Neutral model analysis of landscape patterns from mathematical morphology

Mathematical morphology encompasses methods for characterizing land-cover patterns in ecological research and biodiversity assessments. This paper reports a neutral model analysis of patterns in the absence of a structuring ecological process, to help set standards for comparing and interpreting patterns identified by mathematical morphology on real land-cover maps. We considered six structural classes (core, perforated, edge, connector, branch, and patch) on randomly generated binary (forest, non-forest) maps in which the percent occupancy (P) of forest varied from 1% to 99%. The maps were dominated by the patch class for low P, by the branch and connector classes for intermediate P, and by the edge, perforated, and core classes for high P. Two types of pattern phase changes were signaled by abrupt transitions among the six structural classes, at critical P thresholds that were indicated by increased variance among maps for the same P. A phase change from maps dominated by the patch class to maps dominated by the branch and connector classes was related to the existence of a percolating cluster of forest, and the P threshold varied depending on the co-existence of the core class. A second phase change from the edge class to the perforated class was related to the existence of a percolating cluster of non-core (including non-forest) and represents a change of context from exterior to interior. Our results appear to be the first demonstration of multiple phase changes controlling different aspects of landscape pattern on random neutral maps. Potential applications of the results are illustrated by an analysis of ten real forest maps. The U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

自然变温条件下小菜蛾年生活史及群体生长发育的研究

在变温条件下连续饲养观察小菜蛾两年,摸清了小菜蛾每年可发生12代,发育起点温度C为2.2℃,有效积温K为613.58日度.测算了每一代每头的平均产卵量.结合当地气温资料对小菜蛾的生长发育、冬季活动状况、全年田间虫口变动趋势进行了分析和讨论.     

贫困线视角下农村居民收入对膳食健康的影响研究——基于CHNS数据的微观实证

我国农村居民已基本解决温饱问题,但其膳食健康状况仍缺乏应有的关注,因此分析收入增长对农村居民膳食健康的影响有着重要的现实意义。基于家庭生产理论,利用中国营养与健康调查(CHNS)数据和健康膳食指数(HEI),运用最小二乘虚拟变量回归、门槛回归模型和工具变量回归方法,评估我国农村居民的膳食健康状况,分析收入对农村居民膳食健康的影响,对比分析贫困居民与非贫困居民之间的影响差异,从膳食健康视角评估当前贫困线标准的合理性。结果表明:农村贫困居民与非贫困居民的膳食健康状况存在显著差异,非贫困居民的膳食健康状况明显优于贫困居民;收入对农村居民的膳食健康具有显著的促进作用,贫困居民膳食健康的收入效应明显高于非贫困居民;收入与农村居民的膳食健康存在内生性,不考虑内生性会低估农村居民膳食健康的收入效应;从膳食健康的角度来看,我国的贫困线标准应提升至3 159元,高于当前的贫困线标准(2011年为2 300元)。因此,对于农村居民,收入的持续增长仍是改善农村贫困人口膳食健康的重要途径。如果计划对贫困人口的营养状况进行政策干预,现有的贫困线有必要进行上调。     

基于SRTM DEM的大凌河流域地表水文自动模拟

[目的]基于SRTM DEM,对大凌河流域地表水文进行自动模拟。[方法]以大凌河流域SRTM DEM数据为支撑,在ArcGIS Model-Builder环境下构建大凌河流域地表水文模拟模型。[结果]地表水文模拟模型实现了大凌河流域范围的自动划分和大凌河流域水系的自动提取。同时,也更加便捷地解决了水文模拟中DEM填洼阈值和河网提取阈值的选择问题。大凌河流域范围划分准确,大凌河和相应Ⅰ级支流的提取结果与实际水文情况十分接近,但旁系小支流末梢的提取效果有待改进。[结论]该研究为今后地表水文的模拟提供了科学参考。     

Critical resource levels of pollen for the declining bee Andrena hattorfiana (Hymenoptera, Andrenidae)

The native bee fauna provides an important ecosystem function, but a large proportion of this fauna in Europe is threatened as a result of habitat loss and fragmentation. The solitary bee Andrena hattorfiana is specialised on collecting pollen from the plant-family Dipsacaceae. In northern Europe the major pollen resource is the insect-pollinated herb Knautia arvensis. We quantified the available K. arvensis resource, measured habitat characteristics and performed a flower-visitor survey in 57 well-defined K. arvensis populations in southern Sweden. There was a strong relationship between bee and plant population sizes. In populations with A. hattorfiana present (N = 26), the female bees utilised on average 39% (12-80%) of the total available pollen resource. The nest architecture and nesting biology of A. hattorfiana is described for the first time. By excavating nests, we found that the provisioning for one average bee nest (containing 6 cells) required ca. 72 inflorescences or 11 plant individuals. The results suggest a certain minimum pollen amount needed to host an A. hattorfiana population. For example, for a population of ten reproducing A. hattorfiana ♀ with the average degree of utilisation, the critical resource was predicted as 156 ± 16 individuals (±SE) of the plant K. arvensis, which corresponds to 780 inflorescences or 36,731,978 pollen grains. These findings suggest that calculations via a ‘pollen budget’ can predict critical resources for a given size of specialised bee population, and thereby provide a tool in conservation.     

茶长卷蛾发育起点与有效积温的研究

研究结果表明,茶长卷蛾Homona magnanima(鳞翅目,卷叶蛾科)各虫态及全世代的发育起点温度(C)和有效积温常数(K),以及预测式(N)分别为:卵期C=11.63±1.23(℃),K=100.24±9.99(日度)N=100.24±9.99/T-(11.63±1.23);幼虫期C=3.20±1.83(℃),K=634.08±56.46(日度),N=634.08±56.46/T-(3.20±1.83);蛹期C=10.40±1.74(℃),K=93.83±12.10(日度),N=93.83±12.10/T-(10.40±1.74);全世代C=6.37±1.14(℃),K=822.14±53.95(日度),N=822.14±53.95/T-(6.37±1.14);经推算验证,与各地实际发生世代数基本一致。     

糖蜜酒的除杂除臭淡化增香

本工作采用SC—7(GC)仪,DNP+TWEEN玻璃毛细管柱测定了糖蜜酒精的成分,采取了精制措施,除去了糖蜜酒精中对人体有害及异杂物质,根据需要配制具有一定香型的酒。     

门限自回归模型及其在耕地总量预测中的应用

利用梅州市55年来长时序耕地总量统计资料,引入门限自回归模型对耕地面积进行了预测,并和马尔可夫模型预测结果进行了比较.结果表明,通过门限值的控制作用,门限自回归模型有效地利用时序数据隐含的时序分段相依性这一重要信息,限制了模型误差,从而保证了预测性能的稳健性,有很高的短中期预测精度.     

黑龙港地区浅层地下咸水利用的研究

河北省黑龙港地区淡水资源短缺,是农业生产发展的制约因素。南皮试区(1980～1991)咸水灌溉的研究结果表明,利用2～5g/l的咸水灌溉,小麦、玉米两季亩产达到484.8～622.8kg,比不灌的旱作增产1.06～1.65倍;在汛期集中降雨淋洗的条件下,根层土壤不积盐;实行咸淡水轮灌、混灌,改善水质,增辟水源,获得作物丰产。