Methane emissions from natural and drained peatlands in the Zoigê, eastern Qinghai-Tibet Plateau

Peatlands are one of the major natural sources of methane （CH4）, but the level of CH4 efflux is uncertain, especially in alpine peatlands. In this study, CH4 emission fluxes from natural and drained peatlands on the Qinghai- Tibet Plateau, southwest China, were measured from June to October in 2013 using the opaque static chamber technique and the Fast Greenhouse Gas Analyzer （DLT-100, Los Gatos Research Corp.）. CH4 emission fluxes ranged from 2.07 to 56.33 mg m^-2 h^-1 in natural peatlands and from 0.02 to 0.42 mg m^-2 h^-1 in drained peatlands. Mean CH4 emission flux was 19.13 mg m^-2 h^-1 in natural peatlands and 0.14 mg m^-2 h^-1 in drained peatlands. These results showed that drainage led to a significant decrease in CH4 emissions. CH4 emission fluxes for all sampling plots were significantly correlated with variation in water table depth for linear （R^2 = 0.453, P 〈 0.01） and exponential functions （R^2 = 0.429, P 〈 0.01）.

Effect of mangrove restoration on crab burrow density in Luoyangjiang Estuary,China

Background： Mangrove restoration seeks to restore or rebuild degraded mangrove systems. The methods of mangrove restoration include ecological projects and restoration-oriented technologies, the latter of which are designed to restore the structure, processes as well as related physical, chemical and biological characteristics of wetlands and to ensure the provision of ecosystem services. As important components of mangrove ecosystem, benthic organisms and crabs play a key role in nutrient cycling. In addition, mangrove restoration, such as vegetation restoration measures, can lead to changes in the benthic faunal communities. This study investigates whether the presence of different mangrove species, age and canopy cover of mangrove communities affect the density of crab burrows. Methods： The Luoyangjiang Estuary, in the southeast of Fujian Province, was selected as our research area. A survey, covering 14 sites, was conducted to investigate the impacts of mangrove restoration on the density of crab burrows in four rehabilitated forests with different stand ages and canopy. Results： It was found that differences in vegetation types had a large impact on crab density and that the density of crab burrows was lower on exposed beaches （non-mangrove） than under mature Kondelio condel, Aegiceros corniculatum and Avicennio morina communities. In general, the amount of leaf litter and debris on mangrove mudfiats was greater than on the beaches as food sources for crabs. Two-factor analysis of variance （ANOVA） shows that changes in mangrove species and age since restoration had different effects on crab burrow density. The effect of canopy cover was highly significant on crab burrow density. Conclusions： The results suggest that in the process of mangrove restoration the combined effects of mangrove stand age, canopy cover and other factors should be taken into account. This study further supports the findings of the future scientific research and practice on mangrove restoration and management measures.

Officials'Foreign Experience and Firms'Exports:Evidence from China

This study examines how the foreign experience of local oficials affects firms'exports in China.Using a matched sample from 2000 to 2012,we found that the foreign experience of municipal Party secretaries had a significant impact on the promotion of firms'exports,especially for private firms.This positive impact was more pronounced when officials went abroad at a younger age,stayed abroad for a longer period,returned to China for a longer time,and had greater promotion incentives.We found that officials'foreign experience helped to mitigate the negative impact of institutional distance and provided firms with better access to export subsidies,both of which could promote exporting.There was also a complementary effect when officials and executives both had foreign experience.Overall,our study provides some insights into the economic outcomes of officials'foreign experience and sheds light on the export performance of Chinese firms.

