2000－2010年中国退牧还草工程区生态系统宏观结构和质量及其动态变化

本研究以生态学理论为基础，以空间信息技术为支撑，基于遥感数据、气象数据和地面观测数据，通过多源数据融合、生态模型模拟和尺度转换手段，分析中国退牧还草综合治理工程区2000－2010年生态系统宏观结构和质量的时空分布及变化趋势，探讨生态系统变化的自然和人文驱动机制，为退牧还草工程的生态成效评估提供理论依据。研究结果表明，1）2000－2010年，草地生态系统面积保持平稳，生态系统宏观结构稳定，但局部区域仍存在草地与农田、湿地和荒漠间的相互转化；2）研究区草地退化趋势已得到初步遏制，植被覆盖度略有增长，叶面积指数略呈波动式增加，净初级生产力呈显著上升，草地植被呈现恢复转好态势，生态系统总体质量有所提高，生态环境向良性演变；3）研究区生态状况具有空间差异性，总体转好，局部变差，各亚区整体水平排序为内蒙古东部退化草原治理区＞青藏高原江河源退化草原治理区＞新疆退化草原治理区＞蒙甘宁西部退化草原治理区；4）退牧还草工程的实施有利于草地保护，气候暖湿化促进植被生长与恢复，人类活动干扰局部地区生态系统，三者共同影响研究区总体生态状况。     

土壤养分数据几种特异值处理方法的比较

利用贵州省平坝县马场镇栗木村的13项土壤养分测试数据,对比分析了3σ准则、估计邻域法、影响系数法、邻近点数据比较法4种识别与处理特异值方法的优劣。结果表明:将3σ准则与邻近点数据比较法相结合,对土壤养分测试数据进行特异值处理获得了较好的效果,对提高地质统计学研究结果的精度有积极的作用。     

城市森林对周边小气候时空格局的影响

以对城市森林生态效应的动态评价为目的,研究绿地和非绿地之间的物质交换特点与规律,描述和揭示植物群落的生态效应时空格局。试验对森林周边温度和湿度在空间和时间的梯度变化进行测试。结果表明,杨树林对其周边环境有着明显的降温和增湿效应,中午时段绿地生态场效应最高,下午测试时段对周边空气温湿度的影响与常规是逆反的。     

Experimental Results on the Effects of Nonregular Spatial Patterns of Plants on Yield per Area

Based on several simplifying assumptions, a stochastic approach was developed which allows an estimation of the effects of nonregular spatial patterns of the distribution of individual plants on yield per area (F). In this approach, two random variables were attached to each plant: single plant yield (E) and individual space per plant (A). The latter was estimated by the area of Thiessen polygons. Yield per area was calculated theoretically by the expectation of the ratio E / A. Appropriate approximations of this expectation depend on the means (ē and ā), coefficients of variation (vE and vA) of E and A and their correlation (rEA). Yield per area can be decomposed into two additive terms: the first term gives the commonly used estimate ē/ā— or h(ā)/ā if a functional relationship between E and A is assumed: E = h(A). In this study, the two relationships E = k1 + k2 · ln A and E = A/(k3 + k4A) were used (with appropriately chosen constants k1, k2, k3, and k4). The second term in the decomposition of F can be interpreted as the effect of variable individual plant spaces on yield per area. In this paper, all theoretical concepts and results were applied to 17 experimental data sets of three cultivars of winter oilseed rape (Brassica napus L.). Single plant yields (E) and individual plant areas (A) were positively correlated with correlation coefficients from 0.64 up to 0.91. The ranges for both coefficients of variation were similar: 0.27 ≤ vE ≤ 0.65 and 0.28 ≤ vA ≤ 0.59. One obtains no significant differences in the goodness-of-fit for both tested relationships between E and A although the logarithmic relationship seems to be slightly superior. For only three data sets one obtains negative values for the percentage of the second term in the decomposition of F. This indicates an overestimation of yield per area by the commonly used estimates h(ā)/ā and ē/ā, respectively. These overestimations, however, are less than 5 %. In all other cases with positive values for the second term the yield per area is underestimated by the common estimates. For almost all data sets, however, the percentages of F which are explained by the common estimates are much larger than 90 %.     

