Effects of grazing intensity and grazing exclusion on litter decomposition in the temperate steppe of Nei Mongol,China

Aims Grazing intensity and grazing exclusion affect ecosystem carbon cycling by changing the plant community and soil micro-environment in grassland ecosystems. The aims of this study were: 1) to determine the effects of grazing intensity and grazing exclusion on litter decomposition in the temperate grasslands of Nei Mongol; 2) to compare the difference between above-ground and below-ground litter decomposition; 3) to identify the effects of precipitation on litter production and decomposition. Methods We measured litter production, quality, decomposition rates and soil nutrient contents during the growing season in 2011 and 2012 in four plots, i.e. light grazing, heavy grazing, light grazing exclusion and heavy grazing exclusion. Quadrate surveys and litter bags were used to measure litter production and decomposition rates. All data were analyzed with ANOVA and Pearson’s correlation procedures in SPSS. Important findings Litter production and decomposition rates differed greatly among four plots. During the two years of our study, above-ground litter production and decomposition in heavy-grazing plots were faster than those in light-grazing plots. In the dry year, below-ground litter production and decomposition in light-grazing plots were faster than those in heavy-grazing plots, which is opposite to the findings in the wet year. Short-term grazing exclusion could promote litter production, and the exclusion of light-grazing could increase litter decomposition and nutrient cycling. In contrast, heavy-grazing exclusion decreased litter decomposition. Thus, grazing exclusion is beneficial to the restoration of the light-grazing grasslands, and more human management measures are needed during the restoration of heavy-grazing grasslands. Precipitation increased litter production and decomposition, and below-ground litter was more vulnerable to the inter-annual change of precipitation than above-ground litter. Compared to the light-grazing grasslands, heavy-grazing grasslands had higher sensitivity to precipitation. The above-ground litter decomposition was strongly positively correlated with the litter N content (R² = 0.489, p < 0.01) and strongly negatively correlated with the soil total N content (R² = 0.450, p < 0.01), but it was not significantly correlated with C:N and lignin:N. Below-ground litter decomposition was negatively correlated with the litter C (R² = 0.263, p < 0.01), C:N (R² = 0.349, p < 0.01) and cellulose content (R² = 0.460, p < 0.01). Our results will provide a theoretical basis for ecosystem restoration and the research of carbon cycling.     

震旦鸦雀种群生态的研究

震旦鸦雀是一种小型濒危鸟类,在IUCN和ICBP出版的红皮书中,共同认定为Ⅰ(Indeterminate)级。本文是作者于1985～1986年期间,对种群生态进行研究的首次报道。该鸟栖息于上海沿海芦苇滩中。种群密度1.21±0.57对/公顷。文中还论述数量变动和种群活动的变化规律。在奉贤沿海估计有290～387对。在越冬期中,剥取芦鞘内的寄生虫等为食。由于围垦不断发展,栖息地日益缩小,因此在生存上受到严重威胁。     

我国沙漠中部地区主要不同生态类型植物脯氨酸的累积、光合、呼吸和叶绿素含量

中生植物脯氨酸含量为0．42mg/g.dw, 低于少浆旱生植物（1．73mg/g.dw)。多浆旱生植物脯氨酸含量最高（7．22mg/g.dw),为前两者的17倍和4倍,两类旱生植物在干旱条件下（非灌溉）脯氨酸含量均高于灌水处理。少浆与多浆旱生植物的光合强度（16．74,14．04CO2mg/g.dw.h)差异不大,而中生植物（37．57mg/g.dW.h)略高于多浆旱生植物（4．73CO2Mg/g.dw.h),与中生植物（7.60Co2mg/g.dw.h)接近,光合／呼吸值,少浆,多浆与中生植物分别为2．50,3．09和4．59,说明中生植物的合成明显大于消耗,季节动态中,中生植物显著高于两类旱生植物,叶绿素总量三类植物差异甚微。     

矮嵩草草甸植物蒸腾强度的初步研究

 此项研究工作于1986年5—9月植物生长季节内,在海北高寒草甸生态系统定位站进行。用钴纸法测定了矮嵩草等10种植物的蒸腾强度、垂穗披碱草等3种植物的蒸腾日进程和不同植被覆盖地段的蒸腾—蒸发量,在测定时记录了气温、湿度等有关气象资料,以便分析。研究结果表明：1．矮嵩草等10种植物的蒸腾强度随植物种和所处的物候期而变化,植物生长早期蒸腾强度较低,进入生殖阶段,蒸腾强度明显提高。2．垂穗披碱草等3种植物蒸腾强度日进程呈明显的单峰型曲线,在中午或午后出现峰值,没有午休现象。这同气孔一直开着有关,是矮嵩草草甸植物蒸腾的特征之一。 3．不同植被覆盖地段的蒸腾—蒸发表明,有植被覆盖的地段的蒸腾—蒸发量较裸地的蒸发量为高。     

