DOI: 10.5061/dryad.qv9s4mwdf
title: Spatial patterns of light-demanding tree species in the Yangambi rainforest (Democratic Republic of Congo)

description: We are studying the factors of spatial distribution of light-demanding
 tree species in an undisturbed natural forest to contribute to the
 elucidation of the enigma of the persistence of light-demanding tree
 species in the canopy of the Congo Basin rainforests. Our objective was to
 analyze the current spatial distribution combined with the spatial
 autocorrelation of light-demanding stems species and to carry out a
 Canonical Correspondence Analysis (CCA) to discuss the role that different
 factors may have played in determining the observed spatial pattern. These
 species were subdivided into three regeneration guilds, based on their
 growth speed and longevity: short-lived pioneer (SLP), long-lived pioneer
 (LLP), and non-pioneer light-demanding (NPLD) species. We also compared
 the distribution of these species to that of Gilbertiodendron dewevrei, a
 typical extremely aggregative and locally hyperdominant shade-tolerant
 species. For this purpose, we carried out a selective inventory of all
 stems (at least 10 cm DBH) of light-demanding species in the forest around
 the Moni River, an area rich in individuals of light-demanding species.
 This inventory was carried out along eight transects equidistant by 450 m.
 The total length of these transects was 50.125 km (an area of 250.625 ha).
 The sampling units consisted of contiguous plots (200 m x 50 m) centered
 on the transect (long side parallel to the transect). Each plot was
 divided into 8 sub-plots of 25 m x 50 m. The parameters directly measured
 in the field were diameter at breast height (DBH), wetland indicators,
 topography, and slope. The last three parameters were measured in each
 sub-plot. The wetland indicators were spring, stream (stream 1 to about 3
 m wide that can be forded), river (stream more than 3 m wide and that
 cannot be forded), temporary or periodically flooded swamp, permanent
 swamp, and absence of wetland. The modalities of the topography parameter
 were ridge, plateau, slope break, upward slope, downward slope, and
 lowland. The slope was measured using the SUUNTO clinometer. The longitude
 and latitude were deduced from the Cartesian coordinates (X and Y) of each
 tree, which were measured directly during the inventory. The altitude and
 distance from the nearest watercourse were deduced from the Geographic
 Information System (GIS). The altitude was derived from the digital
 terrain model of the Yangambi region, while the distance to the nearest
 watercourse was derived from a distance to watercourses map of the
 Yangambi region.
description: <b>Data F1 Spatial
 Analysis, column headings correspond to:</b> Tag
 No.: unique number written on an aluminium tag nailed to the
 tree. Transect: identification of the transect in all
 the transects. Segmented transect: Segment of the
 transect that starts from the Moni river. This river divides each transect
 into two. Segment A is east, and Segment B is west.
 Plot: number of the inventory plot. Subplot:
 number of the inventory subplot. Regeneration guild:
 SLP, short-lived pioneer species, LLP, long-lived pioneer species, and
 NPLD, non-pioneer light-demanding species. POM (m):
 Point of Measurement expressed in meters. DBH (cm):
 Diameter at breast height expressed in centimeters.
 Long (m): longitude of the tree expressed in meters.
 Lat (m): latitude of the tree expressed in meters.
 <b>Data F2
 and F3; columns correspond to:</b> Transect:
 identification of the transect in all the transects.
 Segmented transect: Segment of the transect that starts from the
 Moni river. This river divides each transect into two. Segment A is east,
 and Segment B is west. Plot: number of the inventory
 plot. Subplot: number of the inventory
 subplot. Slope: slope of the subplot (measured on the
 transect with the SUUNTO clinometer) expressed in percentage.
 DistanceMilHum: distance in meters between the tree and the
 nearest watercourse. MilHum: wetland
 indicator. Topo: topography in the subplot.
 Altitude: altitude in meters of the subplot
 The remaining columns concern either the abundance of each
 regeneration guild (Data F2) or the abundance of each species (Data
 F3).