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).
Plant phenology or life-history pattern changes seasonally as plants grow, mature, flower, and produce fruit and seeds. Plant phenology follows seasonal patterns, yet annual variation may occur due to annual differences in the timing of rainfall and ambient temperature shifts. Foliage growth and fruit and seed production are important aspects of plant population dynamics and food resource availability for animals.
This study is designed to look at community or population level fluctuations in bees over the season and on a long term basis, over years. Funnel traps are a very low maintenance method of trapping pollinators with zero human bias. The bias of the traps is that the color determines the species and sexes that it attracts. Therefore the traps provide relative abundance that can be compared over the season or year, but individual species cannot be compared within a season. This study is designed to be compared with the data from SEV137 Phenology, to look at spatial and temporal patterns within pollinator and flowering plant communities. Data is not available at this time, but the species list is.
Activating and collecting the traps
When the traps are activated, the worker need only a screwdriver to open the cans and a gallon of propylene glycol to fill the traps. After major rain events, the watered down glycol is collected for disposal and the trap is refilled with undiluted glycol.To collect the specimens, the worker carries 10 small kitchen strainers, a pint size plastic cup and a hammer. The specimens are strained and the old antifreeze is placed back in the paint can. The funnel is left inside the cage with the closed paint can for the inactive period.Back at the truck, the specimens are transferred into labelled vials with 70% ethyl alcohol and stored until they can be processed.Lab Processing
In the lab, the specimens are rinsed of any left over glycol and pinned and labelled according to museum standards. All of 2001 specimens were pinned. In 2002, some of the more common species or species groups were not pinned, but were stored in alcohol with the non-target specimens.Identifications
Identifications are done by Karen Wetherill (Sevilleta LTER) and Terry Griswold (USDA Bee Laboratory, Logan, Utah). Twenty specimens of each species or morphotype are deposited in the Museum of Southwestern Biology (MSB) and 20 are deposited in the arthropod collection of the Sevilleta Long Term Ecological Research Station which is a permanent loan from the MSB. Some specimens were retained by the USDA Bee Laboratory in Logan, Utah. Host codes are Kartez Plant codes as listed on the USDA Plants Database.Sampling design
One blue trap and one yellow trap were installed 10m north or 10m south of each phenology transect. The north or south location of each color of trap was decided by flipping a coin. The phenology transects are the north/south lines of each rodent trapping web and are 200m long. There are five rodent trapping webs at each of the three sites, totalling 30 traps, 15 of each color. One sample equals the sum of one yellow trap and one blue trap. The traps consist of a 2 foot high chicken wire cage with a platform 1 1/2 feet off the ground. The cage prevents wildlife from disturbing the traps. The trap itself rests on the platform and is made up of a one quart paint can with about an inch of propylene glycol and a yellow or blue automotive funnel with a heavy section of pipe glued around the spout to prevent the wind from blowing the funnel. The funnels have been sprayed with blue and yellow Krylon brand flourescent spray paint. The lid of the paint can is left in the cage to close the can when the trap is inactive.The traps are activated in March every year and are left open for 14 days at which point the specimens are collected and the traps are closed for another 14 days. This cycle repeats itself through the month of October.
This file was created on Jan. 14, 2003 by Kristin Vanderbilt. This study began in February of 2001. The first year is to be considered a pilot study as the methods changed for 2002. In the first year, pan traps were used. These were replaced by funnel traps for the year 2002.This file was updated by Karen Wetherill on March 10, 2004 and again on December 7, 2005 and again on July 9, 2008.
All identifications were verified at the USDA Bee Laboratories in Logan, Utah with the help of Dr. Terry Griswold.
Information on data collection
In 2001, the samples were collected once a month, during the same time as the phenology data. Yellow pan traps were put out for 48 hours (or shorter due to evaporation). In 2002, after the traps were replaced with funnel traps which use antifreeze rather than water, the traps were left open for two weeks and then closed for two weeks from February through October. In August 2002, the traps were accidentally closed one week early and then reset for an additional week (August 30th to September 6th) so these samples will be more like the September samples than they are like the July samples.
In 2004 the February collection was not taken.