Trade-off between leaf chlorophyll and betacyanins in Suaeda salsa in the Liaohe estuary wetland in northeast China

Aims Pigment composition is an important functional trait that can be affected by environmental factors.the objective of this study was to investigate the effect of soil salinity on pigment composition in Suaeda salsa by comparing chlorophyll and betacyanin content in the Liaohe estuary wetland,a typical coastal wetland in northeast China.Methods We investigated the plant biomass,percentage of red leaves and pigment content(chlorophyll a,chlorophyll b and betacyanins)in S.salsa in intertidal and supratidal zones of the upper,middle and lower reaches of the Liaohe estuary wetlands.the Na^(+)content of both the soil and plant was also measured.Full analysis of variance and multivariate analysis were used to compare differences in pig-ment content and Na^(+)content between the supratidal and intertidal zones.Important Findings Pigment composition was significantly affected by soil salinity.With increasing soil salinity,the percentage of red leaves was higher in the intertidal zone than in the supratidal zone.In all three reaches,plants had lower chlorophyll a content and higher betacyanin con-tent in the intertidal zone than in the supratidal zone.Compared to chlorophyll a,chlorophyll b was less sensitive to soil salinity.there were no differences in chlorophyll b content between the intertidal and supratidal zones in the upper and lower reaches.Furthermore,pigment composition was associated with both the plant tissue and soil Na^(+)content.Compared to the supratidal zone,the intertidal zone had a higher Na^(+)content in plants.there was a negative rela-tionship between plant chlorophyll content and soil Na^(+)content,but a positive relationship between betacyanin content and soil Na^(+)content.Overall,the results indicated that there might be a trade-off between leaf chlorophyll and betacyanin content in S.salsa to main-tain its growth and survival in high salinity environments.

Soil fauna diversity at different stages of reed restoration in a lakeshore wetland at Lake Taihu,China

Introduction:Wetland soil fauna support material cycling and restoration processes in wetland ecosystems.In our study,we observed variations in wetland soil fauna on the shores of Lake Taihu,China.We examined the relationships between fauna and major environmental factors,and looked at the short-and long-term changes in reed wetlands under restoration and in the natural reed lakeshore.Outcomes:We identified 93 groups of soil fauna in different wetlands and found significant differences in the lakeshore wetlands’soil fauna assemblages,depending on the length of the restoration period.By analyzing the soil fauna community evenness,dominance,number of taxa,and diversity,we found minimal seasonal variation in the soil fauna community diversity and abundance.The abundance of soil fauna in the sites under restoration decreased with depth below the soil surface.The reed restoration was obvious in the succession of the soil fauna groups in the long-term site.Although the restoration had an overall positive long-term effect on the soil fauna communities,there were no obvious short-term changes in the number of individuals.Conclusion:The study explored various potential measures to restore soil fauna in the Lake Taihu wetland and developed a theoretical basis for restoring the lakeshore wetland ecosystem.

Distribution patterns of plant communities and their associations with environmental soil factors on the eastern shore of Lake Taihu,China

Introduction:Plant communities and soil factors might interact with each other in different temporal and spatial scales,which can influence the patterns and processes of the wetland ecosystem.To get a better understanding of the distribution of plants in wetlands and analyze their associations with environmental soil factors,the structure and types of plant communities in the eastern shore area of Lake Taihu were analyzed by two-way indicator species analysis and canonical correspondence analysis(CCA)ordination.The spatial distribution patterns of vegetation and the main factors affecting the distributions were investigated.Outcomes:Sixty-six sampling sites were selected to obtain vegetation species and soil environmental factor data.Results showed that 22 species from the 66 sites could be divided into seven communities:I:Arundo donax;II:A.donax+Phragmites australis;III:Zizania latifolia+Typha orientalis;IV:P.australis+Alternanthera philoxeroides+Polygonum hydropiper;V:P.australis;VI:P.australis+Humulus scandens;and VII:Erigeron acer+Ipomoea batatas+Rumex acetosa.Plant species and soil factors in the CCA analysis showed that I.batatas,E.acer,Chenopodium album,Polygonum lapathifolium,and Acalypha australis were mainly affected by pH,whereas Echinochloa crus-galli,Setaria viridis,and H.scandens were mainly affected by soil total phosphorus.Mentha canadensis and A.donax were mainly affected by soil conductivity,A.philoxeroides was mainly affected by soil organic matter and,Z.latifolia,Metaplexis japonica and P.hydropiper were mainly affected by available phosphorus.Conclusion:These results indicated that different plants adapted to different soil environmental factors and provided basic information on the diversity of Lake Taihu wetland vegetation.