The distribution, structure and function of mesic savanna grasslands are strongly driven by fire regimes, grazing by large herbivores, and their interactions. This research addresses a general question about our understanding of savanna grasslands globally: Is our knowledge of fire and grazing sufficiently general to enable us to make accurate predictions of how these ecosystems will respond to changes in these drivers over time? Some evidence suggests that fire and grazing influence savanna grassland structure and function differently in South Africa (SA) compared to North America (NA). These differences have been attributed to the contingent factors of greater biome age, longer evolutionary history with fire and grazing, reduced soil fertility, and greater diversity of plants and large herbivores in SA. An alternative hypothesis is that differences in methods and approaches used to study these systems have led to differing perspectives on the role of these drivers. If the impacts of shared ecosystem drivers truly differ between NA and SA, this calls into question the generality of our understanding of these ecosystems and our ability to forecast how changes in key drivers will affect savanna grasslands globally. Since 2006, an explicitly comparative research program has been conducted to determine the degree of convergence in ecosystem (productivity, N and C cycling) and plant community (composition, diversity, dynamics) responses to fire and grazing in SA and NA.
Thus far, initial support has been found for convergence at the ecosystem level and divergence at the community level in response to alterations in both fire regimes and grazing. However, there have also been two unexpected findings (1) the ways in which fire and grazing interact differed between NA and SA, and (2) the rate of change in communities when grazers were removed was much greater in NA than in SA. These unexpected findings raise a number of important new questions: (Q1) Will exclusion of grazing eventually affect community structure and composition across all fire regimes in SA? (Q2) Will these effects differ from those observed in NA? (Q3) What are the determinants of the different rates of community change? (Q4) How will these determinants influence future trajectories of change? (Q5) Will the different rates and trajectories of community change be mirrored by responses in ecosystem function over time? This project is based on a large herbivore exclusion study established within the context of long-term (25-50+ yr) experimental manipulations of fire frequency at the Konza Prairie Biological Station (KPBS) in NA and the Kruger National Park (KNP) in SA. The suite of core studies and measurements include plant community composition, ANPP, and herbivore abundance and distribution at both study sites to answer these research questions.
This data set was added to the Sevilleta LTER archive at the request of SEV Principal Investigator Scott Collins.
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).
Grasshoppers are important animals in semi-arid environments, both as herbivores and as food resources for higher level consumer animals. Grasshoppers tend to be numerous and represented by many species in semi-arid environments, especially in desert grasslands. Grasshopper species range from environmental specialists, to environmental generalists. Grasshopper populations tend to change considerably from year to year, often in response to annual variation in rainfall and plant production. The purpose of this study was to monitor grasshopper species composition and abundance over a period of many years from black grama grassland, blue grama grassland, creosotebush shrubland, and pinyon/juniper woodland environments at the Sevilleta, in relation to seasonal and annual variation in precipitation and plant production. Data were collected for all individual species to provide information on community dynamics as well as population dynamics. The working research hypothesis for this study was that grasshopper populations in all environments will correlate positively to seasonal and annual variation in precipitation and plant production. Spring grasshopper populations will be especially high during El Nino years, and late summer populations especially high during La Nina years. This study was initiated in 1992, and is ongoing to the present time.
Physical Dimensions of Sampling Area: 50-meter by one-meter strip transects, between 6, alternating end-points of rodent trap lines on each of 5 rodent trapping webs at each of the 4 sites.
Plot size: Each trapping web is 200-meters diameter, each grasshopper count strip is 50-meters long, by one-meter wide.
Transect Length: 50-meters.
A sample unit consists of 50 by 1-meter strip transect; 6 strip transects per web, 5 webs per site.
Frequency of Sampling
Samples are collected twice each year, early summer and late summer.
Sample size consists of 50-meter by one-meter strip transects.
Visual counts of all grasshoppers on each strip transect. The observer slowly walks each transect, flushing grasshoppers ahead with a one-meter long - inch white PVC pipe. The observer records data on to a voice-activated micro-cassette recorder. Information recorded includes for each individual grasshopper: species, geneder, age class, and the substrate from which the grasshopper was flushed.
Additional Study Area Information
Study Area 1
Study Area Name: Goat Draw (Cerro Montosa)
Site Location Description: Cerro Montosa draw, at north base of Cerro Montosa, Sierra Los Pinos.