Additional Study Area Information
Study Area 1
Study Area Name: Blue Grama Core Site
Study Area Location: The Blue Grama Core Site is one of 5 current core SEVLTER study sites. Core studies include meteorology, rodent abundance, pollinator diversity, monthly phenology, and NPP. Additional studies have examined the Bootleg Canyon fire of 1998 and grass patch dynamics.Elevation: 1670 m
Vegetation: Vegetation is characterized as Plains-Mesa Grassland, dominated by blue and black gramma (Bouteloua gracilis & B. eriopoda) and galleta grass (Hilaria jamesii)North Coordinate:34.3348South Coordinate:34.3348East Coordinate:106.631West Coordinate:106.631Study Area 2
Study Area Name: Five Points Creosote Core Site
Study Area Location: Five Points is the general area which emcompasses the Black Grama Grassland (known as Five Points Grassland) and Creosote Core (Five Points Larrea) study sites and the transition between Chihuahuan Desert Scrub and Desert Grassland habitats. Both core sites are subject to intensive research activities, including measurements of NPP, phenology, pollinator diversity, and ground dwelling arthropod and rodent populations. There are drought rain-out shelters in both the Grassland and Creosote sites, as well as another set in the mixed ecotone with co-located ET Towers. The grassland Small Mammal Exclosure Study is located here, as well as many plots related to patch mapping and biotic transitions.Elevation: 1615 m
Vegetation: The Creosote Core site is characterized as Chihuahuan Desert Scrub, dominated by a creosotebush overstory, with broom snakeweed, purple pricklypear (O. macrocentra) and soapweed yucca as notable shrubs. The site is also characterized by numerous, dense grass dominated patches, reflecting proximity to the Black Grama Core site and the presumably recent appearance of creosotebush. Dominant grasses were black grama, fluffgrass (Dasyochloa pulchellum), burrograss (Scleropogon brevifolia), bushmuhly (M. porteri), and galleta (Pleuraphis jamesii). Notable forb species included field bahia (Bahia absinthifolia), baby aster (Chaetopappa ericoides), plains hiddenflower, Indian rushpea (Hoffmannseggia glauca), Fendler’s bladderpod (Lesquerella fendleri), and globemallow.North Coordinate:34.3331South Coordinate:34.3331East Coordinate:106.736West Coordinate:106.736Study Area 3
Study Area Name: Five Points Grass Core Site
Study Area Location: Five Points is the general area which emcompasses the Black Grama Grassland (known as Five Points Grassland) and Creosote Core (Five Points Larrea) study sites and the transition between Chihuahuan Desert Scrub and Desert Grassland habitats. Both core sites are subject to intensive research activities, including measurements of NPP, phenology, pollinator diversity, and ground dwelling arthropod and rodent populations. There are drought rain-out shelters in both the Grassland and Creosote sites, as well as another set in the mixed ecotone with co-located ET Towers. The grassland Small Mammal Exclosure Study is located here, as well as many plots related to patch mapping and biotic transitions.Elevation: 1616 m
Vegetation: Desert Grassland habitat is ecotonal in nature and the Black Grama Core site is no exception, bordering Chihuahuan Desert Scrub at its southern boundary and Plains-Mesa Grassland at its northern, more mesic boundary. There is also a significant presence of shrubs, dominantly broom snakeweed (Gutierrezia sarothrae), along with less abundant fourwing saltbush (Atriplex canescens), Mormon tea (Ephedra torreyana), winterfat (Krascheninnikovia lanata), tree cholla (Opuntia imbricata), club cholla (O. clavata), desert pricklypear (O. phaeacantha), soapweed yucca (Yucca glauca), and what are presumed to be encroaching, yet sparsely distributed, creosotebush (Larrea tridentata). Characteristically, the dominant grass was black grama (Bouteloua eriopoda). Spike, sand, and mesa dropseed grasses (Sporobolus contractus, S. cryptandrus, S. flexuosus) and sand muhly (Muhlenbergia arenicola) could be considered co-dominant throughout, along with blue grama (B. gracilis) in a more mesic, shallow swale on the site. Notable forb species included trailing four o’clock (Allionia incarnata), horn loco milkvetch (Astragalus missouriensis), sawtooth spurge (Chamaesyce serrula), plains hiddenflower (Cryptantha crassisepala), blunt tansymustard (Descarania obtusa), wooly plaintain (Plantago patagonica), globemallow (Sphaeralcea wrightii), and mouse ear (Tidestromia lanuginosa).North Coordinate:34.3381South Coordinate:34.3381East Coordinate:106.717West Coordinate:106.717
This data set contains records for the numbers of selected groups of ground-dwelling arthropod species and individuals collected from pitfall traps at 4 sites on the Sevilleta NWR, including creotostebush shrubland, both black and blue grama grasslands, and a pinyon/juniper woodland. Data collections begin in May of 1989, and are represented by subsequent sample collections every 2 months. One site (Goat Draw/Cerro Montosa) was discontinued in 2001, and a new site (Blue Grama) was initiated . Only three sites, creosotebush, black grama, and blue grama were continued between 2001-2004.
