Spatial and topographic patterns of canopy gap formation in a mixed dipterocarp forest in Sarawak, Malaysia

Ohkubo, Tadayasu; Tani, Masato; Noguchi, Hideyuki; Yamakura, Takuo; Itoh, Akira; Kanzaki, Mamoru; Lee, Hua Seng; Tan, Sylvester; Ashton, Peter S.; Ogino, Ken

doi:10.3759/tropics.16.151

Cited by 8 publications

(16 citation statements)

References 32 publications

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“…We expected filtering due to moisture limitation at higher elevations; however, trait means shifted toward species and individuals with higher SLA, contrary to expectations that dry conditions favor low SLA (Wright et al 2004, ). Instead, the increase in SLA may be related to greater disturbance from tree fall and landslides at higher elevations that create light gaps and favor younger successional strategies (Ohkubo et al 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Thus marginal sites with low resource (e.g., light) availability should filter out fast‐growing, poorly defended species, causing low latex diversity within sites but high diversity across sites (Janzen 1974, Fine et al 2004, ). At our study site, light availability may be greater at higher elevations on steep ridges where disturbance from tree fall and landslides is likely highest (Ohkubo et al 2007), although soil nutrients are more abundant at lower elevations in valleys ().…”

Section: Introductionmentioning

confidence: 99%

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The role of functional traits and individual variation in the co‐occurrence of Ficus species

Lasky

Yang

Zhang

et al. 2014

Ecology

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The processes that structure assemblages of species in hyper-diverse genera, such as Ficus (Moraceae), are not well understood. Functional diversity of co-occurring species can reveal evidence for assembly processes; however, intraspecific variation may weaken species-level patterns. We studied whether functional and phylogenetic diversity of Ficus species indicated the effects of spatial variation in filters associated with topography or niche partitioning related to resource use and biotic interactions. We also asked whether individual trait patterns supported species-level patterns. We studied six traits (leaf area, succulence, specific leaf area [SLA], maximum diameter breast high [dbh], fruit size, and latex exudation) for 22 Ficus species and 335 individuals > or = 10 cm dbh on a 20-ha forest plot in China. We found that higher elevation was correlated to changes in mean and reduced diversity of five traits, possibly due to frequent disturbances at higher elevations that favored fast-growing, poorly defended species with high SLA. Maximum dbh showed phylogenetic conservatism but high diversity among co-occurring species, suggesting adult stature is an important axis of within-quadrat niche partitioning. At the individual level, trait patterns were qualitatively consistent but were stronger than species-level patterns, especially for the leaf traits with the greatest intraspecific variation (SLA and succulence). Individual-level SLA exhibited the strongest evidence for both traits among and within-quadrat niche partitioning and indicated elevational filtering. Local niche partitioning and elevational filtering likely play an important role in maintaining species and functional diversity in the most speciose genus at our study site. Our results highlight the importance of individual variation, as it may reveal otherwise obscured niche effects.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The role of functional traits and individual variation in the co‐occurrence of Ficus species

Lasky

Yang

Zhang

et al. 2014

Ecology

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“…Third, the four forest types vary not only in belowground resources, but also in slope. The loam soil and parts of the fine loam soil comprise steep slopes with greater occurrence and larger sizes of landslips than do the clay, low-lying parts of fine loam, and sandy loam soils (Ohkubo 2007a(Ohkubo , 2007bYamakura et al 1996). Steep slopes would result in larger, more frequent canopy openings and could explain why the decline in understorey irradiance was not monotonic with increases in soil resource availability.…”

Section: Causes and Consequences Of Soil-related Variation In Light Rmentioning

confidence: 99%

“…Furthermore, elevation and slope vary significantly among soil types: the sandy loam and clay soils occur at the highest and lowest elevations, respectively, and the loam and fine loam soils occur at intermediate elevations in Lambir (Baillie et al 2006). The loam and fine loam soils are located on steep slopes, where there are more frequent landslips (Ohkubo 2007a(Ohkubo , 2007b.…”

