Distribution of plants in a California serpentine grassland: are rocky hummocks spatial refuges for native species?

Gram, Wendy K.; Borer, Elizabeth T.; Cottingham, Kathryn L.; Seabloom, Eric W.; Boucher, Virginia; Goldwasser, Lloyd; Micheli, Fiorenza; Kendall, Bruce E.; Burton, Rebecca S.

doi:10.1023/b:vege.0000026332.57007.7b

Cited by 45 publications

(50 citation statements)

References 40 publications

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“…These results are consistent with those of other studies, which have shown that fertilization increases the invasibility of serpentine grasslands (Turitzin 1982;Huenneke et al 1990;O'Dell and Claassen 2006). The serpentine outcrops in this All N P H20 Ca study were not only lower in N availability, but were also drier and considerably lower in Ca and Ca:Mg ratios than soils in the surrounding matrix (e.g., Huenneke et al 1990;Harrison 1999;Gram et al 2004). However, our results suggest that it is the low N, or low N in combination with other resources that primarily limits the invasion of three invasive grasses, suggesting that metal toxicity is not the primary factor limiting the invasions of these serpentine grasslands by exotic annual grasses.…”

Section: Discussionsupporting

confidence: 82%

“…Regional estimates for N depositions for Santa Barbara County range from 0 to 2 kg ha ¡1 year ¡1 (Takemoto et al 1995), suggesting that anthropogenic eVects on N inputs are minimal in this area. Our Weld site was a serpentine grassland located on south-facing slopes of the San Rafael range at an elevation of approximately 730 m. The grassland is composed of several distinct outcrops of shallow, rocky serpentine soil, which grade into a matrix of deeper, more fertile serpentine soil with a higher organic matter content (Gram et al 2004). The outcrops are dominated by native annual forbs and grasses.…”

Section: Study Systemmentioning

confidence: 99%

“…The matrix community is dominated by several non-native annual grasses, including Avena barbata, Bromus diandrus, Bromus madritensis, and Hordeum murinum. Gram et al (2004) provide a detailed description of the plant communities of both the outcrop and matrix habitats. Although gopher disturbance has been reported to be an important determinant of invasion success in other serpentine grasslands (Hobbs et al 1988), there was little gopher activity observed on the outcrops during the course of our study.…”

Section: Study Systemmentioning

confidence: 99%

“…Invasions in serpentine grasslands are remarkably patchy. Invaders are most successful in deeper, more resource-rich soils, but invader density is low on serpentine outcrops, which remain dominated by native forbs and grasses despite a potentially large pool of non-native propagules (Harrison 1999;Gram et al 2004).…”

Section: Introductionmentioning

confidence: 99%

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Abiotic and biotic resistance to grass invasion in serpentine annual plant communities

2009

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Biological invasions severely impact native plant communities, causing dramatic shifts in species composition and the restriction of native species to spatially isolated refuges. Competition from resident species and the interaction between resource limitation and competition have been overlooked as mechanisms of community resistance in refugia habitats. We examined the importance of these factors in determining the resistance of California serpentine plant communities to invasion by three common European grasses, Avena barbata, Bromus diandrus, and Hordeum murinum. We added seeds of each of these grasses to plots subjected to six levels of resource addition (N, P, Ca, H 2 O, all resources together, and a no-addition control) and two levels of competition (with resident community present or removed). Resource limitation and competition had strong eVects on the biomass and reproduction of the three invaders. The addition of all resources together combined with the removal of the resident community yielded individual plants that were fourfold to 20-fold larger and sixfold to 20-fold more fecund than plants from control plots. Competitor removal alone yielded invaders that were twofold to sevenfold larger and twofold to ninefold more fecund. N addition alone or in combination with other resources led to a twofold to ninefold increase in the biomass and fecundity of the invaders. No other resource alone signiWcantly aVected native or invader performance, suggesting that N was the key limiting resource during our experiment. We found a signiWcant interaction between abiotic and biotic resistance for Bromus, which experienced increased competitive suppression in fertilized plots. The threefold increase in resident biomass with N addition was likely responsible for this result. Our results conWrm that serpentine plant communities are severely N limited, which, in combination with competition from resident species, promotes the resistance of these systems to invasions. Our work suggests that better understanding the relative sensitivities of invaders and residents to the physical environment is critical to predicting how abiotic and biotic factors interact to determine community resistance.

