Generations in captivity increases behavioral variance: considerations for captive breeding and reintroduction programs

Long-term maintenance of captive populations followed by release of captive animals into the wild is one of many approaches to endangered species conservation. To assess captivity's effects on behavior, a simulated predator was presented and response behaviors measured in oldfield mice, Peromyscus polionotus subgriseus. The animals tested were from four populations collected from Ocala National Forest, Florida, and held in captivity for varying numbers of generations: 35, 14, 2, and 0 (wild caught). Results show (1) that the more generations a population has been in captivity, the less likely an individual is to take cover after seeing a predator and (2) variance in predator-response behaviors increases with generations in captivity. These results point to two ways in which captivity can compromise animal behavior and, in turn, the success of reintroduction programs. First, because individuals from populations that have been in captivity for multiple generations seek refuge less often than their wild counterparts, they might experience increased mortality in the wild due to predation. Second, increased behavioral variance could translate into decreased survivorship upon reintroduction. Therefore, more individuals will need to be released to reach the targeted wild population size.     

Soil loss and runoff on semiarid land as amended with urban solid refuse

Organic amendment is a proved method of improving soil physical properties thus affecting runoff and soil erosion. Urban wastes are a potential source of organic matter and their use would also be a convenient way of disposing of them. A field experiment was conducted from October 1988 to September 1993 in a semiarid Mediterranean site to determine the effect of applying several rates (65, 130, 195 and 260 Mg ha⁻¹) of organic urban solid refuse (USR) on total runoff and soil loss. At the lowest rate, total runoff decreased by 67 per cent compared to the control plot. The decrease was 98 per cent when the highest rate was used. The lowest rate reduced total sediment loss by 81 per cent and the highest rate of 99 per cent. The decrease in soil erodibility at the different USR rates varied from 76 to 95 per cent depending on the year for the lowest rate and between 90 and 99 per cent for the other rates. Clear differences in the hydrologic and erosion responses were found between the eight initial rainfall events (during the first 10 months of the experiment) and the remainder of the events. The causes of such differences were due to the initial tillage of the soil by rotovation and the growth of natural vegetation in the treated plots. The mechanical effect of tillage reduced runoff and increased soil erodibility, although the effect was short‐lived. The addition of USR reduced runoff but lasted longer. An applied rate of 90–100 Mg ha⁻¹ could be considered suitable for application in semiarid zones. Copyright © 2000 John Wiley & Sons, Ltd.     

Water Conservation Forest Impacts on the Runoff Generation and Sedimentation at Small Watershed Scale in the Miyun Reservoir Watershed

密云水库集水区水源保护林在北京地区饮用水源保护中起着非常重要的作用．本文给出了该区小流域对比实验的初步研究结果,有林小流域和无林小流域对１９９６年７月３０日降雨过程较为一致的径流响应表明,土壤前期含水量对流域产流有较大的影响,在降雨较多土壤含水量较大的情况下该区产流方式可以表现为饱和地表径流．尽管该区以霍顿超渗产流为主,但对于１９９７年７月３１日至８月１日降雨过程,森林流域产流总量为１３９３．８０ｍ３,无林流域为２２０２．４３ｍ３,森林流域减少洪水总量３６．７％,消减洪峰流量达３７３％．然而,１９９７年７月１９日降雨过程森林流域径流洪峰量与洪水泥沙含量均较无林流域高,这表明预处理措施对径流泥沙过程有极为显著的影响     

马铃薯愈伤组织低温保存的生理变化

对马铃薯愈伤组织在常温(23～25 ℃)和低温(4 ℃)下保存90 d过程中所发生的部分生理变化进行了研究.结果表明,在低温条件下,随着保存时间的延长,SOD活性逐渐下降,但下降幅度明显低于常温条件;POD活性、Pro及可溶性糖含量随着保存时间的延长先上升后下降,POD活性明显低于常温条件,但Pro及可溶性糖含量明显高于常温条件.     

浅谈如何实现农业高效节约用水

主要介绍如何节约农业灌溉用水及提高用水效率的几种措施。     

长江流域湿地资源现状及其保护对策探讨

根据第二次全国湿地资源调查成果,分析了长江流域上游、中游和下游的湿地资源及其湿地保护现状,重点论述了长江流域内国际重要湿地和国家重要湿地的分布数量、湿地面积、保护形式等情况,同时通过对流域内423个重要湿地受威胁状况及其影响面积的调查分析,总结了长江流域湿地面临的主要威胁,探讨了长江流域湿地保护对策,旨在为长江流域湿地保护与综合治理策略研究将提供参考。     

黄河小浪底库区不同人工林水土保持效益研究

采用空间代替时间的方法,通过对黄河小浪底库区不同人工林水土保持效益浅要分析,结果表明:最大吸水率为刺槐>侧柏>20多年生栓皮栎>40多年生栓皮栎,凋落物储量和最大持水量均为20多年生栓皮栎>40多年生栓皮栎>侧柏>刺槐;土壤渗透性能和贮水性能变化较为复杂,侧柏林地的渗透性和贮水性能较其它林地好些,刺槐林地上下层之间变化最大。     

Research advances in genetics and breeding ofpopulus davidiana dode in China

In this paper a general introduction is given to research advances in genetics improvement and breeding of Chinese aspen (Populus davidiana Dode) in China. This introduction includes natural distribution and collection, conservation, gene diversity, provenance trial, crossing breeding, vegetative propagation and disease resistant etc. Based on the current situation of forest tree breeding in China, some strategic suggestions concerning the future development of Chinese aspen genetics improvement in China are presented, taking into consideration the existing domestic demands of forestry production and international trends in forest tree breeding. Responsible Editor: Chai Ruihai     

太湖鸡资源群体遗传变异的检测

应用微卫星标记对江苏省无锡市祖代鸡场有限公司太湖鸡的保种群体进行了遗传变异的分析,计算了群体的杂和度(H)和多态信息含量(PIC)。研究结果表明:30个微卫星标记在太湖鸡保种群体的杂和度为0.504～0.858之间,平均杂和度为0.688,群体的遗传多样性丰富;其中24个微卫星标记在太湖鸡中多态信息含量为高度多态,可作为有效遗传标记用于太湖鸡保种群的遗传分析,而且各座位杂和度的高低与PIC值的大小体现了较高的一致性。本研究结果为太湖鸡开发利用研究提供了基础,也为太湖鸡的合理保护提供了科学根据。     

Traditional conservation of vegetable cowpea in Nigeria

The vegetable cowpea, Vigna unguiculata (L.) Walp. ssp. unguiculata, is cultivated for its fresh pods and leaves in the derived savanna and forest belts of southeastern Nigeria. Nigerian material of this cowpea type with its diverse range of characteristics, is an important resource for improvement of cowpeas. The conservation and maintenance of this useful legume amidst the new varieties released yearly from research stations and seed companies have been accomplished through indigenous traditional methods. These methods have been discussed.