HARNESSING ECOLOGICAL PRINCIPLES AND PHYSIOLOGIC MECHANISMS IN DIVERSIFYING AGRICULTURAL SYSTEMS FOR SUSTAINABILITY: EXPERIENCE FROM STUDIES DEPLOYING NATURE-BASED SOLUTIONS IN SCOTLAND

● Diversification enhances nature-based contributions to cropping system functions. ● Soil management to improve production and ecosystem function has variable outcomes. ● Management of the production-system to use legacy nutrients will reduce inputs. ● Intercrops, companion crops and cover crops improve ecological sustainability. ● Sustainable interventions within value chains are essential to future-proof agriculture. To achieve the triple challenge of food security, reversing biodiversity declines plus mitigating and adapting to climate change, there is a drive to embed ecological principles into agricultural, value-chain practices and decision-making. By diversifying cropping systems at several scales there is potential to decrease reliance on inputs, provide resilience to abiotic and biotic stress, enhance plant, microbe and animal biodiversity, and mitigate against climate change. In this review we highlight the research performed in Scotland over the past 5 years into the impact of the use of ecological principles in agriculture on sustainability, resilience and provision of ecosystem functions. We demonstrate that diversification of the system can enhance ecosystem functions. Soil and plant management interventions, including nature-based solutions, can also enhance soil quality and utilization of legacy nutrients. Additionally, this is facilitated by greater reliance on soil biological processes and trophic interactions. We highlight the example of intercropping with legumes to deliver sustainability through ecological principles and use legumes as an exemplar of the innovation. We conclude that there are many effective interventions that can be made to deliver resilient, sustainable, and diverse agroecosystems for crop and food production, and these may be applicable in any agroecosystem.     

SUSTAINABLE NITROGEN MANAGEMENT IN AUSTRALIAN AGROECOSYSTEMS: CHALLENGES AND OPPORTUNITIES

● There is huge potential for improvement of nitrogen management in Australia. ● N management should incorporate environmental, social and economic sustainability. ● Agronomic, ecological and socioeconomic approaches and efforts are needed. Nitrogen is an essential nutrient that supports life, but excess N in the human-environment system causes multiple adverse effects from the local to the global scale. Sustainable N management in agroecosystems, therefore, has become more and more critical to address the increasing concern over food security, environmental quality and climate change. Australia is facing a serious challenge for sustainable N management due to its emission-intensive lifestyle (high level of animal-source foods and fossil fuels consumption) and its diversity of agricultural production systems, from extensive rainfed grain systems with mining of soil N to intensive crop and animal production systems with excessive use of N. This paper reviews the major challenges and future opportunities for making Australian agrifood systems more sustainable, less polluting and more profitable.     

CHALLENGES PROVIDING MULTIPLE ECOSYSTEM BENEFITS FOR SUSTAINABLE MANAGED SYSTEMS

● For 8000 years, agricultural practices have affected atmospheric CO₂ concentrations. ● Paddy rice cultivation has impacted atmospheric CH₄ concentration since 5000 years ago. ● Modern agricultural practices must include carbon storage and reduced emissions. ● Sustainable management in agriculture must be combined with decarbonizing the economy and reducing population growth. Since humans started practicing agriculture at the expense of natural forests, 8000 years ago, they have affected atmospheric CO₂ concentrations. Their impact on atmospheric CH₄ started about 5000 years ago, as result of the cultivation of paddy rice. A challenge of modern agricultural practices is to reverse the impact cropping has had on greenhouse gas emissions and the global climate. There is an increasing demand for agriculture to provide food security as well as a range of other ecosystem services. Depending on ecosystem management, different practices may involve trade-offs and synergies, and these must be considered to work toward desirable management systems. Solution toward food security should not only focus on agricultural management practices, but also on strategies to reduce food waste, more socially-just distribution of resources, changes in lifestyle including decarbonization of the economy, as well as reducing human population growth.     

