Estimating local biodiversity change: a critique of papers claiming no net loss of local diversity

Abstract

Global species extinction rates are orders of magnitude above the background rate documented in the fossil record. However, recent data syntheses have found mixed evidence for patterns of net species loss at local spatial scales. For example, two recent data meta-analyses have found that species richness is decreasing in some locations and is increasing in others. When these trends are combined, these papers argued there has been no net change in species richness, and suggested this pattern is globally representative of biodiversity change at local scales. Here we reanalyze results of these data syntheses and outline why this conclusion is unfounded. First, we show the datasets collated for these syntheses are spatially biased and not representative of the spatial distribution of species richness or the distribution of many primary drivers of biodiversity change. This casts doubt that their results are representative of global patterns. Second, we argue that detecting the trend in local species richness is very difficult with short time series and can lead to biased estimates of change. Reanalyses of the data detected a signal of study duration on biodiversity change, indicating net biodiversity loss is most apparent in studies of longer duration. Third, estimates of species richness change can be biased if species gains during post-disturbance recovery are included without also including species losses that occurred during the disturbance. Net species gains or losses should be assessed with respect to common baselines or reference communities. Ultimately, we need a globally coordinated effort to monitor biodiversity so that we can estimate and attribute human impacts as causes of biodiversity change. A combination of technologies will be needed to produce regularly updated global datasets of local biodiversity change to guide future policy. At this time the conclusion that there is no net change in local species richness is not the consensus state of knowledge.

Anthropogenic ecosystem disturbance and the recovery debt

“…However, our recovery metric ‘diversity' includes other diversity measurements that account for differences in abundance, which could be responsible for this contrast. Nonetheless, our results agree with the worst scenarios estimated for the effects of land-use change on local species richness of plants and animals11, and with the reanalysis of references1415, showing that spatial and temporal biases in these meta-analysis do not support a no net change of α-diversity16. This highlights that species assemblages could be more resilient to anthropogenic disturbance than populations, even when most individuals are lost.…”

Reintroducing Environmental Change Drivers in Biodiversity–Ecosystem Functioning Research

“…In many ecosystems, environmental change causes biodiversity declines or increases [26–29]. Experiments that directly and randomly manipulate biodiversity are unlikely to predict function in these ecosystems (Fig.…”

Navigating the unfolding open data landscape in ecology and evolution

“…Second, working with a large amount of data requires careful consideration of the possible biases, statistical issues and inferences that can be drawn when using these data. For example, one recent study 32 identified multidimensional biases, gaps and uncertainties in global plant occurrence information data in the GBIF database, while another work 33 examined spatial biases in collected data sets used in two different meta-analysis that (wrongly) concluded that there was no net loss of biodiversity due to anthropogenic disturbances. This does not warn against data reuse, but rather calls for a rigorous scientific approach that identifies and accordingly addresses potential issues.…”