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71.
中国土地流转的区域差异及其影响因素——基于2003-2013年农村固定观察点数据 总被引：2，自引：1，他引：1
土地流转是实现农业适度规模经营的必经之路,理解土地流转的空间差异及影响因素具有重要意义。基于2003-2013年农业部农村固定观察点系统的169511个住户样本,本文揭示了中国土地流转的区域差异,并采用Heckman两阶段模型识别土地流转区域差异的影响因素,旨在为促进土地流转提供科学参考。结果发现：① 2003-2013年间,土地流转率从17.09%上升到24.1%,年均增幅近0.7个百分点;南方土地流转较为活跃,比如福建等地流转率超过30%,而北方土地流转率较低;② 转入土地支付租金平均为283.74元/亩,55.05%的转入户并未支付租金;相反,转出土地获得租金为243.23元/亩,52.63%的农户转出土地未获得租金;目前中国土地的“零租金”流转率超过50%;③ 土地质量、地理区位、交易费用、家庭及村庄特征等对土地流转的区域差异具有显著影响;土地质量和地理区位在平原地区的边际效应较大,但在丘陵和山区,交易成本已成为影响土地流转的重要因素。土地“零租金”流转的实质是土地资源错配的一种表现,丘陵和山区边际化及交易费用偏高降低了土地资源的潜在价值。政府应努力降低土地流转中面临的各类交易费用,建立健全土地流转的补偿机制,同时关注丘陵和山区的土地资产贬值和撂荒现象。 相似文献
72.
73.
Based on the data from the Cost-benefit Data of Farm Produce and the China Agricultural Yearbook, this paper aims to examine
the spatial and temporal change characteristics of total grain production and its affecting factors. The results show that:
1) During 1980 to 2007, total grain production increased from 3.20 × 108 t to 5.02 × 108 t in China, with annual increasing rate of 1.68%. From the regional disparities, most of the regions present increasing trend
of total grain production except for several regions with higher level of economic development; 2) Grain sown area decreased
from 1.17 × 108 ha in 1980 to 1.06 × 108 ha in 2007, which has negative effect on total grain production; 3) The increase of grain yield per unit area caused by land
use intensity changes contributed to the increase of total grain yield greatly. However, as the land use intensity showed
that farmers pay more attention to labor-saving input but not yield-increasing input, the less enthusiasm of farmers in grain
production may become an important constraint on future grain production increase in China; 4) Based on the results, this
paper proposed different land management policies in different regions, for example, the government should protect cultivated
land, promote large scale production. As to the less developed regions, the government should pay more attention to agricultural
subsidies to promote farmers’ enthusiasm in grain production. 相似文献
74.
In‐stream sediment transport plays an important role in delivery of sediment‐associated terrestrial elements. Investigating the history of fluvial sediment regime responding to changes in natural and anthropogenic driving forces provides a theoretical basis for establishment of optimal strategies on catchment management. The present study aims to systematically detect the patterns of change in sediment load at two key hydrological stations (Pengshan and Gaochang) in the Minjiang River and quantitatively evaluate the relative contributions of regional precipitation change and multiple local human activities to the observed sediment variations. Abrupt change in annual sediment load was detected in 1990 at Pengshan and in 1968, 1980 and 1992 at Gaochang. Compared with the baseline period of 1957–1990, precipitation decline and human activities had respectively contributed to 5 × 106 t and 2 × 106 t of reduction in mean annual sediment load at Pengshan during 1991–2007. For the entire Minjiang basin, taking 1956–1968 as the baseline period, precipitation decline and human activities had relatively contributed to 10 × 106 t and 18 × 106 t of reduction in mean annual sediment load at Gaochang during 1969–1980. During 1981–1992, precipitation decline had relatively contributed to 5 × 106 t of reduction in mean annual sediment load, but human activities had led to 3 × 106 t of increase in mean annual sediment load. During 1993–2009, 13 × 106 t and 17 × 106 t of reduction in mean annual sediment load may be attributed to precipitation decline and human activities, respectively. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
75.
Taking the Chaohe River Basin above the Miyun Reservoir in North China as a study area, the characteristics and variation trends of annual runoff and annual precipitation during 1961–2005 were analyzed applying Mann-Kendall test method on the basis of the hydrologic data of the major hydrological station (Xiahui Station) located at the outlet of the drainage basin and the meteorological data of 17 rainfall stations. Human activities including water conservancy projects construction and water diversion as well as implementation of soil and water conservation from 1961 to 2005 were carefully studied using time series contrasting method. The referenced period (1961–1980) that influenced slightly by human activities and the compared period (1981–2005) that influenced significantly by water conservancy and soil conservation measures were identified according to the runoff variation process analysis and abrupt change points detection during 1961–2005 applying double accumulative curve method, mean shift t-test method and Mann-Kendall mutation test technique. Based on the establishment of a rainfall-runoff empirical statistical model, impacts and the runoff-reducing effects of water conservancy and soil conservation measures on runoff reduction were evaluated quantitatively. The major results could be summarized as follows: (1) The annual precipitation in the drainage basin tends to decrease while the runoff has declined markedly since the 1960s, the average annual runoff from 1991 to 2000 was only 90.9% in proportion to that from 1961 to 1970. (2) The annual runoff variations in the drainage basin are significantly related to human activities. (3) During 1981–1990, 1991–2000, 2001–2005 and 1981–2005, the average annual runoff reduction amounts were 1.15×108, 0.28×108, 1.10×108 and 0.79×108 m3 respectively and the average annual runoff-reducing effects were 31.99%, 7.13%, 40.71% and 23.79% accordingly. Runoff-reducing effects by water conservancy and soil conservation measures are more prominent in the low water period. 相似文献
76.
