“退林还耕”?原来是个伪概念

今年以来,我国部分地方对辖区内违规占用耕地种树造林的现象进行纠偏,要求整改复耕、恢复种粮。一些网络自媒体在报道这一现象时,生造了一个叫做“退林还耕”的概念,并且和此前国家出台的“退耕还林”政策相提并论。“退林还耕”这个望文生义的“标题党”概念在网上热传,听着确实顺口,也和国家此前出台的“退耕还林”政策有点对应。

没有“退林还耕”,只有耕地保护

近段时间,所谓“退林还耕”成了网上热词,部分自媒体将其与“退耕还林”政策相提并论。其实大谬不然“退耕还林”早已有之。1999年,党中央、国务院着眼经济社会可持续发展的全局,作出了“退耕还林还草”的重大决策。后来,“退耕还林还草”这一说法被大家约定俗成称为“退耕还林”。

Changes of Organic Carbon in Soil under Different Land Use Patterns in Alpine Agricultural Region of Qinghai

Using organic carbon density grouping method,the change trends of soil total organic carbon(SOC),light fraction content and light fraction organic carbon under 4 land use patterns of returning cultivated land to forest(cropland,artificial forest,inter-cropping of forest and grassland and original sample plot)in alpine agricultural region of Qinghai were studied.The content of SOC was in order:intercropping of forest and grassland > original sample plot > artificial forest > cropland.There was signi...

Carbon Sink Effects in Conversion of Farmland to Forest Project in Karst Drainage Basin——A Case of Hongfenghu Drainage Basin in Guizhou Province

[Objective]Study on carbon sink effects in Conversion of Farmland to Forest Project in Hongfenghu drainage basin in order to provide evidences for assessing carbon sink potential of conversion of farmland to forest in Guizhou Province.[Method]By investigating the implement of Conversion of Farmland to Forest Project in Hongfenghu drainage basin from 2000 to 2006,the carbon sink amount and effect of seven main tree species in the foreat region like Cunninghamia lanceolata,Cryptomeria fortunei,Amygdalus persica,Prunus salicina,Armeniaca vulgaris,Camptotheca acuminate and Catalpa bungei were calculated,based on which the amount of forest carbon sinks in Hongfenghu drainage basin in 2015 was estimated.[Result]Biomass storage and carbon sink amount in middle and young aged forests were increasing over time from 2000 to 2006,which reached 1.05×107 kg by 2006 and would engage more and more potential.Cunninghamia lanceolata has the superior carbon sink capacity in the seven tree species in the research region,of which the amount of carbon sink per unit area will be 106.51 t/hm2 by 2015,followed by Cryptomeria fortunei with the amount of carbon sink per unit area by 99.42 t/hm2.Armeniaca vulgaris has the weakest carbon sink capacity of all the seven species with the amount of 13.03 t/hm2.The total amount of carbon sink in seven tree species was 2.35×107 kg,while the average amount of carbon sink per unit area was 26.17 t/hm2,which could produced economic benefit of 7.17×106 yuan calculated on the price of 305.0 yuan/t or 5.91×106 yuan calculated on the price of 254.1 yuan/t.[Conclusion]Economic benefits of carbon sink effects of Conversion of Farmland to Forest Project in Hongfenghu drainage basin were great with huge appreciation potential.

Study on Evapotranspiration Regularity of 3 Forages in Eastern Qinghai Province

The transpiration rate and transpiration quantity＇of whole plants and foliages of Bromus innerrnis, Medicago sativa and Agropyron cristatum are measured by using improved quick and continuous weighting after being cut off method （QCWC）. The results show that transpiration rate of branches and foliages of Agropyron cristatum is highest in 3 forages, Medicago sativa is second and Bromus innermis is lowest. From July to September, the average transpiration quantity of whole plants and foliages of 3 forages is highest in August, September is second and July is lowest.