AGRI-ENVIRONMENTAL ASSESSMENT OF CONVENTIONAL AND ALTERNATIVE BIOENERGY CROPPING SYSTEMS PROMOTING BIOMASS PRODUCTIVITY

● Agri-environmental assessment of food, feed and/or biogas cropping systems (CS). ● Four-year experiment for the agri-environmental assessment of two innovative CS. ● Biogas CS has equal soil returned biomass than food CS but higher exported biomass. ● Feed and biogas CS present higher biomass productivity, but higher CO₂ emissions. ● CO₂ emissions related to produced biomass are 26% (±5%) lower in biogas CS. Bioenergy, currently the largest renewable energy source in the EU (64% of the total renewable energy consumption), has sparked great interest to meet the 32% renewable resources for the 2030 bioeconomy goal. The design of innovative cropping systems informed by bioeconomy imperatives requires the evaluate of the effects of introducing crops for bioenergy into conventional crop rotations. This study aimed to assess the impacts of changes in conventional cropping systems in mixed dairy cattle farms redesigned to introduce bioenergy crops either by increasing the biomass production through an increase of cover crops, while keeping main feed/food crops, or by substituting food crops with an increase of the crop rotation length. The assessment is based on the comparison between conventional and innovative systems oriented to feed and biogas production, with and without tillage, to evaluate their agri-environmental performances (biomass production, nitrogen fertilization autonomy, greenhouse gas emissions and biogas production). The result showed higher values in the biogas cropping system than in the conventional and feed ones for all indicators, biomass productivity (27% and 20% higher, respectively), nitrogen fertilization autonomy (26% and 73% higher, respectively), methanogenic potential (77% and 41% higher, respectively) and greenhouse gas emissions (15% and 3% higher, respectively). There were no negative impacts of no-till compared to the tillage practice, for all tested variables. The biogas cropping system showed a better potential in terms of agri-environmental performance, although its greenhouse gas emissions were higher. Consequently, it would be appropriate to undertake a multicriteria assessment integrating agri-environmental, economic and social performances.     

AGRONOMIC AND ENVIRONMENTAL BENEFITS OF REINTRODUCING HERB- AND LEGUME-RICH MULTISPECIES LEYS INTO ARABLE ROTATIONS: A REVIEW

● Arable-ley rotations can alleviate soil degradation and erosion. ● Multispecies leys can improve livestock health and reduce greenhouse gas emissions. ● Ley botanical composition is crucial for determining benefits. ● Lack of livestock infrastructure in arable areas may prevent arable-ley uptake. ● Long-term (10–25 years) research is needed to facilitate evidence-based decisions. Agricultural intensification and the subsequent decline of mixed farming systems has led to an increase in continuous cropping with only a few fallow or break years, undermining global soil health. Arable-ley rotations incorporating temporary pastures (leys) lasting 1–4 years may alleviate soil degradation by building soil fertility and improving soil structure. However, the majority of previous research on arable-ley rotations has utilized either grass or grass-clover leys within ungrazed systems. Multispecies leys, containing a mix of grasses, legumes, and herbs, are rapidly gaining popularity due to their promotion in agri-environment schemes and potential to deliver greater ecosystem services than conventional grass or grass-clover leys. Livestock grazing in arable-ley rotations may increase the economic resilience of these systems, despite limited research of the effects of multispecies leys on ruminant health and greenhouse gas emissions. This review aims to evaluate previous research on multispecies leys, highlighting areas for future research and the potential benefits and disbenefits on soil quality and livestock productivity. The botanical composition of multispecies leys is crucial, as legumes, deep rooted perennial plants (e.g., Onobrychis viciifolia and Cichorium intybus) and herbs (e.g., Plantago lanceolata) can increase soil carbon, improve soil structure, reduce nitrogen fertilizer requirements, and promote the recovery of soil fauna (e.g., earthworms) in degraded arable soils while delivering additional environmental benefits (e.g., biological nitrification inhibition and enteric methane reduction). Multispecies leys have the potential to deliver biologically driven regenerative agriculture, but more long-term research is needed to underpin evidence-based policy and farmer guidance.     

