专家访谈：遗产的困惑

与现代农业相比,侗区传统的稻鱼鸭种养殖系统具有农业文化遗产的价值,这种价值对当今和未来解决生态和粮食问题有何意义？     

节水新概念:算算你的水足迹

<正>节水是我们每个人耳熟能详的环保观念,今年春,西南地区历史罕见的特大旱灾,再次唤醒了人们的节水意识。在大多数人的认识里,节水就是珍惜每一滴水、节约使用每一滴水。其实,节水的概念远不止于此。日常生活中,像关紧水龙头、循环利用废水等行为节约的只是你看     

节水、补源,保护衡水湖

随着经济社会发展加快,城镇生活用水和工农业用水增长速度超过供水增长速度,“三生（生活、生产与生态）”用水共享的矛盾严重。城市生活、工业生产与农业生产大量占用生态用水,引起原有生态系统的退化。衡水湖地处的河北省是我国最缺水的省区之一,地表水资源利用率非常高,到处可见“有河则干,有水则污”的景观。从20世纪70年代开始,河北平原大小河流出现了断流。由于地表水缺乏,而大量开采地下水,开采利用率可达150％,形成严重超采。20年来河北平原已累计超采地下水300多亿立方米,致使太行山山前平原地下水位以每年1．5-2米的速度下降,东部平原以每年0．5-1．5米的速度下降。地下水位下降引起一系列生态与环境问题,包括土地干化、地面下沉、河湖干枯、海水入侵等等。水资源短缺已成为困扰河北,影响京、津生态安全、经济社会稳定和健康发展的关键因素。     

洞庭湖区城镇化进程与水资源利用的关系

运用层次分析法与熵权法相结合的方法,构建洞庭湖区城镇化综合发展水平和水资源开发利用综合潜力评价指标体系和响应关系模型,分析2001-2010年洞庭湖区城镇化发展与水资源开发利用的主要影响因素、变化特征以及两者响应特征.结果表明:研究期间,洞庭湖区处于城镇化快速发展时期和规模扩张阶段,经济城镇化和社会城镇化水平滞后于人口城镇化和空间城镇化水平,城镇化发展质量和效益有待提升;伴随城镇化进程的推进,湖区用水负荷逐年增大,水资源利用效率和管理水平稳步提升,其中,水资源本底条件和开发利用程度受湖区水文条件的影响更显著.在2001、2002、2005、2006、2007、2009年,洞庭湖区城镇化的发展在一定程度上受到水资源系统的约束.目前,洞庭湖区将面临提高城镇化水平和质量的双重任务,必须改变传统的外延型扩张模式,提高水资源保障能力.     

蒙古马,牧人的命——专家透视蒙古马

踏上寻访马倌的旅程之前,我们曾经在电话里与一位有过内蒙牧区经历的作家交流对蒙古马命运的看法。他说：“马的消亡是必然的,因为马本身就有破坏草场的一面,现在草场不多了牧民不愿意养马了,叫他们养也不养了。”这是与我们遇到的大多数人一样的说法。尽管当时我们难以完全认可这样的判断,我们还是在本期蒙古马专辑的策划脚本上留下了这样一段话：“当蒙古马彻底被机器取代之时,人失去的不单是一种工具,还是一个有情感的朋友……但是,人类或许不会仅因为这一点原因就停住走向机器时代的步伐,如果马真的没有存在的必要了,那么我们的这本专辑就可能成了为蒙古马送行的挽歌。”[编者按]     

地表水资源供给服务供需关系对节水政策的响应——以大清河流域为例

水资源是基础性自然资源和战略资源,科学量化水资源供给服务的供需关系、识别供需矛盾的突出区域是进行流域水资源管理的重要前提。以大清河流域为例,利用InVEST模型,建立了水资源供给服务空间流动量化方法,预测了用水效率提升、节水灌溉两种节水政策情景对水资源供给服务供需关系的影响。结果表明：(1)流域水资源供给服务和水资源需求量均呈现出上游低、下游高的空间分布格局,农业用水为流域主要用水类型,2010—2015年,流域水资源供给服务增长0.97%,水资源需求量出现了9.6%的下降;(2)2010—2015年,流域整体水资源供给服务的供需比由0.78提升至0.88,服务的空间流动使得上游盈余的水量缓解了中下游的用水压力,但中下游水资源需求大于供给的问题仍普遍存在;(3)提升用水效率、推行节水灌溉这两种节水政策均能够有效改善大清河流域的水资源供需关系,分别可将流域水资源供需比提升至0.97和0.96,基本达到供需平衡。研究可为北方资源型缺水流域水资源供需匹配度的提高、节水政策潜力的评估提供借鉴。     