Responses of terrestrial water cycle components to afforestation within and around the Yellow River basin

Reforestation has attracted worldwide attention because of its multiple environmental benefits,but its impact on water resources is complicated and still controversial. In this study, the authors conducted numerical experiments within and around the Yellow River basin under the Grain-forGreen project using the Weather Research and Forecasting model. The results showed that the terrestrial water cycle process was sensitive to land use/cover change in the study region. Under the increase of mixed forests within and below the basin, the basin-averaged precipitation and evaporation increased by 223.17 and 223.88 mm respectively, but the surface runoff decreased by 2.22 mm from 2006 to 2010. In other words, the forest-induced increase in evaporation exceeded that of precipitation along with decreased surface runoff. Importantly, the afforestation effects on water resources seemed to enhance with time, and the effects of the same vegetation change were different in dry and wet years with different precipitation amounts(i.e. different atmospheric circulation background). It should be noted that it is difficult to obtain one product that can explicitly reflect the spatial distribution of actual land cover change promoted by the Grain-for-Green project in the Yellow River basin, which is an important obstacle to clearly identify the reforestation impacts. A land cover dataset derived from advantages of multiple sets of data therefore needs to be proposed.

Multi-scales Analysis of Driving Forces on Land Use/Cover Change in China:Taking Farmland Returning to Forest or Grassland as a Case

Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country) –regional (province) – local (county) – household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers’ income and improving agricultural production conditions as the main types; at the household scale, the nationalpolicy meeting farmers’ demands and the optimization of individual interests are all driving forces.

Modelling Regional Land Change Scenarios to Assess Land Abandonment and Reforestation Dynamics in the Pyrenees(France)

Over the last decades and centuries,European mountain landscapes have experienced substantial transformations.Natural and anthropogenic LULC changes(land use and land cover changes), especially agro-pastoral activities,have directly influenced the spatial organization and composition of European mountain landscapes.For the past sixty years, natural reforestation has been occurring due to a decline in both agricultural production activities and rural population.Stakeholders, to better anticipate future changes,need spatially and temporally explicit models to identify areas at risk of land change and possible abandonment.This paper presents an integrated approach combining forecasting scenarios and a LULC changes simulation model to assess where LULC changes may occur in the Pyrenees Mountains,based on historical LULC trends and a range of future socio-economic drivers.The proposed methodologyconsiders local specificities of the Pyrenean valleys,sub-regional climate and topographical properties,and regional economic policies.Results indicate that some regions are projected to face strong abandonment, regardless of the scenario conditions.Overall, high rates of change are associated with administrative regions where land productivity is highly dependent on socio-economic drivers and climatic and environmental conditions limit intensive(agricultural and/or pastoral) production and profitability.The combination of the results for the four scenarios allows assessments of where encroachment(e.g.colonization by shrublands) and reforestation are the most probable.This assessment intends to provide insight into the potential future development of the Pyrenees to help identify areas that are the most sensitive to change and to guide decision makers to help their management decisions.

Changes in Land Use and Agricultural Production Structure Before and After the Implementation of Grain for Green Program in Western China–Taking Two Typical Counties as Examples

Soil erosion becomes a serious environmental problem in the world, especially in western China. An effective management practice called the Grain for Green Program(GGP), which was launched in 1999, aims to reduce soil and water loss and alleviate the ecological environment problem in western China. Two typical counties in western China, the Zhongxian(in Chongqing Municipality) and Ansai(in Shaanxi Province) were chosen to evaluate the dynamic changes of land use and agricultural production structure before and after the implementation of the Program in this paper. The results showed that the cultivated land area was reduced by 7.08% from 1989 to 2003. The cultivated land per person was decreased by 8.42% during 1999-2003. Moreover, the stability index of the secondary sector of the economy was increased from 0.91 in the period 1990-1999 to 0.94 in the following ten years. In addition, the stability index of tertiary economic sector increased from 0.88 to 0.92 in Zhongxian county. Meanwhile, the cultivated land area was reduced by 15.48% from 1990 to 1999. The soil erosion modulus was decreased by 33.33% from 1999 to 2006. Also, the stability index of secondary and tertiary economic sectors was 0.86 in the period 1998-2002. However, it decreased by 77% during 2002 to 2007 in Ansai County. These results imply that the Grain for Green Program had different impact on the two regions. Several effective strategies of soil and water conservation have been carried out to ameliorate the sustainable development of ecological environment and economy in these two counties of western China.

