中国山区耕地利用边际化表现及其机理
李升发1,2,3,, 李秀彬1,2,
1. 中国科学院地理科学与资源研究所 中国科学院陆地表层格局与模拟院重点实验室,北京 100101
2. 中国科学院大学,北京 100049
3. 广州地理研究所 广东省地理空间信息技术与应用公共实验室,广州 510070

作者简介:李升发(1986-), 男, 广东三水人, 博士, 助理研究员, 中国地理学会会员(S110010624M), 主要从事土地利用变化研究和土地规划相关工作。E-mail: li_shengfa@126.com

通讯作者:李秀彬(1962-), 男, 河北固安人, 博士, 研究员, 博士生导师, 主要从事土地利用变化及其效应相关研究工作。E-mail: lixb@igsnrr.ac.cn
摘要

耕地利用边际化是当前中国山区土地利用主要变化趋势。利用《全国农产品成本收益资料汇编》资料,本文首先分析2003年以来农业劳动力价格快速上涨的背景下,中国农业生产成本的结构变化以及农户的响应,并对比平原和山区农户对劳动力成本上升的响应方式及程度的差异,发现平原地区能够通过大规模的农业机械替代减少劳动投入,进而有效减少劳动力价格上升所带来的影响,而山区因地形条件限制,劳动生产率提升相对缓慢,并与平原地区的差距不断扩大,导致农业劳动力成本占比不断上涨。随着劳动力成本的快速上涨,中国山区耕地边际化特征明显,以玉米为代表的种植业净利润在2013年普遍降至零以下。2000年以来,中国山区土地利用和植被变化表现为耕地面积减少、森林面积增加、NDVI指数增强,而且在省级层次上,山区县范围NDVI变化率与耕地和森林面积变化率分别具有很强的负相关(r = -0.70)和正相关(r = 0.91),证实了中国山区耕地当前边际化的发展态势。基于以上分析,本文最后对务农机会成本上升、农业劳动力快速析出背景下的山区耕地利用边际化机理进行了总结。这一研究有助于深入认识山区耕地撂荒和森林转型的发展过程。

关键词: 耕地利用边际化; 耕地撂荒; 农业劳动力成本; 农业劳动生产率; 中国山区;
Economic characteristics and the mechanism of farmland marginalization in mountainous areas of China
LI Shengfa1,2,3,, LI Xiubin1,2,
1. Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
2. University of Chinese Academy of Sciences, Beijing 100049, China
3. Guangdong Open Laboratory of Geospatial InformationTechnology and Application, Guangzhou Institute of Geography, Guangzhou 510070, China
Abstract

Farmland marginalization has become the main trend of land-use change in the mountainous areas of China. Using the China Agricultural Production Costs and Returns Compilation (annual survey data of major agricultural production costs and earnings at national and provincial levels), this paper first analyzed the changes in the cost structure of agricultural production and the farmers' responses, under the context of the rapid rise in agricultural labor prices since 2003, and further compared the responses from the mountainous and plain regions. We found that farmers on the plains have reduced their labor input effectively through intensive use of agricultural machinery, which has minimized the impact of the increase in labor price. However, it is a severe challenge for farmers in the mountainous areas to use the same method due to the rough terrains. Thus, the agricultural labor productivity in these areas has increased relatively slowly, causing a widening gap in agricultural labor productivity between the two regions. With the rapid rise in labor costs, the marginalization of cultivated land in the mountainous areas is evident. In 2013, the profit of agricultural production in mountainous China, which takes maize cultivation as a representative, has fallen below zero. Since 2000, the land-use and land cover change in these areas has been characterized by the reduction of farmland area, reforestation, and the enhancement of the NDVI value. The high correlation between the NDVI change rate and the ratio of change in farmland (r = -0.70) and forest (r = 0.91) areas in mountainous areas at provincial level from 2000 to 2010, attests to the trend of farmland marginalization there. Finally, according to the analysis results, we summarized the mechanism of such marginalization against the backdrop of the rapid increase in the opportunity cost of farming and the sharp fall of agricultural labor forces. This study contributes to a deep understanding of the development process of farmland abandonment and forest transformation in the mountainous areas of China.

Keyword: farmland marginalization; farmland abandonment; agricultural labor cost; agricultural labor productivity; mountainous areas; China;
1 引言

土地边际化是指某一土地利用状态的经济生产能力受社会、经济、环境等多个因素改变的共同作用下不断减少的过程,被边际化的土地称为边际土地[1]。当土地净收益减少到零或以下的时候,当前土地用途将转为更为粗放的用途。如果没有可替代的、具有经济生产能力的用途时,这一土地将会被撂荒。耕地撂荒是耕地边际化最为明显的表征。20世纪后半叶以来,耕地撂荒及撂荒后的植被恢复(森林转型)已经成为了全球山地丘陵地区普遍存在的一种农村土地利用边际化现象,在欧洲地区尤甚[2]。研究表明当前全球性的土地边际化和耕地撂荒现象主要是由城市化和工业化不断发展并促使大量农业劳动力脱离农业生产所引起[3,4,5]。在2003年到达刘易斯拐点以后,中国部分地区的耕地出现了边际化利用趋势,耕地撂荒相关调查和报道不断增加[5]。西南财经大学中国家庭金融调查与研究中心对全国29个省、262个县市的住户跟踪调查发现,2011年和2013年分别有13.5%和15%的农用地处于闲置状态[6]。全国山区县抽样调查的结果表明中国山区撂荒现象普遍,截至2014年撂荒率为14.32%[7]。案例调查显示绝大部分耕地撂荒发生在山地丘陵地区[5],如重庆[8,9,10]、四川[11]、福建[12,13]、湖南西部[14,15]、贵州[16]、宁夏南部[17]、甘肃东南部[18]、吉林南部[19]

现有研究已经从地块层次[20,21,22]和农户层次[23,24]揭示了耕地撂荒的原因,即耕地无租化是耕地撂荒的根本原因[20],劳动力成本上升和农业劳动力析出是农户做出撂荒决定的主要原因[24,25],而城镇化和工业化是这一切发生的最主要推动力[26,27]。然而,目前对于耕地边际化和撂荒发生机理并没有进行系统的总结,尤其是没有定量分析撂荒主要发生在山区的机理。鉴于此,本文利用《全国农产品成本收益资料汇编》资料,首先分析20世纪90年代中期,尤其是2003年以来中国农业生产中劳动力成本变化以及农户的响应行为;通过对比山区和平原地区农户面对劳动力成本上升响应能力的差异,揭示中国山区耕地边际化特征和撂荒发生的原因;之后,利用土地利用数据和遥感数据,分析1990-2010年中国山区耕地和森林面积以及2000年以来植被指数的时空变化特征,以作为中国山区耕地利用边际化的现实判断基础。最后,基于上述分析对中国山区耕地撂荒的整个过程和机制进行系统总结。

2 资料和方法
2.1 数据来源

全国及分省农业生产的各项成本、收益以及用工数量数据均来自于国家发改委价格司历年的《全国农产品成本收益资料汇编》。重庆市和黑龙江省的农业机械总动力数据分别来自于历年的《重庆统计年鉴》和《黑龙江统计年鉴》。土地利用数据来自于中国科学院地理科学与资源研究所制作的中国5年间隔陆地生态系统空间分布数据集(1990-2010年),数据空间分辨率为100 m,包括农田、森林、草地、水体与湿地、荒漠、聚落等一级类型的生态系统,综合评价精度达94.3%[28]。NDVI数据来源于地理空间数据云下载的中国MODIS-NDVI月合成产品,空间分辨率为250 m。