To monitor the species composition and relative abundance's of select ground dwelling arthropod taxa and trophic groups from principal long-term study sites/environments in relation to climate change and plant production.
Arthropods have been collected from four subjectively chosen sites on the Sevilleta National Wildlife Refuge (SNWR), representing the following habitat types: pinyon-juniper (elev. 2195 m), black grama grassland, blue grama grassland, and creosotebush shrubland (elev. ~1400 m for all three). At each of the four sites there were 30 traps arranged in five replicate lines with six traps per line. Each line was located outside a mammal trapping web, except at Goat Draw, where mammal trapping webs were installed three years after the arthropod traps. In 1995 Robert Parmenter and Sandra Brantley decided to reduce the number of traps by half. Comparative statistical tests run with data from 15 traps showed no difference in mean abundances of dominant species compared to tests with 30 traps. The interannual variability is high and it is hoped that the long-term aspect of the monitoring will produce clearer patterns than intensive sampling over a short period has done. Traps 1, 3 and 5 were left and traps 2, 4 and 6 were removed. The decision was also made to process samples from only the odd-numbered traps beginning with the 1993 samples. The experimental design was intended to provide data for long-term monitoring of ground arthropods in relation to climate and plant production. The traps within each trap line are subsamples, and data from those should be summed or averaged for a single value per line, per sample period. The lines are intended to serve as replicate samples for each habitat site, however, they were not randomly located. The lines were located to provide a systematic array with trap lines approximately 200 meters from each other on the landscape.
During a collection period the contents of each trap are strained out of the glycol so that it can be reused. Glycol is replenished as needed to keep the cups about half full. Arthropods are transferred from the strainers to glass vials containing site labels. The contents of each trap are stored in a separate vial. Trap condition forms are filled out at the time of collection and kept with the samples. Any traps that are damaged or not functioning are re-set.
Arthropods are collected in pitfall traps, made of a 15 oz. can (11 cm tall and 7.5 cm in diameter) dug into the ground so that the opening of the can is flush with the ground. A screen apron was fitted around the top of the can to prevent rodent digging. Plastic 10 oz. cups about half-full of propylene glycol (ethylene glycol prior to March 1994) are inserted in the can. The glycol is a preservative; no live pitfall trapping of arthropods is done. The traps are covered by raised ceramic lids, 15 cm x 15 cm in size. The traps remain open all year, and samples are collected everly two months during the week of the 15th day of each months, for the months: February, April, Jun, August, October, and December.During a collection period the contents of each trap are strained out of the glycol so that it can be reused, using standard hand-held metal screen kitchen strainers approximately 3 inches diameter. Glycol is replenished as needed to keep the cups about half full. Arthropods are transferred from the strainers to glass vials containing site labels. The contents of each trap are stored in a separate vial. Trap condition forms are filled out at the time of collection and kept with the samples.
Specimens are stored in 70 % ethanol. Specimens are brought back to the UNM Museum of Southwestern Biology (MSB) wet lab for processing. Sample sorting, arthropod identification, and data tabulation are performed only by individuals trained as entomologists, or entomologically experienced graduate students trained in arthropod identification specifically for this project. Individual arthropods are identified to morphospecies and counted. Classifications generally follow Nomina Insecta Nearctica: a checklist of the insects of North America, Volumes 1-4, however, taxonomic levels above family follow Borror, DeLong and Triplehorn's An Introduction to Entomology, 5th edition. Higher classification for Orthopteroids follow Arnett, 2000 (per DLC). And classification of Aranae follows Roth's Spider Genera of North America, 2nd and 3rd editions. The species code, number of individuals, site name and date of collection are entered on a data sheet. After processing, all the samples from one site and date are pooled for long-term storage in sealed jars containing 70% ethanol, at the UNM Biology Field Station, located at the Sevilleta NWR. Detailed procedures for sorting and identifying the arthropods are available from the Sevilleta data manager (firstname.lastname@example.org). Reference collections are maintained at the Sevilleta Field Station and at the UNM Museum of Southwestern Biology Division of Arthropods. Voucher specimens are housed in the UNM MSB Division of Arthropods.
