Spatial pattern of central African rainforests can be predicted from average tree size

Obiang, Nestor Laurier Engone; Ngomanda, Alfred; Mboma, Raymonde; Nzabi, Thomas; Ngoye, Alfred; Atsima, Lydia; Ndjele, Léopold; Mate, Jean-Pierre; Lomba, Christophe; Picard, Nicolas

doi:10.1111/j.1600-0706.2010.18440.x

Cited by 9 publications

(4 citation statements)

References 37 publications

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“…The segregation could additionally be explained by negative density dependence acting independently of Janzen-Connell effects (Clark & Clark, 1984;Hao, Zhang, Song, Ye, & Li, 2007). Other studies in this region suggest the prevalence of negative density dependence (Engone Obiang et al, 2010).…”

Section: Spatial Repulsion Between Species Was Found Except For Thementioning

confidence: 88%

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Determinants of spatial patterns of canopy tree species in a tropical evergreen forest in Gabon

Obiang

Kenfack

Picard

et al. 2019

J Vegetation Science

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Questions We examined the spatial patterns of dominant canopy species in a tropical forest to investigate: (a) what is the niche occupancy of canopy species with respect to topographic gradients; (b) what are the dominant ecological processes that explain their distribution; (c) what are the interactions among the most prevalent canopy species; and (d) what are the interactions between canopy species adults and juveniles trees? Location Rabi permanent CTFS‐ForestGEO plot, Gabon. Methods We selected the four most abundant canopy species and one timber species. We used Berman's test to determine the effect of three topographic variables on the distribution of each species and univariate analysis to model the spatial pattern of each species using either an inhomogeneous Poisson process or an inhomogeneous Cox process. We also used a bivariate form of the pair correlation function (PCF) to determine the spatial interaction between species and the correlation among conspecific adult and juvenile trees. Results Four of the five species had aggregated spatial patterns while Lophira alata showed spatial randomness. Most of the variance in the local tree density was explained by within‐population dispersal processes rather than environmental factors. Bivariate PCF tests showed significant segregation between species associations. Two species exhibited aggregation at small distances between young and adult trees, while others showed either complete spatial randomness at small inter‐tree distances or segregation at large distances. Conclusions This study showed that the spatial pattern in the majority of canopy species was aggregation. Seed dispersal limitation mainly explained the observed aggregation pattern. Habitat filtering, as evidenced by the influence of topographic variables on niche occupancy, marginally, yet significantly, explained this pattern. The different spatial patterns of the principal species permit their coexistence. Spatial segregation among adult and juvenile trees reveals a strong pattern of either species‐specific seed predation or pathogens.

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Section: Spatial Repulsion Between Species Was Found Except For Thementioning

confidence: 88%

“…In addition, Hardy and Sonké (2004) aimed at assessing the species diversity of the forest. Engone Obiang et al (2010) aimed at characterizing the overall spatial pattern of all trees irrespective of their species. None of these previous studies focused on specific species to better understand their ecology from their spatial pattern.…”

Section: Introductionmentioning

confidence: 99%

Determinants of spatial patterns of canopy tree species in a tropical evergreen forest in Gabon

Obiang

Kenfack

Picard

et al. 2019

J Vegetation Science

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“…These models can describe negative or positive interactions between trees, as well as random, regular, and clustered patterns [18]. Stand characteristics can be used to model these interactions [21] and these point processes to generate spatial tree patterns and to simulate realistic stand structures [18,22].…”

Section: Introductionmentioning

confidence: 99%

Modelling the Spatial Structure of White Spruce Plantations and Their Changes after Various Thinning Treatments

