Photosynthetic induction times and photoinhibition in relation to simulated sunflecks (sudden increase of irradiance from 20 to 1,500 lmol m -2 s -1 ) were examined in leaves of co-occurring Fagus lucida (a deciduous tree) and Castanopsis lamontii (an evergreen tree) saplings grown either in a beech forest understory or in an adjacent open site during a late rainy season. Two hypotheses were tested: (1) understory leaves would display faster photosynthetic induction times and greater photoinhibition than open-grown leaves; and (2) evergreen species would have slower photosynthetic induction times and lighter photoinhibition than deciduous species. Times to reach 90% of maximal CO 2 assimilation rate (t 90%A ) and stomatal conductance ðt 90%g s Þ did not differ between species, but showed faster by 3-5 min in open-grown leaves than understory leaves due to higher initial stomatal conductance (g s initial ) and induction state 1 min into simulated sunflecks (IS 1min ) in the former. Our analysis across the published data on photosynthetic induction of 48 broadleaved woody species again revealed the negative correlations between t 90%A and either g s initial or IS 1min , and the similarity of t 90%A and t 90%g s between evergreen and deciduous species. Measurements of maximum PSII photochemical efficiency (F v /F m ) indicated that photoinhibition occurred in saplings in any of the growth habitats during sunfleck-induced photosynthetic induction. Despite no interspecific differences in the degree of photoinhibition, understory leaves of both species suffered heavier photoinhibition than open-grown leaves, as indicated by a stronger decrease of F v /F m in the former. Dynamic changes in the quantum yields of PSII photochemistry and DpHand xanthophyll-regulated thermal dissipation and adjustments in the partitioning of electron flow between assimilative and non-assimilative processes were functional to resist photoinhibition. However, such photoinhibition, together with stomatal and biochemical limitations, would decrease carbon gain during simulated sunflecks, particularly in understory leaves.

We used leaf economics spectrum (LES) theory to explain the bimodal elevational distribution of evergreen tree species, which is one of the most puzzling biogeographic patterns in the world. Our results suggest that elevation acts as an environmental filter to both select the locally adapted evergreen and deciduous species with sufficient phylogenetic variation and distinct leaf economic strategies and regulate their distribution along the elevational gradient based on their coordinated spreading of phylogenetic divergence and leaf economic variation. If species are filtered from regional species pools, changing climate may affect both the species and leaf economic composition of plant communities.

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In field studies during 2000-2005, seasonal dynamics of sugarcane shoot borer Chilo infuscatellus Snellen (Lepidoptera: Crambidae) and its parasitoid Sturmiopsis inferens Tns. (Diptera: Tachinidae) were examined and augmentative releases of the parasitoid against the borer were evaluated at Coimbatore, India. The borer was active throughout the study period with the overall range of 0.3 -28.6% fortnightly deadheart incidence. With considerable yearto-year variation, the borer peaked during July-August in high incidence years but showed indistinct peak activity periods in low attack years. Sturmiopsis inferens was found in all the study years with zero activity in some fortnights and overall maximum parasitism rates of 23.3 and 21.0% in 2000 and 2001, respectively; parasitoid activity dropped drastically in 2002 and the decline continued thereafter. The high parasitism years witnessed distinct peak activity in March and somewhat higher activity in July-August. Simple and multiple correlation analyses showed inconsistent influence of weather parameters on borer and parasitoid activity. Shoot borer activity was weakly related to St. inferens activity either in individual years or in the entire five-year period. Augmentative releases of St. inferens gravid females at dosages of 25-95 females/ha enhanced parasitism rates and reduced borer incidence in some trials but produced variable effects in some other trials. Dosage of parasitoid was not related to post-release parasitism rates in release plots. The results of the field trials and their implications are discussed.

