Temporal variability and nestedness in California grassland species composition

Elmendorf, Sarah C.; Harrison, Susan

doi:10.1890/08-1677.1

Cited by 51 publications

(50 citation statements)

References 49 publications

(62 reference statements)

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“…30; Methods). Local species richness was higher in years of higher rainfall (31,32), as has been seen in other studies in similar grasslands (e.g., ref. 28).…”

supporting

confidence: 87%

“…46), our study and other recent results (8) suggest that declining community diversity may be especially likely in water-limited climates as these become more arid and less productive. In previous analyses of these data, species diversity was higher in wetter years, and species present in drier years were subsets of those found in wetter years (31,32).…”

Section: Discussionmentioning

confidence: 79%

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Climate-driven diversity loss in a grassland community

Harrison

Gornish

Copeland

2015

Proc. Natl. Acad. Sci. U.S.A.

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142

167

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Local ecological communities represent the scale at which species coexist and share resources, and at which diversity has been experimentally shown to underlie stability, productivity, invasion resistance, and other desirable community properties. Globally, community diversity shows a mixture of increases and decreases over recent decades, and these changes have relatively seldom been linked to climatic trends. In a heterogeneous California grassland, we documented declining plant diversity from 2000 to 2014 at both the local community (5 m 2 ) and landscape (27 km 2 ) scales, across multiple functional groups and soil environments. Communities became particularly poorer in native annual forbs, which are present as small seedlings in midwinter; within native annual forbs, community composition changed toward lower representation of species with a trait indicating drought intolerance (high specific leaf area). Time series models linked diversity decline to the significant decrease in midwinter precipitation. Livestock grazing history, fire, succession, N deposition, and increases in exotic species could be ruled out as contributing causes. This finding is among the first demonstrations to our knowledge of climate-driven directional loss of species diversity in ecological communities in a natural (nonexperimental) setting. Such diversity losses, which may also foreshadow larger-scale extinctions, may be especially likely in semiarid regions that are undergoing climatic trends toward higher aridity and lower productivity.L arge-scale elevational and latitudinal range shifts, altered seasonal timing, and disrupted interactions among interdependent species are well-known consequences of recent global warming, all of which are predicted to intensify in coming decades and to be accompanied by increasing rates of global extinction (1-4). Consequences of rapid climate change for the diversity of local ecological communities are far less clear; diversity might increase or decrease at any given location, depending on the particular nature of climatic changes and the potential for dispersal (5-8).

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“…30; Methods). Local species richness was higher in years of higher rainfall (31,32), as has been seen in other studies in similar grasslands (e.g., ref. 28).…”

supporting

confidence: 87%

Section: Discussionmentioning

confidence: 79%

Climate-driven diversity loss in a grassland community

Harrison

Gornish

Copeland

2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

142

167

View full text Add to dashboard Cite

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“…Nestedness has been widely used to measure the structure of biological communities (Fleishman and Murphy 1999;Hylander et al 2005;Meyer and Kalko 2008;Elmendorf and Harrison 2009), including lentic freshwaters (Baber et al 2004;McAbendroth et al 2005;Angeler et al 2008;Wissinger et al 2009), although few studies have explored the factors which may drive this pattern. Factors that lead to consistent differences amongst species in immigration or extinction rates cause strong patterns of nestedness across species assemblages (Wright and Reeves 1992).…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal nested patterns in macroinvertebrate assemblages across a pond network with a wide hydroperiod range

et al. 2010

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Nestedness has been widely used to measure the structure of biological communities and occurs when species-poor sites contain subsets of species-rich ones. Here, we examine nested patterns across the macroinvertebrate assemblages of 91 ponds in Doñana National Park, Spain, and explore temporal variation of nestedness and species richness in 19 temporary ponds over 2 years with differing rainfall. Macroinvertebrate assemblages were significantly nested; both pond spatial arrangement and environmental variation being important in driving nested patterns. Despite the nested structure observed, a number of taxa and ponds deviate from this pattern (termed idiosyncratic), by occurring more frequently than expected in species-poor sites, or having assemblages dominated by species largely absent from species-rich sites. Aquatic adults of winged insects, capable of dispersal, were more highly nested than non-dispersing taxa and life-history stages. Idiosyncratic taxa were found in ponds spanning a wide range of hydroperiods, although nestedness was higher in more permanent waterbodies. Monthly sampling demonstrated a gradual increase of species richness and nestedness from pond filling to April-May, when the most temporary ponds started to dry. Although the degree of nestedness of individual pond assemblages varied from month to month, the overall degree of nestedness in the two study years was practically identical despite marked differences in hydroperiod. Our results suggest that differential colonization and environmental variation are key processes driving the nested structure of Doñana ponds, that macroinvertebrate assemblages change in a predictable manner each year in response to cycles of pond wetting and drying, and that connectivity and environmental variability maintain biodiversity in pond networks.

