奶牛赘生乳头数遗传力的估计及其与产奶量的相关分析

奶牛赘生乳头数呈阈性状特点,本文采用阈性状分析法估测赘生乳头数的遗传力为0.33 0.04,因此,进行表型选择可获得较理想的选择效果。通过其对产奶量的相关分析表明,赘生乳头对产奶量虽无明显影响,但有遗传倾向。它不仅影响乳房的外形,也不利于机械化生产,无疑是一不合意性状,应在奶牛选种工作中予以重视。     

MICROCOMPUTER PROCESSING THE PHOTOGRAPH OF TIMBER WITH HOLE KNOTS

THRESHoLDWhenthetimberswiththeho1eknotsarepassedthesystemofX-raynon-de-structiveinvestigation,thesimulatednu-meralsfigureoftheholeknotsappearinthemonitor.Thesimulatednumeralsfigureisshownintablel.Meanwhilethehistogramofthisfigurearedoublepeakcertainly.Inordertoidentifytheedgeoftheholeknotswithnakedeyeandcarryoutautomatictreatment,Wetakethebinaryva1uetreatmentforthefigure'Thechoos-ingthresholdisaveryimportantpartinthebinaryvaluetreatment.Howtochooseasuitablethreshold?Weshouldpaymuchattenti…     

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.     

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.     

Modeling and field-testing of Ovenbird (<Emphasis Type="Italic">Seiurus aurocapillus</Emphasis>) responses to boreal forest dissection by energy sector development at multiple spatial scales

Although the area disturbed by linear features in forested systems is small relative to many other human disturbances, linear features create significantly more amounts of edge per unit area. In the boreal plains of Alberta, Canada, energy sector exploration has resulted in extensive dissection of the landscape through 8 m wide seismic lines. A spatially explicit model was developed to test how bird abundance might change in response to increasing seismic line density if individuals use seismic lines as territory boundaries or actively avoid these edges. Assuming birds had fixed territory shape and size, increasing seismic line density from 0 to 8 km/km² resulted in a 38% decline and an 82% decline in bird abundance when individuals used lines as territory boundaries or avoided edges by 50 m, respectively. We tested the assumptions of our model using the Ovenbird (Seiurus aurocapillus). Based on radio-telemetry (n = 12), all Ovenbirds crossed seismic lines at some point during the breeding season. However, male Ovenbirds showed a distinct use of one side of the seismic line, suggesting lines acted as territory boundaries. In 12.25 ha plots (n = 24) spot-mapping detected no change in Ovenbird density as linear feature density increased from 0 to 8.6 km/km². In 4 km² landscapes (n = 62) sampled using a grid of nine point-counts, we also detected no changes in Ovenbird numbers across the same range of seismic line densities. Ovenbirds declined with seismic line density at the level of the individual point-count station (12 ha scale), but only when a threshold seismic line density of 8.5 km/km² was reached. Above the threshold, Ovenbirds declined 19% for each 1 km/km² increase in seismic line density. While relatively few places in Alberta’s boreal forest have local seismic line densities of 8.5 km/km², forest dissection could increasingly become an issue if current energy exploration practices continue.     

Bird responses to broad-leaved forest patch area in a plantation landscape across seasons

Although plantation forests have widely replaced native forests worldwide, few studies have examined the effects of plantation forestry on organisms at the landscape level. In this study, we examined the effects of broad-leaved forest patch area (1.4–312 ha) on bird assemblages in a conifer plantation-dominated landscape during wintering and breeding seasons. We also surveyed birds in the plantation matrix and treated the patch area of the matrix as 0. We examined whether the detection rates of species changed suddenly across patch area (threshold) using segmented regression. We found that species richness increased with patch area in both seasons. Responses of detection rates to patch area varied and were categorized as follows: insensitive, linear increase and decrease, quadratic increase and decrease, concave and convex. Thresholds indicating that the detection rate suddenly increased above a certain patch area were found for two species only in the winter. Species responses varied more in the winter than in the breeding season. Certain ecological traits of species were consistently associated with the responses to patch area across seasons (migratory strategy, nesting substrate and foraging trait), while body weight was only associated in the winter. Because species richness and detection rates of many species were high in large patches, large broad-leaved forests (especially >40 ha) should be retained and restored with high priority. Additionally, bird responses to patch area in the winter should not be ignored because many species required large patches during the winter season.     

A probability-based approach to match species with reserves when data are at different resolutions

Gap analysis is a protocol for assessing the extent to which valued biodiversity attributes are represented within protected areas. Such analysis involves overlaying the distribution of biodiversity features (e.g. species) with protected areas, but the protocol entails arbitrary assumptions that affect the outcome of the assessments. In particular, since species’ distributions are usually mapped at a coarser resolution than protected areas, rules have to be defined to match the two data layers. Typically, a grid cell is considered protected if a given proportion is covered by protected areas. Because the effectiveness of protected areas is dependent on the definition of such arbitrary proportions (i.e., thresholds), errors of commission and omission in the level of species’ representation are bound to exist. We propose an alternative approach whereby the contribution of a cell for the representation of species is defined as the expected value of a hyper-geometric random variable. We compare the conventional approach based on fixed thresholds with this new probability-based approach for both static and dynamic conservation scenarios, using a virtual dataset and a 100-plant-species’ dataset for Iberian Peninsula. Results support the view that traditional fixed thresholds yield inconsistent results. Because species present different distributional patterns coinciding differently with protected areas, species-specific and time-specific thresholds should be used. Our approach enables to easily obtain these more adequate threshold values, thus offering a promising method for gap analyses. Future studies should seek to evaluate the performance of this method empirically in different conservation planning contexts.     

作物缺水补偿节水的分子生理机制研究进展

作物缺水补偿节水理论及其技术具有重要理论意义和农业应用潜力, 受到国内外专家的重视并取得一系列重要研究成果, 然而作物适度胁迫缺水产生补偿节水效应的分子生理机制却仍是一个尚待研究的问题。在系统总结近年来的相关进展基础上, 对引起作物适度缺水反弹补偿节水的分子生理过程进行了初步分析探索。作物在发生水分胁迫和复水后, 在根、茎、叶等营养器官生长、渗透调节、蒸腾速率、光合作用等生理活动以及蛋白质活性、生化代谢、分子和基因调节等方面都有相关适应变化。水分亏缺补偿存在阈值范围, 如果控制适当, 在一定水分亏缺强度范围内可提高作物水分利用效率并使作物不减产甚至增产。这种缺水补偿节水技术如能在农业生产上推广应用, 可有效节约水资源, 提高作物经济效益和粮食安全。     

不同类型农田地表粉尘起动摩阻风速的野外观测

[目的]为北方城市空气污染控制提供依据。[方法]选择不同地表类型,观测起尘差异,分析表土微团粒粒度,计算起动摩阻风速。[结果]沙化农田的光滑地表空气动力学粗糙度（Z0s）为0．0012cm,小麦地为0．0021cm,果树苗地的为0．0025cm。有植被覆盖的地表粉尘起动摩阻风速明显高于裸露地表,且随着植被高度增加而增大。延安果树苗地地表起动摩阻风速达到了139：15cm／s。裸露小麦地和果树苗地地表粉尘起动摩阻风速大于裸露沙化农田（7．39cm／s）。小麦返青期、成熟期、收割后地表粉尘起动摩阻风速分别为46．85、98．93、29．05cm／s,裸露地表和幼苗期果树苗地地表粉尘起动摩阻风速分别为26．01和139．15cm／s。[结论]植被高度和土壤结构性质是影响地表粉尘起动摩阻风速的重要因素。