神府东胜煤田扰动地面野外降雨试验

神府东胜煤田是我国探明储量最大的煤田,在开发建设过程中产生了大量的扰动地面,造成了严重的矿区水土流失。为了科学地预测和治理矿区扰动地面的水土流失,采用野外人工模拟降雨试验对神府东胜煤田扰动地面的侵蚀产沙过程进行模拟,深入探讨其侵蚀产沙、产流特征。结果表明:降雨强度是影响扰动地面产流时间的主要因素,产流时间与降雨强度呈负幂函数相关;在试验条件限定的范围内,入渗率随降雨强度和坡度的增大均呈先增大后稳定的趋势,但坡度对其影响较弱;径流率随降雨强度和坡度的增大均呈幂函数增大,且相关系数较高;径流含沙量和侵蚀速率均与降雨强度呈幂函数相关,但相关系数不高;径流量与降雨强度呈很好的线性相关;产沙量与径流量呈幂函数相关,且相关系数较高。     

A GIS-based survey for the conservation of bryophytes at the landscape scale

Geographical information system (GIS) data on landscape features and land use were collected to predict bryophyte diversity and conservation value in order to determine the factors that favour bryophytes at a large geographical scale and propose the relevant conservation measures. Total species diversity and diversity in species of high conservation value were highly correlated, and the landscape features promoting them were the proportion of military lands, steep slopes, and broadleaf woodland. Military lands seemed to be especially important for the conservation of endangered species highly specialized to open habitats maintained by the appropriate level of disturbance. Woodland cover was also as a key factor for bryophyte diversity but landscape heterogeneity, such as steep slopes with a range of contrasting ecological conditions, was required to reach the highest species numbers. The GIS-based approach presented here may help focusing the attention on sites exhibiting the appropriate landscape features in terms of conservation, which is especially relevant in the context of the European network `Natura 2000' for designating, conserving, and managing the sites of high biological value.     

山东省小城镇园林绿化树种与绿地率研究

小城镇建设对于推进中国城市化进程具有十分重要的作用,搞好小城镇绿化对于促进城乡经济发展和精神文明建设意义重大。研究结果表明,山东省小城镇的绿化以草坪和地被植物为主,结构不甚合理;绿地率严重低于国家标准。     

陕西省靖边县沙地水分与植被建设

根据毛乌素沙地靖边县海则滩镇钻孔剖面沙层水分含量的测定,研究了该区沙地剖面水分分布特点、沙层水分存在形式、水分平衡、大气降水对地下水的补给以及植被建设等问题。结果表明,该区500 cm深度范围内沙层剖面含水量的变化特点是草地0-200 cm和灌木林地0-300 cm含水量较低,草地200-500 cm和灌木林地300-500 cm含水量较高;草地沙层含水量明显高于灌木林地,草地含水量变化范围为1.0%~6.0%,平均为3.4%;灌木地含水量变化范围为0.7%~2.8%,平均为1.5%。草地沙层剖面200 cm以下有含量大于3%的高含量薄膜水和含量大于5%的重力水存在,显示大气降水对地下水的补给较强。灌木林地沙层中一般缺少重力水和高含量薄膜水,指示灌木林地降水对地下水补给较弱。该区水分为正平衡,其原因除了降水较多之外,沙层入渗率高和受蒸发消耗较少也是重要原因。由于靖边县沙地区降水量较多,沙地水分活跃层分布深度在200~300 cm之间,较沙漠区分布深度增加了100-200 cm。沙层水分含量的剖面变化表明,该区沙层水分能够满足耐旱灌木林生长的需要,适于发展防风固沙效果好的灌木林。     

豆科灌木－小叶锦鸡儿在我国北方半干旱沙地中的作用

Caragana microphylla Lam., a pioneer leguminous shrub species for vegetation re-establishment, is widely distributed in the semi-fixed and fixed sandy lands of the Horqin region. Some soil chemical and physical properties were measured under the canopy of C. microphylla and in the adjacent open areas to determine the effects of individual shrubs on soil properties. The influence of isolated C. microphylla on chemical and physical properties of the topsoil was significantly different between plots under the shrub canopy and in the shrub interspaces. Beneath the shrub canopy greater amounts of fine particle fractions, a higher water-holding capacity, and a lower bulk density, as well as higher aboveground and belowground litter biomass were found. Soil organic C and total N concentrations were 23%-31.6% and 14%-27.2% higher under the shrub canopies than in the shrub interspaces, respectively, giving rise to ＂islands of fertility＂. In a desertified sandy grassland ecosystem, C. microphylla was believed to play a major role in organic C sequestration, N accumulation, and the hydrologic cycle. Additionally, it has been found to be of ecological importance for vegetative restoration and reversal of desertification.     