Irrigation Water Management for Efficient Water Use in Mulched Onion

Caused by the necessarily imperfect seed placement accuracy of sowing machines and, additionally, caused by many other biotic and abiotic factors, the resulting plant stands exhibit nonregular spatial distributions of its plants. Based on several simplifying assumptions, a stochastic approach is developed which allows an estimation of the effects of nonregular spatial patterns on yield per area. In this approach, two random variables are attached to each plant: single plant yield E and individual space A . The latter is estimated by the area of Thiessen polygons. Yield per area, calculated by the expectation of the ratio E/A , can be approximately expressed dependent on the means ( Ē and Ā ) and coefficients of variation ( v _E and v _A ) of E and A and their correlation ( r _EA ). In relation to the commonly used estimate Ē/Ā for yield per area, one obtains yield decreases if v _A / v _E  <  r _EA . This inequality, however, will be usually valid in the field of applications. The theoretical approaches and results were applied to three experimental data sets for drilled seeds of winter oilseed rape ( Brassica napus L.) (plant density: 60 plants m⁻², row distance: 10 cm). These data sets are characterized by different accuracies of longitudinal distributions within rows (58 %, 101 %, 150 %): yield depression increases with an increasing variability of plant distances within rows.     

我国淡水养殖业发展的空间变化影响因素分析

在陆地农业资源退化和人口总量上升的双重压迫下,淡水养殖有望成为支撑我国居民口粮供给的另一支柱产业。基于2007-2014年我国省域淡水养殖面板数据,探寻了我国淡水养殖区域的格局变化,利用全局Moran’s I指数考察淡水养殖区的空间相关性,并通过构建空间杜宾面板模型分析了产业格局变化的影响因素。研究表明:1我国淡水养殖业呈现出"东南热、西北冷"的特点,省域间的空间相关性逐年显著;2淡水养殖资金投入增加、养殖面积扩大、区域经济发展水平提升会对淡水养殖量有正向的作用,体现我国淡水养殖业由粗放经营向集约化经营的转变;3淡水养殖面积负间接效应反映"过度养殖"和环境污染对淡水资源的破坏会减缓淡水养殖业的发展;4淡水养殖业发展和城镇化的进程之间不矛盾,在未来可以稳定持续地提供淡水产品,成为国家粮食安全和食品安全重要保障。最后从合理规划淡水养殖区域格局、平衡省份间技术推广资金投入和加强对水资源污染的监管3个方面提出了推动淡水养殖业发展的政策建议。     

高功率激光系统中空间滤波器的程序编码

提出了建立大型激光装置的程序编码的初步方案及需要开展的计算机编码工作内容，并完成了空间滤波器系统的Ｆｏｕｒｉｅｒ编码模块，给出了计算图样 。     

Spatial distribution patterns and environmental interpretation of Anthriscus sylvestris clonal buds

Anthriscus sylvestris, a weed found both in Europe and China, is a kind of representative clustered clonal plant and is a foe on dams and banks. It has been widely investigated in Europe for its powerful progenitive ability and tolerance to severely adverse environments. Our aims were to investigate and quantify its spatial distribution patterns in four types of community habitats, using a clustering method and adjacency lattice established by Greig-Smith. We concluded our environmental interpretation based on canonical correspondence analysis (CCA) appended to a Monte Carlo test with randomized seeding. The results indicate that the buds around the parent roots are in an aggregation distribution pattern in all scales (0.002–5.12 m²), but theoretical distribution fitting, like negative binomial and Poisson distribution, show that some sizes of several sampling locations are out of place. For this, spatial ordination gives a satisfactory answer implying the effect of environmental variables such as depth of humus layer, soil moisture, light condition, disturbance intensity and herb abundance. CCA accounts for 64.7% of the total environmental variation and the remaining variation may be counteracted in those five variances or can be interpreted by other factors like accumulating temperature, annual rainfall and altitude in landscape scale. With the aid of temporal sequencing, the suppressed type II (monodominant) may be the former mode of suppressed type I (stable type), where invasion is done with the help of disturbance from both humans and nature. The abundance of A. sylvestris can add to our cognition in diversity resistance hypothesis and our hypothesis on disturbance before or upon immigration. __________ Translated from Journal of Zhejiang Forestry Science and Technology, 2007, 27(3): 1–7, 11 [译自: 浙江林业科技]     

Predicting the spread of postharvest disease in stored fruit,with application to apples

Postharvest diseases can cause considerable damage to harvested fruit in controlled atmosphere storage. Since there is a large cost associated with opening the storage rooms, regular assessment of damage levels is not feasible, and many experts agree on the need for a reliable predictive model. Presented here is a simulation model that predicts the overall incidence of disease in a bin of stored fruit as a function of initial infection levels and the fruit's susceptibility to fungal attack. Uninfected fruit tissue, infected fruit tissue, and fungal growth are modelled by a system of three ordinary differential equations. Simulations of the growth and spread of the pathogen in storage were conducted, with disease incidence measured monthly. The model provides insight into the dynamics of postharvest fungal disease, and forms the basis of a predictive model that could be used by packinghouses to determine how long a given crop of fruit can be stored before the infection risk rises above a predetermined tolerable level.