Estimates of recent biodiversity change remain inconsistent, debated, and infrequently assessed for their functional implications. Here, we report that spatial scale and type of biodiversity measurement influence evidence of temporal biodiversity change. We show a pervasive scale dependence of temporal trends in taxonomic (TD) and functional (FD) diversity for an ~50-year record of avian assemblages from North American Breeding Bird Survey and a record of global extinctions. Average TD and FD increased at all but the global scale. Change in TD exceeded change in FD toward large scales, signaling functional resilience. Assemblage temporal dissimilarity and turnover (replacement of species or functions) declined, while nestedness (tendency of assemblages to be subsets of one another) increased with scale. Patterns of FD change varied strongly among diet and foraging guilds. We suggest that monitoring, policy, and conservation require a scale-explicit framework to account for the pervasive effect that scale has on perceived biodiversity change.
Assessments of spatial patterns of biodiversity change are essential to detect a signature of anthropogenic impacts, inform monitoring and conservation programs, and evaluate implications of biodiversity loss to humans. While taxonomic diversity (
- NSF-PAR ID:
- 10045576
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Global Change Biology
- Volume:
- 23
- Issue:
- 8
- ISSN:
- 1354-1013
- Page Range / eLocation ID:
- p. 2999-3011
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
more » « less
Abstract The study of diversity has become increasingly sophisticated, including the use of measures of phylogenetic diversity.
We calculate the spatial variation in species richness, taxonomic beta diversity, and alpha and beta phylogenetic diversity (
PD α andPD β , respectively) of Atlantic Forest harvestman communities using a data set containing 556 species from 68 sites, distributed in 12 Brazilian states.We compare the congruence of phylogenetic and taxonomic diversity patterns, and also compare
PD α with null model expectations, to check for phylogenetic clustering or overdispersion in communities.Species richness and
PD α are correlated, peaking in southern and south‐eastern coastal sites and decreasing towards the interior and towards the north‐east.PD α in north‐eastern sites was higher than expected, while a clustered phylogenetic pattern characterised most other sites.Communities in the southern and south‐eastern regions were dominated by species from the large family Gonyleptidae, presenting a high richness and a low
PD α . As the dominance of Gonyleptidae decreased towards the north, where local communities have fewer species, but a higherPD α , they contain representatives of other families. The beta diversity was more sensitive to the compositional changes involving closely related Gonyleptidae species, whilePD β is more influenced by deeper phylogenetic compositional changes, between more distant lineages.Phylogenetic diversity may be of special importance to assess the conservation value of distantly related lineages. These species‐poor groups are less likely to influence taxonomic‐based diversity analyses, but their importance for conservation arises from their phylogenetic distinctiveness, captured by
PD α andPD β measures. -
more » « less
Abstract Genetic biodiversity contributes to individual fitness, species' evolutionary potential, and ecosystem stability. Temporal monitoring of the genetic status and trends of wild populations' genetic diversity can provide vital data to inform policy decisions and management actions. However, there is a lack of knowledge regarding which genetic metrics, temporal sampling protocols, and genetic markers are sufficiently sensitive and robust, on conservation‐relevant timescales. Here, we tested six genetic metrics and various sampling protocols (number and arrangement of temporal samples) for monitoring genetic erosion following demographic decline. To do so, we utilized individual‐based simulations featuring an array of different initial population sizes, types and severity of demographic decline, and
DNA markers [single nucleotide polymorphisms (SNP s) and microsatellites] as well as decline followed by recovery. Number of alleles markedly outperformed other indicators across all situations. The type and severity of demographic decline strongly affected power, while the number and arrangement of temporal samples had small effect. Sampling 50 individuals at as few as two time points with 20 microsatellites performed well (good power), and could detect genetic erosion while 80–90% of diversity remained. This sampling and genotyping effort should often be affordable. Power increased substantially with more samples or markers, and we observe that power of 2500SNP s was nearly equivalent to 250 microsatellites, a result of theoretical and practical interest. Our results suggest high potential for using historic collections in monitoring programs, and demonstrate the need to monitor genetic as well as other levels of biodiversity. -