玛曲退化草地生态修复研究

玛曲县是黄河上游地区的主要水源涵养地,草地生态系统服务价值巨大。近几十年来由于全球气候变化和人为因素的影响,草地退化严重,不仅明显制约了牧区经济的发展和当地藏族群众生活水平的提高,而且直接威胁到黄河流域的生态安全。在分析玛曲草地退化现状及发展趋势的基础上,根据生态恢复学原理,探讨了退化草地生态修复的途径,并提出了巩固治理成果的对策。     

半干旱土添加有机改良剂后有机质的化学结构变化

A 9-month incubation experiment using composted and non-composted amendments derived from vine pruning waste and sewage sludge was carried out to study the effects of the nature and stability of organic amendments on the structural composition of organic matter (OM) in a semi-arid soil.The changes of soil OM,both in the whole soil and in the extractable carbon with pyrophosphate,were evaluated by pyrolysis-gas chromatography and chemical analyses.By the end of the experiment,the soils amended with pruning waste exhibited less organic carbon loss than those receiving sewage sludge.The non-composted residues increased the aliphatic-pyrolytic products of the OM,both in the whole soil and also in the pyrophosphate extract,with the products derived from peptides and proteins being significantly higher.After 9 months,in the soils amended with pruning waste the relative abundance of phenolic-pyrolytic products derived from phenolic compounds,lignin and proteins in the whole soil tended to increase more than those in the soils amended with sewage sludge.However,the extractable OM with pyrophosphate in the soils amended with composted residues tended to have higher contents of these phenolic-pyrolytic products than that in non-composted ones.Thus,despite the stability of pruning waste,the composting of this material promoted the incorporation of phenolic compounds to the soil OM.The pyrolytic indices (furfural/pyrrole and aliphatic/aromatic ratios) showed the diminution of aliphatic compounds and the increase of aromatic compounds,indicating the stabilization of the OM in the amended soils after 9 months.In conclusion,the changes of soil OM depend on the nature and stability of the organic amendments,with composted vine pruning waste favouring humification.     

EXCLOSURE LAND MANAGEMENT FOR RESTORATION OF THE SOILS IN DEGRADED COMMUNAL GRAZING LANDS IN NORTHERN ETHIOPIA

In the northern highlands of Ethiopia, establishment of exclosures to restore degraded communal grazing lands has been practiced for the past three decades. However, empirical data on the effectiveness of exclosures in restoring degraded soils are lacking. We investigated the influence of exclosure age on degree of restoration of degraded soil and identified easily measurable biophysical and management‐related factors that can be used to predict soil nutrient restoration. We selected replicated (n = 3) 5‐, 10‐, 15‐, and 20‐year‐old exclosures and paired each exclosure with samples from adjacent communal grazing lands. All exclosures showed higher total soil nitrogen (N), available phosphorus (P), and cation exchange capacity than the communal grazing lands. The differences varied between 2·4 (±0·61) and 6·9 (±1·85) Mg ha⁻¹ for the total N stock and from 17 (±3) to 39 (±7) kg ha⁻¹ for the available P stock. The differences in N and P increased with exclosure age. In exclosures, much of the variability in soil N (R² = 0·64) and P (R² = 0·71) stocks were explained by a combination of annual average precipitation, woody biomass, and exclosure age. Precipitation and vegetation canopy cover also explained much of the variability in soil N (R² = 0·74) and P (R² = 0·52) stocks in communal grazing lands. Converting degraded communal grazing lands into exclosures is a viable option to restore degraded soils. Our results also confirm that the possibility to predict the changes in soil nutrient content after exclosure establishment using regression models is based on field measurements. Copyright © 2011 John Wiley & Sons, Ltd.     

围栏和退化条件下西藏高山嵩草草甸土壤种子库的比较

【目的】研究围栏和退化对西藏邦杰塘高山嵩草草甸土壤种子库的影响,并探讨土壤种子库在地上植被群落构建中的作用,为高寒地区退化草甸生态系统的恢复与重建提供理论参考。【方法】采用幼苗萌发法,研究在围栏、退化条件下,西藏邦杰塘高寒草甸地上植被群落的物种组成、土壤种子库中物种种类、种子数量等特征及地上植被与土壤种子库物种组成之间的关系。【结果】围栏样地的地上植被群落中共出现18个物种,多年生禾本科、莎草科植物占主要地位;退化样地地上植被群落中共出现15个物种,以杂草类植物占据优势,其大多属于菊科、蔷薇科、毛茛科和龙胆科等。退化样地土壤种子库密度达5 489.4粒/m2,显著(P0.05)高于围栏样地的4 029.3粒/m2,退化样地土壤种子库密度主要依赖于菊科、龙胆科、蔷薇科等杂草类种子的输入,3个科的植物种子数占种子总数的64.6%;与退化样地比较,围栏样地土壤种子库的物种多样性指数和丰富度指数均显著提高(P0.05)。围栏样地土壤种子库与地上植被物种组成之间相似性较低,Sorensen相似性指数仅为0.44;退化样地中嵩草属植物严重退化,地上植被群落中依靠种子繁殖的杂草类所占比例较高,地上植被与土壤种子库表现出较高的相似性,相似性指数为0.72。【结论】种子库在地上植物群落构建中起到重要作用,但其对地上植被的贡献大小在围栏和退化条件下表现不同。围栏样地以高山嵩草、大花嵩草、紫花针茅为优势种,围封措施减少了环境的扰动,但其土壤种子库密度较低,说明在群落更新过程中,多年生禾本科、莎草科植物的种子萌生苗只起到辅助作用。