2.2 研究框架和方法

耕地边际化的狭义定义是当前用途下的土地无租化发展过程。导致耕地地租下降的原因是成本上涨或收益减少,又或是两者共同的作用。为促进农民种粮积极性,稳定粮食生产,增加农民收入,中国政府在2008年以来不断提高粮食收购价格,因此可以大致判断导致耕地地租下降的主要原因是成本上涨。在城镇化和工业化进程中,种植业成本快速上涨主要是非农工资上升导致务农机会成本上涨再传导到农业劳动力价格所引起的。面对农业劳动力务农机会成本上升,农户会根据自身的劳动力和耕地资源禀赋,以追求家庭利益最大化为目标重新配置劳动力,并在劳动力析出和劳动力价格上涨共同影响下,以劳动力生产率最大化为目标调整土地利用方式。由于山区和平原地区耕地资源禀赋差异,农户在土地利用调整方式选择上可能会有不同,这种差别会导致山区和平原地区种植业在亩均用工、劳动生产率、劳动力成本占比和净收益(地租)的差异变化,从而导致了土地利用方式和用途的显著差异,并最终通过土地覆盖显现出来(图1)。

图1 耕地边际化分析框架 Fig. 1 Research framework of farmland marginalization

农业劳动生产率计算的方法很多,包括单位时间内劳均农产品重量或产值、单位时间内劳均经营耕地面积、生产单位农产品所消耗的劳动时间等。为比较不同地区、不同时期的农业劳动生产率,本文采用的是单位劳动时间的粮食产量,其计算公式如下:

E = P / L (1)

式中:E为农业劳动生产率;P为亩均粮食产量;L为亩均农业投工量。

与土地利用类型变化相比,NDVI在反映土地利用变化信息更为及时。耕地撂荒之后,其植被恢复的时间在各地区差别很大,即便是在南方山区,撂荒以后的植被恢复也是一个渐进过程,在撂荒后数年内,撂荒地在土地利用类型上可能都不会发生明显变化,但其利用状态可通过NDVI的变化体现。因此,本文除了对山区的土地利用类型变化进行分析外,还利用NDVI数据对山区植被变化情况进行分析。撂荒地NDVI年内变化曲线与正在经营的耕地的NDVI曲线差别主要是高值持续时间更长[29],因此采用NDVI年平均值比采用最大值更能反映山区耕地边际化发展状况。考虑到植被恢复时间,本文选择了2000-2013年的NDVI值年平均变化率来反映山区植被的总体变化趋势。

由于山区的定义具有较大的模糊性和不确定性[30],而本文主要关注的是地形崎岖地区与平坦地区之间农户响应行为的差异,因此本文并不对山区和平原进行严格的定义。受数据获取限制,本文在分析成本和收益变化时选择地形特征最为明显的省份作为山区和平原代表。根据各省地形特征和坡耕地比重,选取了山地丘陵面积占比和6°以上坡耕地比重最高的7个省份作为山区代表,包括重庆、贵州、云南、四川、甘肃、山西和陕西,除山西和甘肃外,其他省份的坡耕地比重在60%以上,其中比重最高的是重庆市,约为85%,是山区的典型代表。选取平原面积占比和6°以下的平坦耕地占比最高的7个省份作为平原代表,包括黑龙江、吉林、河北、山东、河南、江苏和安徽,除吉林省,其他省份的平坦耕地比重均在90%以上,其中黑龙江省的劳均耕地面积高达30.5亩,是中国平原地区农业机械化和规模化发展的典型代表。在分析土地利用和覆盖变化时,为更好地反映山区的变化特征,本文以《中国县域统计年鉴》的山区县作为分析区域,并与丘陵县、平原县进行对比。按照《中国县域统计年鉴》定义,山区县是指县域内的山地面积大于80%的县,全国约有900个,约占全国土地总面积的45%。

3 农业劳动力成本变化及其农户的响应
3.1 种植业成本变化

2003年以来中国农民工工资每年以约10%的增速快速上升[31,32],促使农民务农机会成本上升,继而引起农业生产中劳动力成本的快速上涨。2003-2013年期间,中国3种主粮(稻谷、玉米和小麦)农业劳动力的雇工工价增长了5.1倍,而农资和服务的投入(不含机械作业费)仅增长2倍左右,远低于雇工工价增长速度。因此,在亩均农业生产成本中,劳动力成本以高于农资和服务成本的速度增长。到2011年,3种主粮的亩均劳动力成本首次超过了农资和服务成本,成为了种植业第一大成本(图2)。

图2 1995年来中国3种主粮劳动力成本、农资和服务成本变化 Fig. 2 The labor, materials and service costs for China's three main grain crops since 1995

3.2 农业劳动力成本上升的农户响应行为

劳动力成本与劳动力价格、亩均用工相关。在亩均用工不变的前提下,劳动力价格大幅增加必然导致劳动力成本的快速攀升。为了降低劳动力成本,农户将会通过调整种植结构、种植制度、经营规模或实施要素替代,以最大限度地提高农业劳动生产率、降低亩均用工[33,34],最终达到降低劳动力成本的目的。与此同时,农户农业生产决策目标也从追求土地生产率最大化向追求劳动生产率最大化转变[35]

农业劳动力成本快速攀升对种植结构和制度影响表现在农户趋于扩大高劳动生产率作物的种植面积,并减少较低劳动生产率作物的种植面积,如南方地区增加蔬菜种植面积并减少水稻种植面积,从双季稻改为只种中稻或单季晚稻,而北方地区减少小麦种植并扩大玉米种植面积[36]。农业劳动力成本上升对经营规模表现在外出务工人数上升促使一部分农户将承包耕地转出,而另外一部分劳动生产率更高的农户转入耕地,扩大经营规模[33],实现规模化经营,从而提高了整体的农业劳动生产率。

要素替代是农户在要素间相对价格变动所做出的直接响应。根据诱导技术创新理论,当农业劳动力价格上升使得劳动力成本成为农业生产中最主要的约束因素时,会诱导生产者采用劳动力节约型的农业技术或种植制度[33, 37],亦即增加省工性投入以减少劳动力投入[35]。2003年以来,随着农业劳动力价格快速上升,中国农业生产中的资本投入结构趋向于增加省工性投入,尤其是机械投入。2003-2013年期间,机械作业费的增长率最高,达419%,农药费也增长193%,而种子费、化肥和农家肥费、排灌费仅分别增长190%、147%、59%,原来主要的省工性投入畜力逐渐被机械所取代,减幅33%(图3)。由于省工性投入的增加,中国3种主粮的亩均用工天数快速减少,从11.1 d减少到6.2 d,减幅44%。因此,尽管农业劳动力价格在此期间明显上升,但中国种植业劳动力成本占总成本的比重并没有大幅提高,仅从36.5%提高至41.8%。

图3 1995-2013年中国3种主粮各种物质与服务费用变化 Fig. 3 Different types of materials and service costs for China's three main grain crops during 1995-2013

3.3 山区与平原农户响应差异

3.3.1 山区农业机械化发展受阻 为更清晰地对比山区和平原的机械化程度差异,本文选取了重庆和黑龙江两个不同地形区的典型代表进行分析。从2003年开始,无论是农业机械总动力还是劳均农业机械动力,以黑龙江为代表的平原和以重庆为代表的山区之间的差距均在显著扩大。2003-2013年期间,黑龙江的农业机械总动力增长了1.7倍,而重庆仅增长了0.7倍;黑龙江的劳均农业机械动力增长了1.8倍,而重庆仅增长1.2倍,两者的差距从1.8 kW扩大到4.1 kW(图4)。另外,两个省份的机械使用比例也有显著差异。2010年,黑龙江的玉米机收面积比重高达97%,而重庆仅为16%。

图4 1995-2013年黑龙江和重庆农业机械发展水平对比 Fig. 4 Comparison of agricultural mechanization between Heilongjiang and Chongqing during 1995-2013

3.3.2 山区亩均用工远大于平原地区 2003年,平原省份种植玉米的平均亩均用工数量为8.4个,到2013年下降到5.3个,下降比例为37%。2003年,山区省份的平均亩均用工数量为16.9个,到2013年下降到11.9个,下降比例为30%(图5)。尽管山区省份的亩均用工数量有较为明显的减少,但与平原地区的差距依然显著,2013年的亩均用工数量仍为平原地区的2倍以上。

