Impact of patch size on woody tree species richness and abundance in a tropical montane evergreen forest patches of south India

We examined the effects of forest patch size on woody tree species richness and abundance in tropical montane evergreen forest patches of the Nilgiri region, south India. We sampled woody trees (C 1 cm dbh) from 21 forest patches in the upper Nilgiri hills ([2000 m elevation) and recorded a total of 35,146 individuals of 61 species, 45 genera and 30 families. Species richness and abundance of sapling/shrubs (C 1 to \10 cm dbh) increased significantly with increasing patch size, but the species richness and abundance of small, medium and larger trees (C 10 to\30, C 30 to\60 and C 60 cm dbh, respectively) did not. Overall, forest interior species richness and abundance increased significantly with increasing patch size but edge species richness did not. Species richness and abundance of shade-tolerant and shade-demanding tree species also increased with increasing patch size. The abundance of zoochory dispersed tree species was significantly related to increasing patch size, but those dispersed by autochory did not display any clear relationship between patch size and species richness or abundance. Our findings suggest that with increasing forest patch area, tree compositional patterns may be driven by species specific shade-tolerance adaptations and dispersal patterns. Differential responses in these traits by the plant community within the individual habitat zones of forest edge and interiors likely plays a major role in determining the inherent plant community and thus the subsequent ecological processes of forest patches, including their responses to increasing patch area

Diverse nectar robbers on Alpinia roxburghii Sweet (Zingiberaceae)

This study records for the first time three mammal species as nectar robbers on the ginger Alpinia roxburghii Sweet. We examined the behavior of nectar robbers and compared with earlier studies on a single plant species. We recorded seven species of nectar robbers: three squirrels, one bird, and three bees. Timing of robbing nectars were similar; however, robbing behavior differed among robbers. In particular, squirrels damaged the flower parts while robbing the nectar

Effects of patch size on liana diversity and distributions in the tropical montane evergreen forests of the Nilgiri Mountains, southern India

We investigate the effect of patch size on liana diversity and distribution in 19 patches of montane evergreen forest in the Nilgiri hills, Western Ghats, southern India. Additionally, we examined how liana species richness and community assemblage in both edge (within 10 m of the forest edge) and interior regions of forest patches respond to patch size, in order to infer the impact of forest expansion or reduction on the liana communities. A total of 1276 woody liana individuals of 15 species were identified, belonging to 10 genera and nine families. Total species richness of lianas was significantly positively related to forest-patch area, both when analysed for the entire patch, in addition to both core and edge regions when examined separately. Species richness of larger lianas also showed a significant positive relationship with increasing forest patch area. Community assemblage varied with respect to forest edge, with shade-dependent species only occurring in interior patch regions, shade-averse species in edge regions, and shade-tolerant species occurring throughout. Disturbance also played a role in determining the response of liana diversity to patch size, with heavily disturbed patches showing no relationship between patch size and diversity, whereas positive relationships exist in low to moderately disturbed patches. The most significant result is the change in liana community composition between small and larger fragments. Many species present in smaller patches are also present in edge zones of larger fragments. This suggests that lianas are important structural components of montane forest ecosystems, and their compositional patterns are possibly driven by succession. Moreover, this study reveals the importance of edge effect and patch size in influencing liana species richness and compositional patterns

Can lianas assist rainforest restoration?

Can the strategic incorporation of lianas (woody vines) into rainforest restoration plantings enhance biodiversity-conservation outcomes? Lianas are an integral component of primary tropical rainforests yet are often omitted from rainforest restoration plantings as they may damage trees and compete with them for resources. However, there is increasing evidence that many ecological and physiognomic characteristics of lianas may be of some value to restoration plantings, at least in certain contexts. We propose strategies for experimentally incorporating lianas into rainforest-restoration plantings to explore whether they can expedite rainforest establishment and enhance biodiversity-conservation outcomes

The effect of altitude, patch size and disturbance on species richness and density of lianas in montane forest patches

The species richness and density of lianas (woody vines) in tropical forests is determined by various abiotic and biotic factors. Factors such as altitude, forest patch size and the degree of forest disturbance are known to exert strong influences on liana species richness and density. We investigated how liana species richness and density were concurrently influenced by altitude (1700–2360 m), forest patch size, forest patch location (edge or interior) and disturbance intensity in the tropical montane evergreen forests, of the Nilgiri and Palni hills, Western Ghats, southern India. All woody lianas (≥1 cm dbh) were enumerated in plots of 30 × 30 m in small, medium and large forest patches, which were located along an altitudinal gradient ranging from 1700 to 2360 m. A total of 1980 individual lianas were recorded, belonging to 45 species, 32 genera and 21 families, from a total sampling area of 13.86 ha (across 154 plots). Liana species richness and density decreased significantly with increasing altitude and increased with increasing forest patch size. Within forest patches, the proportion of forest edge or interior habitat influenced liana distribution and succession especially when compared across the patch size categories. Liana species richness and density also varied along the altitudinal gradient when examined using eco-physiological guilds (i.e. shade tolerance, dispersal mode and climbing mechanism). The species richness and density of lianas within these ecological guilds responded negatively to increasing altitude and positively to increasing patch size and additionally displayed differing sensitivities to forest disturbance. Importantly, the degree of forest disturbance significantly altered the relationship between liana species richness and density to increasing altitude and patches size, and as such is likely the primary influence on liana response to montane forest succession. Our findings suggest that managing forest disturbance in the examined montane forests would assist in conserving local liana diversity across the examined altitudinal range