Indocalamus longiauritus (a dwarf bamboo) dominates forest understory and functions as an ecological filter to hinder the regeneration of canopy tree species in many temperate forests. However, the physiological mechanism underlying the function of ecological filters is not clear. In this study, we measured leaf-level carbon capture ability and use efficiency of the dwarf bamboo and the co-existing Fagus lucida (beech) and Castanopsis lamontii (chinkapin) seedlings in forest understory and small gaps in a beech-chinkapin mixed forest in the summer of 2005. The results indicated that I. longiauritus exhibited greater carbon capture ability, as indexed by light-saturated photosynthetic rate (P max ), maximal carboxylation rate, maximal electron transport rate and carboxylation efficiency, than the co-occurring F. lucida and C. lamontii seedlings in both forest understory and small gaps. Higher carbon capture ability in I. longiauritus was related to its greater partition of absorbed light energy to photochemistry. I. longiauritus had higher photosynthetic nitrogen use efficiency than F. lucida and C. lamontii seedlings in both light environments. However, water use efficiency (WUE) in I. longiauritus was higher than F. lucida but lower than C. lamontii. This intermediate WUE in I. longiauritus was related to its intermediate light-saturated stomatal conductance.In addition, I. longiauritus reduced metabolic cost by increasing the ratio of P max to respiration rate, leading to increased net carbon balance. On the other hand, F. lucida and C. lamontii seedlings had greater plasticity of carbon capture ability and leaf structural traits, which might facilitate colonization of gaps and realization of natural regeneration in these species.Keywords Dwarf bamboo AE Beech-chinkapin mixed forest AE Ecological filter AE Carbon capture ability and use efficiency AE Physiological mechanismList of symbols C a CO 2 concentration external to leaf (lmol mol À1 ) C i CO 2 concentration in the intercellular space (lmol mol À1 ) CE Carboxylation efficiency (lmol m À2 s À1 ) Chl n Ratio of leaf chlorophyll to leaf nitrogen in light-harvesting components (mmol g À1 ) Chl area Area-based leaf chlorophyll content (mg m À2 ) Chl mass Mass-based leaf chlorophyll content (mmol g À1 ) F 0 Minimal fluorescence in the dark F m Maximal fluorescence in the dark F s Steady-state fluorescence in the light F 0 m Maximal fluorescence in the light g smax Light-saturated stomatal conductance (mmol m À2 s À1 ) J max Maximal electron transport rate (lmol m À2 s À1 ) J mc Potential rate of photosynthetic electron transport per unit cytochrome f (lmol lmol À1 s À1 ) K c Michaelis-Menten constant of Rubisco for carboxylation (lmol mol À1 ) K o Michaelis-Menten constant of Rubisco for oxidation (mmol mol À1 ) LCP Light compensation point (lmol m À2 s À1 )LMA Leaf mass per area (g m À2 ) LVPD Leaf-to-air vapor pressure deficit (kPa) N area Area-based leaf nitrogen content (g m À2 ) N mass Mass-based leaf nitrogen content (g g À1 ) OIntercellular oxygen conce...

The evolutionary mechanisms underlying the biogeochemical niche conservatism in forests remain incompletely understood. Here we aimed to determine how the strengths of biogeochemical niche conservatism vary among elements and between life forms. We measured leaf concentrations of basal elements (C, N, P, K, Ca, and Mg) in a wide range of life forms in a subtropical montane evergreen broad‐leaved forest. We found that differences in life forms such as evergreen/deciduous woody species and herbaceous/woody species significantly affected leaf elemental composition. The significant phylogenetic signal was present in leaf C, N, K, and Mg concentrations but absent in leaf P and Ca concentrations in all species. These contrasting strengths of biogeochemical niche conservatism were best generated by Ornstein–Uhlenbeck processes toward optima. Woody species were evolutionarily selected to show lower optimal leaf N, P, and K concentrations and higher optimal leaf C, Ca, and Mg concentrations than herbaceous species. The number of optima varied from the least in leaf C concentration to the most in leaf Ca concentration, suggesting the stronger convergent evolution of leaf Ca concentration. The positions of optima toward the tips were more selected in woody species, suggesting the more frequency of species‐specific adaptations in woody species. The positions of optima were also selected at the nodes towards the species groupings from certain life forms (e.g., the group of 12 Polypodiales ferns in leaf Ca evolution and the group of three evergreen Theaceae species in leaf P evolution) that were converged to present similar leaf elemental composition. During the evolution of biogeochemical niche, strong correlations were found among leaf C, N, P, and K concentrations and between leaf Ca and Mg concentrations. In conclusion, the strengths of biogeochemical niche conservatism can vary among elements and between life forms due to the different tempo and mode of Ornstein–Uhlenbeck processes.

The diversification of floral traits is the outcome of evolution by natural selection, and the variation in floral traits between species has a certain correlation with the plant habitats. The northern tropical karst seasonal rain forests have a great habitat heterogeneity, a complex structure of plant community, and abundant endemic components. Analyzing the relationship between the variation of plant traits and their habitats in those forests is helpful to understand species coexistence, coevolution and their adaptations to habitats, and to provide clues for revealing the ecological adaptability of plants and the maintenance mechanisms of biodiversity in karst forests. We conducted a preliminary study at a 15 ha plot of the northern tropical karst seasonal rain forest in Nonggang to examine the differences in floral traits among species and how these traits varied with habitats, when a relatively large number of woody plants bloomed synchronously, with a total of 21 species being found flowering. We divided the 21 species into three preferred habitat types (peak, slope and valley) according to the spatial distribution of species and their habitat associations, and analysed