网围栏,蒙古马的悲剧——专家透视蒙古马

人们哀叹草原的变化时,总爱引用《敕勒歌》里的那句“风吹草低见牛羊”来比照。其实,根本不用追述到那么久远,与五六年前相比,锡林郭勒草原已经大大地改变了面貌,尤其是它的西部地区,除了低矮稀疏的草和狂风过后留在地表的砾石,还有那一道道的把草原隔离成无数条块的铁丝网和角钢桩——近年来草原变化的最显著标志：网围栏。[编者按]     

蒙古马,牵动着一个文化的命运——专家透视蒙古马

当我们结束20来天的马倌寻访时,发现今天的草原上似乎除了矛盾还是矛盾．除了困惑还是困惑——留恋着马却又在自己手中淘汰着马;抱怨人口多了却又都在从外地雇工：知道放牧过度了却不得不多养牲畜才能维持生计,已经看到围栏的问题却又在大力围建,早就懂得草原开垦的危害却又掀起新一轮开垦．旨在恢复生态的项目却常常适得其反,生活改善了生态却恶化了……茫茫草原或许从来没有像今天这样让人感到茫然无措,而这其中的症结究竟在哪里呢？难道草原真的遇到了一道无解的难题？[编者按]     

专家出谋划策，共谋发展江苏生物产业——来自2006江苏生物产业发展高层论坛暨产学研洽谈会的报道

由江苏省经贸委主办的2006江苏生物产业发展高层论坛暨产学研洽谈会4月11日在江苏省会议中心隆重举行。来自江苏省153家生物企业及江苏省各高校和科研院所等300余人参加了本次论坛．大会邀请了陈凯先院士、杨胜利院士、欧阳平凯院士、国家发改委能源所秦世平教授莅临指导并作精彩报告,共谋发展江苏生物产业。     

专家解释:新疆草场暴发的“绿毛虫”为一种灯蛾科昆虫

经昆虫专家核查,新疆草场暴发的“绿毛虫”是鳞翅目灯蛾科的一种害虫（准确学名正在进行鉴定研究）,是新疆北部草场发生较普遍的一种害虫。2003年在新疆的乌苏县和沙湾县曾严重发生60多万亩,最高密度达1500头／m^2。1991年在乌苏和沙湾两县6万亩农田严重受害,其中1万多亩甜菜、油菜、大豆等被毁。     

Deficit Irrigation as a Strategy to Save Water: Physiology and Potential Application to Horticulture

Water is an increasingly scarce resource worldwide and irrigated agriculture remains one of the largest and most inefficient users of this resource. Low water use efficiency (WUE) together with an increased competition for water resources with other sectors (e.g. tourism or industry) are forcing growers to adopt new irrigation and cultivation practices that use water more judiciously. In areas with dry and hot climates, drip irrigation and protected cultivation have improved WUE mainly by reducing runoff and evapotranspiration losses. However, complementary approaches are still needed to increase WUE in irrigated agriculture. Deficit irrigation strategies like regulated deficit irrigation or partial root drying have emerged as potential ways to increase water savings in agriculture by allowing crops to withstand mild water stress with no or only marginal decreases of yield and quality. Grapevine and several fruit tree crops seem to be well adapted to deficit irrigation,but other crops like vegetables tend not to cope so well due to losses in yield and quality. This paper aims at providing an overview of the physiological basis of deficit irrigation strategies and their potential for horticulture by describing the major consequences of their use to vegetative growth, yield and quality of different crops (fruits, vegetables and ornamentals).     

Deficit Irrigation as a Strategy to Save Water： Physiology and Potential Application to Horticulture

Water is an increasingly scarce resource worldwide and irrigated agriculture remains one of the largest and most inefficient users of this resource. Low water use efficiency （WUE） together with an increased competition for water resources with other sectors （e.g. tourism or industry） are forcing growers to adopt new irrigation and cultivation practices that use water more judiciously. In areas with dry and hot climates, drip irrigation and protected cultivation have improved WUE mainly by reducing runoff and evapotranspiration losses. However, complementary approaches are still needed to increase WUE in irrigated agriculture. Deficit irrigation strategies like regulated deficit irrigation or partial root drying have emerged as potential ways to increase water savings in agriculture by allowing crops to withstand mild water stress with no or only marginal decreases of yield and quality. Grapevine and several fruit tree crops seem to be well adapted to deficit irrigation, but other crops like vegetables tend not to cope so well due to losses in yield and quality. This paper aims at providing an overview of the physiological basis of deficit irrigation strategies and their potential for horticulture by describing the major consequences of their use to vegetative growth, yield and quality of different crops （fruits, vegetables and ornamentals）.     

