典型季风海洋型冰川流域水循环过程变化对气候变暖的响应(英文)

Studying the response to warming of hydrological systems in China’s temperate glacier region is essential in order to provide information required for sustainable development.The results indicated the warming climate has had an impact on the hydrological cycle.As the glacier area subject to melting has increased and the ablation season has become longer,the contribution of meltwater to annual river discharge has increased.The earlier onset of ablation at higher elevation glaciers has resulted in the period of minimum discharge occurring earlier in the year.Seasonal runoff variations are dominated by snow and glacier melt,and an increase of meltwater has resulted in changes of the annual water cycle in the Lijiang Basin and Hailuogou Basin.The increase amplitude of runoff in the downstream region of the glacial area is much stronger than that of precipitation,resulting from the prominent increase of meltwater from glacier region in two basins.Continued observations in the glacierized basins should be undertaken in order to monitor changes,to reveal the relationships between climate,glaciers,hydrology and water supplies,and to assist in maintaining sustainable regional development.     

内蒙古温带草原典型草地生态系统生产力对水分在不同时间尺度上的响应

水分是干旱、半干旱区草地生态系统生产力的主要限制因素,但水分如何影响生产力的季节内变异,以往研究相对不足。本研究以内蒙古温带典型草原为研究对象,基于多通道自动原位监测箱系统获得的生态系统日尺度总初级生产力(GPP)及遥感植被归一化指数估算年尺度的地上净初级生产力数据,在不同时间尺度上研究了水分对生产力的影响。结果表明:年降水量对该典型草原草地生态系统地上净初级生产力年际变异无显著影响,但土壤水分显著影响GPP的季节变异,土壤水分解释了GPP季节变异的22%;其他环境因子对生产力的季节变异也有一定影响;温度是生态系统处于干旱时GPP的主要限制因素,GPP随温度的升高而降低;而辐射是生态系统处于湿润时GPP的主要限制因素,GPP随辐射的升高而升高。本研究结果将有利于提升未来降水格局改变对草地生态系统生产力影响的认识。     

放牧对内蒙古羊草群落土壤呼吸的影响

采用静态暗箱法,比较测定了放牧对内蒙古锡林河流域羊草群落土壤呼吸的影响以及水热等相关环境因子与土壤呼吸的关系。结果表明:放牧没有改变羊草群落土壤呼吸的季节性变化特征,但降低了土壤呼吸速率的年幅度;生长季放牧样地土壤呼吸速率显著低于封育样地,非生长季两样地土壤呼吸强度均处于较低水平,而且出现负通量的现象,放牧使羊草群落土壤呼吸年总量下降了约33.95％;从全年来看,无论是围栏还是放牧样地,封育样地和放牧样地土壤呼吸与温度因子均显著正相关(p<0.01,n=15),其中与10cm处地温相关性最好,但放牧降低了土壤呼吸对温度变化的敏感性;生长季水分影响作用高于温度,围栏封育样地0~10cm土壤含水量的变化可以解释土壤呼吸变异的87.4％,放牧样地10~20cm和20~30cm土壤含水量的变化共同可以解释土壤呼吸变异的74.9％。     

Comparison of tree transpiration under wet and dry canopy conditions in a Costa Rican premontane tropical forest

Spatial and temporal variation in wet canopy conditions following precipitation events can influence processes such as transpiration and photosynthesis, which can be further enhanced as upper canopy leaves dry more rapidly than the understory following each event. As part of a larger study aimed at improving land surface modelling of evapotranspiration processes in wet tropical forests, we compared transpiration among trees with exposed and shaded crowns under both wet and dry canopy conditions in central Costa Rica, which has an average 4200 mm annual rainfall. Transpiration was estimated for 5 months using 43 sap flux sensors in eight dominant, ten midstory and eight suppressed trees in a mature forest stand surrounding a 40‐m tower equipped with micrometeorological sensors. Dominant trees were 13% of the plot's trees and contributed around 76% to total transpiration at this site, whereas midstory and suppressed trees contributed 18 and 5%, respectively. After accounting for vapour pressure deficit and solar radiation, leaf wetness was a significant driver of sap flux, reducing it by as much as 28%. Under dry conditions, sap flux rates (J_s) of dominant trees were similar to midstory trees and were almost double that of suppressed trees. On wet days, all trees had similarly low J_s. As expected, semi‐dry conditions (dry upper canopy) led to higher J_s in dominant trees than midstory, which had wetter leaves, but semi‐dry conditions only reduced total stand transpiration slightly and did not change the relative proportion of transpiration from dominant and midstory. Therefore, models that better capture forest stand wet–dry canopy dynamics and individual tree water use strategies are needed to improve accuracy of predictions of water recycling over tropical forests. Copyright © 2016 John Wiley & Sons, Ltd.     

