区域尺度分布式水文模拟的时空分辨率

基于数据实验,就区域尺度分布式水文模拟中时空分辨率匹配问题进行讨论,就分布式水文建模中时空分辨率匹配问题提出建议。结果表明:低分辨率高程数据在区域水文要素空间离散过程中,导致边界错位、高程趋于集中、坡度变缓、河网稀疏失真等不良后果,在区域水文模拟研究中,应根据不同时间尺度对应的科学计算需求,选择适宜的空间分辨率数据进行模型平台构建。     

分布式水文模拟模型在流域水资源管理中的应用

分布式水文模型建立在物理机理的基础上,能够较好地反映流域下垫面条件的影响,能模拟计算降雨产汇流的过程,分析时空分布特性,是目前水文科学研究中的一个重要发展方向。流域水文模拟从模拟的侧重点上可以划分为降雨径流模拟、地下水模拟、流域水循环综合模拟。从流域水资源管理的角度出发,分别介绍上述模型的总体结构、特点及适用领域等。     

易涝易渍农田水文学研究趋势分析

易涝易渍农田是我国南方平原地区重要的农业土地资源,通过改造具有较大的生产潜力,影响这类农田生产水平的关键因素是农田水分季节性过多。对易涝易渍农田水文学问题研究进行了总结分析,明确了在今后的研究中需要注意的问题和有待完善的地方。     

浙江北部沿岸春夏季凤鲚鱼卵及仔、稚鱼分布特征

2008年4-6月,在浙江北部沿岸禁渔区线内（28°30’-30°45’N,121°30’-123°15’E）进行了产卵场生态调查,共设置45个调查站位,鱼卵和仔稚鱼的采集分别使用水平和垂直浮游生物拖网,结果表明：凤鲚卵占该海区各种鱼卵总数量的第四位。表层网和垂直网采集到的凤鲚卵占同网型鱼卵总量的6．08％和2．56％,凤鲚卵出现在5-6月,以5月数量最多,5月份平均分布密度4．82粒／网（表层网）,最高密度值150粒／网,6月平均分布密度3．02粒,网（表层网）、0．11粒／m2（垂直网）,最高分布密度110粒／网。产卵场主要在杭州湾水域,表层水温17．23℃,表层盐度13～31．5,最适表温21～23℃,最适表盐13～26,水深15m以内,透明度0．02～0-3m。凤鲚仔稚鱼在表层网的4-6月和垂直网的6月均采集到,分布面较广,其中表层网采集的凤鲚仔、稚鱼累计居各鱼种仔稚鱼首位,最高分布密度值分别为4月8尾／网、5月2尾／网、6月696尾／网（表层网）和5．9尾／mS（垂直网）。仔、稚鱼分布的表层温度和盐度分别为14．23．5oC、13。33,透明度0．05～1m。     

森林粗木质物残体（CWD）的研究进展

森林粗木质物残体（CWD）在保持森林生态系统的完整性方面发挥着重要的生态功能,影响着系统内外相关的生物和非生物过程,不仅为微生物、节肢动物、鸟类以及哺乳动物提供栖息环境,也是生态系统中重要的碳库和养分库,而且在减少土壤侵蚀和森林水文生态方面具重要的作用．文章总结了CWD的研究历史及状况,系统地阐述了CWD的形成和来源、贮量、分解、碳元素和营养元素的贮藏功能以及CWD对森林的更新作用、对生物多样性的维持和水文生态功能等．对今后CWD研究的重点及方向提出了建议．     

Securing African forests for future drier climates: applying ecophysiology in tree improvement

Increasing incidences of drought-induced tree mortality are being recorded worldwide, including Africa. African forests cover a significant proportion of the continent, which implies that African forest sustainability is threatened from a climate-change perspective. This is especially problematic in a developing nation context, because forest ecosystems such as plantation forestry provide important goods and services that sustain human well-being and economic growth. Disentangling the likely triggers of tree mortality (including those linked to drought) in landscapes would not only explain the mechanisms underlying local die-offs, but also better predict future mortality events. Methods applied in the field of ecophysiology are particularly useful to study in situ plant responses to an environment. We consider the status quo of global peer-reviewed publication outputs during the past century that have made use of key ecophysiological research approaches, specifically studies concerning ‘tree xylem anatomy’, ‘tree xylem cavitation’, ‘tree leaf gas-exchange’ and ‘tree xylem hydraulic conductivity’. We highlight the growth and applicability of this research field in understanding tree ecology. We also assess the role that the forestry sector has had in promoting such research to ensure future-proof forest products. Most importantly, we consider how Africa with its vast forested landscapes fits within this research spectrum. The last decade saw an increase of up to 60% in the total number of articles published, particularly with a focus on tree xylem cavitation and conductivity. Although forest research contributed greatly to the global tally of ecophysiological studies, and such studies in Africa have also increased by up to 88% in the past decade, there remains a general lack of this research topic in the continent. It is clear an optimisation of applied ecophysiological concepts and techniques will promote an improved understanding of tree mortality patterns. We argue that ecophysiological data will be crucial to future-proof tree improvement strategies in African commodity production landscapes, especially given future drier climates.     

