navicat. From the 2007 data, I converted the dry root mass from grams to milligrams and changed depth data to be 0-15 and 15-30 cm. QA/QC'd data. I deleted data line from DWB sample 7, depth 15-30 cm with volume 2600 ml because it was a duplicate. I also changed the depth of DWB sample 12, depth 15-30 cm with volume 2000 to the depth 0-15 cm because the depth 15-30 cm was duplicated. -Changed missing data on volume and weight due to plant being dead to -888. -Changed missing data on volume and weight due to human error to -999. --A. Swann

Quality Assurance: 

Filtered data in Excel then exported it into Navicat using the import wizard.

Additional information: 

Additional Information on the personnel associated with the Data Collection / Data Processing

Sevilleta Field Crew Employee History

Chandra Tucker April 2014-present, Megan McClung, April 2013-present, Stephanie Baker, October 2010-Present, John Mulhouse, August 2009-June 2013, Amaris Swann, August 25, 2008-January 2013, Maya Kapoor, August 9, 2003-January 21, 2005 and April 2010-March 2011, Terri Koontz, February 2000-August 2003 and August 2006-August 2010, Yang Xia, January 31, 2005-April 2009, Karen Wetherill, February 7, 2000-August 2009, Michell Thomey, September 3, 2005-August 2008, Jay McLeod, January 2006-August 2006, Charity Hall, January 31, 2005-January 3, 2006, Tessa Edelen, August 15, 2004-August 15, 2005, Seth Munson, September 9, 2002-June 2004, Caleb Hickman, September 9, 2002-November 15, 2004, Heather Simpson, August 2000-August 2002, Chris Roberts, September 2001-August 2002, Mike Friggens, 1999-September 2001, Shana Penington, February 2000-August 2000.

Ecological Effects of Prescribed Fire on Soils in a Chihuahuan Desert Grassland at the Sevilleta National Wildlife Refuge, New Mexico (2003)

Abstract: 

Fire resulting from natural ignition has become a more common event on the Sevilleta National Wildlife Refuge (NWR) since the exclusion of domesticated livestock. Efforts to return fire to the native landscape has resulted in the use of prescribed fire during periods that meet burn prescriptions. A prescribed fire was performed on the Sevilleta NWR in June 2003. Among the measured site and burn characteristics that were measure, this project sampled soils before and after the fire from 5 previously-sampled locations that were burned in June 2003 and from 5 newly established locations that served as controls. The controls were within an area that was sampled between 1989 and 1996 for similar properties measured in this study and had previously been tested to be similar to the locations burned in 2003. The soil properties that are repeatedly measured at the burn and control locations include: field water content; water-holding capacity; organic matter; field extractable nitrate and ammonium; and potentially mineralizable nitrogen.

Core Areas: 

Data set ID: 

146

Keywords: 

Methods: 

Bridges

The removable bridge is placed upon the end rebar and the middle pin is secured in the depression on the nail beneath the middle hole (#16). The bridge is then leveled and individual pins are inserted to the soil surface. If the surface is firm enough, the pins are left unsecured. If the surface is too soft, the pins are secured with the tip at the soil surface by attaching a clothspin above the bridge. The heights of each pin above the bridge are recorded, and cover is recorded if the pin struck vegetation when being inserted and basal cover is recorded if the pin rested upon the basal portion of a plant at the ground surface. The standard soil bridge developed for the Sevilleta was used. The bridge contains 31 holes at 5 cm intervals with the middle hole used to orientate the bridge above a nail left at the ground surface, and which provides a reference to secure the line and the bridge height. Also referenced at (http://sevilleta.unm.edu/data/contents/SEV065/).

Soil Collection

For inorganic N extractions and potentially mineralizable N measurements, a soil core of 4-cm diameter was taken to 20-cm depth beneath two nearby grass clumps (the two cores were compostited; termed under) and from two bare soil patches (two cores were composited; termed open) within 5 m of the stake identifying each bridge or from the bridge stake with the identification tag (new control bridges). All soil samples were placed into an ice chest and transported on ice directly to the University of New Mexico UNM, where they were sieved (&lt; 2 mm), mixed, and stored at 5 degrees C. All soil N measurements were performed at UNM.