Save the planet: eliminate biodiversity

Recent work in the philosophy of biology has attempted to clarify and defend the use of the biodiversity concept in conservation science. I argue against these views, and give reasons to think that the biodiversity concept is a poor fit for the role we want it to play in conservation biology on both empirical and conceptual grounds. Against pluralists, who hold that biodiversity consists of distinct but correlated properties of natural systems, I argue that the supposed correlations between these properties are not tight enough to warrant treating and measuring them as a bundle. I additionally argue that deflationary theories of biodiversity don’t go far enough, since a large proportion of what we value in the environment falls outside bounds of what could reasonably be called “diversity”. I suggest that in current scientific practice biodiversity is generally an unnecessary placeholder for biological value of all sorts, and that we are better off eliminating it from conservation biology, or at least drastically reducing its role.     

Worming Our Way In and Out of the Caenorhabditis elegans Germline and Developing Embryo

The germline and embryo of the nematode Caenorhabditis elegans have emerged as powerful model systems to study membrane dynamics in an intact, developing animal. In large part, this is due to the architecture of the reproductive system, which necessitates de novo membrane and organelle biogenesis within the stem cell niche to drive compartmentalization throughout the gonad syncytium. Additionally, membrane reorganization events during oocyte maturation and fertilization have been demonstrated to be highly stereotypic, facilitating the development of quantitative assays to measure the impact of perturbations on protein transport. This review will focus on regulatory mechanisms that govern protein trafficking, which have been elucidated using a combination of C. elegans genetics, biochemistry and high‐resolution microscopy. Collectively, studies using the simple worm highlight an important niche that the organism holds to define new pathways that regulate vesicle transport, many of which appear to be absent in unicellular systems but remain highly conserved in mammals .     

Studies on Water Movement Into and Out of Grapevine Fruits During the Ripening

The experiment was carried out during the ripening of grape (Vitis vinifera L. and V. vinifera × V. labrusca) fruits using the technique of dye tracing and measurement of water potential. Under the natural conditions of sufficient soil water supply and those of a high evapotranspiration potentiality on clear days, the water in fruits was transfered, during the morning and afternoon, out of the clusters and into the xylem of shoots; but the fruits capture water in the late afternoon and evening from the xylem of shoots. The diurnal variations of the water exchange between fruits and the xylem of shoots have been described and these variations seemed to be relevant not only to the differences of water potential between leaves and fruits but also to the hydraulic status of fruits. Under the mild water stress, the variations of the diurnal "fruits-shoots" water exchange were similar to those under the conditions of ample water supply, but the rate of "fruits-shoots" water exchange in the lightly stressed vine was decreased as compared with the fully watered vines. After a certain period of severe water stress, the fruits possessed a great capacity of conserving their water and an equilibrium in water potential was set up between leaves and fruits so that the fruits did not lose any more water. Under a sudden severe water stress, the fruits lost water at a higher outflux rate than when the water supply was sufficient. However, this water loss ceased rapidly. The water flowing out from the fruits was privileged to pass in the lateral shoots located above and on the same side of the fruits, and then the water might enter the primary shoot leaves situated above and on the same side of the fruits. Water captured by the fruits of the well watered vines in the evening came from the roots while under severe stress water might be obtained from the roots and also from the leaves as well. The fruit cell water potential, solute potential and pressure potential were different from those of leaves, mainly in the more important differences of water potential necessitated for the volume changes of fruit cell after incipient plasmolysis in com parison with leaves. Finally the relationships between water exchange and water potential dif ferences between "fruits-shoots", associated with the fruits hydraulic status, have been discussed. The possible relationships between water "sink-source" of fruits and the fruit development have been analysed.     

推崇多样性，一种智慧的农耕方式

侗族的传统稻田,事实上是一个天然泽生生态系统的缩版。他们种植的是以高秆糯稻为主的水稻,稻田中还养着鱼,放着鸭,同时,螺、蚌、泥鳅、黄蟮等野生动物以及茭白、水芹菜、莲藕等野生植物也在此生息。一块稻田中,并生的动植物多达一百多种。值得一提的是,稻田中,除了水稻、鱼、鸭归耕种者收获以外,