Comparing System of Wheat Intensification (SWI) with standard recommended practices in the northwestern plain zone of India

The practices of the System of Rice Intensification (SRI) methodology have been extended to wheat and various other crops with reported good results. To assess such reports with respect to wheat, an experiment was conducted at the Indian Agricultural Research Institute, New Delhi during 2011–2012 and 2012–2013. This experiment compared the performance of wheat under System of Wheat Intensification (SWI) and standard recommended practices (SRPs). In 2011–2012, the SWI yield of 7.93 t ha^?1 was 30% higher than for SRP in 2012–2013, climatically a less favorable year, hence SWI performed relatively better with a 46% yield advantage under climate stress. SWI produced 12.5% less in the stressful year, while the reduction for the SRPs ranged from 18% to 31%. Differences in yield attributes and root traits were also observed in favor of SWI. Available N, P, and K in the soil after harvesting was increased with SWI, whereas depletion in nutrients with the SRPs indicated the scope for SWI sustaining soil fertility. Higher yield compensated for higher SWI costs of cultivation. A net return of US$ 1383 ha^?1 was obtained with SWI, 35% more than the US$ 1020 ha^?1 from SRPs. Overall, SWI outperformed the SRPs in terms of yields, climate resilience, and economics.     

不同龄组兴安落叶松林枯落物的水文效应

[目的]分析大兴安岭地区不同龄组兴安岭落叶松林枯落物蓄积量持水特性,为该地区森林水文效应研究提供理论基础和重要依据。[方法]选择不同龄组兴安落叶松天然林为研究对象,通过设置标准样地测定枯落物蓄积量,并采用浸水法测定枯落物持水特性,分析不同龄组兴安落叶松天然林枯落物水文效应。[结果]4个龄组兴安落叶松林枯落物蓄积量变化介于28.03~34.32t/hm2之间,最大持水量介于87.09~109.52t/hm2,最大持水量表现为随着林龄增加而增加的变化趋势,且半分解层的蓄积量都大于未分解层;经统计分析,试验4个龄组兴安落叶松林枯落物未分解层、半分解层的持水量与浸泡时间之间均符合对数关系,且吸水速率与浸泡时间之间也符合指数关系;枯落物对降水的拦蓄能力总体来看,半分解层对降雨的拦蓄能力较未分解层强。[结论]大兴安岭地区不同龄组兴安落叶松林枯落物蓄积量差异显著(除成熟林和近熟林之间),成熟林、近熟林和中林龄对于降水的拦蓄能力较幼龄林强。     

流域尺度根区蓄水能力估算及其对气象要素敏感性分析

根区蓄水能力(SR)在水文模拟、土壤水分运移以及植被生长发育等方面具有十分重要的作用。为对其进行流域尺度的估算,选取太子河上游南甸(峪)流域作为研究区,利用水量累积曲线法(mass curve technique,MCT)估算SR,基于流域出口水文站月径流深,对耦合了融雪模块的概念性水文模型FLEX进行参数率定,获取土壤蓄水能力Su Max,并与MCT的估算结果进行交叉验证。在此基础上设定不同气候情景,分析SR对降雨、融雪、蒸散发的敏感性。结果表明:1)改进的FLEX水文模型可用于模拟研究区径流,获得代表研究区土壤蓄水量多年平均水平的参数Su Max值为27 mm;2)水量累积曲线法得到的多年SR值服从耿贝尔(Gumbel)分布,且FLEX模型获得的根区蓄水能力检验了水量累积曲线法的估算结果;3)SR随蒸散发、降雨和融雪变化的曲线斜率分别为1.37、0.73和0.37,说明SR对蒸散发、降雨和融雪的敏感程度依次减弱,随着蒸散量增加、降雨量减少的幅度增大,敏感程度增强,融雪的增大或减少对SR的影响相近。研究结果为流域尺度根区缺水状况估算及维持植被系统生长发育提供一定依据。     

黄土区大型露天煤矿区生态承载力评价研究--以平朔安太堡露天煤矿为例

露天矿生态承载力的变化与矿区的污染控制、土地复垦与生态重建措施密切相关。本文根据矿区生态承载力内涵及层次特点,从生态系统弹性力、资源环境承载力及生态系统压力度3个方面提出对其进行量化的研究方法。结合高吉喜提出的生态承载力评价方法,构建了较完整的评价指标体系,利用AHP法求得各指标权重值,对矿区生态承载力状况进行静态和动态评价。研究结果表明:平朔安太堡矿区2007年的生态系统弹性力为46.836,中等稳定;资源环境承载力47.127,中等承载;生态系统压力度为1.396,承载超负荷。从动态变化趋势看,平朔安太堡矿区生态系统弹性力波动较强烈,说明矿区生态系统稳定性差,具有明显的脆弱特性;生态系统压力指数的变化说明,1999年前生态系统的压力对矿区生态系统弹性力和资源环境承载力影响较大,而1999年后影响逐渐减弱,矿区1987~2007年生态系统弹性力和资源环境承载力变化趋势相同;1997年后生态弹性力开始上升,资源环境承载力在1999年后也处于明显上升趋势。