Duchâteau

Schneider

Tremblay

et al. 2021

Forests

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Research Highlights: The spatial distribution of trees results from several ecological processes that can be difficult to measure. We applied a point process modelling approach that uses the diameter and species of neighbouring trees to represent inter-tree interactions through repulsive and attractive processes. Thinning treatments slightly influence the tree spatial distribution of trees in white spruce plantations. Integrating this “spatialiser” into growth models could help improve stand simulations following various thinning treatments over larger areas and longer periods. It could also allow for the use of spatially explicit models when tree position is not available. Background and Objectives: Tree spatial patterns result from several ecological processes and have important implications in forest ecology and management. The use of spatial information can significantly improve our understanding of forest structures. However, this implies intensive field work that is rarely integrated into forest inventories. The aims of this study were to develop a spatial distribution simulator of trees in white spruce plantations and to evaluate the influence of thinning treatments. Materials and Methods: A point process modelling approach was used to represent inter-tree interactions through repulsive and attractive process in white spruce (Picea glauca (Moench) Voss) plantations in eastern Quebec, Canada, that had been commercially thinned five years ago. Balsam fir (Abies balsamea (L.) Mill.) and hardwoods together can represent 30–40% of the basal area of these plantations. Results: The diameter and species of each tree’s two closest neighbours were found to be the most important predictors in explaining the observed distances between trees. Despite the short period since thinning treatments, results showed that the treatment had slight significant effects on tree interactions. However, their impact on the global spatial distribution of stands is quite limited. Conclusions: Using only a few readily-available variables (species and diameter of trees), this “spatialiser” will make it possible to assign spatial coordinates to trees and generate realistic stand spatial structures even after various silvicultural treatments.

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“…Effective management of production forests requires prior knowledge of species dynamics (Obiang et al, 2010;Vlam et al, 2014), in particular for the most sought-after species with high market value. For several decades, regulatory measures have been taken by the Congo Basin producer countries (Ouédraogo et al, 2014;Ligot et al, 2019) to ensure the sustainability of the resource.…”

Section: Introductionmentioning

confidence: 99%

Influence of spacing and seed trees on the growth of Pericopsis elata saplings during the first twenty months of a planting trial

Ilunga-Mulala¹,

Hatakiwe²,

Beeckman³

et al. 2021

Biotechnol. Agron. Soc. Environ.

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Description of the subject. Pericopsis elata (Fabaceae) is a long-lived light-demanding tree from African rain forests that produces timber of high economic value. Natural populations suffer from overexploitation and a deficit of natural regeneration. Plantations could increase its production and limit the pressure on natural forests. However, we lack knowledge on the influence of spacing and seed tree origin on tree growth to optimize plantation protocols. Objectives. This study evaluated the impact of sapling density and seed tree origin on the growth in diameter and height of P. elata plants, 20 months after plantation. Method. Seeds were collected on 19 mother trees in a 400 ha natural stand near Kisangani (DRC). In October 2017, seedlings were transplanted in a Nelder design plantation with three replicates, to compare sapling growth at 10 contrasting plant densities under full sun. Diameter and height increments of 540 plants were analyzed according to local competition and maternal origin using generalized additive models. Results. Twenty months after planting, height growth peaked at an intermediate density of 47,000 stems·ha-1 (165.6 ± 39.2 cm·year-1), while diameter growth peaked at a lower density of 4,200 stems·ha-1 (24.6 ± 8.3 mm·year-1). The maternal origin of saplings affected their growth, the coefficients of variation among mother trees reaching 7.6% and 6.4% for diameter and height increments, respectively. The initial diameter affected positively diameter growth while the initial height did not influence height growth. Conclusions. The Nelder design proved useful to assess how plant growth depends both on spacing and genetic factors.

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Spatial pattern of central African rainforests can be predicted from average tree size

Cited by 9 publications

References 37 publications

Determinants of spatial patterns of canopy tree species in a tropical evergreen forest in Gabon

Determinants of spatial patterns of canopy tree species in a tropical evergreen forest in Gabon

Modelling the Spatial Structure of White Spruce Plantations and Their Changes after Various Thinning Treatments

Influence of spacing and seed trees on the growth of Pericopsis elata saplings during the first twenty months of a planting trial

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