Strong intraspecific trait variation in a tropical dominant tree species along an elevational gradient

Functional trait variation of plant species includes both inter-and intraspecific variation;however,traitbased plant ecology generally considers only interspecific variation while ignoring intraspecific variation.One reason for this neglect is that intraspecific variation may be negligible when compared to interspecific variation;however,direct comparisons between inter-and intraspecific variation of plant species are lacking,especially in tropical forests.Here we investigated intraspecific leaf trait variation(leaf area,specific leaf area,leaf thickness,leaf density,leaf chlorophyll content) of Pittosporopsis kerrii Craib(Icacinaceae),the most abundant tree species in the Xishuangbanna tropical seasonal rainforest in southwestern China,along an elevational gradient(703-824 m).We found a substantial range of intraspecific variation in P.kerrii that was never less than 22.1% of range of the interspecific variation among 462 tree species reported before in the same community.Moreover,with increased elevation,both leaf thickness and density increased and specific leaf area decreased significantly.It could be more important for the individuals of P.kerrii to produce thicker and denser leaves to tolerate environmental stress(e.g,soil water availability) rather than having high growth rates at the places with higher elevation in the Xishuangbanna tropical seasonal rainforest.

Description of two new species of Hemiphyllodactylus(Reptilia: Gekkonidae) from karst landscapes in Yunnan, China, highlights complex conservation needs

Karst habitats are hotspots of diversity and endemism. Their naturally fragmented distributions across broad geographic landscapes have led to the complex array of smaller evolutionary ecosystems that present unique challenges from a conservation perspective.Comprehensivebiodiversity assessments of karst habitats have revealed that these ecosystems contain an almost unparalleled level of endemism, and many site-restricted species remain undescribed, thus posing considerable challenges for effective conservation management.Small rock-dwelling species, such as geckos, may be particularly prone to such isolation. In this paper, we discuss one such genus, i.e.,Hemiphyllodactylus, and explore its diversity across karst landforms in Yunnan Province, southwestern China. Based on morphological and genetic data, we describe two new species of Hemiphyllodactylus from karst habitats in Simao District and Yanshan County. A phylogenetic tree for Hemiphyllodactylus was constructed using 1?039 base pairs(bp) of the mitochondrial NADH dehydrogenase subunit 2 gene(ND2). The Simao and Yanshan specimens can be distinguished from all other congeners within their respective subclades based on uncorrected genetic pairwise distances greater than 6.3% and 4.3%respectively, as well as significant morphological differences. The discovery and description of these two new species brings the total number of described Hemiphyllodactylus species in China to 14and indicates many more undescribed species from unsurveyed karst regions await discovery.Our findings suggest that karst ecosystems in Yunnan support a higher diversity of Hemiphyllodactylus than previously known.This study also highlights the importance of karst ecosystems as refugia for sitespecific endemic species and the need for heightened conservation efforts.

Effects of forest fragmentation on nocturnal Asian birds:A case study from Xishuangbanna,China

Owls have the potential to be keystone species for conservation in fragmented landscapes, as the absence of these predators could profoundly change community structure. Yet few studies have examined how whole communities of owls respond to fragmentation, especially in the tropics. When evaluating the effect of factors related to fragmentation, such as fragment area and distance to the edge, on these birds, it is also important in heterogeneous landscapes to ask how ＇location factors＇ such as the topography, vegetation and soil of the fragment predict their persistence. In Xishuangbanna, southwest China, we established 43 transects （200 mx60 m） within 20 forest fragments to sample nocturnal birds, both visually and aurally. We used a multimodel inference approach to identify the factors that influence owl species richness, and generalized linear mixed models to predict the occurrence probabilities of each species. We found that fragmentation factors dominated location factors, with larger fragments having more species, and four of eight species were significantly more likely to occur in large fragments. Given the potential importance of these birds on regulating small mammal and other animal populations, and thus indirectly affecting seed dispersal, we suggest further protection of large f ragments and programs to increase their connectivity to the remaining smaller fragments.

Influence of smoke, heat and fire on germination of woody species occurring in the dry valleys of southwest China

Aims Savannahs depend on fire for their persistence.Fire influences regeneration from seeds in several ways:it converts the environment into a more open space which can benefit the establishment of seedlings,and fire itself can also enhance germination by chemical and physical cues,such as smoke and heat.There is limited information as to how seed of Asian savannah species respond to fire,even though Asia has several dry vegetation types that are associated with fire.Our main question was whether fire enhances or triggers the germination of woody species occurring in southwest Chinese dry valleys,which have savannah vegetation.Methods We conducted tests with heat(80°C)and smoke solution treatments,and tests with real fire by burning grass on top of sand trays containing seeds.We tested 35 species,including savannah species,and gully and forest species.Depending on seed availability,not all species were tested for all treatments.Twenty-six species had total germination>4%and these were used for analysis.Important Findings Heat increased germination of three species(strongest reaction:Dodonaea viscosa),smoke increased germination of five species(strongest reaction:Calotropis gigantea).Both treatments decreased germination for five and seven species,respectively.Real fire was detrimental for most species,except for D.viscosa,which is known to respond positively to heat shock.Even though fire-related cues were not a trigger for germination for most species in our study,fire could still be crucial for regeneration by competition release.

Effects of fragmentation on the seed predation and dispersal by rodents differ among species with different seed size

Fragmentation influences the population dynamics and community composition of vertebrate animals.Frag­mentation effects on rodent species in forests may,in turn,affect seed predation and dispersal of many plant species.Previous studies have usually addressed this question by monitoring a single species,and their results are contradictory.Very few studies have discussed the fragmentation effect on rodent-seed interaction among tree species with different seed sizes,which can significantly influence rodent foraging preference and seed fate.Given that fruiting periods for many coexisting plant species overlap,the changing foraging preference of ro­dents may substantially alter plant communities.In this study,we monitored the dispersal and predation by ro­dents of 9600 seeds,belonging to 4 Fagaceae species with great variation in seed size,in both the edge and inte­rior areas of 12 tropical forest fragments ranging in area from 6.3 to 13872.9 ha in Southwest China.The results showed that forest fragmentation altered the seed fates of all the species,but the intensity and even the direction of fragmentation effect differed between species with large versus small seeds.For the seeds harvested,frag­ment size showed negative effects in forest interiors but positive effects at edges for the 2 large-seeded species,but showed little effect for the 2 small-seeded species.For the seeds removed,negative effects of fragment size only existed among the small-seeded species.The different fragmentation effect on seed dispersal and predation among plant species may,in turn,translate into the composition differences of the regeneration of the whole fragmented forest.