土壤微生物生物地理学：国内进展与国际前沿

土壤微生物生物地理学是研究土壤中微生物空间分布格局及其随时间变化的一门科学,是土壤微生物学和微生物生态学等领域的研究前沿。近年来,尽管土壤微生物生物地理学研究取得了巨大进展,目前仍面临诸多难题与挑战。本文简要回顾了土壤微生物生物地理学的发展历程,重点介绍近年来我国在森林、草地和农田生态系统中土壤微生物生物地理学研究的主要进展。同时进一步阐述了目前土壤微生物生物地理学研究的国际前沿方向,包括微生物群落空间分布及其驱动机制、群落构建过程与共存网络、微生物地理分布与生态系统功能的关联以及预测微生物群落对全球变化的响应。最后,对土壤微生物生物地理学未来的研究方向进行了展望,强调了清晰的微生物物种定义、微生物群落的时间动态、多组学与合成生物学技术以及高精度的预测模型在土壤微生物生物地理学研究中的重要性。     

黄土丘陵沟壑区地表过程响应单元划分及其地形特征提取

地表过程解析与调控是保障人与自然和谐相处的重要途径,高效、合理地划分地表过程响应单元则是开展地表过程研究的重要前提.针对黄土丘陵沟壑区土壤侵蚀的地形地貌分异特征,提出在小流域内以沟谷线、山脊线、分水线和沟缘线相互交叠,构成具有相对均一坡向、坡度与坡位的地表过程响应单元,在ArcGIS9.2中,以Hc-DEM为基础数据,通过确定沟谷线、山脊线、分水线和沟缘线的提取方法,以及响应单元平均坡度、整体坡向、面积与周长等地形特征的测算技术,实现地表过程响应单元的快速划分及其地形特征的高效提取.研究结果对促进黄土丘陵沟壑区以土壤侵蚀为代表的地表过程研究具有重要的基础意义.     

我国亚热带山地土壤发生特性和系统分类研究进展

为了解亚热带山地成土环境下土壤形成规律和分类现状, 推动中西部山地土壤发生学研究和土系建立, 为山地土壤资源的可持续利用提供参考。综述了有关中国亚热带山地土壤的发生发育特性及其系统分类的研究资料, 包括中国亚热带山地的主要地球化学过程和成土过程特点, 亚热带山地土壤分类的主要诊断层、 诊断特性和诊断现象以及高级分类单元的垂直分布规律, 基层分类单元的主要诊断指标。在此基础上, 展望了亚热带山地土壤系统分类研究值得重视的 4个方面：（1）深入理解亚热带山地土壤的地球化学和成土过程;（2） 建立中国亚热带典型山地土壤的代表性土族、 土系, 检验和完善现有基层分类单元的诊断指标体系;（3） 强化山地土壤系统分类中分析指标和数据标准化意识;（4） 重视薄片微形态、 现代仪器分析和计算机新技术的应用。     

基于CA-Markov模型的黄土丘陵区土地利用变化

为探讨黄土丘陵区的土地利用变化规律以及驱动机制,以罗玉沟流域作为典型流域,基于1986、2001年的TM影像为数据源,对土地利用格局分布进行分析,并运用CA-Markov模型,以2001年的土地利用格局为基础,预测了2016年流域的土地利用的空间格局分布。结果表明,罗玉沟流域土地利用格局在1986年以前,以坡耕地为主,面积占59.67%,其次为梯田、草地和林地。从1986年到2001年林地和梯田的面积均有显著增加,坡耕地面积则显著减少,其余土地利用类型面积变化不大。从单一土地利用类型动态度来看,面积增加大     

Conservation planning with dynamic threats: The role of spatial design and priority setting for species’ persistence

Conservation actions frequently need to be scheduled because both funding and implementation capacity are limited. Two approaches to scheduling are possible. Maximizing gain (MaxGain) which attempts to maximize representation with protected areas, or minimizing loss (MinLoss) which attempts to minimize total loss both inside and outside protected areas. Conservation planners also choose between setting priorities based solely on biodiversity pattern and considering surrogates for biodiversity processes such as connectivity. We address both biodiversity processes and habitat loss in a scheduling framework by comparing four different prioritization strategies defined by MaxGain and MinLoss applied to biodiversity patterns and processes to solve the dynamic area selection problem with variable area cost. We compared each strategy by estimating predicted species’ occurrences within a landscape after 20 years of incremental reservation and loss of habitat. By incorporating species-specific responses to fragmentation, we found that you could improve the performance of conservation strategies. MinLoss was the best approach for conserving both biodiversity pattern and process. However, due to the spatial autocorrelation of habitat loss, reserves selected with this approach tended to become more isolated through time; losing up to 40% of occurrences of edge-sensitive species. Additionally, because of the positive correlation between threats and land cost, reserve networks designed with this approach contained smaller and fewer reserves compared with networks designed with a MaxGain approach. We suggest a possible way to account for the negative effect of fragmentation by considering both local and neighbourhood vulnerability to habitat loss.     