Soils Analysis

After determining fresh water content and water-holding capacity (WHC)(White and McDonnell 1988), fresh portions of each sample were adjusted to 50% of determined WHC and subsamples of 20 g dry-weight were apportioned into plastic cups. One subsample of each sample was immediately extracted with 100-ml 2 N KCl for NH4+-N and NO3-N analyses to determine field-available N. Two additional cups were covered with plastic wrap, sealed with a rubber band, and incubated in the dark at 20 degrees C. The plastic wrap minimized water loss during incubation, yet exchange of CO2 and O2 was sufficient to keep the subsamples aerobic during incubation. Moisture content was monitored by mass loss and replenished as needed. After contact and settling for 18-24 h, the clarified KCl was filtered through a Kimwipe and analyzed for NH4+-N and NO3--N+NO2--N on a Technicon AutoAnalyzer (Technicon, Terrytown, NY) as described in White (1986). After incubation for 6 weeks, a subsample of each soil was extracted with KCl and analyzed for NH4+-N and NO3--N+NO2--N. Potentially mineralizable N was determined to be the amount of extractable N in the 6-week extraction.

Organic Matter

Organic matter was determined by loss-upon-ignition in tin cups following heating at 500C for two hours.

Soil Physical/Chemical Properties

Soil cores were taken beneath grass clumps in which the temperature pellets were placed both before and after the fire. At least 300 g of soil were taken to a depth of 10 cm (NOTE:different depth than nitrogen cycling)

Fire Temperature

Fire temperature was determined with pellets supplied by Tempil (2901 Hamilton Blvd., South Plainfield, NJ 07080; www.tempil.com). A set of 15 foil-wrapped tablets, with melting temperatures ranging from 85 C to 1533 C, were strungon wire and suspended about 1 inch above the ground. The fire temperature was assumed to be greater than the temperature at which the corresponding pellet showed signs of melting and less than the temperature of the next highest undamaged pellet. The pellets were suspended within two clumps of dominant grasses at the site (black grama).

Pre-existing briges (1.1 through 1.5) were selected to be included within a prescribed burn area. Data collected from the bridges were consistent with existing data collection: (http//sevilleta.unm.edu/data/contents/SEV065/ ) and included soil surface elevation, plant aboveground cover and basal cover. Soils from beneath a nearby grass clump and from bare interspaces were collected for analysis of soil properties. Soil temperature pellets were placed within grass clumps from beneath which soils were collected. Pre-fire on control and expected burn plots, and post-fire on burn plots only for soil elevation, aboveground plant cover and basal cover, N mineralization potentials, field moisture, water holding capacity, and loss upon ignition for organic matter. Pre and post burn soil samples were collected beneath grass clumps at the existing bridges for analysis of soil properties (sent ot Jane Belnap). Fire temperature was measured with temperature tablets placed about 1 cm above the ground within the grass clump that was sampled for soil properties and in an adjacent grass clump of similar appearance.

Data sources: 

sev146_fireeffects_20150225.txt

Maintenance: 

Changes to the data: Data were updated to include 2007 data on 5/15/2008 by Carl White.

Additional information: 

Additional Study Area Information

Study Area Name: Bridge 1.1

Study Area Location: north end of five bridges; black grama dominated grassland; MacKensie Flats; Site is 5 m area around bridge; Bridges setup in 1994 to monitor changes in soil surface elevations to understand the dynamics of soil particles and associatednutrients.