Soil Erosion Control Degree of the Project of Converting Farmland to Forest in Mountainous Areas at China's Southwest Border:A Case Study in Mangshi,Yunnan Province

There have been few in-depth quantitative studies on soil erosion control and the ecological effects of land use changes. Soil erosion is the first eco-environmental problem particularly in mountainous areas. A major problem in the conversion of farmland to forest is to control soil erosion and improve ecological environment and thus to improve land use sustainability. We report results of calculation and analysis on soil erosion from converted farmland parcels in city of Mangshi （near the SW frontier of China） and the surrounding areas before and after the nine-year （2000-2009） project of converting farmland to forest. There was increased water conservation effect, as a result of decreased soil erosion. The average erosion modulus of the farmland returning to eco-friendly uses decreased by 5,535.59 t/km2·a and the control degree of soil erosion modulus reached 71.00%. The increased soil erosion after the returning in the typical sample area ＂did not drop, but increased＂ as the terraced fields decreased but sloping farmland inereased and yet woodland decreased.

Effects of slope position and land use on the stability of aggregateassociated organic carbon in calcareous soils

Topography and land use affect soil organic carbon(SOC) storage, stabilization, and turnover, through several biogeochemical processes. This study investigated the aggregate composition and SOC content of bulk soils and aggregates at different slope positions under different land uses in a typical karst catchment of southwestern China. Our results show that the proportion of macro-aggregates and the SOC content of bulk soils and aggregates at different slope positions decreased from the upper to the lower slope. The SOC content generally increased with an increase in the mean weight diameter and proportion of macro-aggregates under different land uses. Our results indicate that macro-aggregates in forest and grassland soils make a greater contribution to both aggregate composition and SOC content than that in arable land soils. Therefore,converting farmland to forest or grassland can facilitate the accumulation of macro-aggregates as well as the storage of SOC.

Impacts of Sloping Land Conversion Program on the vegetation in loess hilly and gully area of northern Shaanxi

Aiming at alleviating the serious soil erosion, the Chinese government initiated the Sloping Land Conversion Program （SLCP） in 1999. Now; after 8 years of project implementation, the ecological recovery effects of the SLCP have become the hot issue of academic circle. This paper; raking the loess hill and gully area of northern Shaanxi as an example, presents a methodology for assessing the vegetation restoration effect of SLCP with normalized difference vegetation index （NDVI）. The key components include calculation of the Growing Season NDVI （GSNDVI）, and estimation of the NVDI change induced by climate and SLCP, respectively. Based on the method, the NDVI change between 2000 and 2006 was obtained using the GSNDVI that excluded the noise from snow and ice. After the part of total NDVI change caused to： climate variation was estimated using empiric formulae, we obtained the part induced by human factors, i.e. the SLCP The human induced part of ND VI change was considered as an approximation indicating the effect of the SLCP on the vegetation. Finally, we analyzed the ND VI change characters of the whole study area, different slope lands and different land use types by spatial statistics method. Results show that the vegetation condition is significantly improved by the SLCP, particularly land types that directly involved in the SLCP, such as steeply slope farmlands, degraded grasslands, etc.

Observations on forest restoration in Jilin, China

This paper reviews various forestry practices in Jilin Province, China. The authors emphasize the rich natural diversity of Jilin and the need to focus research efforts on understanding the potential of native species to meet the needs of land-management agencies involved in forest resource exploitation and ecological restoration. The native species of China hold great potential, and deserve more research attention, for meeting these needs. The introduction and testing of exotic species should be dbne only under rigorous scientific testing and after comparison with native species prior to operational introduction into forestry in order to avoid unwanted ecological consequences, including potential problems with alien invasives and pest introductions. The authors also emphasize the need to maintain viable （e.g., genetically diverse and reproductively fit） natural populations of native species in order to protect China＇s valuable natural diversity and maintain the potential of native species to function as future seed sources for local forest and ecological restoration activities.

