不同生态脆弱区土壤侵蚀对土地生产力影响对比研究

通过外业调查、实验测试、大田模拟试验等方法,在土壤侵蚀特征分析基础上,对黄土丘陵和金沙江干热河谷2个生态脆弱区由于土壤侵蚀导致的坡耕地土地生产力衰退进行了对比研究。结果显示,不同生态脆弱区无任何水土保持措施的坡耕地土壤侵蚀,在导致可耕作土层变薄的同时,都造成了不同程度的土壤物理性能和人渗能力下降,土壤养分流失以及土地生物生产能力的衰退。相同强度土壤侵蚀对坡耕地土地生产力的影响,干热河谷区大于黄土丘陵区,是黄土丘陵区的2．1～2．9倍。     

Reproductive Biology in Wild and Silvicultural Managed Populations of Escontria chiotilla (Cactaceae) in the Tehuacán Valley, Central Mexico

Reproductive biology of the columnar cactus Escontria chiotilla was analysed in wild and silvicultural managed populations in the Tehuacán Valley, Central Mexico, where this cactus is under domestication because of its edible fruits. Anthesis is diurnal, flowers opening between 8:00 and 17:00 h, the period between 12:00 and 13:00 appearing to be crucial in pollination success since at this time the maximum opening of flowers, turgidity of stigma, and activity of flower visitors, as well as the highest nectar production and pollen release occur. The bees Apis mellifera, Bombus pensylvanicus and Xylocopa mexicanorum, and the hummingbirds Amazilia violiceps, Cynanthus sordidus and Cynanthus latirostris were the most frequent flower visitors during the crucial period, and were observed contacting both stamens and stigma of E. chiotilla. No differences were found in anthesis nor in flower visitors among both population types. Distances separating the populations studied and bridges of individuals of E. chiotilla between them are within the radius that bees and hummingbirds may travel, indicating that spatial barrier to pollen flow are unlikely. Breeding system is self-incompatible. Production of flowers occurs during the whole year in both population types, allowing continual pollen flow among them. This observation confirms reports of high gene flow among the populations studied in previous population genetics studies. The high pollen flow among wild and managed population explains that however the occurrence of artificial selection, the process of domestication is in incipient stages presumably because gene flow counteracts effects of artificial selection.     

黄河流域棉花品种主要性状时间序列的变化趋势分析

以棉花黄河区试参试品种的主要性状为原始资料,运用线性回归、谐波及交叉谱分析的原理和技术,对各性状时间序列的线性趋势、周期性变化及相关关系进行了研究。线性回归结果显示,铃重、衣分及霜前花率呈增加趋势,生育期及枯萎病指呈下降趋势。谐波及交叉谱分析结果表明,各序列均存在明显的周期性变化,即皮棉产量、铃重、衣分、生育期及霜前花率以14年为主周期,单株铃数以5.6年为主周期,枯、黄萎病指以28年为主周期;且单株铃数、衣分及霜前花率与皮棉产量在2～3年周期上密切相关,铃重及枯、黄萎病指与皮棉产量在7年周期上密切相关,生育期与皮棉产量在9.3年周期上密切相关。这些结果为育种者掌握育种动态、修正育种目标、提高育种水平及棉花品种主要性状的长期预测提供了科学依据。     

云南红河流域木薯细菌性枯萎病发生危害动态研究

采用定点监测、分级调查法对红河流域不同区域的木薯细菌性枯萎病发生情况进行研究。结果表明:(1)木薯细菌性枯萎病在红河流域进入雨季后(5月)开始发病,整个雨季中(5~9月)病害发生较为严重,尤其是进入夏季后温度满足病原菌的发病条件时,病情指数变化曲线和降雨量曲线出现了同升、同降的现象。(2)同一海拔高度下,病情指数呈现出下游大于上游和中游,而危害率则出现相反的趋势,250~300 m海拔观测点的病情指数大小顺序为下游(2.03)>中游(1.96)>上游(1.77),危害率为下游(64.57%)<中游(66.86%)<上游(70.00%);450~500 m海拔观测点的病情指数大小顺序为下游(2.01)>中游(1.77)>上游(1.76),危害率为下游(64.57%)<中游(66.29%)<上游(69.14%)。(3)同一区域则表现出低海拔地区的病情指数和危害率均高于高海拔地区。     

