[Response of seed reproduction of two dominant lakeside species to experimental warming in a typical plateau wetland in Northwestern Yunnan Plateau, China]. / æ»‡è¥¿åŒ—é«˜åŽŸå ¸åž‹æ¹¿åœ°æ¹–æ»¨å¸¦ä¼˜åŠ¿æ¤ç‰©ç§å­ç¹æ®–å¯¹å¢žæ¸©çš„å“åº”.

Based on the forecasted warming scenarios by IPCC, we studied the impacts of warming (increased by 2.0 and 3.5 ℃) on seed reproduction of two lakeside dominant species (Schoeno-plectus tabernaemontani and Sparganium stoloniferum) in a typical plateau wetland (Napahai) in Northwestern Yunnan, by using "open-top chamber" technique. The results showed that warming had significant effects on the seed setting rate of both species, though with interspecific variation. The seed setting rate of S. tabernaemontani was significantly increased under two warming treatments, while that of S. stoloniferum was significantly decreased under the 2.0 ℃ warming treatment and had no variation under the 3.5 ℃ warming treatment. Warming promoted the spike growth of both species. For S. tabernaemontani, under the warming of 2.0 and 3.5 ℃ treatments, the spike length was increased by 82.9% and 89.0%, the spikelet number was increased by 133.3% and 150.0%, the biomass of each individual was increased by 10.1% and 89.6%, and the rate between biomass of per plant panicle and total biomass was increased by 79.5% and 409.3%, respectively. For S. stoloniferum, under the warming of 2.0 and 3.5 ℃ treatments, the spike length was increased by 66.1% and 95.2%, and the rate between biomass of per plant panicle and total biomass was increased by 878.8% and 1052.6%, respectively. Warming significantly increased seed yield of both species. Under the warming of 2.0 and 3.5 ℃ treatments, the seed yield per panicle of S. tabernaemontani was increased by 33.7% and 58.3%, respectively. For S. stoloniferum, the seed yield was increased by 3.4% and 69.5%, respectively. Under the warming of 2.0 and 3.5 ℃ treatments, the seed length of S. tabernaemontani was increased by 5.4% and 6.9%, and the seed length/width was increased by 9.1% and 5.3%, respectively. Warming had no significant effects on the seed shape of S. stoloniferum. The maximum and minimum temperatures were dominant factors affecting seed reproductions of both species. The advance of growing season, the prolonging of nutrition growing period, and accumulation of organic matter induced by warming would provide sufficient nutrient and energy accumulation for the reproduction and development of plants, which would promote seed reproduction capability of both species under the warming conditions.

[The relative contributions of plant quality, simulated rising temperature, and habitat to litter decomposition.] / 植物质量、模拟增温及生境对凋落物分解的相对贡献.

With litter bag methods, we examined mass loss rates and different chemical fractions of litters from two wetland plant species, Zizania caduciflora and Hippuris vulgaris. Those two species examined here varied significantly in their initial litter chemical traits. Experiment was performed under simulated rising temperature (1.5-2.0 ℃), and under three different habitats (air, air-water interface and water-soil interface). The results showed that, during one-year decomposition period, the mass resi-dual rates exhibited distinct seasonal dynamics, and there were strong interactive effects between seasonal dynamics and environmental factors. Different factors contributed differently for the variation of litter decomposition, 28.8% of which being explained by litter quality, 6.3% of which being explained by rising temperature, and 34.9% being explained by habitat. Along with the decomposition, the contents of different chemical fractions (easy or hard to decompose) varied greatly. Among them, nitrogen contents in H. vulgaris decreased by 53.1%, while the lignin contents increased by 45.4%. Overall, habitat was the most important factor driving litter decomposition, the second was litter quality, and rising temperature had minor effect.

[Soil Degradation-Associated Microbial Community Structure Changes in an Alpine Meadow Under Tibetan Pig Herding].

