基于遥感-过程耦合模型的1988～2004年青海三江源区净初级生产力模拟

三江源区不仅是地处青藏高原的全球气候变化的敏感区,也是我国甚至亚洲最重要河流的上游关键源区。作为提供物质基础的植被净初级生产力(Netprimaryproduction,NPP),是评价生态系统状况的重要指标。该文应用已在碳通量观测塔验证,扩展到区域水平的遥感-过程耦合模型GLOPEM-CEVSA,以空间插值的气象数据和1km分辨率的AVHRR遥感反演的FPAR数据为模型主要输入,模拟并分析了1988～2004年该区NPP时空格局及其控制机制。结果表明,该区植被平均NPP为143.17gC·m–2·a–1,呈自东南向西北逐渐降低的空间格局,其中,以森林NPP最高(267.90gC·m–2·a–1),其次为农田(222.94gC·m–2·a–1)、草地(160.90gC·m–2·a–1)和湿地(161.36gC·m–2·a–1),荒漠最低(36.13gC·m–2·a–1)。其年际变化趋势在空间上呈现出明显的差异,西部地区NPP表现为增加趋势,每10a增加7.8～28.8gC·m–2;而中、东部表现为降低趋势,每10a降低13.1～42.8gC·m–2。根据显著性检验,NPP呈增加趋势(趋势斜率b>0),显著性水平高于99%和95%的区域占研究区总面积的13.43%和20.34%,主要分布在西部地区;NPP呈降低趋势(趋势斜率b<0),显著性水平高于99%和95%的区域占研究区面积的0.75%和3.77%,主要分布在中、东部地区,尤以该区长江和黄河等沿线区分布更为集中,变化显著性也更高。三江源NPP的年际变化趋势的气候驱动力分析表明,整个区域水平上该地区植被生产力受气候变化的主导,西部地区暖湿化趋势,造成了该地区生产力较为明显的、大范围的增加趋势;但东、中部地区则主要受人类活动的影响,特别是长江、黄河等河流沿线,是人类居住活动密集的地区,造成这些地区放牧压力较大、草地退化严重,而该地区暖干化趋势加剧了这一过程。

Tidal current observation in the southern Yellow Sea in the summers of 2001 and 2003

Direct current observations in the Yellow Sea interior are very scarce due to intense fishing and trawling activities. Most previous studies on tides in the area were based on coastal measurements or satellite altimeter sea levels and have not been rigorously compared with direct measurements. In this paper, tidal currents are studied with current profiles from three bottom-moored Sontek Acoustic Doppler Profilers (ADPs) deployed in the southern Yellow Sea in summer of 2001 and 2003. The measured current series were dominated by tidal currents. Maximum velocities are between 40-80 cm/s at the mooring stations. M-2 current is the most dominant primary tidal constituent, while MS4 and M-4 are the most significant shallow water tides with much smaller amplitudes than the primary tides.

The environment effect on fish assemblage structure in waters adjacent to the Changjiang (Yangtze) River estuary (1998-2001)

We collected fish abundance data in the Changjiang (Yangtze River) estuary and adjacent waters in November 1998, May 1999, November 2000, and May 2001. Using the data, we evaluated the characteristics of the fish assemblages at each site and investigated the effect of several environmental factors. We used a multivariate analysis, including community ordination methods such as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA), and two-way indicator species analysis (TWINSPAN). We analyzed the biological community structure and environmental factors to determine their spatial distributions, temporal dynamics, and seasonal variations. Among the fish species, five exceeded 5% of the total abundance: Harpodon nehereus (42.82%), Benthosema pterotum (13.85%), Setipinna taty (11.64%), Thryssa kammalensis (9.17%) and Apogonichthys lineatus (6.49%). These were separated into four ecological assemblages: hypsithermal-saline, hypsithermal-brackish, hypothermal-brackish, and hypothermal-saline. We evaluated the degree of influence of environmental factors on the fish community. Our analyses suggested that environmental factors including water depth, salinity, turbidity, transparency, nutrient, and suspended matter formed a synthetic spatial gradient between the coastal and pelagic areas. Ecological and environmental factors changed temporally from 1998 to 2001, and drove the fish community succession. The environmental factors driving the fish community structure included bottom temperature, water depth, bottom and surface pH, surface total phosphorous, and bottom dissolved oxygen. This investigation was completed before completion of the Three Gorges Dam; therefore the results of this study provide an important foundation for evaluating the influence of the human activities.

Holosticha hamulata n. sp and Holosticha heterofoissneri Hu and Song, 2001, two urostylid ciliates (Protozoa, Ciliophora) from intertidal sediments of the Yellow Sea

Two marine urostylid ciliates, Holosticha hamulata n. sp. and Holosticha heterofoissneri Hu and Song, 2001, were investigated using live observation and protargol impregnation. Both species were isolated from Korean intertidal sediments of the Yellow Sea. Holosticha hamulata measures about 150 x 25 pro in vivo, and is characterized by a tripartite body shape with a narrow head, an inflated trunk, and a tail that distally projects ventrally forming a hook-like structure. It is the characteristic body shape that distinguishes H. hamulata distinctly from congeners. Holosticha hamulata differs from H. heterofoissneri, possibly the nearest relative, also by the location of the contractile vacuole (ahead of mid-body versus near posterior body third) and the configuration of the macronucleus (on average, 33 scattered nodules assuming a Y-shape versus 17 nodules that may form a U shape). The average number of the macronuclear nodules is a pronounced feature showing great consistency in populations of each species. However, their arrangement is variable in H. heterofoissneri where the nodules are basically scattered or connected by fine fibers forming an elongate U-shape. The location of the contractile vacuole as a taxonomic feature is discussed and a dichotomous key to the species of Holosticha sensu stricto is provided.

青藏公路与铁路沿途1981年～2001年植被覆盖变化

在青藏公路与铁路沿途区域,利用1981年至2001年的8km分辨率PathfinderNOAA/NDVI数据,基于每个象元变化的年植被峰值计算进行了像元水平的线性趋势分析,并运用地理信息系统(GIS)软件研究了区域植被覆盖的空间分布和动态变化特征.主要结论:①在研究区内,反映植被覆盖的NDVI值在空间上呈现出两端高中间低的态势,依次是农作区和森林区＞高寒草甸＞高寒草原＞荒漠草原;②20年间,研究区植被覆盖程度变化总体趋于稳定,覆盖程度呈减少趋势的区域明显高于增加的区域,植被覆盖程度增减因区域而异;植被覆盖程度增加和显著减少地区主要分布在农作区和高寒草甸区,轻微减少地区主要分布在高寒草原和荒漠草原区;③植被覆盖变化程度在拉萨河谷地、湟水谷地和黄河流域等人类活动比较频繁的区域增减趋势比较明显;而在可可西里地区等人类活动比较少的区域变化轻微.