图5 2013年中国各省玉米种植亩均用工数 Fig. 5 Per mu labor use for maize cultivation at provincial level in China in 2013

图5中可以明显看出,西南部山区省份的亩均投工数量明显高于华北、东北等地区的平原省份,总体上呈现出从东北向西南递增的态势。其中,亩均用工数量最少的黑龙江仅需3.1个,而地形崎岖的贵州、云南、甘肃和重庆亩均用工数量仍高达13个以上,两者相差3倍以上。

3.3.3 山区农业劳动力投入成本占比普遍上涨 山区机械化发展较缓慢,其机械替代劳动的速度低于农业劳动力成本上涨的速度,因此省工性投入增加所节省的成本不足以抵消增加的劳动力成本。以玉米为例,2003-2013年期间,除四川外,其余的6个山区省份的劳动力成本占比普遍呈现出显著的上涨态势,7个山区省份的平均占比从2003年53.82%上升到2013年的63.10%(图6)。反观平原省份,除河北省劳动力成本占比明显上升外,黑龙江、吉林、山东、河南和安徽的占比均表现为显著减少态势,而江苏的比例基本持平,7个平原省份的平均占比从2003年43.88%下降到2013年的30.68%。

图6 2003年和2013年中国山区与平原省份玉米亩均农业劳动力成本比重变化 Fig. 6 Changes in the proportion of agricultural labor costs (maize) between mountainous and plain provinces and municipalities in 2003 and 2013

4 农业劳动生产率及净收益变化的区域差异
4.1 山区和平原的农业劳动生产率对比

从全国总体上看,农业机械的投入有效替代了劳动力,从而促进农业劳动生产率快速提高。以玉米为例,1995-2003年期间,农业劳动生产率保持了缓慢的增长态势。2003年以后,随着机械投入大量增加,农业劳动生产率以年均8.5%的增速快速提高。

由于不同地形条件的农业机械化发展程度存在显著差距,这一差距会导致亩均投工数量的差异,进而导致农业劳动生产率的差距。同样以山区省份和平原省份的玉米生产情况为例,2003年以来,7个山区省份和平原省份的平均玉米劳动生产率差距呈现明显扩大的发展趋势。2003年,7个山区省份平均劳动生产率为22.55 kg/d,7个平原省份为39.53 kg/d,后者是前者的1.75倍;到2013年,7个山区省份平均劳动生产率提高至41.38 kg/d,7个平原省份大幅提高至93.24 kg/d,两者差距扩大到2.25倍(图7)。采用劳均产品产值计算的劳动生产率也得到相同的结论。

图7 中国山区与平原省份玉米种植平均劳动生产率变化 Fig. 7 Changes of average labor productivity in maize cultivation between mountainous and plain provinces and municipalities in China

4.2 山区和平原的耕地利用净收益对比

由于山区农业劳动生产率提升缓慢,劳动力成本无法像平原地区一样通过增加相对廉价的机械投入实现有效压缩,从而导致亩均净利润的减少。对比山区与平原省份的玉米种植情况,2000年以来,受价格波动影响,全国、山区省份和平原省份的净利润处于波动变化中,但平原省份与山区省份的净利润差距在波动扩大。两者的亩均净利润差距从2004年的102元扩大到2013年的197元(图8)。

图8 中国山区与平原省份亩均玉米净利润变化注:2003年及以前缺少分省份净利润数据。 Fig. 8 Changes in profits of maize cultivation between mountainous and plain provinces and municipalities in China

从2004年和2013年各省利润对比看,无论山区省份还是平原省份,玉米亩均利润大多表现为下降趋势,但相较于平原省份,山区省份的下降幅度更大。除山西外,其他6个山区省份的亩均利润均大幅下降,重庆、贵州、云南、陕西和甘肃的亩均利润更是降至零以下,与平原省份形成非常鲜明的对比(表1)。可见,亩均投工过大、劳动力生产率低是导致山区亩均利润急剧下降的最主要原因,地租不断下降表明了山区耕地利用处于被边际化的过程中。随着国家新型城镇化战略的出台,中国城市化进程将保持较快的发展势头,劳动力工资也将继续上涨,进一步促进山区人口迁出和耕地边际化,如果没有公共政策的干预,越来越多的山区坡耕地将可能会被撂荒,或被改为果树、烤烟或林木等其他高产值或省工性农产品。

表1 中国山区和平原省份玉米的亩均利润变化对比(元,2000年不变价) Tab. 1 Comparison of maize profits in mountainous and plain provinces and municipalities (yuan, constant price in 2000)
5 山区县土地利用和覆被变化特征

根据前文分析,2000年以来中国山区耕地因劳动生产率提升缓慢,劳动力成本快速上升,耕地利用净收益被不断压缩,处于边际化发展过程中。另外,1998年以来,中国陆续开展以退耕还林为主的大范围生态工程,将25°以上的坡耕地及水土流失严重地区的耕地转为林草地。因此,可以初步判断,2000年以来中国山区耕地应处于净减少的过程中,相应地,山区森林面积和植被指数应表现为增长趋势。

5.1 土地利用变化

5.1.1 山区县耕地变化 土地利用数据显示,1990-2000年期间,中国山区县处于以开垦为主的耕地增加阶段,10年间耕地增长了1.23%,主要集中在东北地区,新疆、宁夏、甘肃等省份也有明显的耕地开垦现象(图9)。平原县和丘陵县同期的耕地面积分别增加0.71%和3.22%。2000年以后,山区县耕地开垦活动明显减弱,耕地面积普遍减少。2000-2010年期间,全国山区县耕地减少1.13%,而平原县和丘陵县耕地面积分别减少0.20%和1.04%。

图9 1990-2000年和2000-2010年中国山区县耕地面积变化注:图中每个像元大小为10 km×10 km,图10的像元大小相同。 Fig. 9 Farmland area changes in Chinese mountainous counties during the periods 1990-2000 and 2000-2010

从变化类型的县数量来看,1990-2000年期间,山区县中耕地净减少的县数量为468个,占山区县总数的52%,而平原县和丘陵县中耕地净减少的县数量比重分别为71%和56%,表明了山区和丘陵基本趋于平衡状态;平原县因建设用地扩张,大部分地区耕地利用变化表现为净减少。2000-2010年期间,平原县耕地变化情况与前10年相似,耕地减少的县数量增加了61个,比重增加至78%,而山区县和丘陵县耕地净减少的县数量明显增加,尤其是山区县,从468个增加到712个,比重扩大到79%。相应地,耕地净增加的山区县数量从411个减少到114个(表2)。总体上,2000年以来,与丘陵县和平原县相比,中国山区县耕地减少的情况更为明显。进一步对比重庆和黑龙江可以发现,作为山区典型的重庆,2000-2010年期间,山区县耕地面积减少了1.9%,全部13个山区县均呈减少趋势。地形条件相对较好的黑龙江,2000-2010年期间增长0.07%,15个山区县中12个县耕地面积基本保持不变或有小幅增长。

表2 中国各类耕地面积变化类型的县数量 Tab. 2 The number of counties with different types of farmland area changes in China

5.1.2 山区县森林变化 1990-2000年期间,中国山区县范围内森林减少主要集中在东北地区,主要原因是耕地扩张和森林砍伐。福建和浙江以及新疆西部山区也有明显的森林增长,而在西南地区森林砍伐和造林活动并存(图10)。在这期间,全国山区县森林面积净减少0.4%,而平原县和丘陵县面积分别增加0.87%和减少1.6%。

图10 1990-2000年和2000-2010年中国山区县森林面积变化 Fig. 10 Forest area changes in Chinese mountainous counties during the periods 1990-2000 and 2000-2010

