Begun in spring 2013, this project is part of a long-term study at the Sevilleta LTER measuring net primary production (NPP) across three distinct ecosystems: creosote-dominant shrubland (Site C), black grama-dominant grassland (Site G), and blue grama-dominant grassland (Site B). 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 is the change in plant biomass, represented by stems, flowers, fruit and and foliage, over time and incoporates growth as well as loss to death and decomposition. To measure this change the vegetation variables in this dataset, including species composition and the cover and height of individuals, are sampled twice yearly (spring and fall) at permanent 1m x 1m plots within each site. A third sampling at Site C is performed in the winter. The data from these plots is used to build regressions correlating biomass and volume via weights of select harvested species obtained in SEV999, "Net Primary Productivity (NPP) Weight Data." This biomass data is included in SEV999, "Seasonal Biomass and Seasonal and Annual NPP for Core Grid Research Sites."
Each sampling grid contains 40 1x1m quadrats in a 5x8 array. However, only 30 quadrats are sampled at each. These are quadrats 1-15 and 26-40. Thus, the middle two rows (i.e., 10 quadrats) are not sampled. Locating the Sampling Quadrats: Three core sites (B, G, and C) contain five rodent trapping and vegetation sampling webs. The vegetation grids are near these webs at each core site. At the blue grama site, the grid is located at the southern end of web 5, between webs 2 and 4. At the creosote site, the grid is east of web 3, near the road. At the black grama site, the grid is just northeast of web 5.
Collecting the Data:
Net primary production data is collected twice each year, spring and fall, for all sites. The Five Points Creosote Core Site is also sampled in winter. 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.
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.
Niners and plexidecs are additional tools that 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.
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 cm 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 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 shrubs 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, "g" for "grid," along with the site abbreviation, should be added (i.e., gc, gg, gb). The final format for sites B, G, and C should be as follows: npp_core.mm.dd.yy.abgg.xls. File names should be in lowercase.
Other researchers involved with collecting samples/data: Chandra Tucker (CAT; 04/2014-present), Megan McClung (MAM; 04/2013-present), Stephanie Baker (SRB; 2013-present), John Mulhouse (JMM; 08/2009-06/2013).
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.
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.
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
Soils: Rhodic nitisols, Haplic luvisols, Leptic phaeozems
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
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
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.
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).
The overall goal of the rainfall manipulation project is to understand the coupled ecological and hydrological responses of a grassland, shrubland and a mixed grass-shrub vegetation community to extended periods of increased or decreased rainfall. Rainfall manipulation plots have been established in each of these three vegetation communities in the Five Points area of Sevilleta National Wildlife Refuge. In each vegetation community, three control plots, three drought treatment plots, and three water addition plots have been installed, each approximately 10 x 15 m in size. In each plot, vertical profiles of soil moisture probes have been installed under each cover type (canopy and interspace in grassland and shrubland; grass canopy, shrub canopy and interspace at the ecotone (mixed grass-shrub) site). The probes measure differences in infiltration and soil water content and potential associations with these different cover types. In addition, TDR probes have been installed diagonally in each cover type to integrate the water content of the top 15 cm of soil. Each plot contains 18, 1m2 quads made up of 6, 1m2 quads along each of the 3 transects located across each plot. Each spring and fall, the following parameters are measured in every quad: live plant cover, height, and abundance by species; dead plant cover; soil cover; litter cover; and rock cover. Data collection began in the drought and control plots in the spring of 2002. Data collection began in the water addition plots in the spring of 2004.In the grassland and shrubland communities, all nine currently established plots are located together. The three drought plots were located under a single large roof with a 0.5 m path separating each plot (drought treatments ended in 2006). The control plots and water addition plots are similarly grouped, but without the shelter structure. In the ecotone community, the plots are in three groups; each group is comprised of one drought plot, one water addition plot, and one control plot. Control plots received no experimental treatment, while the sliding roofs over the drought plots were used to divert precipitation, producing a long-term drought. The roofs covering the drought plots were lowered when there was no precipitation so that the amount of sunlight received by the drought plots was minimally affected. Water addition was intended to impose a complementary increase in water supply on the water addition plots.
