[Soil respiration rate and its influencing factors in artificial land-bridge islands system]. / äººå·¥é™†æ¡¥å²›å±¿ç³»ç»ŸåœŸå£¤å‘¼å¸é€ŸçŽ‡åŠå ¶å½±å“å› å­.

It is of great significance to understand the pattern of soil respiration rate in fragmented forests for further revealing terrestrial ecosystem carbon cycling. With different habitats (island vs. mainland, island edge vs. island interior) of the artificial land-bridge island system in Thousand Island Lake (TIL) region as the objects, we analyzed the seasonal dynamics of soil respiration rate and its relationships with soil physicochemical factors. The results showed that: 1) Soil respiration rates varied significantly across different seasons, with an order of summer (3.74 µmol·m-2·s-1) > autumn (2.30 µmol·m-2·s-1) > spring (1.82 µmol·m-2·s-1) > winter (1.40 µmol·m-2·s-1). 2) Forest fragmentation had significant effects on soil respiration rate, with soil respiration rate of island (2.37 µmol·m-2·s-1) being significantly higher than that of mainland (2.08 µmol·m-2·s-1) and the soil respiration rate of island edge (2.46 µmol·m-2·s-1) being significantly higher than that of island interior (2.03 µmol·m-2·s-1). 3) Soil temperature significantly promoted soil respiration rate, explaining 56.1% of the total variation. 4) There was a significant positive correlation between soil respiration rate and soil total carbon, ammo-nium nitrogen content, and vegetation coverage. The soil total carbon and ammonium nitrogen content of island edge were significantly higher than those of island interior. In all, forest fragmentation promoted soil respiration rate, with soil physicochemical factors as the drivers for its variation.

Carex borealifujianica (Cyperaceae), a new species of the core Carex clade from Fujian, southeastern China.

A new species, Carex borealifujianica Y.F. Lu & X.F. Jin (Cyperaceae, sect. Occlusae of core Carex clade) is described and illustrated from northern Fujian, China. In addition to morphological comparisons with its relatives, comparative micromorphology of utricles and achenes of seven species in Carex sect. Occlusae was examined. Micromorphology of utricles and achenes revealed the similarity of Carex borealifujianica and C. ligulata. Morphologically, this new species is similar to Carex ligulata in having lateral spikes remote and densely flowered, as well as utricles densely hispidulous, but differs in having 2 or 3 narrowly clavate staminate spikes, leaves 2.5-5 mm wide with sheaths sparsely pilose, and achenes emarginate at the apex. The phylogenetic analysis from two nuclear DNA regions (ETS and ITS) and two chloroplast DNA regions (matK and trnL-F) of 68 taxa resolved C. borealifujianica as a distinct species.

[Edge effect of the plant community structure on land-bridge islands in the Thousand Island Lake].

The research was conducted on 29 land-bridge islands in the Thousand Island Lake (TIL), where long-term monitoring plots were set up during 2009-2010. The community attributes including species richness, Shannon index, plant mean height, plant mean diameter at breast height (DBH) and plant density along the edge-interior gradient from edge to interior forest were calculated to investigate the edge effect. The results showed that the species richness and Shannon index were affected through the whole gradient (larger than 50 m), while the range of edge effect was 20-30 m on mean plant height, and 10 m on plant density and mean DBH. Community attributes differed significantly among the edge gradients. The species richness and Shannon index peaked at the intermediate edge gradient. Plant density decreased and plant mean height increased along the edge to interior gradient. All five community attributes were significantly associated with the edge gradient, also different functional groups, evergreen or deciduous species, trees or shrubs, shade tolerant or shade intolerant species, were differentially influenced by the edge effect. It was demonstrated the influence of edge effect on the fragmented forest community varied with community attributes and functional groups.

[Dynamics of soil arthropod community structure and its responses to forest fragmentation during the decomposition of Castanopsis eyrei leaf litter].

Five evergreen broad-leaved forests (one continuous forest and four fragmented forests) in the mountain areas in the juncture of Zhejiang, Fujian, and Jiangxi Provinces, East China were selected as test objects to study the dynamics of soil arthropod community structure and its responses to forest fragmentation during the decomposition of dominant tree species Castanopsis eyrei leaf litter. A total of 899 soil arthropods were collected, belonging to 9 classes and 25 orders. Lepidoptera was the dominant taxon, accounting for 10% of the individual, while Hymenoptera, Collembola, Diptera, Prostigmata, and Geophilomorpha were the common taxa. The decomposition rate of C. eyrei leaf litter was the highest in August and lower in April-June and December, which was in accordance with the seasonal dynamics of the taxa number and individual number of soil arthropods. Meanwhile, the taxa number, individual number, and species diversity of soil arthropods differed between continuous forest and fragmented forests, suggesting that both area effect and edge effect affected the dynamics of soil arthropod community structure during the decomposition of C. eyrei leaf litter.

[Decomposition of Schima superba leaf litter and dynamics change of soil meso-micro arthropods community structure in evergreen broad-leaved forest fragments].

Taking four evergreen broad-leaved forest fragments within the adjacent mountainous region of Zhejiang, Fujian, and Jiangxi provinces as study objects, and the continuous forest in Gutianshan National Natural Reserve as the control, an investigation was made by litter bag method from June 2004 to April 2006, aimed to understand the community structure and its dynamics change of soil meso-micro arthropods during the decomposition of Schima superba leaf litter. A total of 1050 soil meso-micro arthropods belonging to 8 classes and 23 orders were collected, among which, Lepidoptera, Hymenoptera, Collembola and Diptera were the dominant taxa. The impact of habitat fragmentation on the community composition of soil arthropods was mainly manifested in the differences of rare taxa, and the dominance of different taxa at different decomposition stages of S. superba leaf litter varied with the functions of the taxa in litter decomposition. After two-year decomposition, the mass loss of S. superba leaf litter was 60%-70%, and the species diversity indices of soil arthropods showed certain changes, being different between forest fragments and continuous forest.