Power laws and plant trait variation in spatio‐temporally heterogeneous environments

Hulshof, Catherine M.; Umaña, María Natalia

doi:10.1111/geb.13620

Cited by 5 publications

(5 citation statements)

References 154 publications

(235 reference statements)

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“…astrophysics, geography, mathematics) to affect variance-let alone biodiversity. Specifically, the idea of variance scaling, or that increasing scale begets increasing variance, is a universal phenomenon and is widely studied (Hulshof & Umaña, 2022). It is intuitive, then, that managing large complex landscapes based on hypothesized invasive species effects from highly manipulated, small-scale studies (i.e.…”

Section: F I G U R Ementioning

confidence: 99%

A plea for scale, and why it matters for invasive species management, biodiversity and conservation

McMillan

Fuhlendorf

Davis

et al. 2023

Journal of Applied Ecology

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Invasive species are suspected to be major contributors to biodiversity declines worldwide. Counterintuitively, however, invasive species effects are likely scale dependent and are hypothesized to be positively related to biodiversity at large spatial scales. Past studies investigating the effect of invasion on biodiversity have been mostly conducted at small scales (<100 m2) that cannot represent large dynamic landscapes by design. Therefore, replicated experimental evidence supporting a negative effect of invasive plants on biodiversity is lacking across many landscape types, including large grasslands. We collected data across eight large (333–809 ha) grassland landscapes managed with pyric herbivory—that is the recoupling of fire and grazing—to test how an invasive legume Lespedeza cuneata affected plant and bird communities at spatial grains ranging from 0.1 m2 to >3,000,000 m2. Lespedeza cuneata invasion effects on grassland plant diversity and composition changed with scale, being negative at small spatial grains (0.1 m2) and neutral or positive at large spatial grains (>3,000,000 m2). Lespedeza cuneata abundance did not significantly affect bird diversity at any spatial grain measured. Lespedeza cuneata may negatively affect biodiversity if abundances are greater than those observed in this study. However, previous research suggests that Lespedeza cuneata may not be capable of exceeding 20% canopy cover across large landscapes (>400 ha). Control and eradication strategies can be costly and are fraught with risk. If data do not clearly support a negative Lespedeza cuneata abundance–biodiversity relationship, and if invasion is spatially limited across large landscapes, ongoing control and eradication efforts may be unwarranted and ineffective. Synthesis and applications: Invasive species effects gleaned from small‐scale studies may not reliably predict their effects at larger scales. Although we recognize the importance of small‐scale studies in potentially isolating individual mechanisms, management strategies based solely on results from small‐scale studies of invasion are unlikely to increase or conserve biodiversity across large landscapes. Rather, processes that generate landscape heterogeneity—like pyric herbivory—are probably more important for promoting biodiversity across all scales. Scale is a central problem in ecology, and defining scale in management objectives is essential for effective biodiversity conservation.

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Section: F I G U R Ementioning

confidence: 99%

A plea for scale, and why it matters for invasive species management, biodiversity and conservation

McMillan

Fuhlendorf

Davis

et al. 2023

Journal of Applied Ecology

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“…To better understand the processes underlying the SAR, making a transition from a taxonomically descriptive and pattern-based approach towards a more predictive and generalizable processbased ecological approach, could make functional traits a valuable tool (Ellis et al 2021;Hulshof & Umaña 2023). An increase in traits variation with increasing area size has been demonstrated for lichens, although this is dependent not only on the area size but also on scale and environmental factors (Giordani et al 2019).…”

Section: Implications For Conservation and Future Perspectivesmentioning

confidence: 99%

Species–area relationship in lichens tested in protected areas across Italy

Gheza,

Di Nuzzo,

Giordani

et al. 2023

The Lichenologist

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The species–area relationship (SAR) states that species richness increases with the increase of the sampled area, although other factors can influence the pattern. SARs have been tested on many different organisms, but only rarely on lichens. We aimed to test the SAR, across a wide range of area sizes, for three main substratum-related guilds of lichens, namely epiphytic, epilithic and epigaeic. The test was performed using data from lichen inventories carried out in 44 protected areas of various sizes across Italy. We found a positive correlation of species richness with area size for all three guilds, better fitted by the logarithmic function for epilithic lichens and by the power function for epiphytic and epigaeic lichens. Our results support the fundamental role of area size as the main driver for lichen diversity, suggesting that in an area-based conservation framework, larger protected areas are fundamental to support high lichen species richness. However, finer scale investigations are also required to better elucidate whether and how other environmental factors could interact with area size and modify SAR patterns. Exhaustive lichen inventories could be useful information sources to more robustly test such relationships, and therefore better inform conservation practices.

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“…We suggest that the slope of this relationship will vary as a result of biological processes and spatiotemporal environmental variability (Hulshof & Umaña, 2022), such that at increasing spatiotemporal scales (greater environmental variability) the relationship between log-transformed trait mean and log-transformed trait variance should exhibit steeper positive slopes (Hulshof & Umaña 2022;Kalyuzhny et al, 2014) (Figure 1). A key assumption underlying the integration of spatiotemporal scales into this existing empirical model is that environmental variability increases with both area and time.…”

Section: Introductionmentioning

confidence: 99%

“…In a recent paper, Hulshof and Umaña (2022) call for the characterization of trait variation across spatiotemporal scales by taking advantage of existing empirical models used to characterize taxonomic patterns. Taylor's Power Law is of particular interest, given that it can integrate variation across temporal and spatial scales (Adler et al, 2005; Taylor, 1961; White et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Characterizing tree trait variance over spatiotemporal scales

Umaña

Hulshof

2023

Ecology

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Beyond the study of the mean, functional ecology lacks a concise characterization of trait variance patterns across spatiotemporal scales. Traits are measured in different ways, using different metrics, and at different spatial (and rarely temporal) scales. This study expands on previous research by applying a ubiquitous and widely used empirical model—Taylor's Power Law—to functional trait variance with the goal of identifying general patterns of trait variance scaling (the behavior of trait variance across scales). We compiled data on tree seedling communities monitored over 10 years across 213 2 m2 plots and functional trait data from a subtropical forest in Puerto Rico. We examined trait‐based Taylor's Power Law at nested spatial and temporal scales. The scaling of variance with the mean was idiosyncratic across traits suggesting that the drivers of variation are likely to differ across traits that may make variance scaling theory elusive. However, slopes varied more in space than through time, suggesting that spatial environmental variability may have a larger role in driving trait variance than temporal variability. Empirical models that characterize taxonomic patterns across spatiotemporal scales, like Taylor's Power Law, can provide an insight into the scaling of functional traits, a necessary next step toward a more predictive trait‐based ecology.

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Power laws and plant trait variation in spatio‐temporally heterogeneous environments

Cited by 5 publications

References 154 publications

A plea for scale, and why it matters for invasive species management, biodiversity and conservation

A plea for scale, and why it matters for invasive species management, biodiversity and conservation

Species–area relationship in lichens tested in protected areas across Italy

Characterizing tree trait variance over spatiotemporal scales

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