DOI: 10.5061/dryad.rfj6q57jp
title: Herbivore regulation of savanna vegetation: Structural complexity, diversity, and the complexity–diversity relationship

description: Large mammalian herbivores exert strong top-down control on plants, which
 in turn influence most ecological processes. Accordingly, the decline,
 displacement, or extinction of wild large herbivores in African savannas
 is expected to alter the physical structure of vegetation, the diversity
 of plant communities, and downstream ecosystem functions. However,
 herbivore impacts on vegetation comprise both direct and indirect effects
 and often depend on herbivore body size and plant type. Understanding how
 herbivores affect savanna vegetation requires disaggregating the effects
 of different herbivores and the responses of different plants, as well as
 accounting for both the structural complexity and composition of plant
 assemblages. We combined high-resolution Light Detection and Ranging
 (LiDAR) with field measurements from size-selective herbivore exclosures
 in Kenya to determine how herbivores affect the diversity and physical
 structure of vegetation, how these impacts vary with body size and plant
 type, and whether there are predictable associations between plant
 diversity and structural complexity. Herbivores generally reduced the
 diversity and abundance of both overstory and understory plants, though
 the magnitude of these impacts varied substantially as a function of body
 size and plant type: only megaherbivores (elephant and giraffe) affected
 tree cover, whereas medium- and small-bodied herbivores had stronger
 effects on herbaceous diversity and abundance. We also found evidence that
 herbivores altered the strength and direction of interactions between
 trees and herbaceous plants, with signatures of facilitation in the
 presence of herbivores and of competition in their absence. While
 megaherbivores uniquely affected tree structure, medium- and small-bodied
 species had stronger (and complementary) effects on metrics of herbaceous
 vegetation structure. Plant structural responses to herbivore exclusion
 were species-specific: of five dominant tree species, just three exhibited
 significant individual morphological variation across exclosure
 treatments, and the size class of herbivores responsible for these effects
 varied across species. Irrespective of exclosure treatment, more
 species-rich plant communities were more structurally complex. We conclude
 that the diversity and architecture of savanna vegetation depends on
 consumptive and non-consumptive plant–herbivore interactions; the roles of
 herbivore diversity, body size, and plant traits in mediating those
 interactions; and a positive feedback between plant diversity and
 structural complexity.
description: # **Herbivore regulation of savanna vegetation: structural complexity,
 diversity, and the complexity–diversity relationship**
 [https://doi.org/10.5061/dryad.rfj6q57jp](https://doi.org/10.5061/dryad.rfj6q57jp) This is the README file for datasets contained in the publication: Tyler C. Coverdale, Peter B. Boucher, Jenia Singh, Todd M. Palmer, Jacob R. Goheen, Robert M. Pringle, and Andrew B. Davies. Herbivore regulation of savanna vegetation: structural complexity, diversity, and the complexity–diversity relationship. Ecological Monographs, 2024. Contact author for all files: Tyler Coverdale ([tyler_coverdale@nd.edu](mailto:tyler_coverdale@nd.edu)) ## **Description of the data and file structure** ### Files contained in this repository: 1.     Individual_Field_Data.xlsx 2.     Individual_LiDAR_Data.xlsx 3.     Quadrat_Data.xlsx 4.     Subplot_Data.xlsx 5.     Plot_Data.xlsx 6.     Community_Data.xlsx ### File descriptions: **1.     Individual_Field_Data.xlsx**—this file contains field measurements of individual tree height and canopy dimensions (length and width) for five species of trees (*Acacia brevispica, A. etbaica, A. mellifera*, *B. rotundifolia*, and *C. dichogamus*) surveyed in 2021. Details of data collection methods and long-term tree survey data are available in Alston et al. 2022 (*Ecology*). Trees for which height and canopy dimensions are recorded as “NA” were dead or unable to be surveyed in 2021. ·      ID: concatenated, unique identifier for each UHURU plot comprised of the Site, Block, and Treatment ·      Site: unique site identifier for each UHURU plot corresponding to the South (S), Central (C), and North (N) blocks; see Appendix S1: Figure S1 for details ·      Block: unique block designation within each Site; see Appendix S1: Figure S1 for details ·      Treatment: exclosure treatment designations; see Methods for details of fencing design ·      Species: Genus and species (“Genus_species”) designations of the five tree species included in long-term surveys in the UHURU exclosure plots ·      Height: maximum height (m) of each tree ·      Canopy_Length: diameter (m) of each tree canopy; canopy area is calculated using an elliptical approximation ·      Canopy_Width: diameter (orthogonal to “Canopy_Length”; m) of each tree canopy; canopy area is calculated using an elliptical approximation **2.     