IMPACTS OF CLIMATE CHANGE ON CROP PRODUCTION,PESTS AND PATHOGENS OF WHEAT AND RICE

● An overview of impacts of climate change on wheat and rice crops. ● A review on impacts of climate change on insect pests and fungal pathogens of wheat and rice. ● A selection of adaptation strategies to mitigate impacts of climate change on crop production and pest and disease management. Ongoing climate change is expected to have impacts on crops, insect pests, and plant pathogens and poses considerable threats to sustainable food security. Existing reviews have summarized impacts of a changing climate on agriculture, but the majority of these are presented from an ecological point of view, and scant information is available on specific species in agricultural applications. This paper provides an overview of impacts of climate change on two staple crops, wheat and rice. First, the direct effects of climate change on crop growth, yield formation, and geographic distribution of wheat and rice are reviewed. Then, the effects of climate change on pests and pathogens related with wheat and rice, and their interactions with the crops are summarized. Finally, potential management strategies to mitigate the direct impacts of climate change on crops, and the indirect impacts on crops through pests and pathogens are outlined. The present overview aims to aid agriculture practitioners and researchers who are interested in wheat and rice to better understand climate change related impacts on the target species.     

NITROGEN USE AND MANAGEMENT IN ORCHARDS AND VEGETABLE FIELDS IN CHINA: CHALLENGES AND SOLUTIONS

● Excessive application of N fertilizers in orchards and vegetable fields (OVFs) in China is particularly common. ● Long-term excessive application of N fertilizers has made OVFs hotspots for N surplus and loss in China. ● Nitrate accumulation in the soil profile is the main fate of N fertilizers in OVF systems. ● Reducing the N surplus is the most effective way to reduce N loss and increase NUE. China is the largest producer and consumer of fruits and vegetables in the world. Although the annual planting areas of orchards and vegetable fields (OVF) account for 20% of total croplands, they consume more than 30% of the mineral nitrogen fertilizers in China and have become hotspots of reactive N emissions. Excess N fertilization has not only reduced the N use efficiency (NUE) and quality of grown fruits and vegetables but has also led to soil acidification, biodiversity loss and climate change. Studies using ¹⁵N labeling analysis showed that the recovery rate of N fertilizer in OVFs was only 16.6%, and a high proportion of fertilizer N resided in soils (48.3%) or was lost to the environment (35.1%). Nitrate accumulation in the soil of OVFs is the main fate of N fertilizer in northern China, which threatens groundwater quality, while leaching and denitrification are the important N fates of N fertilizer in southern China. Therefore, taking different measures to reduce N loss and increase NUE based on the main pathways of N loss in the various regions is urgent, including rational N fertilization, substituting mineral N fertilizers with organic fertilizers, fertigation, and adding mineral N fertilizers with urease inhibitors and nitrification inhibitors.     

OPPORTUNITIES AND APPROACHES FOR MANIPULATING SOIL-PLANT MICROBIOMES FOR EFFECTIVE CROP NITROGEN USE IN AGROECOSYSTEMS

● Matching nitrification inhibitors with soil properties and nitrifiers is vital to achieve a higher NUE. ● Enhancing BNF, DNRA and microbial N immobilization processes via soil amendments can greatly contribute to less chemical N fertilizer input. ● Plant-associated microbiomes are critical for plant nutrient uptake, growth and fitness. ● Coevolutionary trophic relationships among soil biota need to be considered for improving crop NUE. Soil microbiomes drive the biogeochemical cycling of nitrogen and regulate soil N supply and loss, thus, pivotal nitrogen use efficiency (NUE). Meanwhile, there is an increasing awareness that plant associated microbiomes and soil food web interactions is vital for modulating crop productivity and N uptake. The rapid advances in modern omics-based techniques and biotechnologies make it possible to manipulate soil-plant microbiomes for improving NUE and reducing N environmental impacts. This paper summarizes current progress in research on regulating soil microbial N cycle processes for NUE improvement, plant-microbe interactions benefiting plant N uptake, and the importance of soil microbiomes in promoting soil health and crop productivity. We also proposes a potential holistic (rhizosphere-root-phyllosphere) microbe-based approach to improve NUE and reduce dependence on mineral N fertilizer in agroecosystems, toward nature-based solution for nutrient management in intensive cropping systems.     

