No abstract

Cypripedium tibeticum, a subalpine orchid species, inhabits various habitats of subalpine forests, mainly including the forest edge (FE), forest gap (FG), and understory (UST), which have significantly different light intensities (FE > FG > UST). However, the ecological and physiological influences caused by different light regimes in this species are still poorly understood. In the present study, photosynthetic, morphological, and reproductive characteristics were comprehensively studied in plants of C. tibeticum grown in three types of habitats. The photosynthetic capacities, such as the net photosynthetic rate, light-saturated photosynthesis (Pmax), and dry mass per unit leaf area (LMA), were higher in FE and FG than in UST according to light availability. Compared with FG, the populations in FE and UST suffer from excessively strong and inadequate radiation, respectively, which was further corroborated by the low Fv/Fm in FE and high apparent quantum yield (AQY) in FG. The leaves of the orchids had various proportions of constituents, such as the leaf area, thickness and (or) epidermal hair, to reduce damage from high radiation (including ultraviolet-b radiation) in FE and capture more light in FG and UST. Although the flower rate (FR) was positively correlated to both Pmax and the daily mean PAR, fruit-set only occurred in the populations in FG. The failures in FE and UST might be ascribed to changes in the floral functional structure and low biomass accumulation, respectively. Moreover, analysis of the demographic statistics showed that FG was an advantageous habitat for the orchid. Thus, C. tibeticum reacted to photosynthetic and morphological changes to adapt to different subalpine forest habitats, and neither full (under FE) nor low (UST) illumination was favorable for population expansion. These findings could serve as a guide for the protection and reintroduction of C. tibeticum and emphasize the importance of specific habitats for Cypripedium spp.

Seasonal and vertical variations of seaweed biomass were examined at Woejodo and Jusamdo of western sea, Korea from July 2006 to April 2007. Annual seaweed biomass was 198.27 g m-2 in wet weight at Woejodo and 417.34 g m-2 at Jusamdo, respectively and biomass of intertidal zone was greater than that of subtidal zone at Jusamdo sites. Seaweeds distributed vertically from mid intertidal to 5 m of subtidal zone at Woejodo and from high intertidal to 10m of subtidal zone at Jusamdo. Seaweed biomass and species number were maximal at lower intertidal zone (27 species, 365.43 g m-2) of Woejodo and at mid intertidal zone (26 species, 684.18 g m-2) of Jusamdo. Seasonal biomass varied from 136.73g m-2 in autumn to 249.33 g m-2 in winter at Woejodo and from 353.37 g m-2 in autumn to 482.07 g m-2 in summer at Jusamdo. Dominant species was Sargassum thunbergii showing highest annual biomass (Woejodo, 94.68 g m-2 ; Jusamdo, 228.59 g m-2) among all seaweeds and finding at various shore levels during the study period. Subdominant species were Corallina pilulifera and Gracilaria textorii at Woejodo, and were Sargassum fusiformis and Chondria crassicaulis at Jusamdo. Thus, we can conclude that Jusamdo shore is better place than Woejodo based on seaweed biomass and vertical distribution, and S. thunbergii is the representative species of the two islands.

A new orchid species, Dendrobium jinghuanum (Epidendroideae, Orchidaceae), from Yunnan Province, China, is described and illustrated based on morphological and molecular data. Morphological investigations indicated this new orchid is similar to D. bensoniae, D. crystallinum, and D. wardianum, but it can be differentiated easily from them by associated characteristics: 7-veined sepals, 9-veined petals, a chestnut blotch on either side of lip disk, an anther cap with distinct crystalline papillae, and stems without swollen nodes. Molecular phylogeny analyses showed that D. jinghuanum is a member of section Dendrobium s.l. and sister to D. bensoniae but not D. crystallinum or D. wardianum.