Search for: All records

Primary productivity response to climatic drivers varies temporally, indicating state-dependent interactions between climate and productivity. Previous studies primarily employed equation-based approaches to clarify this relationship, ignoring the state-dependent nature of ecological dynamics. Here, using 40 y of climate and productivity data from 48 grassland sites across Mongolia, we applied an equation-free, nonlinear time-series analysis to reveal sensitivity patterns of productivity to climate change and variability and clarify underlying mechanisms. We showed that productivity responded positively to annual precipitation in mesic regions but negatively in arid regions, with the opposite pattern observed for annual mean temperature. Furthermore, productivity responded negatively to decreasing annual aridity that integrated precipitation and temperature across Mongolia. Productivity responded negatively to interannual variability in precipitation and aridity in mesic regions but positively in arid regions. Overall, interannual temperature variability enhanced productivity. These response patterns are largely unrecognized; however, two mechanisms are inferable. First, time-delayed climate effects modify annual productivity responses to annual climate conditions. Notably, our results suggest that the sensitivity of annual productivity to increasing annual precipitation and decreasing annual aridity can even be negative when the negative time-delayed effects of annual precipitation and aridity on productivity prevail across time. Second, the proportion of plant species resistant to water and temperature stresses at a site determines the sensitivity of productivity to climate variability. Thus, we highlight the importance of nonlinear, state-dependent sensitivity of productivity to climate change and variability, accurately forecasting potential biosphere feedback to the climate system. 

Abstract Both theory and prior studies predict that climate warming should increase attack rates by herbivores and pathogens on plants. However, past work has often assumed that variation in abiotic conditions other than temperature (e.g. precipitation) do not alter warming responses of plant damage by natural enemies. Studies over short time periods span low variation in weather, and studies over long time‐scales often neglect to account for fine‐scale weather conditions.Here, we used a 20+ year warming experiment to investigate if warming affects on herbivory and pathogen disease are dependent on variation in ambient weather observed over 3 years. We studied three common grass species in a subalpine meadow in the Colorado Rocky Mountains, USA. We visually estimated herbivory and disease every 2 weeks during the growing season and evaluated weather conditions during the previous 2‐ or 4‐week time interval (2‐week average air temperature, 2‐ and 4‐week cumulative precipitation) as predictors of the probability and amount of damage.Herbivore attack was 13% more likely and damage amount was 29% greater in warmed plots than controls across the focal species but warming treatment had little affect on plant disease. Herbivory presence and damage increased the most with experimental warming when preceded by wetter, rather than drier, fine‐scale weather, but preceding ambient temperature did not strongly interact with elevated warming to influence herbivory.Disease presence and amount increased, on average, with warmer weather and more precipitation regardless of warming.Synthesis. The effect of warming over reference climate on herbivore damage is dependent on and amplified by fine‐scale weather variation, suggesting more boom‐and‐bust damage dynamics with increasing climate variability. However, the mean effect of regional climate change is likely reduced monsoon rainfall, for which we predict a reduction in insect herbivore damage. Plant disease was generally unresponsive to warming, which may be a consequence of our coarse disease estimates that did not track specific pathogen species or guilds. The results point towards temperature as an important but not sufficient determinant and regulator of species interactions, where precipitation and other constraints may determine the affect of warming. 

This project was designed to understand the demographic effects of vertically transmitted fungal endophytes (Epichloë spp.) on their grass hosts. The experiment includes seven host-symbiont taxonomic pairs: Agrostis perennans - E. amarillans, Elymus villosus - E. elymi, Elymus virginicus - E. elymi or EviTG-1, Festuca subverticillata - E. starrii, Poa alsodes - E. alsodes, Poa sylvestris - E. PsyTG-1, Schedonorus arundinaceus - E. coenophiala. Experimental plots were established at the Indiana University Lilly-Dickey Woods Research and Teaching Preserve in south-central Indiana, USA in 2007. For each species, 5-10 plots were planted with naturally symbiotic (S+) hosts, and 5-10 plots were plated with hosts that were disinfected of fungal endophytes by heat treatment (S-). Over 15 years (2007-2022) we collected demographic data on the survival, growth, reproduction, and recruitment of all plants in all plots. Beginning in 2018 we also collected data on the locations of all plants in every plot. 

This study was designed to examine community- or population-level fluctuations in bee species at the Sevilleta National Wildlife Refuge, both intra- and inter-annually. From 2002 to 2019, passive funnel traps were used to collect bees at three sites, each representing a different ecosystem type of the southwestern U.S. (Plains grassland, Chihuahuan Desert grassland, and Chihuahuan Desert shrubland). Bees were collected during each month from March through October, and were identified to species by taxonomic experts. 