Ground arthropod species in the following taxonomic groups are collected, counted and identified to morphospecies:-orthopterans, including grasshoppers, field crickets and camel crickets-blattarians, sand cockroaches-mantodeans, only ground mantids-phasmatodeans, walkingsticks-hemipterans, selected taxa only: lygaeids, alydids, one genus of mirid, thyreocorids, cydnids-coleopterans-microcoryphians, bristletails-chilopods-diplopods -isopods-arachnids, including spiders, scorpions, solpugids, uropygids, opiliones.
Specimens are pinned or placed in 70 % ETOH, labeled, and added to the LTER collection or to the UNM Division of Arthropods collection as needed. If the specimens are not needed they are kept in alcohol storage and housed at the Sevilleta Field Station. See: /sevilleta/export/db/work/insect/specieslists/sevrefcoll for a list of specimens vouchered by the MSB. The focus of the pitfall collections is on the adult stage, but nymphs of orthopteroids and hemipterans and immature stages of arachnids are identified to genus or species if possible. If not, these groups have species i.d. numbers for nymphal or immature stages. Larval beetles are not counted. The aleocharine staphylinid species are grouped together under species number Co Sta 001 088.
January 2009Combined all data from 1992-2004. QA/QC'd data from 2001-2004 in excel using a filter and checking data line by line. All data were then imported into Navicat using the import wizard.
Data from 1989-1991 were removed and stored elsewhere. Contact data manager for data. --A.Swann
Field collections are made every even-numberedmonth as close to the 15th as possible.
This study/data set is a subset of the original larger scale Sevilleta LTER data set #: SEV0029; "Arthropod Populations". The number of arthropod taxa included in this data set ("Sevilleta Ground Arthropods") has been reduced to those taxa that are appropriately sampled by pitfall traps, and those taxa or taxonmic ranks that can be easily identified and tabulated by expert technical staff. The number of study sites also was reduced from seven to four for this data set. Associated data sets include climate data from representative Sevilleta LTER meterological stations, and plant production data from Sevilleta LTER above ground net primary production plots, located on or near the arthropod pitfall trap sites.
This file contains mark/recapture trapping data collected from 1989-2012 on permanently established web trapping arrays at 8 sites on the Sevilleta NWR. At each site 3 trapping webs are sampled for 3 consecutive nights in spring and fall. Not all sites have been trapped for the entire period. Each trapping web consists of 145 rebar stakes numbered from 1-145. There are 148 traps deployed on each web: 12 along each of 12 spokes radiating out from a central point (stake #145) plus 4 traps at the center point. The trapping sites are representative of Chihuahuan Desert Grassland, Chihuahuan Desert Shrubland, Pinyon-Juniper Woodland, Juniper Savanna, Plains-Mesa Sand Scrub and Blue Grama Grassland.
Sampling Design Permanent capture-mark-release trapping webs were used to estimate density (number of animals per unit area) of each rodent species at each site. The method makes use of concepts from distance sampling, i.e., point counts or line-intercept techniques. The method makes no attempts to model capture-history data, therefore it was not necessary to follow individuals through time (between sessions). Distance sampling methods allow for sighting or detection (capture) probabilities to decrease with increasing distance from the point or line. The modeling of detection probability as a function of distance forms the basis for estimation. Trapping webs were designed to provide a gradient of capture probabilities, decreasing with distance from the web center. Density estimation from the trapping web was based on three assumptions:1. All animals located at the center of the web were caught with probability 1.0; 2. Individuals did not move preferentially toward or away from the web center; 3. Distances from the web center to each trap station were measured accurately. Each web consisted of 12 trap lines radiating around a center station, each line with 12 permanently-marked trap stations. In order to increase the odds of capturing any animals inhabiting the center of a web, the center station had four traps, each pointing in a cardinal direction, and the first four stations of each trap line were spaced only 5 m apart, providing a trap saturation effect. The remaining eight stations in a trap line were spaced at 10 m intervals. The web thus established a series of concentric rings of traps. Traps in the ring nearest the web center are close together, while the distances separating traps that form a particular ring increase with increasing distance of the ring from the web center. The idea is that the web configuration produces a gradient in trap density and, therefore, in the probability of capture. Three randomly distributed trapping webs were constructed at each site. The perimeters of webs were placed at least 100 m apart in order to minimize homerange overlap for individuals captured in the outer portion of neighboring webs.
