DOI: 10.15493/saeon.gfw.04062025
title: Historic to contemporary higher-plant composition and diversity observations in the Cathedral Peak research catchments, northern Drakensberg, South Africa

description: Historic to contemporary higher-plant composition and diversity observations in the Cathedral Peak research catchments, northern Drakensberg, South Africa
description: The South African Environmental Observation Network located historic, vegetation composition data for the Cathedral Peak research catchment area. In total, three composition surveys have been completed using a descending point technique. The aim of the original survey was to examine the influence of various fire regimes, and abiotic environmental factors on vegetation composition. The South African Environmental Observation Network picked up this historical dataset in order to assess changes in vegetation composition over time in relation to fire and the abiotic environment. Data from the first survey, over the growing season, from 1979 to 1981, is available in a processed format as importance score values. Raw data is available from the following survey from 1984 to 1986, and the most recent survey at the time of this data publication from 2014 to 2017. The latter most survey incorporated a full higher-plant diversity assessment by recording presence-absence data in plots. Analysis of vegetation change, and the influence of different fire regimes was presented in a publication by Gordijn, P., Everson, T., and O’Connor, T. in 2018 (doi: 10.1016/j.ppees.2018.07.005).
description: Historic measurements of grassland and shrubland vegetation diversity were undertaken in the Cathedral Peak research catchments from 1979 to 1981, and repeated measurements from 1984 to 1985. These two surveys were undertaken by the Department of Forestry based at Cathedral Peak. The earlier survey was led by Derek Tomlinson with the assistance of Rick van Wyk; the latter by Terry Everson with a technical assistant. The original survey was designed to assess the role of fire, plus the abiotic environment on vegetation composition in the research catchments. Two reports with multivariate analyses was published (see supplementary materials, ‘RT_SAFRI_1984_Tomlinson(a)’). Composition was recorded using a levy-bridge to collect 200 descending points per plot. The first dataset was processed and only available as importance score (‘composition_plant_tomlinson.csv’), where the relative abundance of individuals are multiplied by the proportion of strikes in a plot for a particular species. Gordijn undertook a re-survey of these plots to generate contemporary data during the early 2010’s. The only way to reasonably compare this data with later period data, by the authors assessments, was via rank abundance analyses as done by Gordijn et al. (2018). This data was extracted from fortran outputs. Raw data for the mid-1980’s (‘composition_plant_everson.csv’) and mid-2010’s (‘composition_plant_gordijn.csv’) survey was available and captured. Presence-absence of species was meticulously recorded in the 18 x 9 m plots during the mid-2010 survey (‘gordijn_presence_absence.csv’). Regarding plot locations; in the mid-1980’s T. Everson only resampled a subset of the full roughly 200 plots sampled from 1979 to 1981 (see ‘plot_locations.csv’). P. Gordijn attempted to locate this subset of plots that were largely marked by metal fencing poles and retained tag numbers, that were just legible owing to rusting. These plots were re-marked by P. Gordijn using metal fence standards. One ‘y’ standard and three smalled droppers marked the plot bounds (see supplementary_info/tomlinson_plot_map/ folder). Plot bound localities were also recorded using a differential GPS and corrected to the nearest base station (see supplementary_info/gordijn_plots/ shapefile). Composition was carefully examined where there was uncertainty around the location of plots with respect to their historical positions. Where unsure about the location of a plot in resampling, these were excluded from analyses (see ‘plot_nomenclature.csv’). Also, in one plot, a footpath had eroded the soil surface so this was not included in analyses. Plots in seeps and wetter lower lying areas were also not analysed by Gordijn et al. (2018) (see ‘plot_nomenclature.csv’). Through this process, 36 plots became available for comparison with historic data. Gordijn, P. used the original 1:5000 topographic map produced by D. Tomlinson to locate vegetation plots. This resource is supplied in the supplementary material (see supplementary_info/tomlinson_plot_map/). GPS coordinates were extracted from the map post georectification of this resource by P. Gordijn (see ‘supplementary_info/tomlinson_plot_map/tom_plots_loc_wgs84.shp’). Hard copies of original data are housed by the SAEON Grasslands node in Pietermaritzburg.