Section: Study Sitementioning

confidence: 99%

“…Gradients defined with respect to one resource may nonetheless also vary with respect to other resources. For example, forests growing on soils of different texture or along elevation gradients often have different disturbance regimes, creating covariation between these environmental factors and light (Matson & Boone 1984, Myster & Fernandez 1995, Ohkubo 2007a, 2007bRichards 1996, Wells et al 1998. 1 Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

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Covariation between understorey light environments and soil resources in Bornean mixed dipterocarp rain forest

2011

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Variation in understorey irradiance is both a cause and consequence of the structure and dynamics of closed-canopy forests, which are also influenced by soil nutrients and water availability. We tested the hypothesis that understorey light regimes differ among four mixed dipterocarp forest types that share the same rainfall, but grow on different soils along an edaphic gradient at one site in Borneo. Based on data from photosynthetically active radiation sensors deployed at 1-m height at 36 locations for 351 sensor-days, we found significant soil-related variation in irradiance. The more productive forest types on clay and fine loam had lower daily photosynthetic photon flux density (PPFD) than those on the more nutrient-depleted and better-drained sandy loam and loam. They also had fewer moderate to high-intensity sunflecks, and a greater proportion of their daily PPFD came from low-intensity light. Understorey irradiance did not, however, monotonically decline with increasing soil resources. Forests on intermediate soils had greater irradiance than those with more and less soil resources, due to steeper slopes. Plant communities arrayed on resource gradients are commonly used to test hypotheses of environmental factors driving their assembly. Our results indicate that consideration of multiple resource dimensions in such tests is critical.

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Trait‐mediated effects of environmental filtering on tree community dynamics

Lasky

Sun

et al. 2013

Journal of Ecology

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Summary1. Individual performance is a function of an individual's traits and its environment. This function, known as an environmental filter, varies in space and affects community composition. However, filters are poorly characterized because dispersal patterns can obscure environmental effects, and few studies utilize longitudinal data linking individual performance to environment. 2. We model the effects of environmental filters on demographic rates of nearly all tree species (99) in a 25-ha subtropical rain forest plot. We develop a hierarchical Bayesian model of environmental filtering, drawing inspiration from classic studies of intraspecific natural selection. We characterize the specific environmental gradients and trait axes most important in filtering of demographic rates across species. 3. We found that stronger filtering along a given trait axis corresponded to less spatial variation in the value of favoured traits. 4. Environmental gradients associated with filtering were different for growth versus survivorship. 5. Species maximum height was under the strongest filtering for growth, with shorter species favoured on convex ridges. Shorter stature species may be favoured on ridges because trees on ridges experience higher wind damage and lower soil moisture. 6. Wood density filtering had the strongest effects on survival. Steep slopes and high available P in the soil favoured species with low-density wood. Such sites may be favourable for fast-growing species that exploit resource-rich environments. 7. Synthesis: We characterized trait-mediated environmental filters that may underlie spatial niche differentiation and life-history trade-offs, which can promote species coexistence. Filtering along trait axes with the strongest effects on local community composition, that is, traits with the strongest filtering, may necessarily have a weaker potential to promote species coexistence across the plot. The weak spatial variation in filters with strong effects on demography may result from long-term processes affecting the species pool that favour habitat generalist strategies.

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Spatial and topographic patterns of canopy gap formation in a mixed dipterocarp forest in Sarawak, Malaysia

Abstract: A B S T R A C T W e o b s e r v e d s p a t i a l a n d topographic patterns of canopy gap formation in

Cited by 8 publications

References 32 publications

The role of functional traits and individual variation in the co‐occurrence of Ficus species

The role of functional traits and individual variation in the co‐occurrence of Ficus species

Covariation between understorey light environments and soil resources in Bornean mixed dipterocarp rain forest

Trait‐mediated effects of environmental filtering on tree community dynamics

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