Anthropic activities lead to a high risk of peatland degradation in the alpine regions. Along with the declined plant productivity and the impaired functioning of the soil carbon sink, the diversity and structure of soil microbial communities are also affected in a degraded peatland ecosystem. Tibetan pig herding is a unique peatland management strategy, which can significantly affect the peatland ecosystem, but it has been rarely studied. The changes in the microbial community structure and its responses to disturbances were studied using a 16S rRNA high throughput sequencing technique in an alpine meadow peatland under Tibetan pig herding disturbance and under control (without Tibetan pig herding) in the Northwestern Yunnan province. The results showed that Tibetan pig herding significantly reduced the α diversity of soil microbes, and the soil microbial community structures were significantly changed by pig herding. The soil microbial communities in the peatland soils were dominated by Proteobacteria, Acidobacteria, and Chloroflexi. Compared with those at the phylum level, the changes at the genus level under pig disturbance were more obvious. It was seen that the relative abundances of Sphingomonas and Hymenobacter significantly increased, while the abundances of Nitrospira and Rhodoplanes significantly decreased under pig herding. Venn diagram analysis revealed that there were 71 and 136 core OTUs in the soil under pig herding and in the control group soil, respectively. Burkholderiales, Pseudomonadales, and Sphingomonadales were the main taxa exclusively found under Tibetan pig herding, and could serve as indicators of soil disturbance. CCA ordination further showed that the distribution of Nitrospira and Rhodoplanes were mainly controlled by soil moisture, available phosphorus, and organic matter contents. Our findings provide an insight into the linkages between the soil microbial communities and the degradation of peatlands in alpine regions.

[Reinvasion of exotic plant species Spartina alterniflora in Chongming Dongtan Nature Reserve of Shanghai].

A demonstration plot in Chongming Dongtan for controlling exotic plant species Spartina alterniflora by using an integrated treatment technique of tussock cutting plus water level controlling was selected to make a 2-year monitoring on the reinvasion process of this plant species. A large number of S. alterniflora seedlings could proliferate and settle down in the hydrological restoring plots by tidal water in spring, and, after two years, the reinvasion community was established, with no obvious differences in its density as compared to the communities in neighboring areas. However, the distance of extension via vegetative propagation was limited. At the plots maintaining waterlogging, the distance of 2-year lateral extension was less than 1 m; at physically isolated plots, there was no any reinvasion of S. alterniflora. The rapid spreading of the seedlings in spring was the key of the fast reinvasion of S. alterniflora, and thus, to completely eradicate the spreading source from neighboring areas, to build isolation barrier to stop the spreading of this plant, and to adopt biological substitute by planting a native species such as Phragmites australis would be the main countermeasures to effectively prevent the reinvasion of S. alterniflora.

[Ecological restoration effect of closed and half-closed degraded wetlands in Northwest Yunnan Plateau, Southwest China].

Selecting the restoration site of Napahai, a representative degraded wetland in Northwest Yunnan Plateau, as test object, a comparative study was made on the changes of plant community species composition, water quality, and soil organic matter (OM) and total nitrogen (TN) contents within stream way, meadow, and lakeside before and after vegetation restoration, aimed to verify the effectiveness of integrated ecosystem restoration at catchment scale. In the early restoration period, the plants at the study site increased from 13 to 28 species, 12 to 22 genera, and 8 to 18 families, and the aboveground biomass increased from 318.56 g x m(-2) to 507.68 g x m(-2). The plant community structure and composition in lakeside and riverside had an obvious change before and after the vegetation restoration. Pollution-tolerant species diminished or disappeared, while the primary swamp communities of Sparganium stoloniferum and Batrachium bungei appeared after their disappearance for many years. After vegetation restoration, soil OM and TN contents increased from 28.85 g x kg(-1) and 0.79 g x kg(-1) to 50.26 g x kg(-1) and 1.45 g x kg(-1), respectively. The TN and TP contents and COD in the water decreased significantly, and their removal rates reached to 67.9%, 79.2%, and 71.2%, respectively. The transparency of water body increased to 179%, indicating that the structure and function of the wetland ecosystem had been substantially improved and restored. It was concluded that the vegetation restoration measures and technology used in closed or half-closed plateau wetland area were effective,