Soil: rocky loam.Slope/Aspect: variable steep slopes, all aspects. Vegetation Community: pinyon/juniper woodland, blue grama understory.Terrain/Physiography: rough, dissected erosional montane hills, slopes, and drainages.Geology/Lithology: variable, rhyolite. Hydrology - surface/groundwater: extensive steep arroyo drainages.Size: approximately 1 by 3 km.History (if known): grazed by cattle until 1973.Elevation: approximately 2,000 meters.Climate (general): semi-arid montane, summer rain.
Study Area 2
Study Area Name: Five Points Creosotebush.
Site Location Description: approximately 2km west of Five Points, McKenzie Flats. Soil: sandy loam.Slope/Aspect: slight north-facing slope.Vegetation Community: Chihuahuan Desert creosotebush/black grama grass.Terrain/Physiography: top of Palo Duro Canyon escarpment to south, gentle slope to north. Geology/Lithology: alluvial outwash, extensive caliche near surface.Hydrology - surface/groundwater: slight drainage to the north.Size: approximately 1 by 2 km.History (if known): intensively grazed by cattle until 1973. Elevation: approximately 1,600 meters.Climate (general): semi-arid, summer rain.
Study Area 3
Study Area Name: Five Points Grass.
Site Location Description: approximately 2km NW of Five Points, McKenzie Flats. Soil: sandy loam.Slope/Aspect: gentle rolling terrain.Vegetation Community: black grama grassland.Terrain/Physiography: gentle rolling terrain.Geology/Lithology: alluvial outwash, limestone and caliche.Hydrology - surface/groundwater: slight drainage to the west.Size: approximately 2 by 2 km.History (if known): intensivey grazed by cattle until 1973. Elevation: approximately 1,600 meters. Climate (general): semi-arid, summer rain.
Additional Information on the Data Collection Period
Data are collected in the early summer (April/May) and late summer (September/October).
SEVILLETA LTER CORE SITE GRASSHOPPERSGrasshopper Species ListUpdated: 01/19/00
CODE, FRM L-H, LATIN NAME
ACPI, G, U, Acantherus piperatusAGDE, GT, U, Ageneotettix deorumAMCOG, U, Amphitornus coloradusARCO, T, P, Arphia conspersaARPS, T, U, Arphia pseudonietanaAUEL, GT, U, Aulocara elliottiAUFE, GT, U, Aulocara femoratumBOAR, A, U, Bootettix argentatusBRMA, GT, U, Brachystola magnaCIPA, T, P, Cibolacris parvicepsCOCR, GT, U, Cordillacris crenulataCOOC, GT, U, Cordillacris occipitalisCOTE, T, U, Conozoa texanaDABI, GT, U, Dactylotum bicolorERSI, G, U, Eritettix simplexHATR, T, U, Hadtrotettix trifasciatusHERU, T, U, Heliaula rufaHEVI, A, U, Hesperotettix viridisHICA, T, U, Hippopedon capitoLAAZ, T, U, Lactista aztecaLEWH, T, U, Leprus wheeleriMEAR, A, U, Melanoplus aridusMEAZ, GT, U, Melanoplus arizonaeMEBO, A, U, Melanoplus bowditchiMEGL, GT, U, Melanoplus gladstoniMELA, GT, U, Melanoplus lakinusMEOC, GT, U, Melanoplus occidentalisMETE, G, U, Mermeria texanaOPOB, G, U, Opeia obscuraPAPA, G, U, Paropomala pallidaPHQU, GT, U, Phlibostroma quadrimaculatumPHRO, T, P, Phrynotettix robustusPSDE, GT, P, Psoloessa delicatulaPSTE, GT, P, Psoloessa texanaSCNI, A, U, Schistocerca nitensSYMO, G, U, Syrbula montezumaTRCA, T, U, Trimerotropis californicusTRFO, H, U, Tropidolophus formosusTRKI, T, U, Trachyrhachis kiowaTRPA, T, U, Trimerotropis pallidipennisTRPI, T, U, Trimerotropis pistrinariaXACO, T, P, Xanthippus corallipesXAMO, T, P, Xanthippus montanus
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 (email@example.com). 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.