DOI: 10.5061/dryad.q778387
title: Data from: Floristic variation within kerangas (heath) forest: re-evaluation of data from Sarawak and Brunei

description: The variation in species composition of trees greater-than-or-equal-to 7.6
 cm gbh in thirty-eight plots (mostly c. 0.2 ha in extent) from
 physiognomically-defined kerangas forest were re-analyzed by principal
 components analysis ordination (species centering and standardization by
 sample norm). Analyses were performed separately on basal area abundances,
 on the densities of trees in three size classes (greater-than-or-equal-to
 7.6, greater-than-or-equal-to 30.5 and greater-than-or-equal-to 61.0 cm
 gbh) and on the density of small and large trees (7.6- &lt; 30.5 and
 30.5- &lt; 61.0 cm gbh). A total of 636 taxa were reduced to 381 for
 analysis, removing those of very low density and plot frequency. Three
 groups of plots were identified: forest at low elevation, and generally
 coastal, on deep humus podzols; forest at intermediate elevation on mostly
 red-yellow podzols with affinities to dipterocarp forest; and forest at
 high elevation on mostly peaty podzols. The first group was divisible into
 five subgroups along a drainage gradient, while the more poorly drained
 plots showing affinities to peat-swamp forest. Forty to eighty of the
 taxa, depending on the criteria for selection, were sufficient to define a
 stable, reduced spatial structure of the data matrix. Two subgroups, both
 coastal on deep podzols, represent the extreme form of kerangas forest per
 se. A comparison of Agathis borneensis- and Shorea albida-dominated plots
 revealed few other associated and differentiating taxa. Patterns were
 clearest from analyses of basal area data and of densities of all and
 small trees. Ordinations and grouping of plots for small, but not large,
 tree densities were similar to those for basal area. Different species
 were differentiated on the basis of the abundance measure, leading to
 group (tabular) definition of associations in a dual manner. A new system
 of summarization is presented which combines basal area, density and
 frequency in a graded hierarchical approach. The association between
 vegetation and soil type was difficult to unravel because of the limited
 environmental space sampled. Soil type was confounded with elevation,
 rainfall and geographical location. A major factor is clay content
 probably affecting nutrient status and water holding properties.
 'Modal analysis' of small tree densities showed clearest
 patterns in this respect. There were no patterns at the family or genus
 level, nor in leaf size spectra within kerangas. Problems in the
 treatment, analysis and summarization of tropical forest data sets are
 discussed. These problems centre on the scale and intensity of field
 sampling and the advantages of measuring small trees leading to a dual
 basal area and density approach. All published studies, including this
 one, within kerangas forest have used inadequate sampling for the purposes
 of revealing species changes with respect to soil type and composition.
description: Kerangas Forest Plots
 DataText to files on
 Bruenig’s KF plot data Of the 57 small plots in Bornean Kerangas (Heath)
 Forest recorded by E. F. Bruenig between 1959 and 1963, in Sarawak
 (Malaysia) and Brunei (Bruenig 1974), 38 (numbered 20-57) were re-analyzed
 by Newbery (1991). Six plots [29,31,32,42,54,55] were 1, two 2 [45,49],
 five 3 [34,35,46,56,57], and twenty-five 5 [the remainder], square chains
 in area (1 ch2 = 405 m2). The common minimum tree girth (gbh) was 3” (7.62
 cm): all trees were measured for gbh and identified. Tree counts were
 divided into three size (gbh) classes: I, 3.0 – 11.9” (7.6 – 30.2 cm); II,
 12.0 – 23.9” (30.5 – 60.7 cm); and III, ≥ 24.0” (≥ 61.0 cm). The two main
 data files are: ‘kerplot_dat.txt’ and ‘kerdict_dat.txt’. The first file
 lists all trees per plot, as columns (1) plot – plot number, (2) gen –
 genus code, (3) spec – species code, (4 – 6) numbers of trees in size
 classes I – III; (7) total number of trees, (8) BA, basal area, in cm2.
 This a space-delimited ASCII file, values left-justified, readable by most
 statistical programs and as input to R. The second file lists all the
 codes with their full Latin names, grouped by family (637 taxa). The names
 were those given as of 1974: the modern user may want to revise them using
 an international plant names’ index. Full background details to the study
 are found in Bruenig (1974). Plot locations and environmental variables
 are also given in Fig. 1 and Table 3 of Newbery (1991). For the purposes
 of numerical analysis, basal area and density of each species per plot
 were calculated per 5-ch2 (cm2 and N resp.). The data set was reduced to
 381 common taxa: procedures and criteria are given in Newbery (1991).
 Three further files given here are: basal area and density abundances in
 the 38 plots as ‘kerbar38_dat.txt’ and ‘kerden38_dat.txt’, with a list of
 the corresponding common-taxon codes in ‘ker38_codes.txt’. The two
 abundance files are written in the Cornell Condensed Format of programs
 DECORANA and CANOCO. With the transformations and options described
 normalized PCA ordinations of the plots in Newbery (1991) can be
 reproduced. Reference: Brunig, E. F. 1974. Ecological Studies in the
 Kerangas Forests of Sarawak and Brunei. Borneo Literature Bureau, Kuching,
 for the Sarawak Forest Department.kerfor38files.zip