One meter2 vegetation quadrats are used to measure the cover and abundance of all plants present along each of the three transects across each plot. These quadrats are also used to measure dead plant foliage, leaf litter, bare soil, and rock covers. One person works on each quad, recording the data into a palm top computer. Two technicians may work independently along the same transect and alternate quadrats.
To begin quadrat measurements, first locate the three pairs of rebar along the length (across the slope, perpendicular to the gutter edge) of each plot, which mark the endpoints of each transect. Once the transect has been located, run a string across the plot attaching it to the two transect endpoint rebar stakes to act as a guideline for measurements. Each transect is measured from the left to the right side of the plot (where left and right are from the perspective of a person standing at the bottom edge of the plot where the gutters are located).
Beginning at the left side of the transect, place the bottom edge of the quadrat along the guidline of the string with the quad pointing away from the gutter edge. After measuring the quadrat, advance the quadrat along the transect by moving the quadrat to the right so that the bottom left corner is moved to the position formerly occupied by the bottom right corner. Repeat this process until the entire width of the transect has been measured. *Note: Beginning in the spring of 2010 only quadrats 2-7 (or meters 2-7) were measured. Before the spring of 2010 there were a variable number of quadrats measured per transect. If the last quadrat did not lie completely within the boundaries of the plot (within the metal edging), the percentage of the plot that lied within the plot boundary was recorded in the comments column of the data sheet and the vegetation data was recorded in the same manner as for the other quadrats. If the last quadrat lied completely within the boundaries of the plot, 100% was recorded in the comments section of the data sheet. This was to ensure that the entire transect had been measured.
General vegetation measurements
The cover, height, and abundance (standing biomass) are recorded for each species of plant inside the quadrat. Vegetation measurements are taken in two layers: a ground level layer that includes all grasses, forbs, sub-shrubs, the bases of Larrea tridentata and bare soil and a “shrub” layer that includes the canopy of Larrea tridentata. The purpose of this approach is to include Larrea canopies, while allowing the cover values of the ground level layer to sum to approximately 100%.
The quadrat boundaries are delineated by the 1 m2 PVC-frame placed above the quadrat. Each PVC-frame is divided into 100 squares with nylon string. The dimensions of each square are 10cm x 10cm and represent 1 % of the total quadrat area or cover. The cover and height of all individual plants of a species that fall within the 1m2 quadrat are measured. Cover is quantified by counting the number of 10cm x 10cm squares intercepted by all individual plants of a particular species, and/or partial cover for individual plants < 1%.
When reading plant cover it is important to stay centered over the vegetation in the quadrat. If you are not directly centered over the vegetation, cover measurements can be over or underestimated by your angle of view (parallax). If the surrounding plants prohibit you from leaning directly over the plants, use a tape measure to delineate a vertical column of intercept. To do this, simply extend the tape measure vertically from the base of the plant up to the frame grid.
Vegetation cover measurements
Cover measurements are made by summing the cover values for all individual plants of a given species that fall within an infinite vertical column that is defined by the inside edge of the PVC-frame. This includes vegetation that is rooted outside of the frame but has foliage that extends into the vertical column defined by the PVC-frame. Again, cover is quantified by counting the number of 10cm x 10cm squares intercepted by each species. Do not duplicate overlapping canopies, just record the total canopy cover on a horizontal plane when looking down on the quadrat through the grid.
Larger cover values will vary but the smallest cover value recorded should never be below 0.1%. When dealing with individual plants that are < 1.00%, round the measurements to an increment of 0.1. Cover values between 1.00 - 5.00% should be rounded to an increment of 0.5 and values > 5.00% are rounded to an increment of 5.
Cover measurements should be calculated separately for living and dead individuals of each species. However, because these measurements are made infrequently, vegetation should be considered live if it represents the current year’s growth (green and yellow). This is particularly important for grasses that may have become senescent during the fall sampling of each year.