North Coordinate: 34.3358
South Coordinate: 34.3358
East Coordinate: -106.6954
West Coordinate: -106.6954

Net Primary Productivity (NPP) Weight Data at the Sevilleta National Wildlife Refuge, New Mexico (1999 - present)

Abstract: 

Several long-term studies at the Sevilleta LTER measure net primary production (NPP) across ecosystems and treatments. Net primary production is a fundamental ecological variable that quantifies rates of carbon consumption and fixation. Estimates of NPP are important in understanding energy flow at a community level as well as spatial and temporal responses to a range of ecological processes. Above-ground net primary production (ANPP) is the change in plant biomass, including loss to death and decomposition, over a given period of time. To measure this change, vegetation variables, including species composition and the cover and height of individuals, are sampled up to three times yearly (winter, spring, and fall) at permanent plots within a study site. The weight data presented here is obtained by harvesting a series of covers for species observed during plot sampling. These species are always harvested from habitat comparable to the plots in which they were recorded. This data is then used to make volumetric measurements of species and build regressions correlating biomass and volume. From these calculations, seasonal biomass and seasonal and annual NPP are determined.

Data set ID: 

157

Core Areas: 

Additional Project roles: 

402
403
404
405
406
407
408

Keywords: 

Methods: 

Generating Cover Range for Harvest Samples:

Prior to making harvest collections, a range of cover values and the number of observations is generated for each plant species recorded at a site from the NPP data. A perl script is located in pc_field/palmtop/npp. This script will generate a list of species with the minimum and maximum cover and number of observations from all excel files in the folder. From these values a range of covers to be harvested will be produced.

To produce a range for a species, first decide the number of samples you will be collecting for that species. 15 samples will be collected for dominant or frequently observed species and 10 samples will be collected for most other species. Next decide if you will be making this range based on counts or cover measurements. The majority of species will be based on cover measurements. Only extremely small plants will be based on count measurements.

For ranges based on cover measurements, start by writing down the cover value one size-class below the smallest cover observed at a site. For example, if the smallest cover observed at a site was 0.5 write down 0.25. If smallest cover value observed is 0.01 do not go below this value. Next write down the cover value one size-class above the largest cover value recorded at a site. These two numbers represent the largest and smallest covers that will be harvested at a site. Within the bounds of these two numbers fill in cover values. Ultimately you will need to end up with either 10 or 15 cover values depending on the observed frequency of the species. Try and keep the numbers as balanced as possible. Smaller covers will have more variability than larger covers and thus it is best to collect duplicates of the smaller cover sizes. Also, as covers increase the size-class increments between covers should also increase. When generating these ranges keep in mind that the purpose of harvest samples is to produce a statistical linear regression equation for each species at each site from which biomass will be estimated. A similar process is used to obtain a range of values for samples that will be based on counts.

Enter the species ranges, date and site into a Sevilleta LTER NPP Harvest Data book. Once this is complete, label collection bags. In general, harvests with covers between 0.01 and 0.5 are collected into coin envelopes and larger covers are placed in paper bags. Label each bag or envelope with the date, site, plant species, sample number, and cover value. Leave a blank spot for height.

Collecting Harvest Samples: 

Collect plants from an area that is close to but not actually on the trapping webs or NPP plots at each site.  Avoid collecting plants near the roadside since these plants may have morphologies that vary from plants on the NPP quadrats. From 1999 to 2003, the site of collection corresponds to the site where the data were collected (see above for site codes).  In 2004, several new sites were added that had been burned by a prescribed fire in 2003.  Separate weight data was needed for the burned and unburned plants at these sites. Therefore, after 2004 a new  variable "type" was added.  And, a new site "L" was added.  "L" refers to all the Lower sites and does not include P or J.  The new variable "type" has four codes.  "B" refers to harvested plants that were burned in the 2003 fire, and "U" refers to plants that were not burned in recent history.  However many plants grow similarly in both treatments, especially annual plants and some perennial forbs.  These plants are designated type "F" and can be harvested from either burned or unburned areas.  Type "A" is the default and applies to all pre-2004 data as well as the Cerro Montosa site P. In Fall of 2010, type "B" refers to samples that were harvested from area of the Sevilleta that were burned by a wildfire in August 2009. The one exception was for creosote that was still harvested from the 2003 prescribed burn area.

Locate individual plants that correspond to the cover values written on a bag. Measure the height of the plant to the nearest cm and write this height on the bag.  Then with a pair of shears clip the foliage and place it in the bag.  It is important to collect all of the foliage and to clip it off as near to the base as possible.  Do not include any root material in the sample.