TRADE-OFFS IN THE DESIGN OF SUSTAINABLE CROPPING SYSTEMS AT A REGIONAL LEVEL: A CASE STUDY ON THE NORTH CHINA PLAIN

● Impacts of 30 cropping systems practiced on the North China Plain were evaluated. ● Trade-offs were assessed among productive, economic and environmental indicators. ● An evolutionary algorithm was used for multi-objective optimization. ● Conflict exists between productivity and profitability versus lower ground water decline. ● Six strategies were identified to jointly mitigate the trade-offs between objectives. Since the Green Revolution cropping systems have been progressively homogenized and intensified with increasing rates of inputs such as fertilizers, pesticides and water. This has resulted in higher crop productivity but also a high environmental burden due to increased pollution and water depletion. To identify opportunities for increasing the productivity and reducing the environmental impact of cropping systems, it is crucial to assess the associated trade-offs. The paper presents a model-based analysis of how 30 different crop rotations practiced in the North China Plain could be combined at the regional level to overcome trade-offs between indicators of economic, food security, and environmental performance. The model uses evolutionary multi-objective optimization to maximize revenues, livestock products, dietary and vitamin C yield, and to minimize the decline of the groundwater table. The modeling revealed substantial trade-offs between objectives of maximizing productivity and profitability versus minimizing ground water decline, and between production of livestock products and vitamin C yield. Six strategies each defining a specific combination of cropping systems and contributing to different extents to the various objectives were identified. Implementation of these six strategies could be used to find opportunities to mitigate the trade-offs between objectives. It was concluded that a holistic analysis of the potential of a diversity cropping systems at a regional level is needed to find integrative solutions for challenges due to conflicting objectives for food production, economic viability and environmental protection.     

IMPROVING FERTILIZATION METHODS AND CROPPING SYSTEMS FOR SUSTAINABLE PRODUCTION OF PEARL MILLET (PENNISETUM GLAUCUM) IN WEST AFRICA: A REVIEW

● Constraints in cultivation and production of pearl millet in West Africa are summarized. ● Production systems and fertilization methods in pearl millet production are highlighted. ● Sustainable production needs integrated cropping systems and fertilizer use efficiency. ● A holistic approach is required to establish a strong collaboration among rural actors. West African countries are among the larger global millet producers but have low yields mainly due to the low quality of their marginal soils. The objectives of this work were to analyze the benefits and constraints of pearl millet production, to summarize the impact of different cropping systems and fertilization modes while proposing a holistic approach for sustainable production. The major constraints on millet yields are low rates or absence of fertilizers, unsuitable cropping systems, and the proliferation of pests and diseases. Intercropping with cowpea is a widely used cropping system in addition to crop rotation, monocropping and agroforestry systems. Microdosing is the best fertilization mode for West African smallholders. It is concluded that integrated systems (breeding new cultivars, intercropping and microdosing) in tied ridges or infiltration pit practices, sustained by the implementation of innovative approaches such as the ‘Science and Technology Backyards’ from China are a promising approach for increasing pearl millet production. In addition, policies such as land protection of the farmers and subsidies of inputs from the government and the effective involvement of farmers and extension officers are necessary in sustaining millet production in West Africa.     