Two Larrea tridentata coverage measurements are taken (LATR2 for canopy and LATR2B for the basal cover). The canopy level layer is estimated using the portion of the canopy that falls within the quadrat. The canopy edge is defined by a straight gravity line from the canopy to the ground (i.e. imagine a piece of string with a weight on the end being moved around the canopy edge). A basal cover is taken at the base of the shrub and includes all woody vegetation that stems from the ground. The purpose of taking two measurements for Larrea is to assess changes in shrub canopy cover without confounding the percent cover estimates of other species obtained using the basal layer. For Larrea seedlings the code LSEED is used and is a separate measurement from the Larrea canopy and basal measurements.
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 tissue is frequently mixed with dead tissue in grass clumps. Provide two sets of measurements for the dead and live foliage, if possible, especially for perennial grass species. In the case that both live and dead are difficult to separate, measure all of the foliage as live. Remember that vegetation should be considered live if it represents the current year’s growth. In general, recently dead foliage is yellow and long-dead foliage is gray.
The cover of forbs is the perimeter around the densest portion of the plant. Measure all foliage that was produced during the current season including any recently dead (yellow) foliage.
Cacti and Yucca:
The cover of cacti and yucca is made by estimating a perimeter around the densest portion of the plant and recorded as a single cover. For cacti that consist of a cluster of pads or jointed stems (i.e., Opuntia phaecantha, Opuntia imbricata), estimate an average perimeter around the series of plant parts and record a single coverage measurement.
Vine cover (and some forbs) is often convoluted. Rather than attempt to estimate cover directly, take a frequency count of 10X10X10cm cubes that the vine is present in.
As with other vegetation measurements, the smallest cover value for seedlings should never be <0.1. If the value of seedling cover is less than 0.1, round up to 0.1. In the comments write “SEEDLING.”
Height is measured with a tape measure as a whole number in centimeters. All heights are vertical heights that are defined as a line parallel to the pull of gravity; this is not necessarily perpendicular to the ground if the ground is sloping. Measure the maximum height of each species identified in the quadrat. Do not measure the heights of every individual plant for a particular species.
The height of Larrea is only taken only at the canopy level (LATR2). Measure the maximum height from the base of the woody vegetation that stems from the ground to the top of the green foliage. No height measurement is needed at the basal level (LATR2B).
Annual grasses and all forbs:
Measure the height from the base of the plant to the tallest part of foliage for that species in the quadrat. Include the height of the inflorescence, if present.
Measure the height from the base of the plant to the tallest part of green foliage for that species in the quadrat. Do not include the inflorescence in the height measurement..
Plants rooted outside but hanging into the quadrat:
Do not measure the height from the ground. Measure only the height of the portion of the plant that is within the quadrat. In the comments section of the data sheet, record “Hang Over.” or “HO”.
Abundance is recorded as the number of individual plants that comprise the cover measurement. For some species, individuals are hard to distinguish. If there is bare space between two units, they should be considered separate individuals.
At the basal level (LATR2B) count the number of Larrea bases present in the quadrat.
Dead plant foliage:
For plants that are dead, but still attached to the soil and standing, just record the cover. Do not measure height or abundance for dead plants. Instead, record “-888” in these spaces on the spreadsheet to signify a value that was intentionally not recorded and enter DEAD in the comments. Cover is quantified by counting the number of 10cm x 10cm squares intercepted by each species. As with live vegetation, plant measurements that are < 1.00% should be rounded to an increment of 0.1. Cover values between 1.00 - 5.00% should be rounded to an increment of 0.5 and values > 5.00% are rounded to an increment of 5.
Remember, if some of the individuals of a plant species, or if portions of the foliage of an individual plant on the quadrat are dead and some alive, provide two sets of measurements for the dead and living foliage. In the case that both live and dead foliage are intermixed and difficult to separate, as in some bunch grasses and shrubs, just record the foliage as live. Any dead plant foliage that is not still attached to the roots and standing is considered leaf litter.