more » « less
Abstract Aims Bryophytes can cover three quarters of the ground surface, play key ecological functions, and increase biodiversity in mesic high‐elevation conifer forests of the temperate zone. Forest gaps affect species coexistence (and ecosystem functions) as suggested by the gap and gap‐size partitioning hypotheses (
GPH ,GSPH ). Here we test these hypotheses in the context of high‐elevation forest bryophyte communities and their functional attributes.Study Site Spruce–fir forests on Whiteface Mountain, NY,
USA .Methods We characterized canopy openness, microclimate, forest floor substrates, vascular vegetation cover, and moss layer (cover, common species, and functional attributes) in three canopy openness environments (gap, gap edge, forest canopy) across 20 gaps (fir waves) (
n = 60); the functional attributes were based on 16 morphologic, reproductive, and ecological bryophyte plant functional traits (PFT s). We testedGPH andGSPH relative to bryophyte community metrics (cover, composition), traits, and trait functional sensitivity (functional dispersion;FDis ) using indicator species analysis, ordination, and regression.Results Canopy openness drove gradients in ground‐level temperature, substrate abundance and heterogeneity (beta diversity), and understory vascular vegetation cover. The
GPH was consistent with (a) the abundance patterns of forest canopy indicator species (Dicranum fuscescens ,Hypnum imponens , andTetraphis pellucida ), and (b)FDis based on threePFT s (growth form, fertility, and acidity), both increasing with canopy cover. We did not find support forGPH in the remaining species or traits, or forGSPH in general; gap width (12–44 m) was not related to environmental or bryophyte community gradients.Conclusions The observed lack of variation in most bryophyte metrics across canopy environments suggests high resistance of the bryophyte layer to natural canopy gaps in high‐elevation forests. However, responses of forest canopy indicator species suggest that canopy mortality, potentially increased by changing climate or insect pests, may cause declines in some forest canopy species and consequently in the functional diversity of bryophyte communities.
-
more » « less
Abstract Question It has been established that community biodiversity has consequences for ecosystem function. Yet research assessing these biodiversity–ecosystem function (
BEF ) relationships usually occurs at only one phylogenetic scale; as such, the dependence ofBEF relationships on phylogenetic scale has not been characterized. We present a novel framework for considering the consequences of biodiversity across phylogenetic scales, allowing us to ask: Do the consequences of intraspecific and interspecific diversity affect the growth, survival, and leaf herbivory of three temperate tree species?Study site Salicaceous tree plantation, Minnesota, northern USA.
Methods We established an experimental plantation consisting of trees of three species within the willow (Salicaceae) family. Two aspen (
Populus tremuloides ,P. alba ) and one willow (Salix nigra ) species were represented by three unique genotypes such that tree neighborhoods varied both in genotype richness (intraspecific diversity) and species richness (interspecific diversity). We assessed the consequences of tree identity and diversity across these two phylogenetic scales for all trees’ aboveground productivity and survival, and for herbivore damage (onP. tremuloides ) at the end of the second full growing season of the experiment.Results Diversity at any phylogenetic scale had no effect on the growth and survival of
P. alba orS. nigra . However, intraspecific diversity increased the likelihood ofP. tremuloides survival while interspecific diversity reducedP. tremuloides survival. Intraspecific diversity also reduced leaf removal and galling herbivory onP. tremuloides , while interspecific diversity had no effect on leaf removal and increased galling herbivory. Neither scale of diversity affected leaf mining.Conclusions Tree diversity within and among populations and species affected plant performance and ecosystem properties differentially, demonstrating that
BEF relationships shift across phylogenetic scales in a taxon‐specific manner. We call for further experiments that explicitly span these scales by measuring ecosystem and physiological responses to the manipulation of diversity within and among species.
