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Data from: Tropical forests structure and diversity: a comparison of methodological choices

Citation

Souza, Cléber Rodrigo et al. (2021), Data from: Tropical forests structure and diversity: a comparison of methodological choices, Dryad, Dataset, https://doi.org/10.5061/dryad.1g1jwstwk

Abstract

1. Large-scale data compilation is increasing steadily in tropical forest research, but the lack of standardized methods for data collection limits drawing inference from large datasets and cross-biome analyses. Different inclusion methods and minimum tree diameter threshold are among these varying factors. To tackle this issue, we evaluated how different approaches for tree sampling affects our understanding of diversity and functioning in different tropical vegetation types.

2. We used a unique dataset of 44 inventory plots (43.54 ha) encompassing an aridity gradient: evergreen moist forests, semideciduous and deciduous tropical forests. Data were collected using the by-tree inclusion method, in which, all stems are measured if the equivalent diameter of the tree reaches the minimum threshold. We simulated the impact of adopting different inclusion methods (by-stem and by-tree) and different minimum diameter thresholds on the estimation of number of trees and stems, biomass and species richness. We used linear mixed models to investigate the effect of minimum diameter threshold and inclusion method on our different response variables. We also evaluated species chance to be sampled under different minimum inclusion criteria.

3. Inclusion method and minimum diameter threshold mainly affect the estimation of number of trees and stems and species richness, especially in deciduous and semideciduous forests, where resprouting is a prevalent strategy. In these forests, many trees that have several stems do not reach the minimum size individually when adopting the by-stem method, yet they do reach the minimum size threshold when all stems are considered together. For these environments under water stress, our analysis showed that using large minimum sizes, such as the 10 cm typically used in rainforests, implies large sampling losses, especially when used jointly with the by-stem inclusion method.

4. The by-tree inclusion method represents an alternative approach that offers a more reliable sampling in different vegetation types, particularly in those habitats where resprouting is a widely encountered strategy along all age classes. We demonstrate the infeasibility of adopting broad and standard minimum thresholds for different tropical vegetation types, particularly considering their widely different ecological strategies.

Usage Notes

This dataset refers to worked data from 44 tropical forest sites, the site details and species list. The data is stored in an xlsx format file containing several sheets referring to different information. The complete column description is present in the READ.ME sheet.

Funding

Conselho Nacional de Desenvolvimento Científico e Tecnológico