Each site containing three webs was sampled for three consecutive nights during spring (in mid May or early June) and summer (in mid July or early August for years 1989 to 1993, then mid September to early October for years 1994 through 2000). In that rodent populations were not sampled monthly over the study period, there is no certainly that either spring or summer trapping times actually captured annual population highs or lows. Based on reproductive data in the literature, an assumption was made that sampling times chosen represent periods of the year when rodents have undergone, and would register, significant seasonal change in density. During each trapping session, one Sherman live trap (model XLF15 or SFAL, H. B. Sherman Traps, Tallahassee, FL) was placed, baited with rolled oats, and set at each permanent, numbered station (four in the center) on each web, for a total 444 traps over three webs. Traps were checked at dawn each day, closed during the day, and reset just before dusk. Habitat, trap station number, species, sex, age (adult or juvenile), mass, body measurements (total length, tail length, hind foot length, ear length), and reproductive condition (males: scrotal or non-scrotal; females: lactating, vaginal or pregnant) were recorded for each initial capture of an individual. Each animal was marked on the belly with a permanent ink felt pen in order to distinguish it from other individuals during the same trapping session. The trap station number for an initial capture related to a particular trapping ring on a web and, therefore, to a particular distance from the center of the web. The area sampled by a ring of traps was computed based on circular zones whose limits are defined by points halfway between adjacent traps along trap lines; an additional 25 m radius was added to the outer ring of traps in order to account for homerange size of individuals caught on the outer ring.
Analytical ProceduresArea trapped and number of individuals caught for each ring of traps was the basis for estimating the probability density function of the area sampled. The program DISTANCE produced the estimators used to calculate density. Where sample size for a particular species and web was less than an arbitrarily chosen n=10, the number of individuals captured during that session was simply divided into the area of the web plus the additional 25 m radius (4.9087 ha). This dataset includes only the raw capture data.
Sherman live traps: model XLF15 or SFAL, H. B. Sherman Traps, Tallahassee, FL
Trap sets require care and cleaning as well as proper storage. Otherwise, webs are made up of durable rebar and aluminum tags which only need repair if disturbed. Tools used in the field - scales and rulers, pouches, trap bags and ziplock supply must be maintained on hand at SevFS for trapping events.
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.
*In fall 2013, the Grassland Core site was not able to be trapped due to government shutdown.
We studied the diversity of arbuscular mycorrhizal fungi (AMF) in a semiarid grassland and the effect of long-term nitrogen (N) fertilization on this fungal community. Root samples of Bouteloua gracilis were collected at the Sevilleta National Wildlife Refuge (New Mexico, USA) from control and N-amended plots that have been fertilized since 1995. Small subunit rDNA was amplified using AMF specific primers NS31 and AM1. The diversity of AMF was low in comparison with other ecosystems, only seven operational taxonomic units (OTU) were found in B. gracilis and all belong to the genus Glomus. The dominant OTU was closely related to the ubiquitous G. intraradices/G. fasciculatum group. N-amended plots showed a reduction in the abundance of the dominant OTU and an increase in AMF diversity. The greater AMF diversity in roots from N-amended plots may have been the result of displacement of the dominant OTU, which facilitated detection of uncommon AMF. The long-term implications of AMF responses to N enrichment for plant carbon allocation and plant community structure remain unclear.
Sampling Design Roots from three Bouteloua gracilis plants were collected from three control and three N-amended plots (a total of 72 plants).
Field Methods Plant samples were collected in plastic bags, kept at 4 C and processed the same or next day after collection.
Lab Procedures Whole roots from one plant from each plot (6 plants/date) were cleaned under running tap water, rinsed twice with sterile water, and dried on paper towels. Roots were determined to be alive if they did not exhibit lesions, were not obviously damaged, possessed a prominent number of root hairs and were connected to green leaves. A subset of these roots were microscopically analyzed to confirm AMF colonization, and the others were stored at -20 C until their DNA was extracted.