Research on Converting Cultivated Land into Forests and Regional Sustainable Development

The capability of sustainable development of Wuchuan County is evaluated comprehensively with theories and methods of regional sustainable development capability evaluation, which are extensively applied at home and abroad. The results indicate that the developing speed and patterns of Wuchuan County cannot satisfy the demand of the regional sustainable development. Moreover, the patterns, distributions, tree species, growing patterns, and other aspects must consider the restriction of ecological water utilization. It is put forward that the standards for selecting the converting lands are slope, desertification degree, and rainfall.In addition, the control of soil erosion and the prevention of land desertification are selected as the dualpurpose of the converting project.

浅析退耕还林与种草养畜的重要意义

保护生态环境、科学利用生态环境是实现经济发展促进农民增收的的重要渠道,退耕还林是我国国务院提出的一项促进农业发展的重要可持续发展战略。在政策的引导下不同的地区有着不同的治理办法,紧紧围绕国家政策,解决农业发展中遇到的问题,实现区域特色农业的发展是我们必须认清的重点。本文主要结合中和镇的实际情况简要分析了退耕还林与种草养畜的重要意义。

Net Primary Productivity Increased on the Loess Plateau Following Implementation of the Grain to Green Program

The spatio-temporal characteristics of net primary productivity（NPP） since implementation of the Grain to Green Program（GTGP） are important for understanding ecological restoration of the Loess Plateau in China. Here, we conduct spatio-temporal analysis of NPP using MODIS datasets（500 m, 8-day intervals） and VPM（Vegetation Photosynthesis Model） from 2000–2015. We found that NPP on the Loess Plateau increased significantly from 2000 to 2015（p0.05）. Significant increases in NPP were observed in core areas of the GTGP, including northern Shaanxi and Lüliang Mountain in Shanxi. NPP in alluvial plains decreased due to urban expansion into cropland. Significant increases in NPP from 2006–2010 were located north of the area of change in 2000–2005. NPP increased across three vegetation types and four slope gradients. In hilly-gully regions prone to soil erosion, such as central and southeastern parts of the Loess Plateau, obvious vegetation restoration was detected.

Responses of Ecosystems to Ecological Compensation in a Key Ecological Function Area of the Loess Plateau

Evaluation of the ecological effects of eco-compensation policies helps analyze policy rationality and feasibility and provides scientific and practical bases for perfecting eco-compensation systems. Taking the key ecological function area of the Loess Plateau, China as a case study, we have evaluated ecosystem responses to the Grain-for-Green Project that commenced in 1999. Six indicators were selected to assess changes in ecosystem structure, quality and function. The results showed that implementation of the Grain-for-Green Project has reduced sloping cropland by 1571 km2 and increased ecological land by 1337 km2. The increase in ecological land alters ecosystem structures across the study area and the decline in sloping cropland reduces farming activity interference; both of these are conducive to the restoration of natural vegetation. From 2000 to 2010, the vegetation cover of grassland, desert and forest ecosystems increased 10.89%, 8.34% and 4.24% respectively and average NPP rose 51%, with an average annual growth rate of around 5%. This indicates that eco-compensation has promoted the improvement of ecosystem quality. Total biomass of ecosystems increased two times on average from 2000 to 2010, meaning that the carbon sequestration capacity of ecosystems also increased. The reduction in the area of water loss and soil erosion and the increase in retained runoff by forests indicate an improvement in ecosystem function and services on the Loess Plateau.

这里康养正好

澧浦镇是全国闻名的花木之乡,全镇苗木种植面积达3万亩。华东地区最大的花卉苗木交易集散中心就在镇上,年交易额曾经高达15亿元。然而,近年来受“退林还耕”、“非粮化”整治、大型苗木交易相关要求的新规制约,澧浦镇的苗木产业发展陷入困局:大树老树销售受到一定限制,小苗杯苗需求不温不火。