用δ~(13)C法研究黑土添加有机物料后有机碳的变化规律

通过室内短期培养实验,利用δ13C的方法研究了外源有机物料分解过程中黑土有机碳的变化规律。结果表明:黑土中添加有机物料后,土壤有机碳的数量明显增加。在有机物料分解过程中,随着培养时间的延长,土壤有机碳的总量在逐渐下降,总的变化趋势是先快后慢,渐趋平缓,到培养结束(30天),有机物料在土壤中净残留率小于50%。黑土有机碳的δ13C值受进入土壤中有机物料的种类所影响,从数量上土壤有机碳的δ13C值可以反映土壤中不同来源有机碳的变化。在小麦秸秆分解过程中,新进入黑土中的有机碳转化较快,而土壤中固有的有机碳转化较慢,添加有机物料可以增加土壤中有机碳的固定。     

Global dung beetle response to tropical forest modification and fragmentation: A quantitative literature review and meta-analysis

Although insects are crucial for maintaining ecosystem function, our understanding of their overall response to human activity remains limited. This is no less true of dung-burying beetles (Coleoptera: Scarabaeidae: Scarabaeinae), which provide a suite of critical ecosystem functions and services, yet but face multiple conservation threats, particularly from landscape conversion. Here we use a review and meta-analysis to synthesize the current knowledge concerning response to tropical forest modification and fragmentation of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae). For every modified habitat type and individual forest fragment across 33 studies, we calculated six dung beetle community parameters, standardized relative to intact tropical forest. We organized modified habitats along an approximate disturbance gradient ranging from selectively logged, late and early secondary forest, through agroforestry, tree plantations, to annual crops, cattle pastures and clear-cuts. Secondary forests, selectively logged forest and agroforests supported rich communities with many intact forest species, while cattle pastures and clear-cuts contained fewer species overall with few forest-dwelling species. Abundance generally declined with increasing modification, but was quite variable. Communities in open habitats were often characterized by hyper-abundance of a small number of small-bodied species, leading to low evenness. Across fragmentation studies, dung beetle species richness, abundance and evenness declined in smaller forest fragments. Richness and abundance sometimes declined in more isolated fragments, although this response appeared to depend on matrix quality. Across both habitat modification and fragmentation studies, geographic location and landscape context appeared to modify dung beetle response by influencing the available pool of colonists. We discuss potential underlying mechanisms and conclude with recommendations for management and conservation and for future research.     

小江流域土地利用变化及其趋势分析

运用遥感和地理信息系统技术，提取了小江流域1987，1995年和2000年土地利用空间数据，分析了1987～2000年间小江流域土地利用类型变化的幅度、速度以及类型之间相互转移，并应用马尔柯夫概率模型对小江流域2015年土地利用格局进行了预测。结果表明：13年来小江流域耕地、林地以及城乡工矿用地面积均显著增加，其中耕地增加最为显著，由1987年的345．1km^2增加到2000年的398．7km^2。小江流域土地利用变化速度很快，年均变化速度达0．49％；对单一土地利用类型来说，城乡工矿用地的年均变化速度最大，年变化率达3．52％，其次为耕地和水域。增加的耕地主要来自草地、林地和水域；林地中除部分转化为耕地外，由12．64％的林地退化成草地；草地和未利用地基本保持不变。到2015年，小江流域耕地、林地、水域和城乡工矿用地面积和比例将会增加，草地和未利用地面积和比例将会下降。     

森林气候可能生产力的动态模拟

根据树森木材积的增长过程，建立了标准材积增长曲线，确定光能利用系数的时间演变。以地区辐射资料计算不同年龄的树木光合生产潜力，并利用湿润系数和日最高、最低温度建立了水分和温度订正函数，最终建立了森林气候生产力的动态模型。     

气候对早稻土壤供肥能力的影响

为了给测土配方施肥提供土壤供肥能力的参考依据，1987年至2005年在土壤肥力较一致的马肝泥田上进行了土壤供肥能力的多点田间试验。结果表明，气候对土壤供肥能力影响显著。土壤供肥能力：高温少雨年份K2O〉N〉P2O5，低温多雨年份P2O5〉K2O〉N，正常年份K2O〉P2O5〉N。土壤供肥比例（N：P2O5：K2O）：高温少雨年份为1：0．23：0．58，低温多雨年份为1：0．29：0．56，正常年份为1：0．25：0．62。     