Materials other than vegetation that are measured in the drought plots include leaf litter, soil, rocks, and buckets (see below). Other than buckets, which occur in very few plots, values should always be recorded for these materials. If they are not present in a given quad, put ”-888” for their cover values so that it is clear that these categories were not simply overlooked during data collection.
Heights and abundances are not recorded for any of these materials. Instead, record “-888” for height and abundance and a numerical value for cover, where applicable (see below). If not recorded in the field, the data manager will do so during the QA/QC process.
Leaf litter includes all detached dead plant material on the soil surface, including woody branches. Cover is quantified by summing the number of 10cm x 10cm squares intercepted by patches of leaf litter. Cover values < 5.00% should be rounded to increments of 1 and cover values > 5.00% should be recorded in increments of 5. If there is no leaf litter in the quadrat, record “LITT” in the “species “ column and record “-888” in the cover, height, and abundance columns.
Some leaf litter cover has distinctive margins and is easy to define and measure. However, leaf litter may occur in diffuse small patches that are separated by bare soil, and distributed throughout the quadrat. For such diffuse cover, determine the actual cover in one typical 10 by 10 cm square (e.g., 0.3), then count the number of squares with diffuse cover (e.g., 5), and multiply the number of squares by the actual cover for a typical square (e.g., 0.3 X 5 = 1.5, then round to 1.0 or 2.0, or if the value had been greater than 5, round to the nearest increment of 5.0) for the total leaf litter cover. All leaf litter measurements are pooled into one observation, and no height or abundance is measured. Only measure leaf litter that is in the open, do not attempt to measure within clumps of grass, etc.
Measure the cover of the area occupied by abiotic substrates. Cover is quantified by summing the number of 10cm x 10cm squares intercepted by abiotic substrates. As with leaf litter, cover values < 5.00% should be rounded to increments of 1 and cover values > 5.00% should be recorded in increments of 5. If there is no soil in the quadrat, record “SOIL” in the species column for that quadrat and record a “-888” for the height, cover, and abundance. Again, when soil is present, only the cover is recorded and “-888” should be entered for height and count.
As a separate entry, estimate the cover of rock (particles >1 cm) occurring within the bare ground. The rock cover estimate can be viewed as an index of how much of the soil surface is rocky or as a subset of the soil cover measurement. The rock cover should still be measured as a sum of the number of 10cm x 10cm squares intercepted by rock. Cover values < 5.00% should be rounded to increments of 1 and cover values > 5.00% should be recorded in increments of 5. Enter “-888” for the height and count. If there is no rock cover in the quadrat, record “ROCK” in the species column and enter “-888” for the height, count, and cover.
For Grass and for Creosote sites treatments are: Plots 1-4 Drought; plots 5-6 Control; Plots 7-9 Watered; For Mixed site treatments are: Plots 3,6,9 Drought; Plots 2,4,8 Control; Plots 1,5,7 Watered.
File created 3/2/2005. -- Kristin VanderbiltUpdated 12/11/2006 --Karen Wetherill Data appended to file on 7/25/2005 -- KLV Data compiled into one file. Metadata entered in EML access database. TK 6 February 2009 data qa/qc in navicat. Made NONE measurements in the following format Cover 0 Height -888 Count -888. Corrected typos and errors. TLK 10 February 2009
On Aug 4, 2009, a lightning strike ignited a fire in the area west of the road from Black Butte to Five-Points. The fire started around 3:30 PM on the 4th. The fire was initially concentrated in the Grassland Drought, SMES, and Monsoon study areas. The next day the fire carried north and east to the Deep Well Meteorological station, Warming, and Nut-Net plot areas. The fire was finally contained by the end of the 5th covering >7800 ha.
Starting in the spring of 2011, only the mixed shrub site will be measured in the spring and in the fall only the mixed shrub and creosote sites will be measured. Measurements at the drought grassland site was discontinued at this time.
Sevilleta Field Crew Employee History
Megan McClung, April 2013-present, Stephanie Baker, October 2010-Present, John Mulhouse, August 2009-Present, 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.
