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831.
Continuous soil erosion has caused serious land degradation in the black soil area of Northeast China. The primary objective
of this study was to determine the effects of accelerated erosion on soil productivity, as measured by soybean (Glycine max L. Merr.) yields. Eight erosion levels, 0, 10, 20, 30, 40, 50, 60, and 70 cm, were simulated by imitating the integrated
process of natural erosion and tillage activity. Each erosion level had two sub-treatments: conventional fertilization and
no fertilization. Soil erosion was found to affect survival probability and to cause remarkable reductions in the Leaf Area
Index (LAI), plant height, pod number, biomass, and yield. Soybean yield was exponentially decreased with the increase of
soil erosion depth. Compared to erosion depth of 0 cm, erosion levels of 10, 20, 30, 40, 50, 60, and 70 cm experienced reductions
in soybean yield by 28.8%, 37.8%, 43.5%, 52.6%, 53.1%, 52.9%, and 64.1% respectively when fertilized whereas the reductions
at those levels were 32.6%, 42.2%, 53.0%, 54.0%, 65.8%, 69.7%, and 72.6%, respectively, when unfertilized. At the erosion
depths of 10, 20, 30, 40, 50, 60, and 70 cm, the yield reductions per 10 cm of soil eroded when fertilized were 28.8%, 18.9%,
14.5%, 13.2%, 10.6%, 8.8%, and 9.2%, averaged 14.9%, but when unfertilized they were 32.6%, 21.1%, 17.7%, 13.5%, 13.2%, 11.6%,
and 10.4%, averaged 17.1%. The results also showed that chemical fertilizers could enhance the yields of eroded soil, but
could not recover the yields to the pre-erosion level. Additionally, the results indicated that the primary reason for the
decrease in soybean yield with increasing erosion depth was the loss of soil organic matter, soil N and P. These results may
aid in selecting effective soil erosion control strategy, forecasting land degradation, establishing soil erosion tolerance,
and evaluating the economic cost of soil erosion in the black soil region in Northeast China
Supported by National Natural Science Foundation of China (Grant No. 40471082) and National Basic Research Program of China
(Grant No. 2007CB407204) 相似文献
832.
绿洲灌区小麦水分生产率及其影响因素的灰色关联分析 总被引:6,自引:1,他引:5
以黑河流域的洪水河灌区为例,利用1995—2006年的灌溉用水量、农作物产量、气象等资料,分析计算了绿洲灌区的小麦水分生产率。结果表明,1995—2000年小麦水分生产率为0.983 kg\5m-3,节水改造项目实施后的2001—2006年为1.070 kg\5m-3,提高了8.9%。水分生产率是衡量农业生产水平和农业用水科学性与合理性的综合指标,其影响因素比较多。根据洪水河灌区小麦生长发育期的实际情况,选取了11个影响因素进行灰色关联分析,结果显示,≥10 ℃积温、农药费用、劳动力和管理费用、化肥施用量、水费依次是影响水分生产率的前5位主要因素。研究表明,在有限的水资源利用条件下,绿洲灌区小麦生产应加大生产资料、劳动力和管理费用等的投入力度,才能生产更多的粮食,以确保区域粮食供给安全。 相似文献
833.
Snow cover is one of the most important factors controlling microclimate and plant growing conditions for Arctic and alpine ecosystems. Climate change is altering snowfall regimes, which in turn influences snow cover and ultimately tundra plant communities. The interest in winter climate change and the number of experiments exploring the responses of alpine and Arctic ecosystems to changes in snow cover have been growing in recent years, but their outcomes are difficult to summarize because of the large variability in manipulation approaches, extents and measured response variables. In this review, we (1) compile the ecological publications on snow manipulation experiments, (2) classify the studies according to the climate scenarios they simulate and response variables they measure, (3) discuss the methods applied to manipulate snow cover, and (4) analyse and generalize the response in phenology, productivity and community composition by means of a meta-analysis. This meta-analysis shows that flowering phenology responded strongly to changes in the timing of snowmelt. The least responsive group of species were graminoids; however, they did show a decrease in productivity and abundance with experimentally increased snow covers. The species group with the greatest phenological response to snowmelt changes were the dwarf shrubs. Their abundance also increased in most long-term snow fence experiments, whereas species richness generally declined. We conclude that snow manipulation experiments can improve our understanding of recently observed ecosystem changes, and are an important component of climate change research. 相似文献
834.
835.