SOIL NITROGEN CYCLING AND ENVIRONMENTAL IMPACTS IN THE SUBTROPICAL HILLY REGION OF CHINA: EVIDENCE FROM MEASUREMENTS AND MODELING

● Soil nitrogen fluxes and influencing factors were reviewed in the subtropical hilly regions. ● Fertilizer application and atmospheric deposition contributed largely to soil nitrogen input. ● High gaseous, runoff and leaching losses of soil nitrogen were measured. ● Soil nitrogen cycles are well modelled with the Catchment Nutrients Management Model. The subtropical hilly region of China is a region with intensive crop and livestock production, which has resulted in serious N pollution in soil, water and air. This review summarizes the major soil N cycling processes and their influencing factors in rice paddies and uplands in the subtropical hilly region of China. The major N cycling processes include the N fertilizer application in croplands, atmospheric N deposition, biological N fixation, crop N uptake, ammonia volatilization, N₂O/NO emissions, nitrogen runoff and leaching losses. The catchment nutrients management model for N cycle modeling and its case studies in the subtropical hilly region were also introduced. Finally, N management practices for improving N use efficiency in cropland, as well as catchment scales are summarized.     

TRANSFORMATION OF AGRICULTURE ON THE LOESS PLATEAU OF CHINA TOWARD GREEN DEVELOPMENT

● Agriculture on Loess Plateau has transformed from food shortage to green development. ● Terracing and check-dams are the key engineering measures to increase crop yields. ● Agronomic measures and policy support greatly increased crop production. ● Increasing non-agricultural income is a key part of increasing farmers’ income. ● Grain for Green Program had an overwhelming advantage in protecting environment. Loess Plateau of China is a typical dryland agricultural area. Agriculture there has transformed from food shortage toward green development over the past seven decades, and has achieved world-renowned achievements. During 1950–1980, the population increased from 42 to 77 million, increasing grain production to meet food demand of rapid population growth was the greatest challenge. Engineering measures such as terracing and check-dam were the crucial strategies to increase crop production. From 1981 to 2000, most of agronomic measures played a key role in increasing crops yield, and a series of policy support has benefited millions of smallholders. As expected, these measures and policies greatly increased crop production and basically achieved food security; but, low per capita GDP (only about 620 USD in 2000) was still a big challenge. During 2001–2015, the increase in agricultural and non-agricultural income together supported the increase in farmer income to 5781 USD·yr^–1. Intensive agriculture that relies heavily on chemicals increased crop productivity by 56%. Steadfast policy support such as “Grain for Green Program” had an overwhelming advantage in protecting the natural ecological environment. In the new era, the integration of science and technology innovations, policy support and positive societal factors will be the golden key to further improve food production, protect environment, and increase smallholder income.     

SUSTAINABLE NITROGEN MANAGEMENT INDEX: DEFINITION,GLOBAL ASSESSMENT AND POTENTIAL IMPROVEMENTS

● A composite N management index is proposed to measure agriculture sustainability. ● Nitrogen management has been moving towards sustainability targets globally. ● The improvement was achieved mainly by yield increase, while Nitrogen Use Efficiency (NUE) stagnated. ● No country achieved both yield and NUE targets and spatial variation is large. ● Region-specific yield targets can be used to supplement the standard Sustainable Nitrogen Management Index (SNMI). To represent the sustainability of nitrogen management in the Sustainable Development Goals indicator framework, this paper proposes a sustainable nitrogen management index (SNMI). This index combines the performance in N crop yield and N use efficiency (NUE), thereby accounting for the need for both food production and environmental protection. Applying SNMI to countries around the world, the results showed improvement in the overall sustainability of crop N management over the past four decades, but this improvement has been mainly achieved by crop yield increase, while global NUE has improved only slightly. SNMI values vary largely among countries, and this variation has increased since the 1970s, implying different levels of success, even failure, in improving N management for countries around the world. In the standard SNMI assessment, the reference NUE was defined as 1.0 (considered an ideal NUE) and the reference yield was defined as 90 kg·ha⁻¹·yr⁻¹ N (considering a globally averaged yield target for meeting food demand in 2050). A sensitivity test that replaced the reference NUE of 1.0 with more realistic NUE targets of 0.8 or 0.9 showed overall reduction in SNMI values (i.e., improved performance), but little change in the ranking among countries. In another test that replaced the universal reference yield with region-specific attainable yield, SNMI values declined (i.e., improved performance) for most countries in Africa and West Asia, whereas they increased for many countries in Europe and South America. The index can be improved by further investigation of approaches for setting region-specific yield targets and high-quality data on crop yield potentials. Overall, SNMI offers promise for a simple and transparent approach to assess progress of countries toward sustainable N management with a single indicator.     