2000-2010年期间,中国山区县范围内森林减少的范围明显缩小,且没有集中分布区。退耕还林还草工程和其他生态工程的实施以及耕地撂荒后自然植被恢复,使得中国山区县范围内的森林面积不断增加,尤其是在贵州、重庆、黄土高原一带的生态脆弱区。这一期间,中国山区县森林面积净增加0.19%,而平原县和丘陵县分别减少0.52%和增加0.42%。同样对比重庆和黑龙江的森林面积变化,前者山区县的森林面积在2000-2010年期间增加了1.70%,而后者则减少了0.24%。

总体上,2000年以来,中国山区县耕地面积与森林面积呈现相反的变化趋势,与农业劳动力成本上升、耕地利润减少趋势相一致。

5.2 NDVI变化

5.2.1 山区县2000-2013年NDVI变化 2000-2013年期间,全国山区县的NDVI总体上呈逐渐增加的趋势,年平均NDVI增加9.9%(图11)。其中,内蒙古、宁夏的年平均NDVI增幅最大,分别达33%和23%;其次是山西、甘肃、青海、贵州、广西、海南、广东和福建等省份,增幅均达10%以上;东北地区的年平均NDVI增幅最小,黑龙江、吉林和辽宁3个省的增幅都在4%以下,而其局部地区出现的NDVI减少可能是由降水减少所致。

图11 2000-2013年中国山区县NDVI变化值 Fig. 11 NDVI variations within mountainous counties in China from 2000 to 2013

5.2.2 NDVI与土地利用变化相关性分析 遥感数据分析结果表明,中国山区县范围内耕地面积因退耕还林和撂荒而不断减少,而森林及NDVI值总体上表现出增长趋势。因此,NDVI变化与耕地和森林的总体变化可能存在相关。相关分析结果表明,2000-2010年分省山区县基期年耕地范围内耕地变化率与2000-2013年NDVI变化率的皮尔森相关系数达-0.70(P < 0.01),表现出较强的负相关性,分省的山区县森林面积变化率与山区县范围的NDVI变化率的皮尔森相关系数高达0.91(P < 0.01),表现出强正相关性(图12)。这一结果进一步证实了中国2000年以来山区耕地减少、森林增长的总体变化趋势,为本文推论提供了良好的现实依据。

图12 中国山区县耕地、森林变化率与NDVI变化率的相关关系 Fig. 12 Correlation between farmland and forest change rate and the NDVI change rate within mountainous counties

6 山区耕地边际化机理

与其他国家和地区的耕地边际化和撂荒的驱动力相同,中国山区当前经历的耕地撂荒的主要驱动力是快速的城市化和工业化进程,是农业劳动力不断析出的结果。

通过总结中国山区耕地利用边际化的表现以及已有的研究[3, 5, 20, 24, 34],综合分析得出中国山区耕地撂荒机理如下:城镇化和工业化的发展提供越来越多的城市务工机会,在刘易斯拐点之后,非农劳动力价格快速上升;农业劳动力务农机会成本的上升促使越来越多农民选择外出务工,从而导致农业劳动力价格的上涨。在农业劳动力价格快速上涨的背景下,提高农业劳动生产率是避免耕地边际化的最有效方法。提高农业劳动生产率的方式包括采取规模化、集约化耕地经营方式,利用省工性机械替代“昂贵”的农业劳动力[37],或扩大劳动生产率较高作物种植面积,以达到劳动生产率最大化目的[34],从而减低由于农业劳动力价格上升带来的成本增加。以地形条件为主的自然条件差异导致了平原和山区农户在提高农业劳动生产率的方式上有着不同的选择。平原地区可以大量增加大型农业机械投入替代价格高涨的人工,从而大幅提高劳动生产率,有效降低劳动力成本,避免耕地利用边际化。在山区,地形等条件严重阻碍其农业机械化发展,农户往往只能通过调整农业结构或种植制度的方式提高劳动生产率,但这种调整方式的效果有限,因此其农业劳动生产率增长缓慢,与平原地区的差距越来越大,使得农业劳动力成本比重快速增大,农业生产利润不断下降,最终导致耕地被边际化[38]。从农业劳动力析出的角度来看,在耕地利用边际化发展过程中,由于山区地形崎岖,亩均投工明显高于平原地区,因此劳均经营耕地面积远小于平原地区,快速城镇化过程中农业劳动力持续大量的析出促使平原地区增加机械投入以“替代”析出的农业劳动力,劳均经营耕地大幅增加,而山区析出的农业劳动力无法被机械所替代,劳均经营耕地增长缓慢,当留守的农业劳动力无法经营所有耕地的时候,劣质、偏远的耕地将会被边际化(图13)。

图13 中国山区耕地边际化机制 Fig. 13 Mechanism of farmland marginalization in Chinese mountainous areas

7 结论和讨论
7.1 结论

随着中国城镇化和工业化进程的不断推进,在农业劳动力析出和务农机会成本快速上涨的背景下,中国山区耕地利用边际化特征明显,具体表现为以下几个方面:

(1)2003年以来,在农业劳动力价格快速上涨带动下,农业机械投入大幅增加,受地形条件限制,山区农业机械化发展受阻,种植业亩均用工远大于平原地区,导致山区的种植业成本明显上涨。

(2)由于机械替代程度的差异,山区和平原的玉米种植平均劳动生产率差距越来越大,从2003年的1.75倍扩大到2013年的2.25倍。

(3)山区劳动生产率提升缓慢,劳动力价格上升造成利润不断减少,2013年山区省份的玉米种植利润普遍降至零以下。

(4)由于山区耕地利用的边际化发展,山区耕地撂荒后的植被恢复以及退耕还林工程实施导致了2000年以来中国山区耕地面积减少、森林面积增加、NDVI指数增强的总体变化趋势。

山区耕地边际化的主要驱动力是城镇化和工业化引起的务农机会成本上升和农业劳动力大量析出,关键原因是山区地形条件限制了机械替代、劳动生产率提升缓慢,在地块层次上,耕地边际化的直接表现是劳动力成本大幅上升压减地租至零或以下;在农户层次上,耕地边际化是农户对家庭土地资源和劳动力资源优化配置的结果;在区域层面上,耕地边际化是农业劳动生产率缓慢提升和农业劳动力大量减少共同作用的结果。

7.2 讨论

耕地边际化是一个国家和地区经济发展到一定程度普遍出现的现象,它对社会经济和生态环境都带来了深刻的影响[5, 39],如何消除山区耕地边际化所带来的负面影响是未来研究的重点。对中国山区而言,耕地边际化有利于改善中国山区生态环境,同时也是中国退耕还林工程顺利实施的有力保障。与此同时,中国作为一个人均耕地资源少、坡耕地比重大的国家,山区耕地边际化对粮食生产的影响仍是一个无法忽视的问题。从本文的分析结果来看,减少山区耕地撂荒最关键是要提高农业劳动生产率,而提高劳动生产率的方式主要有两个:① 通过土地整治实现适度的土地规模经营以增加机械的使用率,减少亩均劳动投入;② 增加农产品附加值,例如推广无法使用机械生产的特色农作物种植等,提高单位劳动经济产出。

The authors have declared that no competing interests exist.