黄河三角洲土地利用/覆盖格局与演化分析

利用1984，1986，1991，1996年和2001年的多源遥感数据，结合GIS空间数据和野外考察资料等，对1984年东营市建市17年来黄河三角洲土地利用／覆盖格局和动态演变规律进行分析。1984年以来，黄河三角洲陆地面积总体上在不断增加。土地利用／覆盖类型以旱地和未利用地为主，旱地的面积有较大的减少，而未利用地的面积变化不大，略有增加。在各个不同的时段内，土地利用／覆盖变化的面积都占1／3左右。在土地利用／覆盖变化类型中，未利用地与耕地之间的双向转换非常频繁，是最重要的两种变化类型，由于次生盐渍化的原因，耕地退化为未利用地在1986年后都占据首位；未利用地与灌草地、灌草地与耕地之间相互转化所占比例也较大。     

华北地区水安全问题的研究与展望

This paper addresses the emergence of water security problems in North China with the aim of highlighting key water resources management and water security issues for the long-term development of North China. Three key problems related to water resources and security issues in North China in the 21st century are addressed, namely 1) the water cycle under environmental change, 2) agricultural water saving, and 3) water security. Development of international research related to these issues is also reviewed. The research plan developed recently by the Chinese Academy of Sciences (CAS) is discussed and suggestions on research and development of water resources science in North China are presented. Thanks to focus on experimental catchments and dedicated research stations, a detailed knowledge of the water cycle on North China farmland has been compiled. A range of techniques that include isotope tracers has been used to acquire hydrologic data. Much research has been devoted to developing distributed hydrological models at different scales. In the well irrigation district, five different water saving irrigation regimes have been investigated, and these regimes have had widespread application, and reduced water use 60-150 mm while they increased water use efficiency (WUE) by 20%-30%. Furthermore, preventing water pollution is the most essential step to ensure North China's water security.     

20世纪50年代以来科尔沁沙地景观时空动态变化探析

研究分析了50年来科尔沁流动沙地和半固定沙地景观时空动态变化,并分析了沙地时空动态变化的主要成因。     

Hydrogen oxidation activities in soil as influenced by pH,temperature, moisture,and season

Summary Hydrogen oxidation in soil was measured at low (1 ppmv) and high (300 ppmv) H₂ concentrations to distinguish between the activities of abiontic soil hydrogenases and Knallgas bacteria, respectively. The two activities also showed distinctly different pH optima, temperature optima, and apparent activation energies. The pH optima for the soil hydrogenase activities were similar to the soil pH in situ, i.e., pH 8 in an slightly alkaline garden soil (pH 7.3) and pH 5 in an acidic cambisol (pH 4.6–5.4). Most probable number determinations in the alkaline acidic soils showed that Knallgas bacterial populations grew preferentially in neutral or acidic media, respectively. However, H₂ oxidation activity by Knallgas bacteria in the acidic soil showed two distinct pH optima, one at pH 4 and a second at pH 6.4–7.0. The soil hydrogenase activities exhibited temperature optima at 35–40°C, whereas the Knallgas bacteria had optima at 50–60°C. The apparent activation energies of the soil hydrogenases were lower (11–23kJ mol^-1) than those of the Knallgas bacteria (51–145 kJ mol^-1). Most of the soil hydrogenase activity was located in the upper 10 cm of the acidic cambisol and changed with season. The seasonal activity changes were correlated with changes in soil moisture and soil pH.     

不同利用方式下红壤坡地土壤水分时空动态变化规律研究

利用连续3年土壤水分定位观测数据，研究了红壤坡地不同利用方式下土壤水分的时空动态变化规律。结果表明：土壤水分时空动态变化主要受降雨和植被类型的影响。土壤水分季节变化分为相对稳定期、消耗期和补给期三个时段；土壤剖面（0～90cm）水分含量从表层到深层表现为增长型，依据2003年土壤水分标准差和变异系数。将土壤剖面划分为活跃层、次活跃层和相对稳定层3个层次；土壤剖面水分变异系数随降雨量和土层深度的增加而减小，随植被根系的增长而变大。平水年，深根系区与浅根系区土壤水分变化差异表现在30cm深度以下，而丰水年其差异主要表现在土壤表层（0～30cm）；无论平水年还是丰水年，深根系区土壤水分变幅均比浅根系区大。