Individual_LiDAR_Data.xlsx**—this file contains remote sensing measurements of vertical biomass distribution and vertical biomass variability (coefficient of variation) for individual trees of two species (*Acacia etbaica *and *A. mellifera*). ·      ID: concatenated, unique identifier for each UHURU plot comprised of the Site, Block, and Treatment ·      Site: unique site identifier for each UHURU plot corresponding to the South (S), Central (C), and North (N) blocks; see Appendix S1: Figure S1 for details ·      Block: unique block designation within each Site; see Appendix S1: Figure S1 for details ·      Treatment: exclosure treatment designations; see Methods for details of fencing design ·      Species: Genus and species (“Genus_species”) designations ·      Minimum_Height: minimum height (m) of all LiDAR points within the canopy footprint of each tree; note that LiDAR points below 0.05m were excluded ·      Height_25: 25th percentile height (m) of all LiDAR points within the canopy footprint of each tree ·      Height_75: 75th percentile height (m) of all LiDAR points within the canopy footprint of each tree ·      Max_Height: maximum (98th percentile; m) height of all LiDAR points within the canopy footprint of each tree ·      CoV: coefficient of variation of all LiDAR points within the canopy footprint of each tree **3.     Quadrat_Data.xlsx—** this file contains field and remote sensing measurements of herbaceous layer abundance (disc pasture meter and pin frame) and diversity (species richness), as well as the presence/absence of overlying trees &gt;1m in height. All data were collected from 1,796 1m2 quadrats within the UHURU experimental exclosure plots. ·      ID: concatenated, unique identifier for each 1m2 quadrat comprised of the Site, Block, Treatment, and Rebar ·      Site: unique site identifier for each UHURU plot corresponding to the South (S), Central (C), and North (N) blocks; see Appendix S1: Figure S1 for details ·      Block: unique block designation within each Site; see Appendix S1: Figure S1 for details ·      Treatment: exclosure treatment designations; see Methods for details of fencing design ·      Rebar: unique quadrat identifier within each UHURU plot; see Appendix S1: Figure S1 for details ·      Geolocation_Method: method used to locate each quadrat for comparison with LiDAR data. “Diff_GPS” indicates quadrats located by surveying the permanent rebar in the field with a differential GPS; “Estimated” indicates quadrats located by inferring their position relative to quadrats surveyed with the differential GPS (*i.e.*, quadrats whose permanent rebar stake was missing or unable to be located) ·      Herb_SR: total number of unique herbaceous-layer species within each 1m2 quadrat ·      Herb_Pinhits: total number of pin hits recorded in each 1m2 quadrat using a 10-pin frame ·      Herb_Biomass: dry weight (kg/ha) of herbaceous vegetation estimated with a disc pasture meter ·      Tree_Present: inferred presence (“Present”) or absence (“Absent”) of overlying trees based on the minimum height of the tree-only canopy height model (CHM) ·      Herb_Cover: total areal coverage (%) of herbaceous vegetation &lt;1m tall within each 1m2 quadrat ·      Herb_Max_Height: maximum (98th percentile; m) height of all LiDAR points identified as herbaceous vegetation within each 1m2 quadrat ·      Herb_Mean_Height: mean height (m) of all LiDAR points identified as herbaceous vegetation within each 1m2 quadrat ·      Herb_Rumple: rumple of the herbaceous layer within each 1m2 quadrat ·      Herb_Rugosity: rugosity of the herbaceous layer within each 1m2 quadrat ·      Herb_CoV: coefficient of variation of all LiDAR points identified as herbaceous vegetation within each 1m2 quadrat. The coefficient of variation of height cannot be calculated for quadrats with no herbaceous vegetation, and these cells are listed as "NA".  **4.     Subplot_Data.xlsx—** this file contains remote sensing measurements of six structural metrics (98th percentile height, mean height, median height, coefficient of variation of height, rumple, and rugosity) and field measurements of species richness and tree density for the tree layer collected from 1,296 10m x 10m subplots within the UHURU experimental exclosure plots. Detailed descriptions of LiDAR-derived metrics and field surveys can be found in the Methods. ·      ID: concatenated, unique identifier for each 10m x 10m subplot comprised of the Site, Block, Treatment, and Subplot ·      Subplot: unique subplot identifier within each UHURU plot; see Appendix S1: Figure S1 for details ·      Site: unique site identifier for each UHURU plot corresponding to the South (S), Central (C), and North (N) blocks; see Appendix S1: Figure S1 for details ·      Treatment: exclosure treatment designations; see Methods for details of fencing design ·      Block: unique block designation