If you cannot find a natural clump of foliage of a particular cover value you may take a sub-sample from a larger plant.  This should be done only when absolutely necessary. The most important thing to remember is that foliage harvests need to have a similar morphology to plants measured on the quadrats.  If a sub-sample must be taken try to collect a sample that seems representative of a cover that would occur naturally on a quadrat.

After a sample has been collected fold the bag so that no portion of the sample can fall out.  When all the samples of a species have been collected, indicate that the collection of that species is complete in the Harvest Data book.  Place the samples into a large plastic garbage bag and try to keep them in a cool location until you are able to store them.

Sorting Harvest Samples: 

Empty the contents of a single bag onto a large tray or newspaper. Pick through the foliage and separate live stems, leaves and inflorescence from dead material. For Fall, consider any yellow or green material as live material and any brown or gray material as dead. Store the dead material in a separate bag.  For Spring, consider only green material as live and discard yellow, brown and gray material.   When you have finished sorting live from dead, place the live material back in the original bag and discard the dead material, except for Fall samples.  Bags containing sorted material are then placed in a drying oven located at the Sevilleta field station.  Dry the bags for 4 days at 50 degrees C or until completely dry.  It usually takes 6-10 days for cacti to dry in the oven and the samples should be dried separately from other samples.  Before placing cacti in the oven perforate them several times with a knife to promote the escape of moisture.  Remove the bags with the samples from the oven when they are completely dry. The plants should be very brittle. Store the plants in a dry location until weighed.

Weighing Harvest Samples: 

Try to weigh the samples as soon after drying as possible so that the do not re-absorb any moisture.  Sort the bags by species and site so that these can be weighed at the same sitting. Remove the sample from the bag and place it into a tarred tray.  Make sure that no portion of the plant remains in the bag.  Weigh the sample to the nearest centigram.  Record the date of collection, site (L, the lower flats or P, the pinyon-juniper), the type of collection (A, unburned or B, burned) plant species, sample number, cover value, height and weight into the Sevilleta LTER NPP Harvest Mass Data book.  Set the sample aside.  When all samples of a particular species and site have been weighed, combine the dry material and retain 50g for a voucher specimen.  Discard any excess material.  If there is not enough dry material to make up 50g just retain what is there.  Place the voucher specimen into a paper bag labeled voucher with the date of collection, site (L or P), type (A or B), plant species, and approximate weight of the sample. 

Notes:  In 1999 and 2000, all species from all sites were collected.  In 2001and seasons 1 and 2 of 2002, only those species that had not yet been encountered were harvested.  In Fall of 2002, the regressions were studied and many species with irregular regressions were harvested again.  In winter of 2003, much of the data was lost and has not been recovered.  From spring of 2003 to the present, problem species (bad or inconsistant regressions),  new species, and dominant species at each site have been harvested each season.

Data sources: 

sev157_nppweight_20161218

Additional information: 

Additional Information on the personnel associated with the Data Collection / Data Processing

Employee History for Sevilleta Field Crew

Mike Friggens, 1999-September 2001;Karen Wetherill, February 7, 2000-August 2009; Terri Koontz, February 2000-August 2003, August 2006-August 2010; Shana Penington, February 2000-August 2000; Heather Simpson, August 2000-August 2002; Chris Roberts, September 2001-August 2002; Caleb Hickman, September 9, 2002-November 15, 2004; Seth Munson, September 9, 2002-June 2004; Maya Kapoor, August 9, 2003- January 21, 2005, April 2010-Present; Tessa Edelen, August 15, 2004-August 15, 2005; Charity Hall, January 31, 2005-January 3, 2006; Yang Xia, January 31, 2005-Present; Michell Thomey, September 3, 2005-August 2008; Jay McLeod, January 2006-August 2006; Amaris Swann, August 25, 2008-January 2013; John Mulhouse, August 21, 2009-June 2013; Stephanie Baker, October 2010-present; Megan McClung, April 2013-present; Chandra Tucker, April 2014-present

2003 Prescribed Burn Effect on Chihuahuan Desert Grasses and Shrubs at the Sevilleta National Wildlife Refuge, New Mexico: Fuel Load Study (2003-present)

