Habitat fragmentation narrows the distribution of avian functional traits associated with seed dispersal in tropical forest

AbstractLeaf phenology based classification of woody species into discrete evergreen and deciduous categories is widely used in ecology, but these categories hide important variation in leaf phenological behaviour. Few studies have examined the continuous nature of deciduousness and our understanding of variation in quantitative estimates of leaf shedding behaviour and the causes and consequences of this is limited. In this study we monitored leaf phenology in 75 woody species from a seasonally dry tropical forest to quantify three quantitative measures of deciduousness, namely: maximum canopy loss, duration of deciduousness, and average canopy loss. Based on proposed drought tolerance and drought avoidance strategies of evergreen and deciduous species, respectively, we tested whether the quantitative measures of deciduousness were related to leaf functional traits. Additionally, to understand the functional consequences of variation in deciduousness we examined relationships with the timing of leaf flushing and senescing. We found wide and continuous variation in quantitative measures of deciduousness in these coexisting species. Variation in deciduousness was related to leaf function traits, and the timing of leaf flushing. Along a continuous axis ranging from evergreen to deciduous species, increasing deciduousness was associated with more acquisitive leaf functional traits, with lower leaf mass per area and leaf dry matter content, and greater leaf nitrogen content. These results indicate that the continuous nature of deciduousness is an important component of resource acquisition strategies in woody species from seasonally dry forests.

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Frugivory and seed dispersal by carnivorous mammals: functional traits

Ecosistemas ◽

10.7818/ecos.2015.24-3.07 ◽

2015 ◽

Vol 24 (3) ◽

pp. 43-50 ◽

Cited By ~ 8

Author(s):

Juan Pedro González-Varo ◽

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José María Fedriani Laffite ◽

Alberto Suárez-Esteban

Keyword(s):

Seed Dispersal ◽

Functional Traits

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The role of great apes in seed dispersal of the tropical forest tree species Dacryodes normandii (Burseraceae) in Gabon

Journal of Tropical Ecology ◽

10.1017/s0266467415000322 ◽

2015 ◽

Vol 31 (5) ◽

pp. 395-402 ◽

Cited By ~ 9

Author(s):

Barbara Haurez ◽

Kasso Daïnou ◽

Nikki Tagg ◽

Charles-Albert Petre ◽

Jean-Louis Doucet

Keyword(s):

Seed Dispersal ◽

Tropical Forest ◽

Tree Species ◽

Central Africa ◽

Great Apes ◽

Forest Tree ◽

Sampling Effort ◽

Predator Species ◽

High Germination ◽

Visit Duration

Abstract:The identification of seed dispersers and predators is essential to understand the effect of anthropogenic disturbances, and the associated defaunation process, on tropical forest dynamics in Central Africa. In this study, the animals involved in seed predation and dispersal of Dacryodes normandii (Burseraceae), an endozoochorously dispersed tree species endemic to Gabonese forests, were identified in a site in south-east Gabon using two complementary methods: direct observation and camera-trap monitoring of fruit piles. The combined sampling effort (172 h of direct observations and 796 d of camera trapping) led to the identification of six disperser and eight predator species of D. normandii seeds. With high frequency of consumption (88% and 57% of their visits, respectively) and long visit duration (83 and 23 min, respectively), the western lowland gorilla and central chimpanzee were identified as the main dispersers of this species. Seeds passed through the gorilla gut exhibited high germination success (68%). Rodents were identified as predators of D. normandii seeds, potentially displaying rare secondary dispersal through scatter-hoarding. The results of this study highlight the importance of great apes in the seed dispersal of this tree species.

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Analysing Amazonian forest productivity using a new individual and trait-based model (TFS v.1)

Geoscientific Model Development ◽

10.5194/gmd-7-1251-2014 ◽

2014 ◽

Vol 7 (4) ◽

pp. 1251-1269 ◽

Cited By ~ 63

Author(s):

N. M. Fyllas ◽

E. Gloor ◽

L. M. Mercado ◽

S. Sitch ◽

C. A. Quesada ◽

...

Keyword(s):

Tropical Forest ◽

Functional Traits ◽

Amazon Basin ◽

Census Data ◽

Soil Nutrient ◽

Forest Growth ◽

High Rate ◽

Mean Annual Precipitation ◽

Water Fluxes ◽

Amazonian Forest

Abstract. Repeated long-term censuses have revealed large-scale spatial patterns in Amazon basin forest structure and dynamism, with some forests in the west of the basin having up to a twice as high rate of aboveground biomass production and tree recruitment as forests in the east. Possible causes for this variation could be the climatic and edaphic gradients across the basin and/or the spatial distribution of tree species composition. To help understand causes of this variation a new individual-based model of tropical forest growth, designed to take full advantage of the forest census data available from the Amazonian Forest Inventory Network (RAINFOR), has been developed. The model allows for within-stand variations in tree size distribution and key functional traits and between-stand differences in climate and soil physical and chemical properties. It runs at the stand level with four functional traits – leaf dry mass per area (Ma), leaf nitrogen (NL) and phosphorus (PL) content and wood density (DW) varying from tree to tree – in a way that replicates the observed continua found within each stand. We first applied the model to validate canopy-level water fluxes at three eddy covariance flux measurement sites. For all three sites the canopy-level water fluxes were adequately simulated. We then applied the model at seven plots, where intensive measurements of carbon allocation are available. Tree-by-tree multi-annual growth rates generally agreed well with observations for small trees, but with deviations identified for larger trees. At the stand level, simulations at 40 plots were used to explore the influence of climate and soil nutrient availability on the gross (ΠG) and net (ΠN) primary production rates as well as the carbon use efficiency (CU). Simulated ΠG, ΠN and CU were not associated with temperature. On the other hand, all three measures of stand level productivity were positively related to both mean annual precipitation and soil nutrient status. Sensitivity studies showed a clear importance of an accurate parameterisation of within- and between-stand trait variability on the fidelity of model predictions. For example, when functional tree diversity was not included in the model (i.e. with just a single plant functional type with mean basin-wide trait values) the predictive ability of the model was reduced. This was also the case when basin-wide (as opposed to site-specific) trait distributions were applied within each stand. We conclude that models of tropical forest carbon, energy and water cycling should strive to accurately represent observed variations in functionally important traits across the range of relevant scales.

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