within each Site; see Appendix S1: Figure S1 for details ·      Total_Trees: total number of trees &gt;1m tall within each 10m x 10m subplot ·      Tree_SR: total number of unique tree species (with at least one individual &gt;1m tall) within each 10m x 10m subplot ·      Tree_Cover: total areal coverage (%) of trees &gt;1m tall within each 10m x 10m subplot ·      Tree_Max_Height: maximum (98th percentile; m) height of all LiDAR points identified as trees within each 10m x 10m subplot ·      Tree_Mean_Height: mean height (m) of all LiDAR points identified as trees within each 10m x 10m subplot ·      Tree_CoV: coefficient of variation of all LiDAR points identified as trees within each 10m x 10m subplot. Coefficient of variation of height cannot be calculated for subplots with no trees, and these cells are listed as "NA". ·      Tree_Rugosity: rugosity of the tree layer within each 10m x 10m subplot ·      Tree_Rumple: rumple of the tree layer within each 10m x 10m subplot **5.     Plot_Data.xlsx—** this file contains field and remote sensing measurements of tree and herbaceous structure, diversity, and abundance collected from the 36 1-ha UHURU experimental exclosure plots. ·      ID: concatenated, unique identifier for each UHURU plot comprised of the Site, Block, and Treatment ·      Site: unique site identifier for each UHURU plot corresponding to the South (S), Central (C), and North (N) blocks; see Appendix S1: Figure S1 for details ·      Block: unique block designation within each Site; see Appendix S1: Figure S1 for details ·      Treatment: exclosure treatment designations; see Methods for details of fencing design ·      Herb_SR_Total: total number of unique herbaceous species present within each 1-ha exclosure plot ·      Herb_SR_Quad: average number of unique herbaceous species per 1m2 quadrat within each 1-ha exclosure plot ·      Herb_Shannon: Shannon diversity index for the herbaceous plant community within each 1-ha exclosure plot ·      Herb_Cover: percent cover (%) of the herbaceous plant community within each 1-ha exclosure plot ·      Herb_Max_Height: maximum (98th percentile; m) height of the herbaceous community within each 1-ha exclosure plot ·      Herb_Mean_Height: mean height (m) of the herbaceous community within each 1-ha exclosure plot ·      Herb_Rumple: rumple of the herbaceous community within each 1-ha exclosure plot ·      Herb_Rugosity: rugosity of the herbaceous community within each 1-ha exclosure plot ·      Herb_CoV: coefficient of variation of height for all herbaceous vegetation within each 1-ha exclosure plot ·      Tree_Cover: percent cover (%) of the tree community within each 1-ha exclosure plot ·      Tree_Max_Height: maximum (98th percentile; m) height of the tree community within each 1-ha exclosure plot ·      Tree_Mean_Height: mean height (m) of the tree community within each 1-ha exclosure plot ·      Tree_Rumple: rumple of the tree community within each 1-ha exclosure plot ·      Tree_Rugosity: rugosity of the tree community within each 1-ha exclosure plot ·      Tree_CoV: coefficient of variation of height for all trees within each 1-ha exclosure plot ·      All_Cover: percent cover (%) of all vegetation within each 1-ha exclosure plot ·      All_Max_Height: maximum (98th percentile; m) height of all vegetation within each 1-ha exclosure plot ·      All_Mean_Height: mean height (m) of all vegetation within each 1-ha exclosure plot ·      All_Rumple: rumple of the entire plant community within each 1-ha exclosure plot ·      All_Rugosity: rugosity of the entire plant community within each 1-ha exclosure plot ·      All_CoV: coefficient of variation of height for all vegetation within each 1-ha exclosure plot **6.     Community_Data.xlsx**—this file contains field measurements of herbaceous community composition collected from 1,796 1m2 quadrats within the UHURU experimental exclosure plots. Data are the total number of 1m2 quadrats per plot (maximum: 49 quadrats/plot) in which each species is present. ·      ID: concatenated, unique identifier for each UHURU plot comprised of the Site, Block, and Treatment (see above for details concerning Site and Treatment abbreviations) ·      Columns B-JB: abundance (# of quadrats present per plot) for each species (“Genus_species”) included in the bi-annual UHURU herbaceous layer survey; for details and additional survey data, see Alston et al. 2022 (*Ecology*) ## **Sharing/Access information** Long-term data from the UHURU (Ungulate Herbivory Under Rainfall Uncertainty) experiment has been published previously and can be accessed at the links, below: * Kartzinel et al. 2014 (*Ecology*): **[https://doi.org/10.1890/13-1023R.1](https://doi.org/10.1890/13-1023R.1)** * Alston et al. 2022 (*Ecology*): **[https://doi.org/10.1002/ecy.3649](https://doi.org/10.1002/ecy.3649)** ## **Contact** For additional details and for questions concerning remote sensing (LiDAR) data products, contact Tyler Coverdale ([tyler_coverdale@nd.edu](mailto:tyler_coverdale@nd.edu)).