Impact of agricultural intensification on soil organic carbon＂ A study using DNDC in Huantai County, Shandong Province, China

Using the biogeochemical model den itrification/decomposition （DN DC）, the dynamic changes of soil organic carbon （SOC） of farmland from the 1980s to 2030s were investigated in Huantai County, a typical intensive agricultural region in the Huang- Huai-Hai Plain of China. Prior to modelling, validation of the DNDC model against field data sets of SOC from Quzhou Experimental Station in the Huang-Huai-Hai Plain was conducted at the site scale. We compared the simulated results with the observed SOC in Huantai County during 1982-2011 under two different classification methods of simulation unit （the first method integrated soil type and land use of Huantai County to form the overlapped modeling units; the second selected the 11 administrative towns as the modeling units）, and achieved a high accuracy in the model simulation with the improvement of the model parameters. Regional SOC （0-20 cm） density and stocks for Huantai County in the years 2012-2031 were predicted under different scenarios of farming management. Compared with current management practices, optimized fertilization （20% decrease of mineral N）, crop straw incorporation （90%） and appropriate animal manure input （40 kg N ha-1 yr-1） could achieve the highest level of SOC density （56.8% higher than 2011） in the period of 2012-2031. The research highlighted the importance of crop straw incorporation, optimized N fertilization and integration of crop production with ani- mal husbandry on the farmland carbon sequestration for maintaining a high land productivity in the Huang-Huai-Hai Plain.

Identification of agricultural systems in the mountains of Northeast Thailand

Agricultural systems in Thailand's northeastern mountains are described in terms of their type of crops, marketing channels, and labor requirements. Five distinctive systems are identified: The Field crop system, Fruit tree system, Industrial tree plantation system, Specialty crop system and Agro-tourism system. The different systems are compared with each other in order to identify their respective strengths and weaknesses as development models. The Field crop system covers the largest area of agricultural land and is found in all mountainous villages but it generates very low net profits per hectare. The Specialty crop system and Agro-tourism system generate very high net profits per hectare but cover only a small land area and have a restricted spatial distribution. Expansion of these high value systems may be limited because they are capital and labor intensive and require highly skilled farmers to manage them successfully. If these constraints can be overcome, they may offer a useful model for mountain agricultural development.

Multiple Cropping Intensity in China Derived from Agro-meteorological Observations and MODIS Data

Double-and triple-cropping in a year have played a very important role in meeting the rising need for food in China.However,the intensified agricultural practices have significantly altered biogeochemical cycles and soil quality.Understanding and mapping cropping intensity in China′s agricultural systems are therefore necessary to better estimate carbon,nitrogen and water fluxes within agro-ecosystems on the national scale.In this study,we investigated the spatial pattern of crop calendar and multiple cropping rotations in China using phenological records from 394 agro-meteorological stations(AMSs)across China.The results from the analysis of in situ field observations were used to develop a new algorithm that identifies the spatial distribution of multiple cropping in China from moderate resolution imaging spectroradiometer(MODIS)time series data with a 500 m spatial resolution and an 8-day temporal resolution.According to the MODIS-derived multiple cropping distribution in 2002,the proportion of cropland cultivated with multiple crops reached 34%in China.Double-cropping accounted for approximately 94.6%and triple-cropping for 5.4%.The results demonstrat that MODIS EVI(Enhanced Vegetation Index)time series data have the capability and potential to delineate the dynamics of double-and triple-cropping practices.The resultant multiple cropping map could be used to evaluate the impacts of agricultural intensification on biogeochemical cycles.

Farming-Biodiversity Segregation or Integration? Revisiting Land Sparing versus Land Sharing Debate

Land Sparing (LSP) was proposed to spatially segregate biodiversity and production in order to maximize both, while Land Sharing (LSH) defenders posit that farming and nature integration is preferable, through eco-agriculture and low-input systems. Based on a multidisciplinary review on historical land-use data, ecological aspects, agricultural production potential, economic and food security topics, we summarize LSP/LSH major findings and caveats. Although LSH still has to address some issues, LSP relies on a series of assumptions that are not supported by data, particularly regarding the positive effects of intensification on agriculture expansion. Furthermore, we developed conceptual models to theoretically predict the responses of biodiversity and ecosystems services in dynamic landscapes with different natural habitat proportions and different intensification levels on the farmed areas. Agriculture intensification may expand farmland reducing habitat area fostering population declines at the “natural” patches (via habitat reduction and decreasing species intra patch flux through the matrix), as well as at the farm site by direct effect of intensification (heterogeneity reduction and pesticide use), leading to a species extinction and ecosystems services loss. This multiple negative effect of agriculture intensification is worsening in regions where habitat proportion is below 30%, such as in many tropical biodiversity hotspots, making LSH a much safer strategy for conservation and food security.