Rôle des héritages latéritiques et du niveau des nappes dans l'évolution des modelés et des sols en zone intertropicale forestière humide

Analysis of landscapes and soil covers from the outer to the inner part of a $75\text{km}\times 60\text{km}$ watershed in the South-Cameroon rainforest zone, characterized by important remnants of inherited ferricretes and stable hydrostatic base levels, indicates that the development of present landforms has not involved significant erosion by slope retreat because of the relative preservation of downslope residual ferricrete and that soil covers have vertically decayed under in situ geochemical process. To cite this article: D. Bitom et al., C. R. Geoscience 336 (2004).     

The influence of an extreme drought event in the fish community of a southern Europe temperate estuary

Between 2003 and 2006, a severe drought occurred throughout the Mondego River catchment's area, inducing lower freshwater flows into the estuary. As a consequence, both 2004 and 2005 were considered as extreme drought events. From June 2003 to June 2006, the fish assemblage of the Mondego Estuary was sampled monthly in five stations during the night, using a 2 m beam trawl. Fish abundance was standardized as the number of individuals per 1000 m² per season and the assemblage was analyzed based on ecological guilds: estuarine residents, marine juveniles, marine adventitious, freshwater, catadromous and marine species that use the estuary as a nursery area. A total of 42 species belonging to 23 families were identified, with estuarine residents and nursery species dominating the fish community. Variations in the fish community were assessed using non-metric MDS, being defined as three distinct periods: summer and autumn 2003, 2004/2005 and winter and summer 2006. The main drought-induced effects detected were the depletion of freshwater species and an increase in marine adventitious in 2004/2005, due to an extended intrusion of seawater inside the estuary and a significant reduction in abundance during the driest period of estuarine resident species. Nevertheless, from the management point of view, it could be stated that although some variations occurred due to environmental stress, the main core of the Mondego Estuary fish community remained relatively unchanged.     

南大洋及相邻温带海域夏季小型浮游动物的摄食作用

小型浮游动物在海洋食物网中扮演着重要的角色。2012年12月—2013年3月,利用稀释培养方法开展了南大洋及温带海域小型浮游动物对浮游植物的摄食实验研究。结果表明,浮游植物的生长率为0.04—0.89 d~(–1),小型浮游动物对浮游植物的摄食率为0.07—1.29 d~(–1)。浮游动物日摄食量占浮游植物现存量的6.4%—72.5%,对浮游植物初级生产力的摄食压力也较大,为14%—776.9%。尽管本实验中浮游动物的摄食率可能被高估,但在南大洋及温带海域生态系统中,小型浮游动物对浮游植物仍具有重要的调控作用。     

The Spring Phytoplankton Bloom in the Coastal Temperate Ocean: Growth Criteria and Seeding from Shallow Embayments

A method based on time-series of conductivity, temperature and depth (CTD) profiles which successfully determines favourable phytoplankton growth conditions for the spring bloom in nearshore temperate coastal waters was developed. The potential for shallow embayments to influence phytoplankton species composition in larger adjacent waters was also investigated. At temperate latitudes, such embayments should have favourable phytoplankton growth conditions earlier in the spring than open waters as bathymetry limits vertical mixing and thus increases light availability. The study area was Nanoose Bay, which is connected to the Strait of Georgia, British Columbia. Data were collected 2–3 times per week during the winter-spring of 1992 and 1993. A mooring with 5 current meters was placed at the mouth of the bay in 1992. The conservation equation for a scalar was used to estimate the balance between advective transport and biological source and sink terms. Variability in physical conditions and biological response between years was tremendous. Results indicate that seeding from the bay was not possible in 1992 but could have been in 1993. However, to conclusively determine the importance of Nanoose Bay on the spring bloom species composition in the Strait of Georgia, more extensive work is required. This revised version was published online in August 2006 with corrections to the Cover Date.     

Rainforest carbon financing in New Zealand: A case study of REDD+ on Māori land

This study examines a case study of the Rarakau Rainforest Conservation Project on Māori‐owned land in western Southland – New Zealand's first and only REDD+ project. It explores the potential for REDD+ projects on Māori land throughout the country. Key findings show that REDD+ is technically feasible in New Zealand, but commercially dependent on (currently low) demand in the domestic retail carbon offset and ‘corporate social responsibility’ market. Market research suggests that there is sufficient demand to cater to the needs of a small number of REDD+ projects, but insufficient demand to roll out a nation‐wide scheme.