Spatial distribution of gaps along three catenas in the moist forest of Taï National Park, Ivory Coast

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Cambridge University Press is collaborating with JSTOR to digitize, preserve and extend access to Journal of Tropical Ecology.http://www.jstor.org ABSTRACT. The spatial distribution of canopy gaps was analysed on three sites (total 71 ha) in the tropical moist forest of TaY National Park, Ivory Coast. Pattern analysis revealed a clustered distribution of gaps for two of the three sites. Catena dependent gap formation processes might explain local differences in the occurrence and distribution of gaps. Gap densities, sizes and percentage forest area in gap phase are higher on the upper and middle slope than on the crest or lower slope. As a consequence, regeneration of gap dependent tree species might be directed to the catena positions with the highest disturbance regime. The spatial distribution of gap dependent species can be clumped, not only due to the regeneration within gaps, but also due to the clustered nature of gap distribution on its own.

Effects of topography, soil type and forest age on the frequency and size distribution of canopy gap disturbances in a tropical forest

“…Greater gap area fractions at higher slopes have been found for other sites. Poorter et al (1994) found higher gap area fractions on the upper and middle slope than on the crest or lower slope.…”

“…In addition to problems arising from diverse criteria used to classify gaps, comparative studies also conflate effects of the external drivers to forest disturbance, e.g., storm frequency (Espirito-Santo et al, 2010) and rainfall regime (Foster and Brokaw, 1982), with intrinsic environmental factors that may also influence the probability of treefall e.g., soil type (Vandermeer et al, 1994;VanderMeer and Bongers, 1996;Ashton and Hall, 1992), topographic position (Poorter et al, 1994), and forest age (Numata et al, 2006). In this study, we provide the first analysis at the landscape scale of how forest age, topography and soil type influence gap disturbance patterns in a tropical forest.…”

“…We interpret this as a consequence of the greater frequency of emergent trees and the greater heterogeneity of canopy heights in the old-growth vs. the secondary forest. When canopy heights are relatively homogeneous, there is a protective effect with respect to wind exposure from the canopy of neighboring trees; conversely, when the canopy heights of neighboring trees are very different, there may be greater chance of turbulent wind currents causing treefalls, as has been suggested to occur at forest edges and existing gaps (Poorter et al, 1994;Ferreira and Laurence, 1997). Additionally, the greater abundance of lianas in the secondary forest (DeWalt et al, 2000) might partially account for the lower ratio of large gaps, since propagation of tree fall damage to nearby trees might be reduced by the supporting effect of liana tangles.…”

Gap edge attributes in Neotropical rainforest, Ecuador

“…However, spatial analysis conducted in the moist forest of Tal National Park in South-West Ivory Coast, West Africa, showed that the occurrence of gaps is often not random, with some sites more likely to have gaps than others places (Poorter et al, 1994). Other studies also suggested that canopy gaps in old-growth Neotropical lowland forests are not spatially randomly distributed, but rather clustered around specific sites such as those with shallow soils (Van der Meer & Bongers, 1996).…”

“…A high level of disturbance will result in many gaps or in large gaps. This will lead to a relatively high proportion of species depending on forests gaps (Poorter, Jans, Bongers, & Van Rompaey, 1994). Gap size may be computed by different methods based on two and three dimensional projections of the canopy gap.…”