退化和恢复过程驱动的荒漠草地生态系统有机碳密度变化

荒漠草地是陆地生态系统的重要组成部分,研究退化和恢复荒漠草地生态系统碳密度的变化特征,是精确评估荒漠草地在全球气候变化中作用的关键,也能为中国碳达峰和碳中和提供数据支撑和理论依据.通过野外调查取样和室内分析,研究了腾格里沙漠南缘天然荒漠草地、重度退化荒漠草地和通过植被建设恢复良好的人工-天然荒漠草地的生态系统碳密度,主...     

小球藻(Chlorella vulgaris)的异养生长特性研究

小球藻（Ｃｈｌｏｒｅｌｌａ ｖｕｌｇａｒｉｓ）可以利用葡萄糖、果糖、乙酸盐等有机碳源异养生长。在异养条件下,最适环境条件为温度３０～３２℃、ｐＨ５．５～６．５。该小球藻可以利用硝酸盐、铵盐、尿素和一些结构简单的氨基酸（如甘氨酸）作为唯一氮源生长,在由铵盐和硝酸盐组成的混合氮源中生长时,优先利用铵盐。该小球藻对增减基中不同营养物的利用给增减基的ｐＨ带来不同的影响。利用葡萄糖和果糖为唯一碳源时增减基的     

北麂列岛岩相潮间带底栖生物群落的组成特征

本文报导了1997.7-1998.4期间北麂列岛岩相潮间带底栖生物群落的组成特征.研究结果表明:总平均生物量和栖息密度分别为5091.80g·m-2和4269个·m-2; 生物量和栖息密度的水平分布为关帝山＞大筲箕屿＞海利＞壳菜岙,垂直分布为中潮区＞低潮区＞高潮区,生物量和栖息密度的季节变化分别为冬季＞春季＞秋季＞夏季和冬季＞秋季＞春季＞夏季.数量的水平分布主要受海岸开敞度及浪击度的影响、垂直分布主要受潮区及浪击度的影响、季节变化主要受温度和动植物繁殖的影响.     

内蒙古草原羊草群落优势物种对气候变暖的响应

通过对内蒙古锡林河流域羊草草原地区1981~1994年14年的温度观测和植被调查数据的逐年滑动平均处理,分析该地区气候和植被的相互关系以及随时间的动态变化特征。研究结果表明,内蒙古羊草草原地区的气温在研究期内具有冬、夏半年高低温变化不一致的特点：冬半年最低温度升高最为明显,最高温度升高较为明显,平均温度升高明显;夏半年最低温度升高最为明显,最高温度反而有某种程度的下降,平均温度升高不明显;全年最低温度升高最为明显,最高温度升高较为明显,平均温度升高明显。全年平均温度的升高主要是冬半年温度升高所致。羊草群落的前6种优势植物种对气温变化有不同的响应：第1、3、5优势种羊草(最优建群种)、寸草苔、变蒿的重要值和地上初级生产力随着最低温度的升高有明显的下降趋势,第2、4、6优势种大针茅(次优建群种)、西伯利亚羽茅、冰草的重要值和地上初级生产力由于种间互补作用而略有升高。这种由于竞争能力相近物种对环境变化的不同适应以及种间竞争排斥和共生互补关系,增加了植物群落种群动态变化的复杂性。因此,在研究与模拟羊草草原对温度变化响应的机理时,不仅要考虑不同温度的变化对植物的影响,还要考虑物种之间的相互作用。     

浮游植物生物量研究Ⅱ.胶州湾网采浮游植物细胞体积转换生物量

基于浮游植物细胞体积转换法获得的胶州湾浮游植物细胞生物量,计算了胶州湾水体中同采浮游植物生物量,并与浮游植物细胞计数结果进行了周年变化的比较和优势种分析。研究结果表明,调查期内,浮游植物细胞数量出现两次高峰(主峰1月份,次峰9月份),转换生物量仅出现一次高峰(8月份);优势种分析表明,上述峰值期的不同,与浮游植物群落结构及不同种群细胞的个体大小密切相关。浮游植物细胞体积转换生物量不仅能较客观地反映浮游植物现存量,又能从群落、种群结构角度解释能量分布及不同种群对浮游植物生物量的各自贡献。     