CONSTRUCTION OF AN INDEX SYSTEM FOR SUSTAINABILITY ASSESSMENT IN SMALLHOLDER FARMING SYSTEMS

● A five-step process for quantifying smallholder farming system sustainability is proposed. ● Definition of system boundary, functional unit, and indicators depends on research issues. ● Weighting, conversion, and aggregation methods tightly relates to the validity of assessment results. Smallholder farming systems are important for global food security, but these faces multiple environmental challenges hindering sustainable development. Although sustainable smallholder agriculture issues have been widely discussed and addressed by scientists globally, harmonized approaches in evaluating sustainability are still lacking. This paper proposes a five-step process for constructing a sustainability assessment method for smallholder farming systems, namely definition of system boundary, indicator selection, indicator weighting, indicator conversion, and indicator aggregation. The paper summarizes the state-of-art progresses in agricultural sustainability assessment at different stages, and systematically discussed the benefits and limitations of weighting and aggregation methods. Overall, this evaluation process should be useful by providing rational and comprehensive results for quantifying the sustainability of smallholder farming systems, and will contribute to practice by providing decision-makers with directions for improving sustainable strategies.     

HIGH QUALITY DEVELOPMENTAL APPROACH FOR SOIL AND WATER CONSERVATION AND ECOLOGICAL PROTECTION ON THE LOESS PLATEAU

● Analyse the effects of ecological management measures undertaken so far. ● Point out the main problems that confront effective ecological management. ● Suggest some measures to guide ecological management and high-quality development. ● Develop some models to improve the quality of clear waters and green mountains. ● Provide scientific and technological support for green and eco-friendly development. The Loess Plateau is the core area in the Yellow River basin for implementing environmental protection and high-quality development strategies. A series of ecological projects has implemented aimed at soil and water conservation and ecological management on the Loess Plateau over the past 70 years. The effects of the ecological projects are apparent mainly through a marked increase in vegetation cover, controlled soil erosion and reduced flow of sediment into the Yellow River, continual optimization of the industrial structure and increased production from arable land, poverty alleviation and greater prosperity, and optimal allocation of space for biological organisms. Major problems have also been analyzed in ecological management including the fragile ecosystem of the region, maintaining the stability of vegetation, lower agricultural productivity and continued risk from natural disasters. Some suitable schemes and models have been developed for the coordinated development of the region through research and demonstration, striking the optimum balance between rural industry and ecology, and increased regional capacity to supply high-quality ecological products. Countermeasures to address the problems are suggested to guide ecological management and high-quality development in the future.     

ENVIRONMENTAL ATTITUDES AND CONSUMER PREFERENCE FOR ENVIRONMENTALLY-FRIENDLY BEVERAGE PACKAGING: THE ROLE OF INFORMATION PROVISION AND IDENTITY LABELING IN INFLUENCING CONSUMER BEHAVIOR

This study examined whether urban Chinese consumers with stronger environmental values have higher valuations for plastic beverage bottles that are made of post-consumer recycled material(rPET) or that come in large sizes that use plastic more efficiently. It also assesses the effectiveness of environmental information provision and green identity labeling in increasing consumer willingness to pay for environmentally-friendly packaging. The results suggest that urban Chinese consumers are willin...     

