Niebuhr, B. B. | Search bioRxiv

bioRxiv2023

The Atlantic Forest of South America: spatiotemporal dynamic of remaining vegetation and implications for conservation

The Atlantic Forest in South America (AF) is one of the worlds most diverse and threatened biodiversity hotspots. We present a comprehensive spatiotemporal analysis of 34 years of AF landscape change between 1986-2020. We analyzed landscape metrics of forest vegetation only (FV), forest plus other natural vegetation (NV), and investigated the sensitivity of metrics to linear infrastructure. Currently, remnants comprise about 23% of FV and 36% of NV, and have decreased by 2.4% and 3.6% since 1986, respectively. Linear infrastructure negatively affected large fragments (>500,000 ha) by breaking them apart. Our findings suggest that AF protection legislation adopted in mid-2005 has taken effect: between 1986-2005, there was a loss of FV and NV (3% and 3.45%) and a decrease in the number of FV and NV fragments (8.6% and 8.3%). Between 2005-2020, there was a relative recovery of FV (1 Mha; 0.6%), slight loss of NV (0.25 Mha; 0.15%) and increase in the number of FV and NV fragments (12% and 9%). Still, 97% of the vegetation fragments are small (<50 ha), with an average fragment size between 16 and 26 ha. Furthermore, 50-60% of the vegetation is <90 m from its edges, and the isolation between fragments is high (250-830 m). Alarmingly, protected areas and indigenous territories cover only 10% of the AF and are very far from any fragments (>10 km). Our work highlights the importance of legislation and landscape dynamics analysis to help monitor and keep track of AF biodiversity conservation and restoration programs in the future. HighlightsO_LIThere is 23% forest and 36% natural vegetation cover remaining in the Atlantic Forest. C_LIO_LIBetween 1986-2020, native forest cover decreased by 2.4% and natural vegetation by 3.6%. C_LIO_LISince 2005, there has been a 1 Mha increase in forest area by small fragments (1 ha). C_LIO_LIRoads and railways reduced by 56%-89% fragment size, especially on large fragments. C_LIO_LIAlarmingly, 97% of fragments are small (<50 ha) and 60% are under edge effect (<90 m). C_LI

ecology↗

bioRxiv2022

Estimating the cumulative impact and zone of influence of anthropogenic infrastructure on biodiversity

O_LIThe concept of cumulative impacts is widespread in policy documents, regulations, and ecological studies, but quantification methods are still evolving. Infrastructure development usually takes place in landscapes with preexisting anthropogenic features. Typically, their impact is determined by computing the distance to the nearest feature only, thus ignoring the potential cumulative impacts of multiple features. We propose the cumulative ZOI approach to assess whether and to what extent anthropogenic features lead to cumulative impacts. C_LIO_LIThe approach estimates both effect size and zone of influence (ZOI) of anthropogenic features and allows for estimation of cumulative effects of multiple features distributed in the landscape. First, we use simulations and an empirical study to understand under which circumstances cumulative impacts arise. Second, we demonstrate the approach by estimating the cumulative impacts of tourist infrastructure in Norway on the habitat of wild reindeer (Rangifer t. tarandus), a nearly-threatened species highly sensitive to anthropogenic disturbance. C_LIO_LISimulations show that analyses based on the nearest feature and our cumulative approach are indistinguishable in two extreme cases: when features are few and scattered and their ZOI is small, and when features are clustered and their ZOI is large. Empirical analyses revealed cumulative impacts of private cabins and tourist resorts on reindeer, extending up to 10 and 20 km, with different decaying functions. Although the impact of an isolated private cabin was negligible, the cumulative impact of cabin villages could be much larger than that of a single large tourist resort. Focusing on the nearest feature only underestimates the impact of cabin villages on reindeer. C_LIO_LIThe suggested approach allows us to quantify the magnitude and spatial extent of cumulative impacts of point, linear, and polygon features in a computationally efficient and flexible way and is implemented in the oneimpact R package. The formal framework offers the possibility to avoid widespread underestimations of anthropogenic impacts in ecological and impact assessment studies and can be applied to a wide range of spatial response variables, including habitat selection, population abundance, species richness and diversity, community dynamics, and other ecological processes. C_LI

ecology↗