Increasing temperature causes flowering onset time changes of alpine ginger Roscoea in the Central Himalayas

Recent herbarium-based phenology assessments of many plant species have found significant responses to global climate change over the previous century. In this study, we investigate how the flowering phenology of three alpine ginger Roscoea species responses to climate change over the century from 1913 to 2011, by comparing between herbarium-based phenology records and direct flowering observations. According to the observations, flowering onset of the three alpine ginger species occurred either 22 days earlier or was delayed by 8–30 days when comparing the mean peak flowering date between herbarium-based phenology records and direct flowering observations. It is likely that this significant change in flowering onset is due to increased annual minimum and maximum temperatures and mean annual temperature by about 0.053°C per year. Our results also show that flowering time changes occurred due to an increasing winter–spring minimum temperature and monsoon minimum temperature, suggesting that these Roscoea species respond greatly to climate warming resulting in changes on flowering times

Impact of Striped-Squirrel Nectar-Robbing Behaviour on Gender Fitness in <i>Alpinia roxburghii</i> Sweet (Zingiberaceae)

<div><p>Nectar-robbing has the potential to strongly affect male and female reproductive fitness of plants. One example of nectar theft is that shown by striped-squirrels (<i>Tamiops swinhoei</i>) on a number of ginger species, including <i>Alpinia roxburghii</i> and <i>A</i>. <i>kwangsiensis</i> (Zingiberaceae). In this study, we used a fluorescent dye as a pollen analogue, and measured fruit and seed output, to test the effect of squirrel nectar-robbing on <i>A</i>. <i>roxburghii</i> reproductive fitness. Pollen transfer between robbed and unrobbed flowers was assessed by comparing 60 randomly established plots containing robbed and unrobbed flowers. The frequency of squirrel robbing visits and broken styles were recorded from a number of flowers for five consecutive days. Two bee species (<i>Bombus eximius</i> and <i>Apis cerana)</i>, were the primary pollinators, and their visitation frequency was recorded for six consecutive days. The results showed that fluorescent powder from unrobbed flowers was dispersed further, and to a greater number of flowers than that placed on robbed flowers. Additionally, robbing flowers caused significant damage to reproductive organs, resulting in lower fruit and seed sets in robbed than in unrobbed flowers and influencing both male and female fitness. The frequency of the primary pollinator visits (<i>B</i>. <i>eximius</i>) was significantly higher for unrobbed plants than for robbed plants. The present study clearly shows the negative impact of squirrel robbing on <i>A</i>. <i>roxburghii</i> male reproductive fitness and neutral impact on female reproductive fitness.</p></div

Assessment of Roscoea population size in the Central Himalayas based on historical herbarium records and direct observation for the period 1913-2011

The collection of plant specimens and their preservation within herbaria is invaluable in the documentation of temporal species change and the conservation of genetic plant resources. Historical plant collections enable an accurate determination of species geographical distribution at both the local and regional scale. In this study, we directly collected samples from Roscoea populations at various locations throughout Central Nepal and examined these along with those of the long-term historic herbarium data in order to assess their population size. A total of 136 plant collections were analyzed including 94 herbarium collections records (HR) covering 3 species, and 42 population collections of direct field observations (DFO) covering 5 species. Through our analysis of both the HR and DFO collections we found that: R. alpina and R. purpurea both possess a large population and wide geographic distribution, whilst, R. capitata and R. tumjensis both exhibit a narrow geographic range although the former has a moderate sized population and R. tumjensis a low population and restricted range. Finally, R. auriculata had a wide geographic distribution however it

(a) Posterior means of florescent powder dispersal probability (%) among robbed (closed circles) and unrobbed (open circles) plots. (b) Effects of robbing on florescent powder dispersal probability (c) Effects of distances on florescent powder dispersal probability.

<p>The effects of distances were calculated with respect to that measured for 0–2 m (i.e., the effect for 0–2 m was set to zero and was used as a benchmark). Bars represent the 95% confidence interval of the posterior distribution in each figure.</p