In 1989, line-intercept transects were installed to evaluate temporal and spatial dynamics across vegetation transition zones. Currently, a 400m transect is sampled at a grassland site (Deep Well) which is dominated by Bouteloua eriopoda (black grama) and, near the southern end of the transect, B. gracilis (blue grama). A second grassland site (Five Points), dominated by B. eriopoda and, to the south, Larrea tridentata (creosote), is also sampled. Both sites are sampled twice a year, in May/June and September/October, and measurements are taken at a one-centimeter resolution. The biannual sampling protocol detects potential responses in both cool and warm season plants as well as pre- and post-monsoon dynamics. Several transects have been discontinued and data archived within SEV200.
Preparing Transects for Measurement:
A 100m measuring tape is unrolled and affixed to permanent pieces of rebar hammered into the ground at each of the four segments of a 400 m transect. For example, a tape is attached to the 0 meter (north) rebar stake and run to the 100 meter (south) stake. The tape is stretched as tightly as possible to get the straightest line. Windy days should be avoided as the wind moves the tape and results in inaccurate data.
Crew members work independently, each doing a 100 m segment simultaneously. Microcassette recorders and standard microcassettes are used to record the data. File names should be written on the cassettes as "fp" (Five Points), "dw" (Deep Well), or "dwb" (Deep Well-burn) for the location, followed by the transect number, date, and initials of the recorder. An introductory statement is recorded on the cassette (e.g. "It's May 9, 2099, Joe Smith recording at Deep Well Transect 2."
Each species or substrate (i.e., bare soil, litter) that intersects the tape and occupies at least one centimeter is recorded whether rooted beneath the tape or not. Observations are recorded at the cm level, the point at which the species or substrate first crosses the tape being stated. This starting location is noted but the ending point is considered to be the starting point of the next species or substrate. For example, Bouteloua eriopoda encountered at 12m 79cm, litter encountered at 12m 82 cm, bare soil at 12m 85 cm, and so forth.
8/12/2010-The data in this file has been QA/QC'd and imported into MySQL. Unknown forbs were identified as UNKNO for the species code. (ALS) 12/08/2009-The data in this file has been QAQC'd in My SQL and on-line as well. Due to wildfire at Sevilleta LTER on Aug 5 2009, some plants were not identified. New variables were added, such as BGRASS (burned grass), BVEG (burned vegetation), BSHRUB (burned shrub), and BFORB(burned forb). We will replace those variables when we can identify them in the following seasons. (YX) 12/20/2008-The data has been QAQC'd in My SQL. All plant codes have been updated to current Kartesz codes as listed in the USDA Plants Database found at http://plants.usda.gov/. Questionable identifications and mistakes were updated to the best of my (data manager's) ability. Old codes are maintained in the database and can be obtained by contacting the data manager. (KRW)
Changes to the data: This dataset (SEV004) includes all active line intercept data from Transect 1 at both Deep Well and Five Points. Old species codes are maintained in the database and can be obtained by contacting the data manager. Old data and metadata can be found in: /export/db/local/htdocs/data/archive/plant/transect/data_oldformat but this data has NOT been vigorously QAQC'd and contains errors. Contact the Sevilleta LTER data manager for data and metadata in this older format.
On Aug 4, 2009, a lightning strike ignited a fire in the area west of the road from Black Butte to Five-Points. The fire started around 3:30 PM on the 4th. The fire was initially concentrated in the Grassland Drought, SMES, and Monsoon study areas. The next day, the fire carried north and east to the Deep Well Meteorological station, Warming, Deep Well Line Intercept transect, and Nut-Net plot areas. The fire was finally contained by the end of the 5th covering >7800 ha.
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; 08/2009-06/2013), 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), Heather Simpson (HLS; 08/2000-08/2002), Chris Roberts (CR; 09/2001-08/2002), Shana Penington (SBP; 01/2000-08/2000), 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), Mike Friggens (MTF; 1999-09/2001), Tessa Edelen (MTE, 08/2004-08/2005).
ARPUP6 changed to ARPU9 03/05/2015; SPWR changed to SPPO6 03/05/2015
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