DOI: 10.5521/forestplots.net/2020_1
title: Data set from Argentinian plots from: 'Untangling the importance of niche breadth and niche position as drivers of tree species abundance and occupancy across biogeographic regions '. Global Ecology and Biogeography 2020. https://doi.org/10.1111/geb.13139

description: Data package for 'Untangling the importance of niche breadth and niche position as drivers of tree species abundance and occupancy across biogeographic regions '. Global Ecology and Biogeography 2020.
ABSTRACT
Despite decades of interest in how ecological niches shape species commonness and rarity at local and regional scales, the relative importance of different niche mechanisms within and across ecosystems remains unresolved. We tested the relative importance of niche breadth (range of environmental conditions where species occur) and niche position (marginality of a species’ environmental distribution relative to the mean environmental conditions of a region) in determining tree-species abundance and occupancy across three major biogeographic regions: a high-diversity, lowland tropical forest in the Bolivian Amazon; a low- to intermediate-diversity, premontane subtropical forest in the Argentinian Andes; and a low-diversity temperate (oak hickory) forest in the Missouri Ozarks, USA. We calculated abiotic-niche breadth and niche position for each species in regional-scale networks of 0.1-ha forest plots using 16 climate, soil, and topographic variables. For each region, we used model selection to test the relative importance of niche breadth and position in determining local abundance and occupancy. To account for species-environment associations caused by other mechanisms (e.g., dispersal), we used a null model that randomized associations between species occurrences and local environmental conditions. We found strong support for the niche-position hypothesis. In all regions, species that occurred in sites with non-marginal environmental conditions (low values of niche position) had higher local abundance and occupancy. Moreover, observed relationships between occupancy and niche position differed significantly from random species-environment associations in all regions, whereas the relationship between local abundance and niche position only differed from random species-environment associations in Argentina. In contrast, we found little to no support for the niche-breadth hypothesis. Observed relationships between both local abundance and niche breadth, and occupancy and niche breadth, did not differ significantly from random species-environment associations. Abiotic-niche position was more important than abiotic-niche breadth in shaping regional patterns of species commonness and rarity across temperate, sub-tropical, and tropical forests. In all three forests, tree species with widespread geographic distributions are associated with environmental conditions commonly found throughout the region, suggesting that niche position has similar effects on species occupancy across contrasting biogeographic regions. Our findings imply that conservation efforts aimed at protecting populations of common and rare tree species should prioritize conservation of both common and rare habitats.