Fig 1.
Locations of the 1,857 Ficus trees marked in the study area.
Red circles denote surveyed trees, grey circles denote trees that were not surveyed. The linear pattern at this scale indicates the association between roads and the distribution of Ficus trees. Kaziranga National Park and Panbari Forest Reserve contain the only relatively intact forests in the study area.
Table 1.
Characteristics of the isolated Ficus trees and the two control tree categories included in the study.
Fig 2.
Incidence functions for six frugivore species.
Species are a) Great Pied Hornbill Buceros bicornis; b) Red-vented Bulbul Pycnonotus cafer; c) Great Myna Acridotheres grandis d) Blue-eared Barbet Megalaima australis; e) Coppersmith Barbet Megalaima haemacephala; f) Black-hooded Oriole Oriolus xanthornus. Green curves represent forest-dependent species, blue represent habitat-generalists, and red represent matrix-specialists. The curves are the predicted probability of occurrence, generated through a logistic regression model, with distance from the nearest primary forest as the predictor variable for each species’ presence/absence data at 122 isolated Ficus trees. The incidence function curves of all 33 frugivore species are displayed in S1 Fig. The figures were constructed using the R package “GGplot2” [33].
Table 2.
Differences between species richness, abundance, and functional diversity parameters across the three tree categories.
Table 3.
Morisita similarity matrix of multiple communities, estimated from the abundance of frugivores recorded in three tree types (n = 31 surveys for each group).
Table 4.
Generalized Linear Model results with Akaike Information Criterion scores for finite samples for variables affecting three measures of frugivore assemblage at isolated Ficus trees in Assam, India.
Table 5.
Correlation coefficients for the parameters retained in the “best” performing models (see Table 4).
Fig 3.
Quantile regression estimation of changes in frugivore abundance in isolated Ficus trees as a function of distance from the nearest primary forest in rural Assam, India.
A) is a scatter plot of n = 122 isolated Ficus trees with 0.05, 0.10, 0.25, 0.50 (median), 0.75, 0.90, and 0.95 quantile and the least squares mean regression estimates. B) shows the sample estimates for the slope (thick red line) with thin red lines connecting the endpoints of the 95% confidence intervals. The grey line represents the mean slope. The figures were constructed using the R package “GGplot2” [33].
Fig 4.
Scatter plot of observed (grey points) versus expected (black points) functional dispersion for frugivorous birds in isolated Ficus trees.
The sample size was 122 isolated Ficus trees in a human-modified landscape in Assam, India. Trend lines are linear regressions for both observed FDis (grey line; R2 = 0.16) and expected FDis (black line; R2 = 0.99). Expected FDis scores are the mean of 10,000 iterations of a quasi-swap null model, where row and column totals were held constant.
Fig 5.
Canonical correspondence analysis showing the relationships between the abundance of individual frugivorous species and constrained environmental parameters.
The direction of influence of the environmental parameters is indicated by the solid black lines, and annotations are: TS = tree size, FS = fruit size, L = land-use intensity, D = distance from nearest primary forest. Species names are colour coded according to classifications of habitat preference drawn from the literature. Common names are provided in S1 Fig. Some species names are abbreviated to aid interpretation. They are: Alofla = Alophoixus flaveolus, Pycjoc = Pycnonotus jocosus, Bucbic = Buceros bicornis, Megaus = Megalaima australis, Stumal = Sturnia malabarica, Gracon = Gracupica contra, Meghae = Megalaima haemacephala, Pyccar = Pycnonotus cafer, Trepho = Treron phoenicoptera, Corlev = Corvus levaillantii, A = Acridotheres tristis, M = Megalaima asiatica, Meglin = Megalaima lineata, Acrgra = Acridotheres grandis.