Arbuscular mycorrhizal fungi reduce ammonia emissions under different land-use types in agro-pastoral areas

Ammonia(NH3)emissions,the most important nitrogen(N)loss form,always induce a series of environmental problems such as increased frequency of regional haze pollution,accelerated N deposition,and N eutrophication.Arbuscular mycorrhizal(AM)fungi play key roles in N cycling.However,it is still unclear whether AM fungi can alleviate N losses by reducing NH3emissions.The potential mechanisms by which AM fungi reduce NH_(3)emissions in five land-use types(grazed grassland,mowed grassland,fenced grassland,artificial alfalfa grassland,and cropland)were explored in this study.Results showed that AM fungal inoculation significantly reduced NH3emissions,and the mycorrhizal responses of NH3emissions were determined by land-use type.Structural equation modeling(SEM)showed that AM fungi and land-use type directly affected NH_(3)emissions.In addition,the reduction in NH_(3)emissions was largely driven by the decline in soil NH_(4)^(+)-N and pH and the increases in abundances of ammonia-oxidizing archaea(AOA)amoA and bacteria(AOB)amoB genes,urease activity,and plant N uptake induced by AM fungal inoculation and land-use type.The present results highlight that reducing the negative influence of agricultural intensification caused by land-use type changes on AM fungi should be considered to reduce N losses in agriculture and grassland ecosystems.

A perspective on greenhouse gas emission studies integrating arbuscular mycorrhiza

Climate change is a global emergency.It is only possible to pace down global change through addressing the triggers of it,greenhouse gas emissions.Despite commendable progress,we think that there is plenty of room to further make the studies addressing global change realistic,through integrating into them biotic interactions.We make a case for this statement through a bibliometrics analysis on agricultural studies exploring greenhouse gas emissions that consider arbuscular mycorrhiza.We show that even though mycorrhizal studies account right now for a small fraction of the agricultural literature,they get cited more often.We further demonstrate that mycorrhizal studies are typically more descriptive in their nature,which we support through comparing the keywords they list.We subsequently use the opportunity to identify shortcomings and opportunities to further integrate mycorrhiza into agricultural studies assaying greenhouse gas emissions.We finally make a call to better integrate arbuscular mycorrhiza into global change studies.

Cropland expansion facilitated the outbreak of cereal aphids during 1951–2010 in China

Landscape-scale pattern could affect ecosystem service such as biocontrol of agricultural pests. Additionally, pest outbreak has been shown to be interwoven with land-use intensity. In the present research, we collected and analysed the 60-year data of cereal aphids and wheat area during 1951–2010 in China. Regression model was applied to analyse the relationship between pest damage and cropland expansion. Results showed that the percentage of cereal aphid outbreak area in wheat area increased rapidly during 1951–2010. It was 9 % during 1951–1960, while it was above 60 % during 2001–2010. In addition, effect of cropland expansion on damage of cereal aphids was significantly positive, which indicated that cropland expansion in agricultural landscape may enhance pest damage greatly.Finally, we concluded that cropland expansion was one of the most important drivers of increasing pest outbreak,which should be considered in sustainable management of cereal aphids combined with other factor(e.g. climate changes and resistant variety) at large spatiotemporal scale.

Functional diversity and trait composition of butterfly and bird communities in farmlands of Central Romania

Cultural landscapes all over the world harbor species communities that are taxonomically and functionally diverse.In Eastern Europe,but also in many other regions of the world,the conservation of this farmland biodiversity is threatened by land use intensification and abandonment.In order to counteract the negative effects of land use change in such landscapes,a thorough understanding of the functional relationships between species and their environment is crucial.In this study,we investigated the relationship of functional traits of butterfly and bird communities and environmental conditions in 120 sites in traditional farmlands of southern Transylvania,Romania.First,we compared taxonomic diversity(i.e.,Shannon diversity)with functional diversity(i.e.,functional dispersion),and second,we linked species traits to environmental variables by performing RLQ analyses.Functional traits indicating reproduction,movement,and feeding behavior related with environmental variables describing heterogeneity,amount of woody vegetation,and topography at three different spatial scales.We found positive relationships between taxonomic and functional diversity,as well as strong linkages between species traits and environmental conditions for both groups.Specifically,butterfly composition was most strongly influenced by land use type and life-history strategies.Bird composition was most strongly related to the amount of woody vegetation and nesting and foraging strategies.We conclude that maintaining the typical features of traditional farming landscapes,especially a small-scale heterogeneity in arable land and gradients of woody vegetation cover,would be desirable in order to sustain a high functional diversity in southern Transylvania in the future.