Abstract: 

The U.S. Fish and Wildlife's plan to apply a prescribed burn to a large portion of Mckenzie Flats was deemed an opportunity to study the effects of fire on the vegetation at the boundary between shrubland and grassland. This study actually was undertaken on an area that had prescribed fire applied to 8 of 16 (300 m x 300 m) plots 10 years before in 1993. This previous study had also examined the effects of fencing to exclude the indigenous prong-horn antelope. In the 2003 study the prescribed fire was applied to the northeastern half of the 16 plots while the southwestern plots were intentionally protected. Sampling prior to the prescribed burn included quantification of fuel load (ie. the standing biomass of all grasses and forbs in the area to be burned). These measurements were made using Daubenmire quadrat frames that are 5 cm x 20 cm and delineate a 0.1 square meter area. Four samples were taken adjacent to the six 3 m x 4 m quadrats in each of the eight plots that were to be burned. Quadrat frames were laid down over the vegetation and all vegetation rooted within the frame was clipped at ground level. This material was bagged, oven-dried and weighed. Following the prescribed burn, re-measurements were made in the fall of 2004 and continue to be measured every fall when vegetation has reached its annual peak biomass.

Core Areas: 

Data set ID: 

165

Keywords: 

Purpose: 

To study the effects of fire on the vegetation at the boundary between shrubland and grassland.

Data sources: 

sev165_burnxfuel_12092013.txt

Methods: 

Sampling:

Within each 300 m x 300 m plot, 3 m x 4 m quadrats were marked off with rebar for use in a previous burn experiment. Each of these quadrats also had a rebar on the southern edge of the quadrat with a numbered tag. Six of these quadrats were randomly selected in each plot. Measurements were made using a Daubenmire quadrat frame. These frames are PVC squares that are 5 cm x 20 cm that gives an enclosed area of 0.1 m2. From each corner of the 3 m x 4 m quadrat, a distance of 2.5 m was taped off and the Daubenmire frame was placed on the ground over vegetation. All vegetation rooted within the frame was clipped at ground level and placed in a paper sack. This included all live and dead standing material. Exceptions were made where the frame was located within the canopy of bushes or yuccas. The designation for the four niners in each quadrat was A through D, with A in the SW corner moving clockwise to D in the SE corner.

Laboratory techniques:

All samples were dried at 60 degrees C for 48 hours and then weighed.

Specific location:

Data were collected from 16 (300 m x 300 m) plots designated as the "Burn Antelope Exclosure" plots. These plots are located on the southern end of Mckenzie Flats. The plots are laid out in a 4 by 4 square with 300 m buffer between each plot. The plots are enclosed within a 440 ha box.

The bounding coordinates of this large box are:

               Latitude Longitude

NW corner 34.3138 106.6926 

NE corner 34.3202 106.6711 

SE corner 34.3024 106.6634 

SW corner 34.2960 106.2960

This large expanse has a variable mix of grass species. The 2 dominant species are black grama (Bouteloua eriopoda) and blue grama (Bouteloua gracilis). There are also sizeable patches of mule grass (Scleropogon brevifolius). A mixture of the drop seed species are present as well. These include Sporobolus cryptandrus, Sporobolus contractus, Sporobolus flexuosus and Sporobolus airoides. Galleta grass (Pleuraphis jamesii) and a couple of Muhlenbergia species are also present. Within this grass matrix are also several shrubs and subshrubs. The most noticeable shrub is creosote bush (Larrea tridentata). Other common non-grasses are Yucca glauca, Ephedra torreyana and Gutierrezia sarothrae.

Maintenance: 

Original file created on 2/27/07 D.M.

Data checked for errors and all years combined. 1/23/09 TLK

Checked data for errors along with assessing if all data points were present for 2003-2009. 2005 is the last year that Quad 3084 was sampled. 11 January 2010 tlk.

Quality Assurance: 

 

Data were entered and then visually assessed for any errors.

