21世纪初我国粮食供需的新空间格局

利用2000-2003年县级统计数据,揭示21世纪初我国粮食供需的空间格局。我国粮食供需平衡以东西分异规律为主,其次是南北分异。地势第二级阶梯以东,主要余粮区分布最广,北方明显多于南方;胡焕庸线以西,常年缺粮区为主;两线之间,潜在缺粮区居多。东北地区、华北平原生产全国近70%的余粮。长江中下游以南地区既是我国温饱水平缺粮总数最多的地区,也是第三大余粮生产区。地势第二级阶梯上的农牧交错带,温饱水平缺粮总量列第二位,是我国粮食安全最脆弱的地区。上述地区主要位于环境变化敏感地带,粮食安全自然风险最大。因此,加强环境变化对粮食供需平衡的影响研究,对深入认识我国粮食供需平衡的稳定性具有重要的现实意义和理论价值。     

偏心不耦合装药爆炸应力场研究及应用

中深孔光面爆破或预裂爆破质量对永久边坡的长期稳定性与安全性至关重要。利用偏心不耦合装药爆炸应力场的全息动光弹研究成果,对传统不耦合装药结构进行了改进,使高边坡光面爆破或预裂爆破效果得到明显改善,减少了因爆破效果不佳而造成悬、浮石滑落的事故隐患。并在实践中取得了一些有益的经验,可供同仁借鉴。     

Within-nest temporal polyethism in the honey bee

A well-regulated division of labor has been one of the core adaptations leading to the success of the social insects. Honeybee division of labor has been classically viewed as a sequence of age-related changes in task performance. Kolmes questioned this view arguing that his studies did not support the existence of any age-related within-nest specialization. To resolve this controversy, Kolmes and Seeley conducted a joint study with mixed results. They found support for a cell cleaning caste, but diverged on whether their results supported distinct nursing and middle age castes. In this paper, I follow up on their work to resolve the question of caste number in within-nest honey bees. To determine whether nurses (typically aged 4–12 days) and middle-aged bees (aged 12–20 days) have distinct task repertoires, I conducted focal animal observations on a large number of workers in both age groups working within the same nests at the same time. The results support their being two castes of within-nest bees. Young bees specialized on brood care tasks, while middle-aged bees specialized on nectar processing and nest maintenance. Middle-aged bees were observed caring for brood in less than 1% of the observations. Moreover, both castes exhibited movement patterns that correspond to the traditional view that nurses stay within the broodnest, while middle-aged bees move around a great deal in search of work throughout the nest. A review of studies conducted since the debate of Seeley and Kolmes supports the reliability of these results. This work has relevance for proximate models of temporal polyethism, as it is often assumed by such models that there is only one within-nest caste in the honeybee.     

Conserving Biodiversity and Ecosystem Function through Limited Development: an Empirical Evaluation

Abstract:  Suburban, exurban, and rural development in the United States consumes nearly 1 million hectares of land per year and is a leading threat to biodiversity. In response to this threat, conservation development has been advanced as a way to combine land development and land conservation while providing functional protection for natural resources. Yet, although conservation development techniques have been in use for decades, there have been few critical evaluations of their conservation effectiveness. We addressed this deficiency by assessing the conservation outcomes of one type of conservation development project: conservation and limited development projects (CLDPs). Conducted by land trusts, landowners, and developers, CLDPs use revenue from limited development to finance the protection of land and natural resources. We compared a sample of 10 CLDPs from the eastern United States with their respective baseline scenarios (conventional development) and with a sample of conservation subdivisions—a different conservation development technique characterized by higher-density development. To measure conservation success, we created an evaluation method containing eight indicators that quantify project impacts to terrestrial and aquatic ecosystems at the site and in the surrounding landscape. The CLDPs protected and managed threatened natural resources including rare species and ecological communities. In terms of conservation benefits, the CLDPs significantly outperformed their respective baseline scenarios and the conservation subdivisions. These results imply that CLDPs can offer a low-impact alternative to conventional development and a low-cost method for protecting land when conventional conservation techniques are too expensive. In addition, our evaluation method demonstrates how planners and developers can incorporate appropriate ecological considerations when designing, reviewing, and evaluating conservation development projects.     

20世纪下半叶上海市居住用地扩展模式、强度及空间分异特征

基于多时相土地利用图与遥感影像资料,建立空间研究网格,通过土地利用扩展强度指数的空间分析,对1947～2002年上海市建成区居住用地扩展模式、强度及空间分异特征进行了研究。结果表明:①上海市建成区居住用地空间扩展并不是持续增长的,其扩展强度与速度均从建国初期开始减小,在1964～1979年期间达到最低值后又逐渐增大,总体上表现为先降后升的发展变化;②居住用地扩展模式随时间发生较大变化,由建国初期以核心建成区为主的渐进式扩展(1947～1964年)转变为跳跃式扩展(1964～1988年),到近些年又发展成兼具渐进扩展与跳跃扩展特征的混合扩展模式(1988～2002年),城市用地功能由简单趋于复杂和多元化;③不同时期居住用地扩展过程差异较大,其行为特征受国家宏观政策及社会经济发展等因素的影响,可以为复杂的城市扩展动力机制研究提供更多素材。     

