More Like this

1. Riparian plant species differ in sensitivity to both the mean and variance in groundwater stores

   https://doi.org/10.1093/jpe/rtaa049  

   Steinberg, Kelly A ; Eichhorst, Kim D ; Rudgers, Jennifer A ( October 2020 , Journal of Plant Ecology)

   Hui, Dafeng (Ed.)

   Abstract Aims Determining the ecological consequences of interactions between slow changes in long-term climate means and amplified variability in climate is an important research frontier in plant ecology. We combined the recent approach of climate sensitivity functions with a revised hydrological ‘bucket model’ to improve predictions on how plant species will respond to changes in the mean and variance of groundwater resources. Methods We leveraged spatiotemporal variation in long-term datasets of riparian vegetation cover and groundwater levels to build the first groundwater sensitivity functions for common plant species of dryland riparian corridors. Our results demonstrate the value of this approach to identifying which plant species will thrive (or fail) in an increasingly variable climate layered with declining groundwater stores. Important Findings Riparian plant species differed in sensitivity to both the mean and variance in groundwater levels. Rio Grande cottonwood (Populus deltoides ssp. wislizenii) cover was predicted to decline with greater inter-annual groundwater variance, while coyote willow (Salix exigua) and other native wetland species were predicted to benefit from greater year-to-year variance. No non-native species were sensitive to groundwater variance, but patterns for Russian olive (Elaeagnus angustifolia) predict declines under deeper mean groundwater tables. Warm air temperatures modulated groundwater sensitivity for cottonwood, which was more sensitive to variability in groundwater in years/sites with warmer maximum temperatures than in cool sites/periods. Cottonwood cover declined most with greater intra-annual coefficients of variation (CV) in groundwater, but was not significantly correlated with inter-annual CV, perhaps due to the short time series (16 years) relative to cottonwood lifespan. In contrast, non-native tamarisk (Tamarix chinensis) cover increased with both intra- and inter-annual CV in groundwater. Altogether, our results predict that changes in groundwater variability and mean will affect riparian plant communities through the differential sensitivities of individual plant species to mean versus variance in groundwater stores. 

   more » « less
2. Middle Rio Grande riparian plant cover sensitivity to variability in groundwater depth collected by the Bosque Ecosystem Monitoring Program

   https://doi.org/10.6073/pasta/b0bb59fd39e327b2452be059cc6a8440  

   Eichhorst, Kim D ( January 2020 , Environmental Data Initiative)

   Determining the ecological consequences of interactions between slow changes in long-term climate means and amplified variability in climate is an important research frontier in plant ecology. We combined the recent approach of climate sensitivity functions with a revised hydrological ‘bucket model’ to improve predictions on how plant species will respond to future changes in both the mean and variance of groundwater resources. We leveraged spatiotemporal variation in a long-term dataset of riparian vegetation cover to build the first groundwater sensitivity functions (GSFs) for common plant species of dryland riparian corridors. Our results demonstrate the value of this approach to identifying which plant species will thrive (or fail) in an increasingly variable climate layered on top of declining groundwater stores. Riparian plant species differed in sensitivity to both the mean and variance in groundwater levels. Rio Grande cottonwood (Populus deltoides ssp. wislizenii) cover was predicted to decline with greater interannual groundwater variance, while coyote willow (Salix exigua) and other native wetland species were predicted to benefit from greater year-to-year variance. No non-native species were sensitive to groundwater variance, but patterns for Russian olive (Elaeagnus angustifolia) predict declines under deeper mean groundwater tables. Warm air temperatures modulated groundwater sensitivity for cottonwood, which was more sensitive to variability in groundwater in years/sites with warmer maximum temperatures than in cool sites/periods. Cottonwood cover declined most with greater intra-annual coefficients of variation (CV) in groundwater, but was not significantly correlated with inter-annual CV, perhaps due to the relatively short time series (16 y) relative to cottonwood lifespan. In contrast, non-native tamarisk (Tamarix chinensis) cover increased with both intra- and inter-annual CV in groundwater. Altogether, our results predict that changes in groundwater variability and mean will affect riparian plant communities through the differential sensitivities of individual plant species to mean versus variance in groundwater stores. 

   more » « less
3. Introduced annuals mediate climate‐driven community change in Mediterranean prairies of the Pacific Northwest, USA

   https://doi.org/10.1111/ddi.13426  

   Reed, Paul B. ; Pfeifer‐Meister, Laurel E. ; Roy, Bitty A. ; Johnson, Bart R. ; Bailes, Graham T. ; Nelson, Aaron A. ; Bridgham, Scott D. ; Irl, ed., Severin ( November 2021 , Diversity and Distributions)

   How climate change will alter plant functional group composition is a critical question given the well‐recognized effects of plant functional groups on ecosystem services. While climate can have direct effects on different functional groups, indirect effects mediated through changes in biotic interactions have the potential to amplify or counteract direct climatic effects. As a result, identifying the underlying causes for climate effects on plant communities is important to conservation and restoration initiatives.