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Cropland abandonment has emerged as a prevalent phenomenon in the mountainous areas of China. While there is a general understanding that this new trend is driven by the rising opportunity cost of rural labor, rigorous theoretical and empirical analyses are largely absent. This paper first develops a theoretical model to investigate household decisions on farming scale when off-farm labor market is accessible and there is heterogeneity of farmland productivity and distribution. The model is capable of explaining the hidden reasons of cropland abandonment in sloping and agriculturally less-favored locations. The model also unveils the impacts of heterogeneity of household labor on fallow decisions and the efficiency loss due to an imperfect labor market. The model is empirically tested by applying the Probit and Logit estimators to a unique household and land-plot survey dataset which contains 5258 plots of 599 rural households in Chongqing, a provincial level municipality, in Southwest China. The survey shows that more than 30% of the sample plots have been abandoned, mainly since 1992. The econometric results are consistent with our theoretical expectations. This work would help policy-makers and stakeholders to identify areas with a high probability of land abandonment and farming practice which is less sustainable in the mountainous areas.
DOI:10.1016/j.landusepol.2016.06.014      [本文引用:3]
[25] Li Xiubin, Zhao Yuluan.Forest transition, agricultural land marginalization and ecological restoration. China Population, Resources and Environment, 2011, 21(10): 91-95.
[本文引用:1]
[李秀彬, 赵宇鸾. 森林转型、农地边际化与生态恢复. 中国人口·资源与环境, 2011, 21(10): 91-95.]
中国20世纪80年代迎来了国 家土地利用形态的转型,即代表自然生态空间的森林面积降至低谷后反转向上,代表人类干扰较强的耕地面积从扩张到收缩。这是生态状况从整体恶化向整体改善转 变的最直接原因。森林转型对应着国家经济社会发展的阶段性演进过程,存在着必然性。其直接原因,是农林交错带的农业在与森林竞争土地资源的过程中失去优 势。伴随工业化和城市化的劳动力价格上升,生活水平提高带来的林木产品需求增加,是森林竞争力提高和农业竞争力下降的经济驱动力;而转型前农业扩张引起的 生态退化,则是其政策驱动力。在中国森林转型初期,政策起到了关键的促进作用。随着城市化的加速发展,人口年龄结构向老年型转变,中国迎来了劳动力工资持 续上涨的阶段。以坡耕地为代表的劳动力密集型农地利用方式,由于难以实现机械化,劳动生产率与平原区农业的差距将越来越大,被"边际化"的可能性越来越 高。这给森林面积或自然生态空间的进一步扩张提供了机会。
[26] MacDonald D, Crabtree J R, Wiesinger G, et al. Agricultural abandonment in mountain areas of Europe: Environmental consequences and policy response. Journal of Environmental Management, 2000, 59(1): 47-69.
Agricultural abandonment reflects a post war trend in western Europe of rural depopulation to which isolated and poorer areas are most vulnerable. The commercialisation of agriculture, through technological developments, and the influence of Common Agricultural Policy have increased productivity and focused agricultural activity on more fertile and accessible land thus transforming traditional approaches to farming. In many areas this has lead to a decline in traditional labour intensive practices and marginal agricultural land is being abandoned. The problems that these trends create are particularly marked in mountain areas. The social and economic impacts of these changes have been well documented. However, the implications for environmental policy are less well recognised. This paper reviews the literature on abandonment and gives a comparative analysis of European mountain case studies to assess the environmental impacts of land abandonment and decline in traditional farming practices. It finds abandonment is widespread and that, while the influence of environmental changes is unpredictable due to environmental, agricultural and socio-economic contextual factors, abandonment generally has an undesirable effect on the environmental parameters examined. The application of agri-environment policy measures in relation to abandonment is discussed and suggestions for future policy are proposed.
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[27] Kozak J.Forest cover change in the Western Carpathians in the past 180 years: A case study in the Orawa Region in Poland. Mountain Research and Development, 2003, 23(4): 369-375.
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[28] Xu Xinliang, Liu Jiyuan, Zhang Zengxiang, et al.A time series land ecosystem classification dataset of China in five-year increments (1990-2010). Journal of Global Change Data & Discovery, 2017, 1(1): 52-59.
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[徐新良, 刘纪远, 张增祥, . 中国5年间隔陆地生态系统空间分布数据集(1990-2010)内容与研发. 全球变化数据学报, 2017, 1(1): 52-59.]
中国陆地生态系统类型空间分布数据集是在 1990 年,1995 年,2000 年,2005 年和 2010 年卫星遥感数据基础上,结合地面调查研发的连续 25 年每 5 年间隔的中国生态系统数据集.该 分类系统共划分为 7 个生态系统类型,包括:农田生态系统,森林生态系统,草地生态系统, 水体与湿地生态系统,荒漠生态系统,聚落生态系统和其他生态系统.数据空间分辨率为 100 m. 其中,水体和湿地生态系统变化不大,聚落生态系统由占据总面积 1.65%(1990)增至 2.09% (2010);农田生态系统由 18.65%(1990)增至 18.80%(2010);而草地生态系统由 31.98%(1990) 降至 31.56%(2010);森林生态系统由 23.74%降至 23.64%(2010).这种变化总量在 5 年间隔 期间呈波动变化特点.关键词:中国;陆地生态系统;空间分布;5 年间隔;100 m;1990-2010DOI: 10.3974/geodp.2017.01.08
[29] Alcantara C, Kuemmerle T, Prishchepov A V, et al.Mapping abandoned agriculture with multi-temporal MODIS satellite data. Remote Sensing of Environment, 2012, 124: 334-347.
78 Agricultural abandonment can be mapped across large areas from MODIS 250m. 78 Abandoned agriculture was widespread in Eastern Europe (15.1% of the total area). 78 Using multiple years of MODIS data did not increase classification accuracy. 78 Phenology metrics in conjunction with NDVI data improved classification accuracies.
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[30] Jiang Xiaobo, Zeng Hongcheng.Quantifying mountain regions of China: A case study in Sichuan. Journal of Mountain Science, 2009, 27(1): 24-32.
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[江晓波, 曾鸿程. 量化中国山区范围: 以四川省为例. 山地学报, 2009, 27(1): 24-32.]
[31] Fang C, Du Y, Wang M.Migration and Labor Mobility in China. New York: United Nations Development Programme, Human Development Report Office, 2009.
China has witnessed the largest labor migration since the reform and opening up policies were implemented. According to the most recent statistics, the total number of rural to urban migrant workers reached 136 million. Migrants are defined as persons who have left out of township for more than 6 months. The migration flow has propelled the economic and societal transition in China through labor productivity enhancement and social restructuring. Accordingly, the Chinese government has improved the migration policies with increasing migration flow and the changes of labor market situations. This report is organized as follows. Section one briefly introduces when and how the migration started by reviewing the history, size and trend, impacts of migration in China and the vulnerability of migrants. Section two reviews the main migration policy changes in the past three decades. Section three illuminates the Lewisian turning point that marks economic development and transitioning in China. Section four discusses the relevance of China experiences to other developing economies in terms of economic development and migration policy changes.