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“…In dry-lands, inter-annual climatic fluctuations are high, forcing species to cope with extreme values of the environmental factors. Consequently, they often exhibit a dynamic turnover involving shifts in the abundance of response groups when a rainy year is followed by a severely dry one, especially in communities dominated by annual species (Aronson & Shmida 1992, Adler & Levine 2007, Elmendorf & Harrison 2009). Therefore, in contrast to more mesic areas, less abundant species in dry-lands are likely to play a major role in the ecosystem resilience, as a consequence of their capability of exploiting outstanding environmental conditions, as proposed by the complementarity hypothesis (Grime 1998, Walker et al 1999, Loreau 2000.…”

Section: Evenness and Quantification Of Less Abundant Speciesmentioning

confidence: 99%

Advantages of the point-intercept method for assessing functional diversity in semi-arid areas

Nunes¹,

Tapia²,

Pinho³

et al. 2015

iForest

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© iForest -Biogeosciences and Forestry IntroductionSemi-arid ecosystems are characterized by water scarcity and often by low soil productivity. Due to global change, they are highly vulnerable to losses of biodiversity, which underpins many critical ecosystem services (Reynolds et al. 2007). The more dramatic effects on these ecosystems are often preceded by subtle changes in relative species' abundance and/or in the dominance of specific functional traits (Chapin et al. 2000, Scheffer et al. 2001. Even in less abundant functional groups (e.g., nitrogen-fixers), the loss of critical traits that ensure ecosystem functioning and resilience may have important consequences (Grime 1998, Walker et al. 1999. The detection of such changes may be a hint of significant ecosystem transitions.Species richness has traditionally been used to assess an ecosystem's response to environmental factors, and has been related to ecosystem multi-functionality (Maestre et al. 2012a). These relationships are largely modulated by other community attributes, such as species evenness and functional identity and divergence, which often respond more rapidly to environmental constraints than richness, and may have a strong impact on ecosystem processes (Chapin et al. 2000, Mouillot et al. 2011, Maestre et al. 2012b. Functional diversity, defined as the value, range, and relative abundance of the functional traits of biological communities in a given ecosystem, was shown to be a better and more universal predictor of ecosystem vulnerability than species diversity, which does not reflect the uneven role played by species in the maintenance of ecosystem processes (Tilman et al. 1997, Díaz et al. 2007). Functional diversity is usually assessed by the use of several metrics (e.g., communityweighted mean and functional richness, evenness, and divergence). Recent investigations have demonstrated the better predictive ability of indexes that consider species abundances rather than richness alone (Schleuter et al. 2010, Mouillot et al. 2011. However, there is no consensus on the best field method for functional diversity assessment. Biomass (Prieur-Richard et al. 2002), frequency (De Bello et al. 2005), and most commonly cover (Frenette-Dussault et al. 2012, Lavorel et al. 2008 Semi-arid areas are particularly susceptible to the loss of biodiversity as a consequence of global change. Species functional traits are key drivers of functioning and resilience of ecosystems, thus monitoring of functional trait diversity is urgently needed. The assessment of functional diversity requires the quantification of species and/or their traits in the field, though there is no consensus on the best plant-sampling method to be used. The aim of this study was to compare the performance of the point-intercept (PT) method with two area-based approaches, the modified-Whittaker (MW) and Dengler (DE) methods, to assess functional diversity in semi-arid areas. The herbaceous community of a savanna-like Mediterranean woodland was surveyed at the two extremes of a regional...

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Temporal variability and nestedness in California grassland species composition

Cited by 51 publications

References 49 publications

Climate-driven diversity loss in a grassland community

Climate-driven diversity loss in a grassland community

Spatio-temporal nested patterns in macroinvertebrate assemblages across a pond network with a wide hydroperiod range

Advantages of the point-intercept method for assessing functional diversity in semi-arid areas

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