   Western Pacific Northwest (Oregon and Washington), USA.

   Utilizing a 3‐year experiment in three prairie sites across a 520‐km latitudinal climate gradient, we manipulated temperature and precipitation and recorded plant cover at the peak of each growing season. We used structural equation models to examine how abiotic drivers (i.e. temperature, moisture and soil nitrogen) controlled functional group cover, and how these groups in turn determined overall plant diversity.

   Warming increased the cover of introduced annual species, causing subsequent declines in other functional groups and diversity. While we found direct effects of temperature and moisture on extant vegetation (i.e. native annuals, native perennials and introduced perennials), these effects were typically amplified by introduced annuals. Competition for moisture and light or space, rather than nitrogen, were critical mechanisms of community change in this seasonally water‐limited Mediterranean‐climate system. Diversity declines were driven by reductions in native annual cover and increasing dominance by introduced annuals.

   A shift towards increasing introduced annual dominance in this system may be akin to that previously experienced in California grasslands, resulting in the “Californication” of Pacific Northwest prairies. Such a phenomenon may challenge local land managers in their efforts to maintain species‐rich and functionally diverse prairie ecosystems in the future.

    

   more » « less
4. Groundwater Well Data from the Middle Rio Grande Valley Riparian Zone, New Mexico (1999-2014)

   https://doi.org/10.6073/pasta/93d78d60c4672a8120d573d844739286  

   Thibault, Jim ; Dahm, Clifford ( January 2021 , Environmental Data Initiative)

   This study originated with the objective of parameterizing riparian evapotranspiration (ET) in the water budget of the middle Rio Grande of New Mexico.  We hypothesized that flooding and invasions of non-native species would impact the ecosystem's use of water.  Our objectives were to measure and compare the ET of native (Rio Grande cottonwood, Populus deltoides ssp. wizleni) and non-native (saltcedar, Tamarix chinensis, Russian olive, Eleagnus angustifolia) bosque (woodland) communities and to evaluate how water use is affected by climatic variability resulting in high river flows and flooding as well as drought conditions and deep water tables.  This data set contains water table levels monitored at nine sites along the Rio Grande riparian corridor between Albuquerque and Bosque del Apache National Wildlife Refuge.  Data date to 1999.  Two sites remain active and are well into their second decade of monitoring.  One is in a xero-riparian, non-flooding, saltcedar woodland within the Sevilleta National Wildlife Refuge.  The other is in a dense, monotypic saltcedar thicket at the Bosque del Apache NWR that is subject to flood pulses associated with high river flows.   

   more » « less
5. Vegetation on mesic loamy and sandy soils along a 1700‐km maritime Eurasia Arctic Transect

   https://doi.org/10.1111/avsc.12401  

   Walker, Donald A. ; Epstein, Howard E. ; Šibík, Jozef ; Bhatt, Uma ; Romanovsky, Vladimir E. ; Breen, Amy L. ; Chasníková, Silvia ; Daanen, Ronald ; Druckenmiller, Lisa A. ; Ermokhina, Ksenia ; et al ( February 2019 , Applied Vegetation Science)

   How do plant communities on zonal loamy vs. sandy soils vary across the full maritime Arctic bioclimate gradient? How are plant communities of these areas related to existing vegetation units of the European Vegetation Classification? What are the main environmental factors controlling transitions of vegetation along the bioclimate gradient?

   1700‐km Eurasia Arctic Transect (EAT), Yamal Peninsula and Franz Josef Land (FJL), Russia.

   The Braun‐Blanquet approach was used to sample mesic loamy and sandy plots on 14 total study sites at six locations, one in each of the five Arctic bioclimate subzones and the forest–tundra transition. Trends in soil factors, cover of plant growth forms (PGFs) and species diversity were examined along the summer warmth index (SWI) gradient and on loamy and sandy soils. Classification and ordination were used to group the plots and to test relationships between vegetation and environmental factors.

   Clear, mostly non‐linear, trends occurred for soil factors, vegetation structure and species diversity along the climate gradient. Cluster analysis revealed seven groups with clear relationships to subzone and soil texture. Clusters at the ends of the bioclimate gradient (forest–tundra and polar desert) had many highly diagnostic taxa, whereas clusters from the Yamal Peninsula had only a few. Axis 1 of a DCA was strongly correlated with latitude and summer warmth; Axis 2 was strongly correlated with soil moisture, percentage sand and landscape age.

   Summer temperature and soil texture have clear effects on tundra canopy structure and species composition, with consequences for ecosystem properties. Each layer of the plant canopy has a distinct region of peak abundance along the bioclimate gradient. The major vegetation types are weakly aligned with described classes of the European Vegetation Checklist, indicating a continuous floristic gradient rather than distinct subzone regions. The study provides ground‐based vegetation data for satellite‐based interpretations of the western maritime Eurasian Arctic, and the first vegetation data from Hayes Island, Franz Josef Land, which is strongly separated geographically and floristically from the rest of the gradient and most susceptible to on‐going climate change.

    

   more » « less