[本文引用:1]
[1] Liu Chengwu, Li Xiubin.The character and diagnostic criterion for marginiastion of the arable land. Progress in Geography, 2005, 24(2): 106-113.
[本文引用:1]
[刘成武, 李秀彬. 农地边际化的表现特征及其诊断标准. 地理科学进展, 2005, 24(2): 106-113.]
<p>本文对农地边际化与边际土地的概念与本质、农地边际化在区域土地利用中的表现特征及其诊断标准进行了理论探讨。农地边际化是一种受社会、经济、政治和环境等因素综合驱动作用的过程,一种在现有的土地利用和社会-经济结构条件下,农地变得不再具有经济生产能力的过程。在农地边际化过程中,农户会有不同的行为响应,从而导致区域土地利用在&ldquo;集约度、播种面积、用途转移与土地经营制度&rdquo;等方面发生重大变化;农地利用的&ldquo;边际收益指标&rdquo;、&ldquo;集约度指标&rdquo;与&ldquo;播种面积指标&rdquo;是诊断农地边际化的三大指标。一般而言,如果该农地利用的&ldquo;边际收益&rdquo;为负,且在随后的土地利用过程中出现了&ldquo;集约度下降、播种面积缩小,甚至弃耕撂荒&rdquo;等变化特征,可以初步判断该农地利用出现了边际化现象。但不同类型农地边际化,其诊断标准也有差异。</p>
[2] Meyfroidt P, Lambin E F.Global forest transition prospects for an end to deforestation. The Annual Review of Environment and Resources, 2011, 36: 343-371.
Although global rates of tropical deforestation remain alarmingly high, they have decreased over the period 2000–2010, and a handful of tropical developing countries have recently been through a forest transition—a shift from net deforestation to net reforestation. This review synthesizes existing knowledge on the occurrence, causes, and ecological impacts of forest transitions and examines the prospects and policy options for a global forest transition. The ecological quality of forest transitions depends on multiple factors, including the importance of natural forest regeneration versus plantations. Given an increased competition for productive land between different land uses, a global forest transition will require major technological and policy innovations to supply wood and agricultural products. In the globalization era, national strategies aimed at forest protection and sustainable use of forest resources may have unintended effects abroad owing to a displacement of land use across countries. Deci...
DOI:10.1146/annurev-environ-090710-143732      [本文引用:1]
[32] Lu Feng. Wage trends among Chinese migrant workers: 1979-2010. Social Sciences in China, 2012(7): 47-67.
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[卢锋. 中国农民工工资走势:1979-2010. 中国社会科学, 2012(7): 47-67.]
[33] Xin Liangjie, Li Xiubin, Tan Minghong, et al.The rise of ordinary labor wage and its effect on agricultural land use in present China. Geographical Research, 2011, 30(8): 1391-1400.
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[辛良杰, 李秀彬, 谈明洪, . 近年来我国普通劳动者工资变化及其对农地利用的影响. 地理研究, 2011, 30(8): 1391-1400.]
[34] Tian Yujun, Li Xiubin, Xin Liangjie, et al.Impacts of the rise of labor opportunity cost on agricultural land use changes: A case study of Ningxia Hui Autonomoous Region. Journal of Natural Resources, 2009, 24(3): 369-377.
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[田玉军, 李秀彬, 辛良杰, . 农业劳动力机会成本上升对农地利用的影响: 以宁夏回族自治区为例. 自然资源学报, 2009, 24(3): 369-377.]
目前我国农业劳动力机会成本上升趋势明显。于是劳动力资源成为农业生产决策的最关键因子;农户倾向于选择劳动生产率高的土地利用类型,同时促使部分劣质土地退出农业生产(即出现农地边际化)。论文以宁夏回族自治区为例,利用统计数据和农户调查数据来验证上述推断。研究结果表明劳动力机会成本上升对农地利用变化产生明显影响。具体为:①2003年以来,宁夏劳动生产率高的农作物(马铃薯、水稻、玉米)种植面积扩大,劳动生产率低的农作物(小麦)种植面积则缩小;②农地利用结构趋于单一化;③部分劣质土地退出农业生产。
[3] Rudel T K, Coomes O T, Emilio Moranc F, et al.Forest transitions: Towards a global understanding of land use change. Global Environmental Change, 2005, 15(1): 23-31.
Places experience forest transitions when declines in forest cover cease and recoveries in forest cover begin. Forest transitions have occurred in two, sometimes overlapping circumstances. In some places economic development has created enough non-farm jobs to pull farmers off of the land, thereby inducing the spontaneous regeneration of forests in old fields. In other places a scarcity of forest products has prompted governments and landowners to plant trees in some fields. The transitions do little to conserve biodiversity, but they do sequester carbon and conserve soil, so governments should place a high priority on promoting them.
DOI:10.1016/j.gloenvcha.2004.11.001      [本文引用:2]
[4] Lambin E F, Meyfroid P.Land use transitions: Socio-ecological feedback versus socio-economic change. Land Use Policy, 2010, 27(2): 108-118.
The concept of land use transition highlights that land use change is non-linear and is associated with other societal and biophysical system changes. A transition in land use is not a fixed pattern, nor is it deterministic. Land use transitions can be caused by negative socio-ecological feedbacks that arise from a depletion of key resources or from socio-economic change and innovation that take place rather independently from the ecological system. Here, we explore whether the sources of land use transitions are mostly endogenous socio-ecological forces or exogenous socio-economic factors. We first review a few generic pathways of forest transition as identified in national case studies, and evaluate the varying ecological quality of expanding forests associated with these pathways. We then discuss possible explanatory frameworks of land use transitions. We use the case of the recent forest transition in Vietnam as an illustration. Socio-ecological feedbacks seem to better explain a slowing down of deforestation and stabilization of forest cover, while exogenous socio-economic factors better account for reforestation. We conclude by discussing the prospects of accelerating land use transitions in tropical forest countries.
DOI:10.1016/j.landusepol.2009.09.003      [本文引用:1]
[5] Li Shengfa, Li Xiubin.Global understanding of farmland abandonment: A review and prospects. Journal of Geographical Sciences, 2017, 27(9): 1123-1150.