福建省森林生态系统NPP的遥感模拟与分析 总被引:1,自引:0,他引:1
利用MODIS遥感影像,结合气象资料等数据,采用BEPS过程模型对2004年福建省的森林生态系统植被净初级生产力(NPP)进行了模拟验证。研究结果表明,2004年福建省森林生态系统NPP平均值为578.97gC/m2·a,NPP总量累计达到46.18×106tC;不同林地NPP全年平均值大小依次为:竹林≈阔叶林>杉木>马尾松,其值分别为:788.6gC/m2·a,780.0gC/m2·a,519.8gC/m2·a,437.3gC/m2·a;时空分析结果表明,2004年6-8月NPP形成较为明显的"坑"形分布形态,主要的原因之一很可能是有效降水量偏少;在空间分布上,福建省森林生态系统NPP与海拔高程显著相关,体现了该地区森林生态系统NPP空间分布的地域特征,这在一定程度上表明随着海拔上升,山高坡陡,人类对森林生态系统的干扰活动减少,有助于森林生态系统生产力的提高和维持。最后,分析了应用BEPS过程模型模拟福建省森林生态系统净初级生产力的不确定性问题。 相似文献
836.
通过岩芯观察描述、铸体薄片鉴定、毛细管压力分析以及扫描电镜等分析测试手段,结合测井解释成果,分析了镇泾油田长6与长8油层组油井产能的差异及其影响因素。结果表明:沉积相带、储层微观特征、裂缝发育程度、封盖条件以及储层伤害等是决定镇泾油田油井产量的关键因素。因此,在镇泾油田长8和长6油层组开发过程中,应根据不同沉积相带及其储层特征的差异,从改进油井施工工艺等方面入手,调整开发方案,改善储层的渗流能力,从而提高油井的产能。 相似文献
837.
从耕地总量动态平衡的内涵、理论基础着手,重点评述了耕地总量动态平衡的实施效果、耕地质量、区域平衡、影响因素、实现措施以及研究方法,认为当前研究存在相关成果与具体实践“不对称”,忽略土地开发整理过程中的生态环境影响,政策实施中不注重将城市化所产生的现代生产要素转化到平衡区域耕地综合生产能力上,区域平衡缺乏理论与实践支持以及相关法规不配套等问题。因此,建立和完善实施耕地总量动态平衡的技术支撑体系,系统构建耕地总量动态平衡的研究框架体系以及深入探讨耕地生态与社会价值及其成本核算体系等显得尤为重要。 相似文献
838.
松辽盆地深层火山岩含气储层产能预测 总被引:9,自引:4,他引:5
松辽盆地深层火山岩是当前大庆地球物理、地质、地球化学研究的主要领域之一,已取得丰硕的成果,火成岩含气储层产能作为一个表示动态特征的参数,是储层评价的重要指标之一,本文讨论了火成岩含气储层的产能与测井响应之间的关系,探讨了根据测井资料应用人工神经网络技术预测火成岩含气储层产能的方法,利用已知气井测试结果和测井资料作为网络的训练样本,根据网络学习训练结果,输入测井资料等静态参数,可预测储集层的产能,根据这种关系采用神经网络技术实现了测井对产能的预测评价,从而为大庆深部火成岩含气储层的开发提供了一定的依据。 相似文献
839.
Using meteorological data and RS dynamic land-use observation data set, the potential land productivity that is limited by
solar radiation and temperature is estimated and the impacts of recent LUCC processes on it are analyzed in this paper. The
results show that the influence of LUCC processes on potential land productivity change has extensive and unbalanced characteristics.
It generally reduces the productivity in South China and increases it in North China, and the overall effect is increasing
the total productivity by 26.22 million tons. The farmland reclamation and original farmlands losses are the primary causes
that led potential land productivity to change. The reclamation mostly distributed in arable-pasture and arable-forest transitional
zones and oasises in northwestern China has made total productivity increase by 83.35 million tons, accounting for 3.50% of
the overall output. The losses of original farmlands driven by built-up areas invading and occupying arable land are mostly
distributed in the regions which have rapid economic development, e.g. Huang-Huai-Hai plain, Yangtze River delta, Zhujiang
delta, central part of Gansu, southeast coastal region, southeast of Sichuan Basin and Urumqi-Shihezi. It has led the total
productivity to decrease 57.13 million tons, which is 2.40% of the overall output. 相似文献
840.
对观音山水库水化学、浮游生物及利用进行了调查研究。(1)库水属S、中营养型,含盐量很低;营养元素N/P平均95.6,磷是限制性因子。2)浮游生物量平均4.5247mg/L,其中浮游植物量平均3.0606mg/L,以硅藻、裸藻和甲藻占优势;浮游动物量平均1.4641mg/L,以枝角类和桡足类占优势,分别占69.2%和30.2%。(3)鱼产力为1128kg/hm2,鲢、鳙、鲤每公顷放养尾数分别为922、645和470(都在13.3cm或13.3cm以上)。(4)提出渔业利用意见。 相似文献