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The probability of an analysis returning the correct sign (direction) of a taxon's response to forest degradation as a function of the number of single-year surveys in which that taxon was detected. (A) Each grey line represents an analysis for one taxon (n = 494). (B) Violin plots showing the distribution of probabilities of a single-year survey returning the correct sign for seven taxonomic groups. Points indicate the probability for individual taxa within each group.
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The functional stability of ecosystems depends greatly on interspecific differences in responses to environmental perturbation. However, responses to perturbation are not necessarily invariant among populations of the same species, so intraspecific variation in responses might also contribute. Such inter-population response diversity has recently b...
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... having impacted forest growth patterns both through time and across space at our study site (19). We did, however, find that an extended logging event that occurred in the middle of our decade of observations, and that further reduced the biomass across large portions of the SAFE Project study area, influenced the pattern of survey results ( Fig. S3C; í µí¼ (2) 2 = 37.4, p < 0.001). We found increased intra-population response diversity for survey pairs occurring within the logging events relative to survey pairs occurring in non-disturbed years, indicating that species responses are more variable during extreme land use change events. This increased response diversity did not ...
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... estimate that any given taxon needs to be analysed in each of three surveys to gain reliable insight into the impacts of forest degradation (Fig. 3A). Of the four response diversity classes, getting the direction (sign) of an effect wrong is the most immediately problematic: it could lead directly to management decisions that are the exact opposite of what is needed. We therefore used Bayesian hierarchical models to estimate the observed variation within and among taxon-specific ...
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... the observed variation within and among taxon-specific surveys, and so determine the probability that analysis of a single-year survey will return the correct sign. This probability was less than 80 % -the assumed power of standard statistical tests -for one fifth of all taxa (n = 109; 21 %), but varied significantly among taxonomic groups (Fig. 3B, Kruskal-Wallis: í µí¼ (6) 2 = 78.9, p < 0.001). Birds were most likely to return correct signs from a single survey, while invertebrates were the least likely. On average, three surveys were needed to ensure a 90 % probability of getting the right direction of effect for 90 % of taxa (Fig. ...
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... %), but varied significantly among taxonomic groups (Fig. 3B, Kruskal-Wallis: í µí¼ (6) 2 = 78.9, p < 0.001). Birds were most likely to return correct signs from a single survey, while invertebrates were the least likely. On average, three surveys were needed to ensure a 90 % probability of getting the right direction of effect for 90 % of taxa (Fig. ...
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... study site: a general year effect; El Niño events that occurred in 2010 and again in 2015/16; and a salvage logging operation that impacted large areas of the landscape over the years 2012-2015. The first of these was tested by quantifying, for each year, the proportion of pairwise comparisons involving that year that exhibited response diversity (Fig. S3A). We quantified this proportion for each of the years for which we had survey data (2010 -2020 inclusive), and tested for an effect of the number of years separating the two surveys on the whether they had invariant or different response patterns. This was tested using using a binomial GLMM, including taxon identity as a random effect. ...
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... within an El Niño or logging event. For each group, we quantified the proportion of pairwise comparisons that exhibited invariant responses (Fig S3B,C). If either of these events were a strong driver of meaningful response diversity, we would expect to see a higher proportion of taxa exhibiting response diversity in survey pairs either straddling or embedded within these disturbance events. ...
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... having impacted forest growth patterns both through time and across space at our study site (19). We did, however, find that an extended logging event that occurred in the middle of our decade of observations, and that further reduced the biomass across large portions of the SAFE Project study area, influenced the pattern of survey results ( Fig. S3C; í µí¼ (2) 2 = 37.4, p < 0.001). We found increased intra-population response diversity for survey pairs occurring within the logging events relative to survey pairs occurring in non-disturbed years, indicating that species responses are more variable during extreme land use change events. This increased response diversity did not ...
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... estimate that any given taxon needs to be analysed in each of three surveys to gain reliable insight into the impacts of forest degradation (Fig. 3A). Of the four response diversity classes, getting the direction (sign) of an effect wrong is the most immediately problematic: it could lead directly to management decisions that are the exact opposite of what is needed. We therefore used Bayesian hierarchical models to estimate the observed variation within and among taxon-specific ...