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Section: Discussionsupporting

confidence: 82%

Section: Study Systemmentioning

confidence: 99%

Section: Study Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Abiotic and biotic resistance to grass invasion in serpentine annual plant communities

2009

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“…We then parameterize and apply this model to understand the potential for invasive plant impacts on native annual plant persistence in a spatially heterogeneous serpentine soil landscape in California. Invasions are widespread in these landscapes, and they have likely reduced the connectivity and extent of local native patches within the broader metapopulation (9,19). Serpentine landscapes support a disproportionate number of rare and threatened plant species, and therefore have a high conservation value (20).…”

mentioning

confidence: 99%

Plant invasions and extinction debts

Gilbert

Levine

2013

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

171

205

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Whether introduced species invasions pose a major threat to biodiversity is hotly debated. Much of this debate is fueled by recent findings that competition from introduced organisms has driven remarkably few plant species to extinction. Instead, native plant species in invaded ecosystems are often found in refugia: patchy, marginal habitats unsuitable to their nonnative competitors. However, whether the colonization and extinction dynamics of these refugia allow long-term native persistence is uncertain. Of particular concern is the possibility that invasive plants may induce an extinction debt in the native flora, where persistence over the short term masks deterministic extinction trajectories. We examined how invader impacts on landscape structure influence native plant persistence by combining recently developed quantitative techniques for evaluating metapopulation persistence with field measurements of an invaded plant community. We found that European grass invasion of an edaphically heterogeneous California landscape has greatly decreased the likelihood of the persistence of native metapopulations. It does so via two main pathways: (i) decreasing the size of native refugia, which reduces seed production and increases local extinction, and (ii) eroding the dispersal permeability of the matrix between refugia, which reduces their connectivity. Even when native plant extinction is the deterministic outcome of invasion, the time to extinction can be on the order of hundreds of years. We conclude that the relatively short time since invasion in many parts of the world is insufficient to observe the full impact of plant invasions on native biodiversity. metacommunity | metapopulation | invasive species | spatial ecology | temporal lag I ntroduced species are often considered a leading threat to native biodiversity (1, 2). However, recent syntheses show that competition from introduced species, and plant invaders in particular, has only rarely resulted in extinction (3-6). This trend has emerged because, in the short term at least, invasive plants do not completely extirpate native plant species but rather reduce their distribution and abundance, often restricting them to isolated habitat refugia (7-9). Despite well-established cases of native plants occupying distinct refugia and outperforming invasive plant species in those habitats (8, 10, 11), the long-term dynamics of native species in these refugia are poorly understood. Given the global prevalence of plant displacement by invasions, it is important to develop a general method for predicting how extinction debts may develop following invasions.The metapopulation framework, which considers a network of isolated populations connected via dispersal, provides an excellent starting point for understanding the long-term consequences of invasions. When native populations are relegated to spatially isolated refugia, their long-term persistence is regulated by the colonization and extinction dynamics in their entire metapopulation (12). A large body of work sugges...

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lakeCoSTR: A tool to facilitate use of Landsat Collection 2 to estimate lake surface water temperatures

et al. 2023

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Although remote sensing of lake surface water temperature has been ongoing for decades and has led to important discoveries regarding the warming of lake surface temperature in some regions, the ability to access and use remote sensing data is still primarily limited to remote sensing experts. Effective use of remote sensing data involves technical skills in coding (often in multiple programming languages), application of appropriate atmospheric corrections, and integrating spatially heterogeneous remote sensing data with in situ data obtained at specific geographic locations. To improve access to remote sensing data and broaden the understanding of changes in lake surface water temperature over the past four decades, we created lakeCoSTR (lake Collection 2 Surface Temperature Retrieval), a user‐friendly, cloud‐based script that gives ecologists lacking specialized training in remote sensing the ability to access the Landsat Collection 2 temperature estimates for lakes with a surface area of at least 0.4 ha. Additionally, if in situ data are provided, a paired dataset can be created within the tool. To demonstrate lakeCoSTR, we retrieved surface water temperature data for a lake with a long monitoring history, Lake Sunapee, NH, USA, and compared long‐term surface temperature trends between data obtained via lakeCoSTR and in situ measurements. When compared with Landsat Collection 1 temperature estimates derived from a single‐channel algorithm, the Landsat Collection 2 data from lakeCoSTR required no calibration to in situ data. This suggests that lakeCoSTR can be used to document temporal trends in lakes and to reprocess analyses that relied on Collection 1 data. From 1983 until 2020, remotely sensed surface water temperature estimates at Lake Sunapee increased by 0.07–0.09°C year−1 during July and August, a trend that agreed with long‐term in situ record. As climate change continues to impact freshwater systems, a better understanding of long‐term temperature data will be vital. Remotely sensed data, like those acquired using lakeCoSTR, may provide a window into temperature trends for lakes.

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Distribution of plants in a California serpentine grassland: are rocky hummocks spatial refuges for native species?

Cited by 45 publications

References 40 publications

Abiotic and biotic resistance to grass invasion in serpentine annual plant communities

Abiotic and biotic resistance to grass invasion in serpentine annual plant communities

Plant invasions and extinction debts

lakeCoSTR: A tool to facilitate use of Landsat Collection 2 to estimate lake surface water temperatures

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