11种微藻脂类和EPA／DHA组成的研究

研究了１１种微藻在可比较的条件下,其生物量、总脂含量和多不饱和脂肪酸（ＥＰＡ／ＤＨＡ）有组成。结果表明：卡德藻（Ｔｅｔｒａｓｅｌｍｉｓ ｓｐ．）的生物量最大,细胞干重可达０．１４０ｇ／（Ｌ．ｄ）;南极冰藻（Ｂｅｒｋｅｌｅｙａ ｒｕｔｉｌａｎｓ）次之,可达０．０７４ｇ／（Ｌ．ｄ）。以叉鞭金藻（Ｄｉｃｒａｔｅｒｉａ ｉｎｏｒｎａｔａ）和球等鞭金藻（Ｉｓｏｃｈｒｙｓｉｓ ｇａｌｂａｎａ）的总酯含量最高,     

Spatiotemporal distribution of protozooplankton and copepod nauplii in relation to the occurrence of giant jellyfish in the Yellow Sea

The occurrence of the giant jellyfish, Nemopilema nomurai, has been a frequent phenomenon in the Yellow Sea. However, the relationship between the giant jellyfish and protozoa, in particular ciliates, remains largely unknown. We investigated the distribution of nanoflagellates, ciliates, Noctiluca scintillans, and copepod nauplii along the transect 33~N in the Yellow Sea in June and August, 2012, during an occurrence of the giant jellyfish, and in October of that year when the jellyfish was absent. The organisms studied were mainly concentrated in the surface waters in summer, while in autumn they were evenly distributed in the water column. Nanoflagellate, ciliate, and copepod nauplii biomasses increased from early June to August along with jellyfish growth, the first two decreased in October, while N. scintillans biomass peaked in early June to 3 571 pg C/L and decreased in August and October. In summer, ciliate biomass greatly exceeded that of copepod nauplii （4.61-15.04 ~tg C/L vs. 0.34-0.89 pg C/L）. Ciliate production was even more important than biomass, ranging from 6.59 to 34.19 ~tg C/（L.d） in summer. Our data suggest a tight and positive association among the nano-, micro-, and meso-zooplankton in the study area. Statistical analysis revealed that the abundance and total production of ciliate as well as loricate ciliate biomass were positively correlated with giant jellyfish biomass, indicating a possible predator-prey relationship between ciliates and giant jellyfish. This is in contrast to a previous study, which reported a significant reduction in ciliate standing crops due to the mass occurrence ofN. nomurai in summer. Our study indicates that, with its high biomass and, in particular, high production ciliates might support the mass occurrence of giant jellyfish.     

Biomass allocation patterns of alpine grassland species and functional groups along a precipitation gradient on the Northern Tibetan Plateau

Variations in the fractions of biomass allocated to functional components are widely considered as plant responses to resource availability for grassland plants. Observations indicated shoots isometrically relates to roots at the community level but allometrically at the species level in Tibetan alpine grasslands. These differences may result from the specific complementarity of functional groups between functional components, such as leaf, root, stem and reproductive organ. To test the component complementary responses to regional moisture variation, we conducted a multi-site transect survey to measure plant individual size and component biomass fractions of common species belonging to the functional groups： forbs, grasses, legumes and sedges on the Northern Tibetan Plateau in peak growing season in 2010. Along the mean annual precipitation （MAP） gradient, we sampled 7o species, in which 2o are in alpine meadows, 20 in alpine steppes, 15 in alpine desert-steppes and 15 in alpine deserts, respectively. Our results showed that the size of alpine plants is small with individual biomass mostly lower than 1.0 g. Plants keep relative conservative component individual responses moisture functional fractions across alpine grasslands at the level. However, the complementary between functional components to variations specifically differ among groups. These results indicate that functional group diversity may be an effective tool for scaling biomass allocation patterns from individual up to community level. Therefore, it is necessary andvaluable to perform intensive and systematic studies on identification and differentiation the influences of compositional changes in functional groups on ecosystem primary services and processes.