鲢、鳙在天然条件下的摄食强度(Ⅱ)武汉东湖鲢、鳙周年摄食强度的研究

武汉东湖的鲢(Hypophthalmichthy molitrix)鳙(Aristichthys nobilis)在天然条件下摄食强度具季节性变化。摄食强度高峰处于夏季,低谷处于冬季。在实验条件下,按周年采样期间水温变化范围,测定鱼的肠管排空率。食物通过鱼肠管时间(Y_p—h)与水温(X_t—℃)的关系为: 鲢Y_p=270.63 X_t~(0.6408) 鳙Y_p=280.46 X_t~(0.6642) 根据修正后Bajkov公式(D=C (24.A)/n),估算鱼的日粮。鱼日粮(Y_D)与水温(X_t)关系为: 鲢Y_D=0.2683e~(0.1503X_t) 鳙Y_D=0.0075X_t~(2.2715) 计算鱼在天然条件下周年月粮及年粮。鲢、鳙对天然饵料年消耗量分别为18.924公斤及17.39公斤,饵料系数分别为18.02及13.38。     

金针菇生料袋栽及营养基质的研究

呼吸是代谢的中心,呼吸强度在一般情况下可作为生理活性的指标。本文通过对金针菇、平菇,香菇各生长阶段呼吸强度的测定,为金针菇生料袋栽的可行性提供了生理依据;从栽培技术上证明生料袋栽的成败关键是温度和把握栽种时间;生料袋栽不会引起霉菌污染;金针菇培养料中添加适量的维生素B₁、B₂可明显提高经济效益。     

解磷微生物的分离测定与盆栽试验

从土壤中分离筛选了具有解磷工的真菌２株,细菌３株,分别测定了它们在实验室条件下对磷矿粉中不容性磷的溶解转化强度,其中解磷红曲霉菌（Ｍｏｎａｓｃｕｓｓｐ）ＰＢ１,曲霉菌（Ａｓｐｅｒｇｉｌｌｕｓｓｐ）ＰＢ２的解磷强度分别为８６．５％和５９．４％显著高于解磷细菌,其解磷过程与培养液ｐＨ值下降密切相关,用红曲霉菌ＰＢ１进行的油盆栽肥效试验结果表明,ＰＢ１＋磷矿粉＋猪粪盆栽处理与对照（磷矿粉＋猪粪）相比,油     

牦牛放牧强度对青藏高原典型高寒草地节肢动物多样性的影响

【目的】气候变化与过度放牧正在不同程度地威胁着青藏高原高寒草地生态系统功能。大型食草动物放牧活动与地上节肢动物多样性在理论上存在着紧密联系,然而目前对其关联仍不清楚。【方法】本研究选用青藏高原极具代表性的本土大型食草动物——牦牛Bos grunniens作为放牧牲畜,利用metabarcoding技术结合传统植物样方调查手段,在青藏高原典型高寒草地调查了重度放牧(3头/hm²)、中度放牧(2头/hm²)、轻度放牧(1头/hm²)和禁牧4种放牧强度下草地地上节肢动物α多样性(Simpson, Chao1, ACE和Shannon-Wiener)、相对丰度、β多样性、植物群落α多样性(Shannon-Wiener多样性指数、物种丰富度和Pielou均匀度指数)以及地上节肢动物α多样性与植物群落α多样性的关系。【结果】结果表明,不同放牧强度下典型高寒草地地上节肢动物α多样性均无显著差异,但中度放牧有增加节肢动物多样性的趋势;各放牧强度下地上节肢动物的优势目均为直翅目(Orthoptera),禁牧、轻度放牧、中度放牧和重度放牧下...     

闽南渔场主要游泳动物时空生态位特征及其影响因素

根据2019—2021年在闽南渔场进行的秋季、冬季、春季和夏季四个航次定点底拖网调查资料,利用相对重要性指数、种群聚集强度、生态位宽度、生态位重叠及冗余分析对主要游泳动物时空生态位特征及其影响因素进行研究。结果表明,(1)调查海域共鉴定出游泳动物214种,主要优势种有18种,优势种存在明显的季节更替现象;夏季优势种的丛生指数和平均拥挤度较高,春季较低;(2)在时间维度上,须赤虾(Metapenaeposis barbata De Haan)生态位宽度最大(0.99), 7组种对时间生态位重叠值等于1.00;在空间维度上,带鱼(Trachurus japonicus Temminck&Schlegel)生态位宽度最大(2.57),空间生态位重叠值超过0.6的种类占71.3%;在时空维度上,带鱼生态位宽度最大(2.45),鹿斑仰口鲾(Leiognathus ruconius Hamilton)与赤鼻棱鳀(Thrissa kammalensis Bleeker)时空生态位重叠值最大(0.94);(3)冗余分析表明,底层温度和底层盐度是影响闽南渔场主要游泳动物时空生态位特征的重要环境因...