黄河流域棉花主要品种SSR指纹图谱构建及遗传差异分析

 利用SSR分子标记构建了2009－2010年黄河流域23个主要棉花品种和2010年山东省区试4个品系的分子指纹图谱并进行遗传多样性分析。63对引物在27份供试材料中共扩增到多态性条带254条,平均每对引物4.03条。22对引物在23个品种（系）上具有特征谱带,除鲁棉研21号、鲁棉研36号、鲁436、邯棉559外,均可用1对引物进行鉴定;采用引物组合法只需要5对引物就能将27份供试材料区分开,并利用这5对引物构建了上述品种（系）的数字指纹图谱。遗传多样性分析显示,27个品种（系）间遗传相似系数介于0.5394~0.9685之间,平均为0.6878,并且同一省份所选育的品种（系）大都聚到同一类群,说明黄河流域选育的品种还存在一定的地域局限性。     

伊犁河谷土壤含盐量空间变异和格局分析

基于区域变量理论,在GPS和GIS技术支持下,通过地统计学的半变异函数和Kriging空间插值,以察布查尔县为例,定量分析伊犁河谷不同层次土壤盐分的空间异质性.结果表明:0～20 cm、20～40 cm、60～80 cm层土壤盐分的半变异函数符合球状模型,40～60 cm层符合高斯模型.不同层次土壤盐分之间的空间自相关...     

Optimizing reserve expansion for disjunct populations of San Joaquin kit fox

Expanding habitat protection is a common strategy for species conservation. We present a model to optimize the expansion of reserves for disjunct populations of an endangered species. The objective is to maximize the expected number of surviving populations subject to budget and habitat constraints. The model accounts for benefits of reserve expansion in terms of likelihood of persistence of each population and monetary cost. Solving the model with incrementally higher budgets helps prioritize sites for expansion and produces a cost curve showing funds required for incremental increases in the objective. We applied the model to the problem of allocating funds among eight reserves for the endangered San Joaquin kit fox (Vulpes macrotis mutica) in California, USA. The priorities for reserve expansion were related to land cost and amount of already-protected habitat at each site. Western Kern and Ciervo-Panoche sites received highest priority because land costs were low and moderate amounts of already-protected habitat resulted in large reductions in extinction risk for small increments of habitat protection. The sensitivity analysis focused on the impacts of kit fox reproductive success and home range in non-native grassland sites. If grassland habitat is lower quality than brushland habitat resulting in higher annual variation in reproductive success or larger home ranges, then protecting habitat at the best grassland site (Ciervo-Panoche) is not cost-efficient relative to shrubland sites (Western Kern, Antelope Plain, Carrizo Plain). Finally, results suggested that lowest priority should be given to three relatively high-cost grassland sites (Camp Roberts, Contra Costa, and Western Madera) because protecting habitat at those sites would be expensive and have little effect on the expected number of surviving kit fox populations.     

花江峡谷示范区主要经济植物病虫害及防治对策

经过野外调查与初步鉴定整理，花江峡谷喀斯特石漠化综合防治技术示范区，花椒病虫害26种，金银花病虫害3种，石榴病虫害10种，砂仁病虫害1种，葡萄病虫害3种，对主要病虫害提出相应的防治对策。     

Using occurrence records to model historic distributions and estimate habitat losses for two psammophilic lizards

Estimating historic distributions of species is a critical step in evaluating current levels of habitat loss, evaluating sites for potential restoration and reintroductions, and for conservation planning at a landscape scale. However historic distributions can be difficult to estimate objectively because substantial habitat changes may have occurred prior to comprehensive surveys. As a means to address this question, we evaluated a novel approach by creating spatial niche models for two species of psammophilic lizards. Using a partitioned Mahalanobis D² analysis and abiotic variables that were independent of anthropogenic change, we created niche models for the federally threatened Coachella Valley fringe-toed lizard (Uma inornata) and for the flat-tailed horned lizard (Phrynosoma mcallii). The niche models estimated that within the Coachella Valley there were originally 32,164 ha of potential habitat for the fringe-toed lizard and 33,502 ha of potential habitat for the horned lizard. After screening these estimates of historic habitat for current conditions that would render that potential habitat unsuitable, we calculated a 91-95% loss of potential habitat for the fringe-toed lizard and an 83-92% loss for the horned lizard. Unlike the fringe-toed lizard, the horned lizard also occurs outside the Coachella Valley. Conducting a similar analysis throughout its range would provide an objective estimate of the total habitat loss experienced by this species. This information could be used to address whether granting it federal or state protection is warranted. For species whose distributions can be modeled with abiotic variables such as soils, elevation, topography, and climate, this approach may have broad applications for resolving questions regarding their current levels of habitat loss and regional conservation planning.