Since the 1950 s, noteworthy farmland abandonment has been occurring in many developed countries and some developing countries. This global land use phenomenon has fundamentally altered extensive rural landscapes. A review of global farmland abandonment under the headings of "land use change driving mechanisms impacts and consequences policy responses" found the following:(1) Farmland abandonment has occurred primarily in developed countries in Europe and North America, but the extent of abandonment has varied significantly.(2) Changing socio-economic factors were the primary driving forces for the farmland abandonment. And land marginalization was the fundamental cause, which was due to the drastic increase of farming opportunity cost, while the direct factor for abandonment was the shrink of agricultural labor forces.(3) Whether to abandon, to what extent and its spatial distributions were finally dependent on integrated effect from the physical conditions, laborer attributes, farming and regional socio-economic conditions at the village, household and parcel scales. With the exception of Eastern Europe, farmland abandonment was more likely to occur in mountainous and hilly areas, due to their unfavorable farming conditions.(4) A study of farmland abandonment should focus on its ecological and environmental effects, while which is more positive or more negative are still in dispute.(5) Increasing agricultural subsidies will be conductive to slowing the rate of farmland abandonment, but this is not the only measure that needs to be implemented. Due to China's rapid urbanization, there is a high probability that the rate of abandonment will increase in the near future. However, very little research has focused on this rapid land-use trend in China, and, as a result, there is an inadequate understanding of the dynamic mechanisms and consequences of this phenomenon. This paper concludes by suggesting some future directions for further research in China. These directions include monitoring regional and national abandonment dynamics, analyzing trends, assessing the risks and socio-economic effects of farmland abandonment, and informing policy making.
DOI:10.1007/s11442-017-1426-0      [本文引用:5]
[35] Chen Yuqi, Li Xiubin.Structural change of agricultural land use intensity and its regional disparity in China. Acta Geographica Sinica, 2009, 64(4): 469-478.
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[陈瑜琦, 李秀彬. 1980年以来中国耕地利用集约度的结构特征. 地理学报, 2009, 64(4): 469-478.]
基于中国农产品成本收益资料与中国农业统计年鉴等基础数据,在对耕地利用集约度进行内部结构划分的基础上,系统分析了1980-2006年间中国粮食作物劳动集约度和资本集约度及其构成的时空变化规律。结果表明:国家尺度上的劳动集约度由1980年的398.5日/hm2快速降低到2006年的130.25日/hm2,下降幅度达67.37%,下降的阶段性明显。资本集约度总量不断上升,其中种子、化肥和农药等增产性资本投入比重逐渐减小,在四大资本投入类型中所占比重由90.36%(1980年)下降到73.44%(2006年),相反,作为省工性投入的机械,所占比重由9.64%(1980年)迅速增加到26.56%(2006年),资本投入的内部结构变化逐渐成为影响中国粮食单产的重要因素。区域尺度上,经济发达地区劳动投入相对较少,资本投入,尤其是省工性资本投入比重较大,农户在耕地利用中更加注重追求劳动生产率;而经济相对落后地区劳动集约度较高,资本集约度较低,资本投入中仍以增产性投入为主,体现了当地农民在耕地利用中追求土地生产率最大化的经营目标。
[36] Zhu Huiyi, Li Xiubin, Xin Liangjie.Intensity change in cultivated land use in China and its policy implications. Journal of Natural Resources, 2007, 22(6): 907-915.
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[6] Gan Li, Yin Zhichao, Tan Jijun.China Household Finance Survey Report 2014. Chengdu: Southwestern University of Finance and Economics Press, 2015.
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[甘犁, 尹志超, 谭继军. 中国家庭金融调查报告2014. 成都: 西南财经大学出版社, 2015.]
[7] Li Shengfa, Li Xiubin, Xin Liangjie, et al.Extent and distribution of cropland abandonment in Chinese mountainous areas. Resources Science,2017,39(10): 1801-1811.
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[36] [朱会义, 李秀彬, 辛良杰. 现阶段我国耕地利用集约度变化及其政策启示. 自然资源学报, 2007, 22(6): 907-915.]
近年来,随着社会经济的快速发展和市场经济的不断完善,我国耕地利用中,农户利益最大化的个体追求逐步由耕地产出最大化向劳动力效益最大化方向发展,粮食生产对于农户的重要性在下降,导致我国粮食生产中耕地、资本和劳动力投入在1998年后出现下降趋势,北京、天津、上海、浙江、福建、江西、湖北、广东等省(市)区甚至出现耕地利用集约度总体下降的情况。耕地利用集约度的这一变化对我国粮食安全将产生深远的影响。文章在分析上述情况后认为,为实现我国粮食安全的国家目标,需要在耕地保护政策的基础上,进一步采取政策措施提高粮食生产的规模效益,以缓解粮食安全的国家目标与个体利益最大化的农户目标之间的冲突。
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[37] Wang Xue, Li Xiubin, Tan Minghong, et al.Remote sensing monitoring of changes in winter wheat area in North China Plain from 2001 to 2011. Transactions of the Chinese Society of Agricultural Engineering, 2015, 31(8): 190-199.
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[王学, 李秀彬, 谈明洪, . 华北平原2001-2011年冬小麦播种面积变化遥感监测. 农业工程学报, 2015, 31(8): 190-199.]
为及时、准确地获取华北平原冬小麦时空分布信息,构建多源遥感监测系统,基于MODIS EVI时间序列数据和两景TM影像,建立华北平原冬小麦时序波谱曲线库,并结合农作物物候历制订统一规则,在此基础上,重建华北平原2001-2011年冬小麦播种面积时空变化过程。结果表明:1)多源遥感监测系统提取华北平原2001-2011年冬小麦信息,在栅格尺度上获得了稳定的较高分类精度,平均为76.36%;在县域行政单元尺度上,2011年的冬小麦遥感监测面积与统计数据的耦合度也较高(决定系数为0.89,均方根误差为1.29×104 hm2);2)华北平原2001-2011年的冬小麦播种面积呈持续上升趋势,2011年比2001年增加了156.05×104 hm2(14.96%);3)冬小麦播种面积大致呈"南增北减"的时空变化格局:平原中南部的鲁西南平原、胶莱平原、豫东平原和皖北平原冬小麦种植面积扩张趋势显著;而北部的京津冀地区冬小麦面积明显收缩。该研究旨在为华北平原调整农业种植结构、制订粮食安全策略及优化水资源管理提供数据支持,也可为大范围、长时间尺度的作物播种面积时空变化遥感监测提供方法借鉴。
[7] [李升发, 李秀彬, 辛良杰, . 中国山区耕地撂荒程度及空间分布: 基于全国山区抽样调查结果. 资源科学, 2017, 39(10): 1801-1811.]
耕地撂荒是当前全球山区主要的土地利用变化现象,它深刻地改变了山区农村土地利用结构、农业景观和农户生计,并带来了巨大的生态环境和社会经济效应.2000年以来,随着中国劳动力成本的快速上升和农村劳动力的大量析出,中国山区农业因地形限制,机械化发展受阻,耕地面临着较大的撂荒风险.越来越多的案例研究和报道表明中国山区耕地撂荒现象越演越烈.中国山区面积广、坡耕地比重大,耕地撂荒不仅关系到山区农地的合理利用政策和山区可持续发展政策的制定,并可能引起粮食安全问题,但目前仍缺少全国层面的定量化评估研究.因此,本研究通过开展大范围的抽样调查对中国山区县撂荒规模进行了推算,以期为相关政策制定以及耕地边际化进一步研究提供参考.研究结果表明,在235个调查村庄中,78.3%的村庄出现耕地撂荒现象;基于县样本统计的2014-2015年全国山区县耕地撂荒率为14.32%;山区耕地撂荒率在省级尺度上呈现出南高北低的空间格局,其中,长江流域一带的山区耕地撂荒率最高,东北的长白山区最低.
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[8] Li Jing.Study on abandonment of cultivated land in mountin areas based on labor emigration [D]. Chongqing: Southwest University, 2013.
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[李静. 基于劳动力析出的山区耕地撂荒研究[D]. 重庆: 西南大学, 2013.]
[9] Shi Tiechou, Xu Xiaohong.Extraction and validation of abandoned farmland parcel in typical counties of Chongqing. Transactions of the Chinese Society of Agricultural Engineering, 2016, 32(24): 261-267.
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[史铁丑, 徐晓红. 重庆市典型县撂荒耕地图斑的提取与验证. 农业工程学报, 2016, 32(24): 261-267.]
[10] Zhang Bailin, Yang Qingyuan, Yan Yan, et al.Characteristics and reasons of different households' farming abandonment behavior in the process of rapid urbanization based on a survey from 540 households in 10 counties of Chongqing municipality. Resources Science, 2011, 33(11): 2047-2054.
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[张佰林, 杨庆媛, 严燕, . 快速城镇化进程中不同类型农户弃耕特点及原因: 基于重庆市十区县540户农户调查. 资源科学, 2011, 33(11): 2047-2054.]
运用参与式农村评估法、Logistic分析法,基于农户兼业活动探讨不同类型农户弃耕特点及原因,为破解生态脆弱的贫困地区农地资源低效利用问题提供参考。结果表明:①重庆市农户兼业普遍,根据非农收入比重、劳动力配置状况和生计策略,将农户划分为纯农户、I兼农户和II兼农户;②农户耕地转出行为普遍,无偿转出比重偏高。II兼农户弃耕及有偿转出比重均最高,与I兼农户相比,纯农户耕地转出的户数多,但转出面积少且多为无偿转出;旱地撂荒较水田普遍,撂荒的多为地块破碎、耕作条件差的地块;③由于家庭成员年龄偏老、劳动能力偏弱等的局限,纯农户会放弃对区位偏远、零星分散地块的耕种;I兼农户更关注土地经济收益,将资本投入到耕作条件好的地块;II兼农户主要基于收益最大化原则,倾向于将要素投入到非农产业,有偿转出耕地。研究认为,根据不同类型农户弃耕特点及原因制定相应政策措施来引导其土地利用行为,是整合区域土地资源、提高农地利用效率的有效途径。
[11] Xu Li. How to solve the problem of farmland abandonment in the process of urbanization: A case study in Sichuan Province. ural Economy, 2010(3): 21-24.
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[徐莉. 城市化进程中如何解决农地抛荒问题: 以四川省为例. 农村经济, 2010(3): 21-24.]
随着我国城市化进程的加快,工业和城市占用土地快速增加,导致耕地面积不断减少.同时,农村劳动力不断流向城市,各地农村出现了土地抛荒日益严重的现象,不仅造成土地资源的极大浪费,而且增加了我国的粮食安全隐患.本文以四川省为例,总结了当前农地抛荒的特点及原因,认为农业的比较效益低,"劣等地"的地租更低、土地流转交易成本高是城市化进程中农地抛荒的根本原因,建议通过调整农村产业结构、推进农业产业化进程,推广农业科学技术、改善农业生产条件、提高农业生产力,推进土地流转和集中、促进农地适度规模经营,实行农地抛荒责任追究制度等措施,有效遏制农地抛荒现象.
[12] Luo Shengkui. Causes and countermeasures of farmland abandonment in Yongding County. Fujian Agricultural Science and Technology, 2008(3): 88-89.
