Data from: Both the selection and complementarity effects underpin the effect of structural diversity on aboveground biomass in tropical forests
Data files
Oct 25, 2023 version files 245.39 KB
Abstract
Aim: Despite mounting empirical evidence regarding the positive effects of forest structural diversity (STRDIV) on forest functioning, the underlying biotic mechanisms and controlling abiotic factors remain poorly understood. This study provides the first assessment of the interactive effects of STRDIV and diversity in species and functional traits on aboveground biomass (AGB) in natural forests in West and East Africa.
Location: West and East Africa
Time period: 2014-2020
Major taxa studied: Woody plants
Methods: Using data from 276 plots and 7993 trees of 207 species distributed across various types of natural forests and major climatic zones of Africa, linear mixed-effects and structural equation models, we have evaluated how alternative causal relationships between STRDIV and taxonomic and functional diversity attributes influence AGB, while accounting for the effects of environmental covariates. We also assessed the consistency of these relationships across floristically and environmentally homogenous forest types.
Results: We found that the positive effects of STRDIV on AGB were underpinned by both the community-weighted mean (CWM) of trait values (selection effects) and species richness (niche complementarity), but the relative importance of these effects varied depending on forest types. Across the forest types, STRDIV primarily mediated the effects of CWM of traits and species richness on AGB. We also found that STRDIV–AGB relationships were constrained by resource (water and nutrient) availability.
Main conclusions: Our findings provide novel insights into the role of functional traits as key determinants of the effects of STRDIV on AGB in tropical forests. We suggest that forest management and climate change mitigation strategies aimed at conserving biodiversity and fostering biomass storage through increased STRDIV should focus on maintaining high levels of functionally dominant species while also increasing tree species diversity.
README: Both the selection and complementarity effects underpin the effect of structural diversity on aboveground biomass in tropical forests
https://doi.org/10.5061/dryad.dfn2z3582
Description of the data and file structure
The zipped file in Dryad contains the data necessary to reproduce the statistical analyses published in the manuscript "Both the selection and complementarity effects underpin the effect of structural diversity on aboveground biomass in tropical forests" in Global Ecology and Biogeography by Noulèkoun et al.
The file includes 3 files, whose content is described below.
1- Main database "dataall_Noulekoun_GEB"
This is .csv document that contains all the variables used in the statistical analysis are displayed along with their values per plot. The names of the variables are abbreviated in this document and their description is provided in the second file entitled "Description_abbreviations_Noulekoun" (see also Table below). The column "age-years" includes some cells with n/a values, which should be considered as missing values. These missing values are the age of the old-growth forests, which were not measured in our study.
2. "Description_abbreviations_Noulekoun"
This is an excel document there the description of all abbreviations is provided (see also Table below).
3. "R_script_Noulekoun_GEB"
This is the R code used to perform the analysis. Ample details are provided on how the analysis was done in the document.
Table: Variable abbreviations
| Abbreviations | Description |
|---|---|
| plot_uniq_ID | Plot unique ID |
| country | Country of data sampling |
| plot_size_ha | Plot size in ha |
| growth | Forest growth stage (either old ofr young) |
| age_years | Age of forest provided for only young-growth forests |
| latitude | Latitude (standardized values are provided) |
| longitude | Longitude (standardized values are provided) |
| altitude | Elevation (m) |
| PREC | Mean annual precipitation (MAP, mm) |
| Temp | Mean annual temperature (MAT, degrees) |
| CMI | Climatic moisture index (mm) |
| clay1m | Clay content (%) |
| sand1m | Sand content (%) |
| silt1m | Silt content (%) |
| cec1m | Cation exchange capacity (cmol/kg) |
| soc1m | Soil organic carbon (g/kg) |
| ph1m | pH (H2O |
| cwmwd | Community-weighted mean of wood density (g/cm3) |
| cwmhm | Community-weighted mean of maximum tree height (m) |
| cwmsla | Community-weighted mean of specific leaf area (mm2 /mg) |
| cwmla | Community-weighted mean of leaf area (cm2) |
| cwmlcc | Community-weighted mean of leaf carbon content (%) |
| cwmlnc | Community-weighted mean of leaf nitrogen content (%) |
| cwmlt | Community-weighted mean of leaf thickness (mm) |
| cwmrd | Community-weighted mean of rooting depth (cm) |
| Hd5 | Shannon structural diversity index for 5 cm DBH class |
| Hd10 | Shannon structural diversity index for 10 cm DBH class |
| Hd15 | Shannon structural diversity index for 15 cm DBH class |
| Hh5 | Shannon structural diversity index for 5 m height class |
| Hh10 | Shannon structural diversity index for 10 m height class |
| Hh12 | Shannon structural diversity index for 12 m height class |
| cvdbh | Coefficient of variation of DBH |
| cvheight | Coefficient of variation of height |
| aridity_class | Aridity classes |
| sd_plots | Standardized values of plot size |
| sd_prec | Standardized values of mean annual precipitation |
| sd_temp | Standardized values of mean annual temperature |
| sd_CMI | Standardized values of climatic moisture index |
| sd_elevation | Standardized values of elevation |
| sd_clay1m | Standardized values of clay content |
| sd_sand1m | Standardized values of sand content |
| sd_silt1m | Standardized values of silt content |
| sd_cec1m | Standardized values of cation exchange capacity |
| sd_soc1m | Standardized values of soil organic carbon |
| sd_ph1m | Standardized values of pH |
| sd_richness | Standardized values of species richness |
| sd_agb.mg.ha | Aboveground biomass |
| sd_Hd5 | Standardized values of Shannon structural diversity index for 5 cm DBH class |
| sd_Hd10 | Standardized values of Shannon structural diversity index for 10 cm DBH class |
| sd_Hd15 | Standardized values of Shannon structural diversity index for 15 cm DBH class |
| sd_Hh5 | Standardized values of Shannon structural diversity index for 5 m height class |
| sd_Hh10 | Standardized values of Shannon structural diversity index for 10 m height class |
| sd_Hh12 | Standardized values of Shannon structural diversity index for 12 m height class |
| sd_fdis | Standardized values of functional dispersion |
| sd_cwmwd | Standardized values of community-weighted mean of wood density |
| sd_cwmhm | Standardized values of community-weighted mean of maximum tree height |
| sd_cwmsla | Standardized values of community-weighted mean of specific leaf area |
| sd_cwmla | Standardized values of community-weighted mean of leaf area |
| sd_cwmlcc | Standardized values of community-weighted mean of leaf carbon content |
| sd_cwmlnc | Standardized values of community-weighted mean of leaf nitrogen content |
| sd_cwmlt | Standardized values of community-weighted mean of leaf thickness |
| sd_cwmrd | Standardized values of community-weighted mean of rooting depth |
| sd_cvdbh | Standardized values of coefficient of variation of DBH |
| sd_cvheight | Standardized values of coefficient of variation of height |
Methods
The dataset results from forest inventories conducted in 276 plots, distributed across four West African countries (Benin, Burkina Faso, Togo, and Ghana) and one East African country (Ethiopia) from 5°40ʹ W to 48°23 ʹE longitude and 3°18ʹ N to 15°03ʹ N latitude. The plots spanned various climate types of the region, including arid, semi-arid, dry sub-humid, and humid, and covered a broad range of topographic and edaphic gradients. The forest inventories were conducted between 2014 and 2020. The plot size was on average 0.1 ha and ranged from 0.02 to 0.25 ha. Within each plot, several key dendrometric parameters including height and diameter at breast height (DBH) were systematically recorded for all living individual trees that met specific criteria. Environmental factors were also either recorded in the field or downloaded from publicly available databses.