Africanized honeybee habitat suitability: a comparison between models for southern Utah and southern California

The Africanized honeybee (AHB; Apis mellifera scutellata) is an invasive species which poses a threat to the United States' agricultural industry because of potential decline in pollination services. Previous research has confirmed that the AHB may still expand its range farther north and that limiting environmental factors for AHB distribution vary across the country. This study examines similarities and differences in AHB distribution and the relative importance of environmental factors between two regions of the southwestern United States: southern Utah and southern California. The Maximum Entropy (MaxEnt) modeling approach was used to create two species distribution models of the AHB. First a model was created based on AHB presence data in Utah. This model was used to estimate the Utah distribution and also to project the California distribution based on Utah environmental preferences. The second model was created to predict distribution in California and to project distribution in Utah based on AHB environmental preferences in California. The level of influence of each variable was measured through percent contribution and permutation importance. Model performance was assessed through the area under the receiver operating characteristic curve (AUC). Models estimated AHB presence with high accuracy (AUC > 0.95) in original environments, but were less accurate (AUC < 0.8) in novel environments. Minimum temperature was the primary controlling factor of AHB distribution in each model, and other variables followed similar ranking of importance between the two models. Species response curves varied substantially between the two models. Models did not transfer well from one region to the other because of local differences in response curves and the relative importance of environmental variables, suggesting that AHB in these regions may not have realized their potential geographic range.     

Modeling the Invasion of Holly (Ilex aquifolium): Spatial Relationships and Spread Trajectories

In this study, we investigated the environmental factors associated with the establishment of invasive English holly (Ilex aquifolium) and the spatiotemporal trajectories of its potential spread. We collected georeferenced presence and absence and demographic data of holly between 2011 and 2014 in Saint Edward State Park, Washington. We analyzed them through a spatially explicit framework that combines multiple logistic regression, cellular automata, and bivariate quadratic modeling. Results showed that the presence of holly is influenced by the proximity to evergreen coniferous vegetation and forest edge, distance to streams, forest structure, and slope direction. Our study confirmed that local environmental conditions, species characteristics, and vegetative and dispersal mechanisms play a significant role in determining the rate and success of holly establishment across the different phases of invasion. Invasive species management plans should consider both species characteristics and their habitat and the interactions among them when planning long-term strategies for control and eradication.     

2005-2013年中国新增造林植被生物量碳库固碳潜力分析

本文利用2005-2013年林业统计年鉴中每个省市新造林面积和遥感分类提取得到的2010年土地覆被类型,结合公开发表的各类森林生长方程和各个时期的森林存活率,估算了中国新造林在2005-2100年生物量碳库变化及其固碳潜力。结果表明：2005-2013年中国新造林面积达到4394×10⁴ hm²,在自然生长状况下,到2020年新造林蓄积量增加16.8亿m³,生物量增加1.6 Pg,生物量碳库0.76 Pg C;新造林生物量碳库在2005-2100年中将增加2.11 Pg C,相当于目前现有森林生物量碳库的25%,约是过去20年森林总碳汇的1.5倍;新造林生物量碳密度逐年增加,最高达到48.1 Mg/hm²。整合林业统计年鉴以及遥感解译的森林类型对新造林生物量固碳潜力分析,研究表明新造林具有较大的碳汇潜力,对中国现有森林碳汇平衡有重要贡献。     

中国新型城镇化的空间格局演变及影响因素分析——基于285个地级市的面板数据

对中国2003~2012年285个地级市的新型城镇化水平进行测度,对其空间格局的演变进行深刻剖析。基于距离平方倒数权重矩阵,检验空间相关性,建立空间计量模型分析其影响因素,得出以下结论：① 新型城镇化的空间格局总体呈东高西低态势,且不断向内陆地区扩展,大城市水平明显高于中小城市;② 中国城市的新型城镇化水平具有明显的空间相关性,劳动力、投资水平、经济发展、政府能力、基础设施以及产业结构均起到正向的促进作用,且经济发展、劳动力与基础设施具有显著的正向空间溢出效应,其他几个变量均为负溢出。③ 估计效果最好的SDM模型显示不仅是本地区解释变量,还包括周边地区的相关变量都会影响各城市新型城镇化进程。     