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[罗胜奎. 永定县耕地抛荒成因分析与解决对策. 福建农业科技, 2008(3): 88-89.
近年来,永定县各乡镇不同程度地出现耕地抛荒现象。为充分了解耕地抛荒的原因,以进一步提出相应的解决对策,县农技站于2007年4月17~30日结合春耕生产检查对当前农村土地承包中出现的耕地抛荒现象进行了专项调研。现将调查结果报道如下。1耕地抛荒现状据2007年4月17~30日调查,
[13] Yi Meiying. Reasons and countermeasures of cultivated land abandonment in Songxi County. Modern Agricultural Science and Technology, 2014(18): 330-331.
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[伊梅英, 松溪县耕地抛荒的原因及对策. 现代农业科技, 2014(18): 330-331.]
[14] Luo Pinghu, Tang Yu, Kang Hongjun, et al.Empirical study on factors influencing farmers' willingness to cropland abandonment in Hunan Province. Acta Agriculturae Zhejiangensis, 2015, 27(8): 1494-1498.
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[罗湖平, 唐禹, 康红军, . 湖南省农户耕地抛荒意愿影响因素实证研究. 浙江农业学报, 2015, 27(8): 1494-1498.]
从农户视角出发,运用Logistic模型对湖南省9县9村耕地抛荒现象中的农户意愿影响因素进行实证分析。结果表明,农户耕地距离因素和农户文化程度因素对模型产生了正相关的显著影响,农户耕作季数因素和农户耕作收入满意度因素对模型产生了负相关的显著影响。<br>
[38] Strijker D.Marginal lands in Europe: Causes of decline. Basic and Applied Ecology, 2005, 6(2): 99-106.
Dieser Artikel analysiert die Ver01nderungsmechanismen landwirtschaftlicher Bodenbewirtschaftung. Intensivierung von Bodenbewirtschaftung einerseits und das Wegziehen vom Land anderseits hatten bedeutende Konsequenzen für Landschaft und Biodiversit01t. Der Grundmechanismus dahinter ist eine Ver01nderung in den relativen Preisen von Inputs und Output. In diesem Sinne haben die allgemeinen wirtschaftichen Entwicklungen die Ver01nderungen landwirtschaftlicher Bodenbewirtschaftung bestimmt. In West-Europa war der schnelle Anstieg der Opportunit01tskosten von Arbeit der Hauptfaktor hinter Mechanisierung und Intensivierung der Landwirtschaft. Auch die gemeinsame Agrarpolitik der EU hat Intensivierung stimuliert. Rezente politische Entwicklungen haben wichtige Anreize für weitere Intensivierung reduziert. Diese Tatsache jedoch l02st das Problem der Abnahme landwirtschaftlicher Low-input-Syteme in Europa nicht. Der einzige Weg, diese Systeme aufrechtzuerhalten, sind spezifisch auf Natur bezogene Ma08nahmen.
DOI:10.1016/j.baae.2005.01.001      [本文引用:1]
[39] Queiroz C, Beilin R, Folke C, et al.Farmland abandonment: Threat or opportunity for biodiversity conservation? A global review. Frontiers in Ecology and the Environment, 2014, 12(5): 288-296.
Farmland abandonment is changing rural landscapes worldwide, but its impacts on biodiversity are still being debated in the scientific literature. While some researchers see it as a threat to biodiversity, others view it as an opportunity for habitat regeneration. We reviewed 276 published studies describing various effects of farmland abandonment on biodiversity and found that a study's geographic region, selected metrics, assessed taxa, and conservation focus significantly affected how those impacts were reported. Countries in Eurasia and the New World reported mainly negative and positive effects of farmland abandonment on biodiversity, respectively. Notably, contrasting impacts were recorded in different agricultural regions of the world that were otherwise similar in land-use and biodiversity characteristics. We showed that the conservation focus (pre- or post-abandonment) in different regions is an important factor influencing how scientists address the abandonment issue, and this may affect how land-use policies are defined in agricultural landscapes.
DOI:10.1890/120348      [本文引用:1]
[15] Huang Jianqiang, Li Lutang.Dilemma of idling arable land in mountainous areas and its causes and countermeasures: Take Huitong County as an example. Journal of UESTC (Social Sciences Edition), 2009, 11(4): 11-14.
[本文引用:1]
[黄建强, 李录堂. 山区耕地抛荒困境及其原因解读与对策: 以湖南省会同县为例. 电子科技大学学报(社科版), 2009, 11(4): 11-14.]
无论是山区政府,还是村官与农户,都存在着耕地抛荒与不抛荒的困境.通过调查研究,透过这种困境与矛盾,发现还隐藏着许多深层次问题,据此建立了农村人力资源与耕地抛荒面积的模型,提出了摆脱困境的具体思路,期望为山区农业的发展、政府政策的制定和粮食安全提供参考.
[16] Zhao Yuluan, Zhang Meng, Li Xiubin, et al.Farmland marginalization and policy implications in mountainous areas: A case study of Renhuai City, Guizhou. Journal of Resources & Ecology, 2016, 7(1): 61-67.
Farmland resources in mountainous areas are important for regional food security and ecological security. Studies concerning changes in farmland use in mountainous areas are of considerable significance in China. Here, we analyzed marginalization characteristics of farmland in Renhuai city from 2005 to 2011 and driving factors using land information systems, surveys of farmer households and statistical data. Our results indicate that from 2005 to 2011, 3095.76 hm2 of farmland was converted to forest land and natural reserve, accounting for 5.45% of the total farmland area. This suggests significant marginalization of farmland. Marginalization of farmland in mountainous areas was affected by topography, labor forces and effectiveness of land management. Farmland with a greater slope gradient was more likely to be abandoned; among marginalized land in Renhuai, a slope greater than 15 accounted for 62.26%. A high non-agricultural employment rate of rural labor force and annual income per capita of farmer households in mountainous areas were consistent with high speed farmland marginalization. Low land management benefits were the key reason for farmland marginalization. Although farmland marginalization was advantageous for eco-environment protection and sustainable development in mountainous areas, it resulted in inefficient land resource utilization. A win-win model for the exploitation and utilization of sloping farmland should be explored for production development and environmental protection.
DOI:10.5814/j.issn.1674-764X.2016.01.008      [本文引用:1]
[17] Tian Yujun, Li Xiubin, Ma Guoxia, et al.Influences of labor emigration from agriculture on the production abandonment of cultivated land in ecological sensitive areas. China Land Science, 2010, 24(7): 4-9.
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[田玉军, 李秀彬, 马国霞, . 劳动力析出对生态脆弱区耕地撂荒的影响. 中国土地科学, 2010, 24(7): 4-9.]
研究目的:以宁夏南部山区为 例,研究农业劳动力析出对生态脆弱区耕地撂荒的影响。研究方法:二分类logistic回归模型。研究结果:撂荒耕地面积与劳动力外出数量、时间及农户所 拥有的耕地总面积呈正相关;耕地中的坡耕地和旱地首先被撂荒。研究结论:劳动力析出会促使农户撂荒部分质量差的耕地;这种撂荒行为有助于生态环境的自然恢 复。
[18] Chang Lianyu.Investigation and thinking on the cropland abandonment in Jingning County. Agricultural Development and Equipment, 2014(8): 21-22.
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[常连余. 静宁县农村耕地撂荒情况的调查与思考. 农业开发与装备, 2014(8): 21-22.]
土地是农民长期赖以生存的最基本生产资料,是逐年递减的有限资源。要解决好静宁县48万人口的吃饭问题,确保粮食安全,县委、政府根据国家政策制订了一系列富民、惠民政策,如取消农业税、对种粮农民种粮直接补贴、良种补贴、农机具补贴和重大农业技术推广专项补贴等,以调动广大农民种粮积极性。然而,耕地的减少,大量的农村劳动力外出和农产品价格的持续走低等原因,致使农村耕地撂荒面积与日俱增。耕地撂荒加速了土地干旱、瘠薄、盐碱的进程,影响土地质量,好地变差地,熟土变生土,导致了严重水土的流失,影响粮食安全。针对这一问题,调查了耕地撂荒的原因,提出解决农村耕地撂荒的对策建议。