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... the observed variation within and among taxon-specific surveys, and so determine the probability that analysis of a single-year survey will return the correct sign. This probability was less than 80 % -the assumed power of standard statistical tests -for one fifth of all taxa (n = 109; 21 %), but varied significantly among taxonomic groups (Fig. 3B, Kruskal-Wallis: í µí¼ (6) 2 = 78.9, p < 0.001). Birds were most likely to return correct signs from a single survey, while invertebrates were the least likely. On average, three surveys were needed to ensure a 90 % probability of getting the right direction of effect for 90 % of taxa (Fig. ...
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... %), but varied significantly among taxonomic groups (Fig. 3B, Kruskal-Wallis: í µí¼ (6) 2 = 78.9, p < 0.001). Birds were most likely to return correct signs from a single survey, while invertebrates were the least likely. On average, three surveys were needed to ensure a 90 % probability of getting the right direction of effect for 90 % of taxa (Fig. ...
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... study site: a general year effect; El Niño events that occurred in 2010 and again in 2015/16; and a salvage logging operation that impacted large areas of the landscape over the years 2012-2015. The first of these was tested by quantifying, for each year, the proportion of pairwise comparisons involving that year that exhibited response diversity (Fig. S3A). We quantified this proportion for each of the years for which we had survey data (2010 -2020 inclusive), and tested for an effect of the number of years separating the two surveys on the whether they had invariant or different response patterns. This was tested using using a binomial GLMM, including taxon identity as a random effect. ...
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... within an El Niño or logging event. For each group, we quantified the proportion of pairwise comparisons that exhibited invariant responses (Fig S3B,C). If either of these events were a strong driver of meaningful response diversity, we would expect to see a higher proportion of taxa exhibiting response diversity in survey pairs either straddling or embedded within these disturbance events. ...
Citations
... We summarized taxon responses from 8,130 combinations of surveys and taxa. We compiled biodiversity data from 55 published data sources (Supplementary Table 1), from which we extracted presence-absence data following the methods of ref. 123. Previous analyses of multi-taxa biodiversity data have demonstrated that comparisons of presence-absence data among taxa are more robust than analyses of abundance data 23,124 . ...
... Moreover, abundance data were not available for all taxa, meaning that presence-absence data are the highest-level data that allowed us to use exactly the same analysis method for all taxa. Data sources that sampled multiple years were split into separate, annual surveys, allowing us to more accurately align biodiversity observations with forest degradation measurements taken at different time points, and to account for year-to-year variation in taxon-specific responses to the same ecological gradient 123 . Data sources that included multiple sampling methods were also split into separate, method-specific surveys 123 . ...
... Data sources that sampled multiple years were split into separate, annual surveys, allowing us to more accurately align biodiversity observations with forest degradation measurements taken at different time points, and to account for year-to-year variation in taxon-specific responses to the same ecological gradient 123 . Data sources that included multiple sampling methods were also split into separate, method-specific surveys 123 . This process resulted in a total of 127 surveys being used for analysis. ...
Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems¹ that provide refugia for large amounts of biodiversity2,3, so we cannot afford to underestimate their conservation value⁴. Here we present empirically defined thresholds for categorizing the conservation value of logged forests, using one of the most comprehensive assessments of taxon responses to habitat degradation in any tropical forest environment. We analysed the impact of logging intensity on the individual occurrence patterns of 1,681 taxa belonging to 86 taxonomic orders and 126 functional groups in Sabah, Malaysia. Our results demonstrate the existence of two conservation-relevant thresholds. First, lightly logged forests (<29% biomass removal) retain high conservation value and a largely intact functional composition, and are therefore likely to recover their pre-logging values if allowed to undergo natural regeneration. Second, the most extreme impacts occur in heavily degraded forests with more than two-thirds (>68%) of their biomass removed, and these are likely to require more expensive measures to recover their biodiversity value. Overall, our data confirm that primary forests are irreplaceable⁵, but they also reinforce the message that logged forests retain considerable conservation value that should not be overlooked.