重庆市新型城镇化质量与生态环境承载力耦合分析

本文以重庆市为研究对象,采用耦合分析法,通过分析新型城镇化质量和生态环境承载力主要指标,构建新型城镇化质量与生态环境承载力耦合协调模型,计算2000-2012年重庆市及各区县新型城镇化质量与生态环境承载力的耦合度,评价重庆市新型城镇化质量和生态环境承载力耦合阶段及水平,分析生态环境承载力与新型城镇化发展质量的耦合分类,为探索可持续发展的城镇化道路提供数据参考。结果显示：2000-2012年,① 重庆全市耦合度处于在0.967~1.000之间,显示出重庆市的新型城镇化质量与生态环境承载力的耦合阶段处在高水平耦合时期;② 重庆市区县新型城镇化质量与生态环境承载力耦合度分布基本符合“一圈两翼”的空间分异规律,耦合度范围在0.884~1.000之间,也处于生态环境与城镇化质量高耦合时期;③ 但重庆市各区县新型城镇化质量与生态环境承载力存在明显区域差异,尤其是生态环境承载力指数的空间差异比较明显,根据耦合状况可以大致分为4种区县耦合类型。表明重庆市快速城镇化的后果导致都市区生态压力增大,生态承载力空间差异显著的现实将导致原有城镇化发展方式面临不可维系局面,亟需调整城镇化发展方式;发展新型城镇化应通过优化资源利用方式,调整产业空间布局和升级产业达到疏导人口分布和提升城镇化发展质量的目的,最终缓解生态环境因城镇化快速发展带来的压力。     

新制度经济学视角下高校周边商业街分异研究——以湖南师范大学和湖南大学本部校区为例

高校扩招带来了其周边商业街的蓬勃发展,已有研究从不同角度对其展开论述,新制度经济学的发展与完善为理解高校周边商业街的分异提供了新的可能性。以湖南师范大学和湖南大学本部校区的4条商业街为例,从新制度经济学的角度解释高校周边商业街分异现象,以期丰富新制度经济学视角微观实证研究的内容。实地调研发现,制度对高校周边商业街的分异具有重要作用,正式制度对不同主体的约束作用不同,进而形成一系列非正式制度,从而共同维系了商业街的发展。最后,从制度的角度对高校周边商业街的发展提出了建议。     

新型天气雷达发射脉冲包络检测集成系统设计与实现

实现一种新型天气雷达发射脉冲包络检测集成技术,高度集成数控衰减器、包络检波器、A/D转换器和FPGA(Field Programmable Gate Array)处理器;能快速准确的对发射机脉冲特性进行检测,无需其他仪器和工具辅助,全自动测试,自动生成测试报告并根据测试结果给出检修建议,能够有效解决台站天气雷达对发射脉冲包络传统测试和维护的单一测试仪器功能,有效降低人为测试误差,减少天气雷达故障诊断和日常维护带来的制约和影响,促进天气雷达测试、维护维修保障的标准化和自动化。     

Polymetallic Nodule Mining, Waste Disposal, and Species Extinction at the Abyssal Seafloor

The size of individual mining blocks for polymetallic nodule extraction seems to be rather small, not more than 100 km² in the French mining claim. Even when adding an additional resedimentation zone to the directly impacted area, the size of the affected seabed would remain below 200 km². We assume that even rare species in the abyss inhabit larger areas and propose discussions of the International Seabed Authority and other stakeholders for the different subregions on mining strategies from the perspective of exploitation versus species extinction and conservation. Although impacts of waste disposal at the abyssal seafloor are different from those of nodule mining, the 200 km² concept may also be applied.     

Species richness of the genus Molgolaimus (Nematoda) from local to ocean scale along continental slopes

This study investigated the distribution of Molgolaimus species (Nematoda) at different hierarchical spatial scales and observed the turnover of species along bathymetrical transects and among transects in two separate geographical regions. Samples from six transects (200–2000 m) from the Southern Oceans (SO) and four bathymetric transects (50–2000 m) from the Western Indian Ocean (WIO) were compared. Of the 30 species recorded, only one was common to both regions. WIO had higher local species richness than the SO. In both regions, the local scale was the greatest contributor to the total species richness. In the SO, there was no difference between species turnover at the different spatial scales, however, in the WIO, the turnover along bathymetrical transects was higher than among separated transects. For the particular genus studied, the evidence suggests that the study area in WIO has more widespread species and was better sampled, while the SO has many restricted species and it is most probably characterized by different biogeographical provinces. At the ocean scale (i.e. WIO versus SO), evolutionary histories may have strongly influenced nematodes species composition, while at local and regional scales, ecological processes are probably promoting species co‐existence and speciation. The high co‐existence of certain species at local scale is partially explained by species preference for different sediment layers.