Microscopy The microscopy results showed very low AMF colonization, as a compromise between the need for a large sample of clones (to reliably characterize the AMF community within each plant) and a significant sample of plants from control and N-amended plots (to study the effect of nitrogen on colonization), we decided to select 3 plants from control and 3 plants from N-amended plots and sequence approximately 100 clones per plant using fungal and AMF specific primers.
DNA Extraction Three to five roots segments (approximately 3 cm long) from each plant were used for DNA extraction. DNA was extracted using a DNeasy plant Mini Kit (Qiagen, Chatsworth, CA). Primers NS31 and AM1 were used to specifically amplify AMF (Helgalson et al., 1998; Simon et al., 1992). For each of the 6 root samples, a total of 25 to 47 random clones were sequenced, 260 sequences in all. PCR was performed using the following protocol: initial denaturation at 95 C for 5 min, followed by 30 cycles of 95 C for 30 s, 53 C for 30 s, and 72 C for 45 s, with a final extension of 72 C for 7 min. DNA was amplified in 25 uL reactions with 12.5 uL Premix Taq (Takara Bio), 1.0 uL of each primer (5 uM), 3 uL of BSA 1%, 6.5 uL of milliQ water, and 1 uL of template DNA. The first PCR products were cleaned with ExoSAP-IT (USB, Cleveland, Ohio) and 1 uL of the cleaned PCR product was used as template for the second PCR. Products were cloned with TOPO-TA cloning kit (Invitrogen, Carlsbad, CA) following the manufacturer's instructions. Clones were amplified and sequenced using rolling circle amplification (TempliPhi, Amersham, Buckinghamshire, England) and BigDye Terminator v1.1 Sequencing Kit (Applied Biosystems, Foster City, CA), respectively. Sequencing was conducted at the Molecular Biology Facility of The University of New Mexico. Forward and reverse sequences were assembled and edited with Sequencher 4.0 (Gene Codes, Ann Arbor, MI).
Sequence Analysis The program CHIMERA CHECK 2.7 of the Ribosomal Database Project (http:// rdp.cme.msu.edu/html/analyses.html) was used to check for chimeric 18S nrDNA sequences. Sequences were BLASTed against GenBank and information from GenBank obtained using phd, bioperl scripts and a mysql database written by George Rosenberg, Molecular Biology Facility of the University of New Mexico. Glomeromycota sequences were submitted in GenBank under accession numbers EF154520 and EF154698. OTUs were determined using the DOTUR program (Schloss and Handelsman, 2005). Distance matrices generated with the F84 evolutionary model using the DNADIST program from PHYLIP (Felsenstein, 2005) were used as input files to DOTUR. A similarity level of 97% has been used as the lower boundary to define OTUs in several studies of AMF (e.g. Helgason et al., 1999). We performed our analysis using both 97 and 99% of similarity to evaluate how mycorrhizal fungi at different taxonomic levels respond to N deposition. Rarefaction curves and diversity estimators (Chao, ACE) were calculated for the pooled data (N and control plots) and for N and control treatments with DOTUR. The effect of N enrichment on the AMF community also was evaluated in a phylogenetic context using UniFrac (Lozupone and Knight, 2005). The UniFrac metric estimates differences between microbial communities inhabiting different environments based on phylogenetic distances. In our study, we used this metric to evaluate the percentage of branch length in a phylogenetic tree that leads to descendants from N- amended and control plots. A phylogenetic tree generated with PAUP 4.0b10 (Swofford, 2002) that include all the Glomeromycota sequences from this study was used as input file to calculate UniFrac significance. Trees were constructed using the neighbor-joining (NJ) algorithm and maximum parsimony (MP) in PAUP 4.0b10 (Swofford, 2002). Bootstrap values were estimated from 1000 replicates for the MP and NJ analysis. A NJ phylogenetic tree that includes only representative OTUs (defined at 99% similarity with DOTUR) was used for normalized weighted principal coordinate analysis in UniFrac (Lozupone and Knight, 2005). The weighted UniFrac accounts for the relative sequence abundance in each sample. The NJ tree and a text file that includes OTU abundances for each sample were used as input files.
PTC 200, Pertier Thermal Cycler PCR machine DNA Engine
Changes to the data: File created on 6/13/2008 by Andrea Porras-Alfaro.
Data are available from Genbank: http://www.ncbi.nlm.nih.gov/Entrez/index.html Accessions EF154520-EF154698
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