怀洪新河（安徽段）森林长廊建设规划要点浅析

怀洪新河是安徽境内第三大人工河流,河道两侧林木已陆续采伐,亟待更新并将建成森林长廊。通过对怀洪新河（安徽段）森林长廊建设类型、方式及建设布局的确定,提出河道管理区域内人工造林和更新改造的技术方案,旨在为森林长廊的建设提供参考,改善河道生态环境。     

鹤峰县天保工程建设成效定量分析

天保工程建设是生态环境建设的重要措施,是人与自然和谐发展的重要基础。我们对鹤峰实施天保工程以后,森林资源变化情况、水土流失变化情况等重要生态环境因子进行了详细调查,并与天保工程实施前比较,结果表明:5年来,鹤峰县天保工程建设取得了阶段性成效,生态、经济、社会三大效益显著,折算总效益784 959.90万元。     

森林土壤氧化亚氮排放对氮输入的响应研究进展

大气中氧化亚氮（N2O）浓度的上升加剧了全球变暖。森林土壤在调节大气N2O浓度中发挥着至关重要的作用。近年来,氮（N）输入对森林土壤N2O通量的影响备受关注。然而,森林土壤N2O排放对N输入响应的机制,尤其是植物和微生物对N2O通量的调控作用尚缺乏系统研究。因此,本文综述了N输入如何通过森林植被（根系N吸收、凋落物分解和形成丛枝菌根）和土壤微生物（微生物量和群落组成）调控N2O产生途径从而影响森林土壤N2O排放。结果表明,植物的竞争性氮吸收能降低氮输入对N2O排放的促进作用,其作用大小可能主要取决于土壤“氮饱和”状态。植物凋落物主要通过分解过程中的养分归还和次生代谢产物释放来影响氮输入背景下的森林土壤N2O排放,前者具有促进作用,而后者具有抑制作用。丛枝菌根主要通过吸收有效氮和水分、促进团聚体形成以及改变N2O相关功能基因群落调控森林土壤N2O通量。N输入导致的土壤酸化或养分限制,通常会降低微生物量和/或改变微生物群落组成,从而控制N2O排放。N输入对N2O不同产生途径也会造成影响,受土壤湿度、N2O底物浓度以及N2O相关功能基因丰度（AOB、 AOA、nirK、 nirS和nosZ）的调控。未来在模型预测中,需要将植物氮吸收、凋落物分解、菌根以及N2O产生途径充分纳入模型,以提高模型预测准确性,为全球变化背景下制订森林管理政策和温室气体减排措施提供支持。     

井冈山国家级自然保护区森林土壤养分含量的空间变化

以井冈山国家级自然保护区为研究区,采集了57个土壤剖面的5个不同深度(0~10、10~20、20~40、40~60、60 cm)的土壤样品,对土壤样品的有机碳、全氮、全磷和全钾等指标进行了测定,并结合森林类型数据和DEM高程数据,对不同森林类型及高程条件下的土壤养分状况进行比较分析。结果表明:①土壤有机碳含量最大,全磷含量最小,各土壤养分含量均随土壤深度的增加而递减;②土壤类型的空间分布呈现海拔梯度特征,黄棕壤的分布海拔最高,依次为黄壤、黄红壤,红壤的分布海拔最低;③全磷、有机碳及C/N随着海拔高度的上升呈增加趋势。全钾含量随着海拔高度的上升呈下降趋势;④不同森林类型土壤养分存在差异,常绿阔叶林、落叶阔叶林和常绿落叶阔叶混交林的各土壤养分含量均较高;山顶矮林和温性针叶林除全氮和全钾含量外,其他土壤养分值显著高于其他林型;竹林及灌木林的土壤养分条件相对较差;⑤不同森林类型土壤养分含量的空间分布规律与其分布的海拔高度范围有关。     

风水复合侵蚀下锡林河流域不同管理方式 草地表土粒度特征

结合锡林河流域风水侵蚀情况,对锡林河流域围封天然草地、放牧草地、封育种植草地表层(0~5 cm)土壤粒度特征及其与风蚀、水蚀关系进行研究,结果表明:封育种植草地较放牧和天然草地在降低土壤风蚀和水蚀方面均起到了较明显的作用;锡林河流域草地表层土壤粒度组成以砂粒为主,其所占比例为75%~82%,放牧草地较天然草地及封育种植草地土壤粒度粗化明显,封育种植草地中蒙古冰草+草木樨草地土壤颗粒分选性较差,其余草地土壤颗粒分选性均为中等;研究区内粒径在160μm左右土壤颗粒为易受侵蚀土壤颗粒;研究区土壤粒度组成特征与风蚀、水蚀均有明显相关性,尤其与近地面20 cm风速和径流产流总量联系最为密切。     

天保工程对东北和内蒙古重点国有林区保育土壤生态效益的影响

为了直观地反映天然林资源保护工程所带来的生态效益,体现重大生态工程的巨大作用,实现林业及生态的可持续发展,依据LY/T1721-2008《森林生态服务功能评估规范》,应用分布式测算方法,对东北和内蒙古重点国有林区天保工程保育土壤物质量及价值量进行评估.结果表明:1)截至2015年,9个优势树种固土和保肥总量分别为13.17亿t/a和8 203.72万t/a,比天保工程实施前分别增加2.36亿t/a和1 738.23万t/a;2)9个优势树种固土和保肥总价值分别为905.29和2 408.92亿元/a,比天保工程实施前分别增加455.44和699.69亿元/a;3)桦木林和阔叶混交林固土效益突出,而红松林和樟子松林固土效益不显著;落叶松林和阔叶混交林保肥效益均最好,樟子松林保肥效益较差;4)对森林实施保护,能有效改善其生态系统服务功能,使森林保育土壤生态效益得到相应的提升.研究为评估天保工程区森林的其他生态服务功能,以及后续天保工程的实施提供科学依据.     