Additional information: 

Field Crew:

Mike Friggens 1999-September 2001; Karen Wetherill February 7, 2000-August 2009; Terri Koontz February 2000-August 2003; August 2006-Present; Shana Pennington February 2000-August 2000; Heather Simpson August 2000-August 2002; Chris Roberts September 2001-August 2002; Caleb Hickman September 9, 2002-November 15, 2004; Seth Munson September 9, 2002-June 2004; Maya Kapoor August 9, 2003-January 21, 2005; April 2010-present; Tessa Edelen August 15, 2004-August 15, 2005; Charity Hall January 31, 2005-January 3, 2006; Yang Xia January 31, 2005-August 2009; Michell Thomey September 3, 2005-August 2008; Jay McLeod January 2006-August 2006; Amaris Swann August 25, 2008-January 2013; John Mulhouse August 2009-Present; Amanda Boutz August 2009-2010; Stephanie Baker October 2010-Present; Megan McClung April 2013-Present

Point-Quarter Harvested Plant Weight Measurements to Estimate Shrub ANPP in a Chihuahuan Desert Creosote Shrubland at the Sevilleta National Wildlife Refuge, New Mexico (2007- present)

Abstract: 

In an effort to better quantify NPP of Creosotebush in the Five-Points region, it was decided to test the Point-Quarter method against the standard 1-m2 quadrat method that has been in use since 1998. Transects were laid out across the 5 mammal trapping webs as well as across burned and unburned plots of the Mixed Shrub site (MS). Repeat measures of the same bushes are performed seasonally. Whole shrubs of various size classes are collected and sorted and weighed to develop regressions for biomass.

Core Areas: 

Data set ID: 

202

Additional Project roles: 

504
505
506
507
508
509
510

Keywords: 

Data sources: 

sev202_pqweight_20161103

Methods: 

Shrub Harvesting
Creosote shrubs of various size classes are measured . Height of the shrub is measured as well as the diameter of the crown at its widest point and also a diameter perpendicular to this first diameter. The shrubs are then harvested.

Sorting and Drying
Creosote shrubs are separated into leaves, twigs (small stems that are left after removing all of the green leaves), and stems (the large main stems of creosote. After the samples are sorted they are dried for up to five days.

Weights and Measurements
The dry weight for all samples leaves, twigs, and stems are recorded. For each stem sample, the length (cm) of each stem is measured and recored as total stem length (the sum of all stems). A small, medium, and large bush from both burned and unburned treatments are randomly selected for future C/N analysis.

Maintenance: 

January 2009: All data sets (Winter, Spring, and Fall) for 2007-2008 were combined, checked for errors, and imported into Navicat. Variables site was added and burned and unburned were used as treatments instead. Any calculated measurements (i.e. volume, twig+leaf weight, etc.) were removed from data set. -Changed missing data on volume and weightt due to plant being dead to -888. -Changed missing data on volume and weight due to human error to -999. -- A. Swann

Quality Assurance: 

Data were scanned by eye to catch mistakes. Data were then filtered in excel to determine if all parameters were met. Data were combined and imported into Navicat using the import wizard.

Additional information: 

Additional Personnel Associated with the Data Collection / Data Processing

Sevilleta Field Crew Employee History

Chandra Tucker, April 2014-present, Megan McClung, April 2013-present, Stephanie Baker, October 2010-Present, John Mulhouse, August 2009-June 2013, Amaris Swann, August 25, 2008-January 2013, Maya Kapoor, August 9, 2003-January 21, 2005 and April 2010-March 2011, Terri Koontz, February 2000-August 2003 and August 2006-August 2010, Yang Xia, January 31, 2005-April 2009, Karen Wetherill, February 7, 2000-August 2009, Michell Thomey, September 3, 2005-August 2008, Jay McLeod, January 2006-August 2006, Charity Hall, January 31, 2005-January 3, 2006, Tessa Edelen, August 15, 2004-August 15, 2005, Seth Munson, September 9, 2002-June 2004, Caleb Hickman, September 9, 2002-November 15, 2004, Heather Simpson, August 2000-August 2002, Chris Roberts, September 2001-August 2002, Mike Friggens, 1999-September 2001, Shana Penington, February 2000-August 2000.

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