{"Abstract":["This dataset includes estimated plant aboveground live biomass data\n measured in 1 m x 1 m quadrats at several sites and experiments\n under the Sevilleta LTER program. Quadrat locations span four\n distinct ecosystems and their ecotones: creosotebush dominated\n Chihuahuan Desert shrubland (est. winter 1999), black\n grama-dominated Chihuahuan Desert grassland (est. winter 1999), blue\n grama-dominated Plains grassland (est. winter 2002), and\n pinon-juniper woodland (est. winter 2003). Data on plant cover and\n height for each plant species are collected per individual plant or\n patch (for clonal plants) within 1 m x 1 m quadrats. These data\n inform population dynamics of foundational and rare plant species.\n Biomass is estimated using plant allometries from non-destructive\n measurements of plant cover and height, and can be used to calculate\n net primary production (NPP), a fundamental ecosystem variable that\n quantifies rates of carbon consumption and fixation. Estimates of\n plant species cover, total plant biomass, or NPP can inform\n understanding of biodiversity, species composition, and energy flow\n at the community scale of biological organization, as well as\n spatial and temporal responses of plants to a range of ecological\n processes and direct experimental manipulations. The cover and\n height of individual plants or patches are sampled twice yearly\n (spring and fall) in permanent 1m x 1m plots within each site or\n experiment. This dataset includes core site monitoring data (CORE,\n GRIDS, ISOWEB, TOWER), observations in response to wildfire (BURN),\n and experimental treatments of extreme drought and delayed monsoon\n rainfall (EDGE), physical disturbance to biological soil crusts on\n the soil surface (CRUST), interannual variability in precipitation\n (MEANVAR), intra-annual variability via additions of monsoon\n rainfall (MRME), additions of nitrogen as ammonium nitrate\n (FERTILIZER), additions of nitrogen x phosphorus x potassium\n (NutNet), and interacting effects of nighttime warming, nitrogen\n addition, and El Niño winter rainfall (WENNDEx). To build allometric\n equations that relate biomass to plant cover or volume, the dataset\n "SEV-LTER quadrat plant cover and height data all sites and\n experiments" is used with a separate dataset of selectively\n harvested plant species "SEV-LTER Plant species mass data for\n allometry." Together, these datasets produced \u201cSEV-LTER quadrat\n plant species biomass all sites and experiments\u201d using the scripts\n posted with the allometry dataset. Data from the CORE sites in this\n dataset were designated as NA-US-011 in the Global Index of\n Vegetation-Plot Databases (GIVD). Data from the TOWER sites in this\n dataset are linked to Ameriflux sites:\n ameriflux.lbl.gov/doi/AmeriFlux/US-Seg and\n ameriflux.lbl.gov/sites/siteinfo/US-Ses."]} 

This is data for vegetation canopy cover measured from each of the SMES study plots. Vegetation canopy cover was measured from each of the 36 one-meter2 quadrats twice each year. Animal consumers have important roles in ecosystems, determining plant species composition and structure, regulating rates of plant production and nutrient, and altering soil structure and chemistry. The purpose of this study is to determine whether or not the activities of small mammals regulate plant community structure, plant species diversity, and spatial vegetation patterns in Chihuahuan Desert shrublands and grasslands. The purpose of this study is to determine whether or not the activities of small mammals regulate plant community structure, plant species diversity, and spatial vegetation patterns in Chihuahuan Desert shrublands and grasslands. What role if any do indigenous small mammal consumers have in maintaining desertified landscapes in the Chihuahuan Desert? Additionally, how do the effects of small mammals interact with changing climate to affect vegetation patterns over time? This study will provide long-term experimental tests of the roles of consumers on ecosystem pattern and process across a latitudinal climate gradient. The following questions or hypotheses will be addressed. 1) Do small mammals influence patterns of plant species composition and diversity, vegetation structure, and spatial patterns of vegetation canopy cover and biomass in Chihuahuan Desert shrublands and grasslands? Are small mammals keystone species that determine plant species composition and physiognomy of Chihuahuan Desert communities? Do small mammals have a significant role in maintaining the existence of shrub islands and spatial heterogeneity of creosotebush shrub communities? 2) Do small mammals affect the taxonomic composition and spatial pattern of vegetation similarly or differently in grassland communities as compared to shrub communities? How do patterns compare between grassland and shrubland sites, and how do these relatively small scale patterns relate to overall landscape vegetation patterns? 3) Do small mammals interact with short-term (annual) and long-term (decades) climate change to affect temporal changes in vegetation spatial patterns and species composition? 4) Do small mammals interact with other herbivore and granivore consumers enough to affect the species composition and abundances of other consumers such as ants and grasshoppers?