番茄青枯病抑病土壤根际微生物群落特征及其抑制性传递机制

根际微生物在宿主植物抵御土传病害发生过程中发挥着重要作用。为探究抑病土壤与感病土壤根际微生物群落特征及其微生物群落构建机制,分别采集抑病土和感病土中的番茄根际土壤,采用实时荧光定量PCR技术检测两种根际土壤中的病原菌含量,并利用16SrRNA基因扩增子高通量测序技术分析抑病和感病土中番茄根际土壤微生物群落多样性、组成、结构以及基于零模型的微生物群落构建机制的差异。结果表明,与感病土相比,抑病土壤中番茄的青枯病病情指数明显降低（病情指数分别为47.5和22.5）,其根际中细菌群落具有更高的alpha多样性、更丰富的放线菌门、厚壁菌门以及芽孢杆菌科和链霉菌科等有益微生物,较低的青枯病菌丰度（病原菌丰度降低了12.22倍）并伴随着较高的随机性过程,因此抑病土壤受病害胁迫的适应性较强。将感病土壤与抑病土壤按照一定比例进行混合,形成了仅有感病土D10H0、感病土与抑病土质量比为1︰1的D5H5以及仅有抑病土D0H10这三种处理以进一步检测抑病土壤抑病特性的可传递性。结果表明,随着抑病土比例的增加,番茄青枯病病情指数逐步降低,D10H0、D5H5和D0H10的病情指数分别为41.67、29.17与...     

农田环境下无人机图像并行拼接识别算法

为改善在农田环境下无人机图像计算速度和效率,该研究提出了一种农田环境下无人机图像并行拼接识别算法。利用倒二叉树并行拼接识别算法,通过提取图像拼接中的变换矩阵,实现拼接识别同时进行。根据边缘设备的CPU核心数和图像数量自动将图像拼接识别任务划分为多个子进程,并分配到不同核心上执行,以提高在农田环境下的计算效率。试验结果表明：相同试验环境和数据集条件下,倒二叉树并行拼接算法的拼接耗时相较于商业软件平均减少了60%～90%左右;在农田环境下,倒二叉树并行拼接识别相较于串行拼接识别的耗时减少了70%,图像识别的平均像素交并比提升了10.17个百分点,说明在农田环境下采用多线程倒二叉树并行算法可以更好地利用农田环境下边缘设备的计算资源,大幅提升无人机图像的拼接和识别的速度,为无人机的快速实时监测提供技术支撑。     

近十年来核素示踪技术在土壤侵蚀研究中的应用进展

随着核素示踪技术在土壤侵蚀研究中应用的深入,土壤侵蚀研究进入了一个快速发展阶段。本文阐述了近十年来137Cs2、10Pbex7、Be、复合示踪及REE-INAA示踪等几种主要核素示踪技术在土壤侵蚀速率、泥沙沉积速率、泥沙来源和坡面侵蚀过程等研究中的应用新进展,并对今后的研究方向和发展趋势进行了分析。     

社会转型期城市家庭购买决策的夫妻角色研究

作为购买决策主体，家庭是一种非常特殊的组织，在中国社会和经济的双重转型期，家庭内部的角色结构也在发生变迁。以三个中等城市家庭为对象，调查结果显示家庭消费决策的夫妻角色呈明显专门化，夫妻在决策不同阶段的感知影响力也不同。这一结果可能为企业的营销传播策略、市场细分策略设计提供理论依据。     

Microphytic crusts,shrub patches and water harvesting in the Negev Desert: the Shikim system

Human-made contour banks are a central component of theShikim water harvesting system in Israels Negev Desert.Efficient water capture depends on the presence of a stable microphytic crustwhich directs surplus surface runoff into the banks where it is stored. We usedsimulated rainfall to examine the impact of soil surface disturbance on runoffand sediment transport, and the effect of this on the efficiency of resourcecapture within the Shikim system. Two disturbance regimes:1) removal of the microphytic crust only, and 2) removal of the crust and shrubpatches by cultivation, were compared with an undisturbed control. In theundisturbed state, 32% of rainfall was redistributed as runoff. This runoffpenetrated approximately 27% deeper under the shrub patches compared with themicrophytic crust. When the microphytic crust was destroyed by simulatedtrampling, the runoff coefficient declined to 13%, and there was no significantdifference in water penetration between shrub and crust patches. Completedestruction of the shrub hummocks and crust by cultivation resulted in adeclinein the runoff coefficient to 6%. The result of sustained disturbance in thesepatchy Negev shrublands is a breakdown in spatial heterogeneity, a loss ofecosystem function, a reduction in ecosystem goods and services such as plantdiversity and production, and ultimately a reduction in pastoral productivity.These results reinforce the view that microphytic crusts are critical for theefficient operation of the Shikim water harvesting system.Given that practices such as cultivation and trampling which disturbmicrophyticcrusts result in enhanced infiltration, crusts should be left intact tomaximisethe water harvesting efficiency in these desert landscapes.This revised version was published online in May 2005 with corrections to the Cover Date.