立体式植物修复受重金属污染农田土壤的探讨

农田土壤遭受重金属污染是江西省乐平市乐安河沿岸的重要环境问题。采用实验小区的方法,研究了乔、灌、草多层次植物对重金属污染地区土壤的修复作用。结果表明,利用木本植物和对重金属吸收较好的草本植物组成立体模式来净化污染面积较大的土壤,效果明显,简便易行,经济效益大,是治理重金属Cu、Cd复合污染的一条新途径。     

城市地表形态对热环境的影响——以上海市为例

基于遥感与GIS技术,利用Landsat7-ETM+影像反演地表温度,用社会经济统计数据、土地利用现状数据和道路交通网络数据计算城市景观形态参数以表征地表特征,从行政区(县)、5km间距同心环带和局部区块3个水平上划分空间单元建立数据样本,分析城市地表形态对热环境空间分布格局的影响。结果表明:(1)景观混合度和景观分裂度对地表温度有恒定的负向影响,区块连通性与地表温度负相关;(2)景观分裂度对热环境的影响取决于地类属性:分裂度大的增温地类,地表增温效应弱;分裂度大的降温地类,地表降温效应强;(3)人口密度和经济密度可对地表温度产生恒定正向影响;(4)人口密度、建设用地比例和房屋建筑比例是分布在区(县)尺度、同心圆环尺度和典型区块尺度上影响地表热环境最显著的地表形态要素。     

江苏省乡村性空间格局及影响因素研究

基于城乡一体化思想,在分析乡村性内涵基础上,采用人口密度等指标构建乡村性评价体系,以全国第五、六次人口普查等数据为基础,借助SPSS、ArcGIS、Geoda软件,探讨了江苏省县域单元乡村性空间格局及影响因素。结果表明：(1)2000～2010年,江苏全省县域单元乡村性逐渐减弱,并呈现出阶梯状的空间分布态势;(2)各县域乡村性指数并不表现为完全随机状态,而是存在显著的正空间相关性。热点区域分布在沭阳县与泗阳县交界处为核心的圈层结构,冷点区域集中在乡镇工业发达的苏锡常地区;（3）社会环境、交通、资本、工业化和城市化、政策等因素是乡村性变化的主要影响因素;（4）未发现乡村性加强的现象;在数据可获得情况下,以乡镇为单元研究乡村性将具有更强的现实指导意义     

芦芽山华北落叶松林土壤剖面细菌群落分布格局

微生物群落是维持森林土壤生态系统结构和功能的关键组分.细菌群落在土壤剖面上的垂直分布对森林土壤碳库和土壤营养循环具有重要影响.利用Illumina MiSeq高通量测序技术,分析了芦芽山华北落叶松(Larix principis-rupprechtii)林腐殖质层及0～80 cm土层细菌群落特征,探究影响土壤剖面细菌群落结构的驱动机制.结果表明,细菌群落的α多样性随土壤深度的增加显著单调降低,群落结构在土壤剖面上有显著差异.放线菌门(Actinobacteria)、变形菌门(Proteobacteria)的相对丰度随着土壤深度增加而降低;酸杆菌门(Acidobacteria)和绿弯菌门(Chloroflexi)的相对丰度随土层深度的增加而增加.RDA分析结果表明,土壤NH⁺₄、 TC、 TS、 WCS、 pH、 NO^-₃和TP是决定土壤剖面细菌群落结构的重要因子,其中pH的影响最为显著.分子生态网络分析表明,凋落物层和亚表层土壤(10～20 cm)细菌群落的复杂性较高,深层(40～80 cm)土壤细...     

土地利用结构与空间格局对鄱阳湖流域中小河流水质的影响

为揭示土地利用结构与空间格局对中小河流水质的影响机制,于2022年1月与2022年7月在鄱阳湖流域3条中小河流的25个采样点收集水样.采用Bioenv分析、Mantel检验与方差分解量化不同空间尺度的土地利用结构与空间格局对水质的影响,使用广义加性模型拟合水质与土地利用结构与空间格局的关系,广义线性模型构建分段回归模型,并基于逐步递归法计算阈值.结果表明：①土地利用结构与空间格局对河流水质的平均解释率在丰水期（59.72%）大于枯水期（48.95%）;子流域与河岸100 m是土地利用结构与空间格局影响中小河流水质的关键尺度,平均解释率分别为54.70%和64.88%;土地利用结构与空间格局的共同解释部分是驱动河流水质变化的重要因素,占总解释率的66.90%.②土地利用结构对中小河流水质的影响具有显著的阈值效应,当子流域尺度下建设用地占比低于2%、耕地占比低于8%和林地占比高于82%,河岸缓冲区尺度下建设用地占比低于12%、耕地占比低于41%和林地占比高于49%时,均能明显改善水质.③空间格局对中小河流水质的影响也具有阈值效应但弱于土地利用结构,当子流域尺度下斑块形状值大于28.77和斑块多样性大于0.69,河岸缓冲区尺度下斑块形状值大于2.99和斑块多样性大于1.02时,均能改善水质.以上结果表明,加强对子流域与河岸100 m尺度的土地利用的管理,合理规划土地利用结构与空间格局能够有效地防止水质恶化.