Reciprocal transfer effects on denitrifying community composition and activity at forest and meadow sites in the Cascade Mountains of Oregon

In order to examine the effects of disturbance, vegetation type, and microclimate on denitrification and denitrifier community composition, experimental plots were established at the H. J. Andrews Experimental Forest in the Cascade Mountains of Oregon. Soil cores were reciprocally transplanted between meadow and forest and samples were collected after 1 and 2 years. Denitrifying enzyme activity (DEA) was measured using the acetylene block assay and terminal restriction length polymorphism profiles were generated with nosZ primers that target the gene coding for nitrous oxide reductase. Nitrate concentrations, C mineralization, and water content were measured to gain additional insights into soil properties controlling DEA. Meadow soils were significantly higher in DEA than forest soils, and the highest DEA levels were observed in cores transferred from the meadow into the forest. Nitrate concentrations were also different between forest and meadow soils, but did not correlate to DEA. DEA was higher in open versus closed cores, suggesting an association between denitrification and the rhizosphere. Denitrifier communities of undisturbed forest and meadow soils shifted through a 4-year period but remained distinct from each other. Similarly, denitrifier communities clustered by vegetation type of origin regardless of manipulation, suggesting that the overall denitrifier communities are well buffered against environmental changes.     

Management strategies to increase stand structural diversity and enhance biodiversity in coastal rainforests of Alaska

Coastal rainforests of southeast Alaska have relatively simple species composition but complex structures with high diversity of tree ages, sizes and forest canopy layers, and an abundant understory plant community. Wildlife and fisheries resources also play an important role in the ecological functioning of forest and aquatic systems. Clearcutting has greatly altered these forest ecosystems with significant decreases in structural diversity of forest stands and greatly reduced wildlife habitat. This paper synthesizes information on management options in older forests that have never been actively managed, and in younger forests to increase diversity of stand structures and their associated effects on biodiversity. Light to moderate levels of partial cutting in old-growth forests can maintain the original diversity of overstory stand structures and understory plant communities. In younger forests that develop after clearcutting, mixed alder-conifer stands provide more heterogeneous structures and significantly higher understory biomass than in pure conifer forests. Research has shown that red alder increases diversity and abundance of understory plants, and provides forage for deer and small mammals. Results also show a clear linkage between alder and improved invertebrate diversity in aquatic systems. A combination of light partial cutting in older forests along with inclusion of red alder in conifer-dominated forests could provide the greatest amount of diversity and maintain the complex stand structures that are an important component of these forest ecosystems.     

Empirical analysis and prediction of nitrate loading and crop yield for corn-soybean rotations

Nitrate nitrogen losses through subsurface drainage and crop yield are determined by multiple climatic and management variables. The combined and interactive effects of these variables, however, are poorly understood. Our objective is to predict crop yield, nitrate concentration, drainage volume, and nitrate loss in subsurface drainage from a corn (Zea mays L.) and soybean (Glycine max (L.) Merr.) rotation as a function of rainfall amount, soybean yield for the year before the corn-soybean sequence being evaluated, N source, N rate, and timing of N application in northeastern Iowa, U.S.A. Ten years of data (1994-2003) from a long-term study near Nashua, Iowa were used to develop multivariate polynomial regression equations describing these variables. The regression equations described over 87, 85, 94, 76, and 95% of variation in soybean yield, corn yield, subsurface drainage, nitrate concentration, and nitrate loss in subsurface drainage, respectively. A two-year rotation under average soil, average climatic conditions, and 125 kg N/ha application was predicted to loose 29, 37, 36, and 30 kg N/ha in subsurface drainage for early-spring swine manure, fall-applied swine manure, early-spring UAN fertilizer, and late-spring split UAN fertilizer (urea ammonium nitrate), respectively. Predicted corn yields were 10.0 and 9.7 Mg/ha for the swine manure and UAN sources applied at 125 kg N/ha. Timing of application (i.e., fall or spring) did not significantly affect corn yield. These results confirm other research suggesting that manure application can result in less nitrate leaching than UAN (e.g., 29 vs. 36 kg N/ha), and that spring application reduces nitrate leaching compared to fall application (e.g., 29 vs. 37 kg N/ha). The regression equations improve our understanding of nitrate leaching; offer a simple method to quantify potential N losses from Midwestern corn-soybean rotations under the climate, soil, and management conditions of the Nashua field experiment; and are a step toward development of easy to use N management tools.     

不同经营方式对黑土水稳性团聚体组成及微粒有机质积累分布的影响

长期定位试验研究松嫩平原典型中厚黑土区水稳性团聚体组成和微粒有机质积累分布规律结果表明,不同培肥模式和耕作制度对水稳性团聚体组成有很大影响,耕地团聚体组成以<1mm水稳性团聚体占绝对优势;微粒有机碳(POM C)主要存在于水稳性大团聚体中,且其含量随粒级减小而下降,这对维持耕地黑土大团聚体(>0 .2 5mm)水稳定性起重要作用