The worldwide extension and intensification of farming during the last century has led to ecosystem degradation and caused a series of environmental problems.Conservation of ecosystem services in agricultural regions has been implemented by top-down government actions or initiated by resilience scientists in the developed countries,but little attention was paid in the developing countries,especially in some remote mountainous regions.The present paper presents a case study showing how local farmers obtained both maximal societal outcomes and agroecosystem conservation interests in the absence of distinct boundaries between agricultural and protected ecological areas in the densely populated purple-soiled hilly region of southwestern China.The local community(Yanting County) has developed a mosaic agricultural-forestry-fishery-stock breeding system with spatially targeted land uses,diverse agricultural productions and multiple ecological partnerships.It indicates that the local farmers have hereditarily perceived sound strategies on maximizing sustainable societal outcomes and optimizing tradeoffs among macro-market,state policy,new technological facility and ecological reinforcement. 相似文献
77.
超高层建筑巨型框架结构的巨型柱在大震作用下有时会出现往复拉压受力情形,为提高巨型柱的抗震能力,目前有的超高层建筑巨型框架结构采用了多腔体钢管混凝土巨型柱。为深入研究这种巨型柱的腔体在往复拉压荷载下的性能退化问题,取这种巨型柱中有代表性的矩形腔体,进行了3个配钢率为7.53%和1个配钢率为3.77%的相同截面矩形柱在往复拉压荷载下的工作性能试验研究。4个试件均沿杆长对中分成左右不同构造的两段,左杆段为有栓钉区段,右杆段为无栓钉区段。通过试验,比较分析了各试件的承载力、刚度及其退化过程、栓钉的作用和破坏特征。给出了抗拉、抗压承载力计算公式,计算结果与试验符合较好。研究表明:在矩形钢管腔体内设置栓钉可明显提高构件的抗拉、抗压工作性能;增加矩形钢管的钢板厚度可明显提高钢板对栓钉的约束能力,从而提高栓钉与混凝土共同工作的性能。 相似文献
78.
不同类型农户撂荒及其影响因素研究——以重庆市12 个典型村为例 总被引：20，自引：0，他引：20
近年来,耕地撂荒因与耕地流失及粮食安全紧密联系而备受关注。反映撂荒现状并揭示其影响因素,有利于政府制定科学的政策、规划和计划。现有的研究多将农户作为一个整体,较少考虑到不同类型农户撂荒的差异。以重庆市12 个典型村为例,在农户类型划分的基础上,分析不同类型农户撂荒的差异,运用多元线性回归模型定量分析不同类型农户撂荒的影响因素。研究表明：① 不同类型农户撂荒的差异主要体现在撂荒户数比重、户均撂荒面积、撂荒面积占承包地面积比重随耕作半径的变化情况、撂荒地现状及不同时间段撂荒面积;② 野生动物影响和人均耕地面积是影响不同类型农户撂荒的共同原因。此外,影响基本型农户的因素包括户主外出经历、耕作半径和房屋离集镇距离;影响自然资产型农户的因素包括农业劳动力比重、户主外出经历、地块平均面积和耕地收益;影响人力资产型农户的因素包括家庭人口、非农收入、耕地转出面积和耕作半径。 相似文献
79.
Effectiveness of farmland transfer in alleviating farmland abandonment in mountain regions 总被引：4，自引：1，他引：3
Farmland abandonment is a type of land use change in the mountain region, and this change is under rapid development. Whether farmland transfer can prevent this process and promote the effective allocation of land resources or not is a question worth studying and discussion. With the help of the previous research findings, the objective of this paper was to find out the role of farmland transfer on preventing farmland abandonment, by using the methods of multiple view with two factors, and single factor correlation analysis. The results showed that: (1) At village level, a significant negative correlation between farmland transfer and farmland abandonment existed in the study site, with R2 = 0.7584. This correlation of farmland with high grade farming conditions presented more outstandingly. The fitted curve for the farmland at Level I had the largest R2 at 0.288, while that for the farmland at Level IV had the smallest R2 at 0.103. Which indicated that farmland transfer could prevent the abandonment of farmland with high grade farming conditions? (2) At plot level, the abandonment rate of farmland with high grade farming conditions was significantly lower than that of farmland with poor grade farming conditions. It was the lowest at 10.49% for the farmland with Level I farming conditions, whereas the farmland with Level I farming conditions was 26.21%. Abandoned farmland was mainly contributed by farmland with Level IV farming conditions in the study site. (3) At village level, the role of farming conditions on farmland abandonment was insignificant. The univariate correlation analysis revealed that the abandonment ratio was negatively correlated with the proportions of farmland at Levels I and II and their accumulated proportion; however, their R2 were small at 0.194, 0.258, and 0.275, respectively. The abandonment of farmland with high farming conditions still existed. The abandonment ratios of farmland at Levels I and II were high at 9.96% and 10.60%, respectively. This presented that farmland transfer on behalf of the land rental market was still not developed. (4) However, the village possessed the high rate of farmland transfer, and its rate of farmland abandonment with high grade farming conditions was all lower. When the transfer ratios of farmland were over 20%, the abandonment ratios of farmland at Levels I and II were 6.47% and 6.92%, respectively. Farmland abandonment was still controlled by the improvement of land rental market. And the functions of land rental market optimizing the utilization of farmland resources have been presented to a certain degree. (5) To further improve the marketing degree of land rental, the probability of farmland abandonment could be reduced. Especially, their function to farmland with high grade farming conditions was very obvious, and could avoid the waste of farmland resources with high grade farming conditions. 相似文献
80.