A NEW APPROACH TO HOLISTIC NITROGEN MANAGEMENT IN CHINA

● Progress on nitrogen management in agriculture is overviewed in China. ● 4R principles are key to high N use efficiency and low N losses in soil-crop systems. ● A new framework of food-chain-N-management is proposed. ● China’s success in N management provides models for other countries. Since the 1980s, the widespread use of N fertilizer has not only resulted in a strong increase in agricultural productivity but also caused a number of environmental problems, induced by excess reactive N emissions. A range of approaches to improve N management for increased agricultural production together with reduced environmental impacts has been proposed. The 4R principles (right product, right amount, right time and right place) for N fertilizer application have been essential for improving crop productivity and N use efficiency while reducing N losses. For example, site-specific N management (as part of 4R practice) reduced N fertilizer use by 32% and increased yield by 5% in China. However, it has not been enough to overcome the challenge of producing more food with reduced impact on the environment and health. This paper proposes a new framework of food-chain-nitrogen-management (FCNM). This involves good N management including the recycling of organic manures, optimized crop and animal production and improved human diets, with the aim of maximizing resource use efficiency and minimizing environmental emissions. FCNM could meet future challenges for food demand, resource sustainability and environmental safety, key issues for green agricultural transformation in China and other countries.     

INTERACTIONS BETWEEN ABOVE AND BELOW GROUND PLANT STRUCTURES: MECHANISMS AND ECOSYSTEM SERVICES

● Aboveground to belowground energy transfer. ● Importance of symplasmic nature of sieve tubes. ● Hydraulic, electrical and chemical energy transfer. ● Decreased soil organic C storage over 8000 years. Interactions between above and below ground parts of plants can be considered under the (overlapping) categories of energy, material and information. Solar energy powers photosynthesis and transpiration by above ground structures, and drives most water uptake through roots and supplies energy as organic matter to below ground parts, including diazotrophic symbionts and mycorrhizas. Material transfer occurs as water and dissolved soil-derived elements transport up the xylem, and a small fraction of water moving up the xylem with dissolved organic carbon and other solutes down the phloem. The cytosolic nature of sieve tubes accounts for at least some of the cycling of K, Mg and P down the phloem. NO₃^– assimilation of above ground parts requires organic N transport down phloem with, in some cases, organic anions related to shoot acid-base regulation. Long-distance information transfer is related development, biotic and abiotic damage, and above and below ground resource excess and limitation. Information transfer can involve hydraulic, electrical and chemical signaling, with their varying speeds of transmission and information content. Interaction of above and below ground plant parts is an important component of the ecosystem service of storing atmospheric CO₂ as organic C in soil, a process that has decreased since the origin of agriculture.     

APPLICATION AND DEVELOPMENT OF ‘GREEN’ PREVENTIVE AND CONTROL TECHNOLOGIES IN GUIZHOU TEA PLANTATIONS

● Application of plant defense inducers against tea diseases. ● Application of natural enemies against insect pests. ● Application of Trifolium repens against weeds. The application and development of ‘green’ preventive technologies in tea plantations is an important means of ensuring tea quality and ecological safety. Ecological, agronomic and biological controls are the main preventive measures used in Guizhou Province. This paper summarizes the ‘green’ preventive technologies being applied in Guizhou tea plantations, including the use of plant defense inducers to regulate tea plant responses to pathogens, natural enemies to control pest species causing damage to shoots and Trifolium repens to control the main weed species. In addition, it summarizes the integrated ‘green’ preventive technologies being used in Guizhou and provides a foundation for the ecological maintenance of tea plantations.     

ECOLOGICAL NETWORKS IN AGROECOSYSTEMS: APPROACHES AND APPLICATIONS

● Agricultural intensification reduced the complexity and connectance of soil food webs. ● Agricultural intensification impaired the robustness of pollination networks. ● High connectance in co-occurrence networks indicates efficient nutrient utilization. Complex network theory has been increasingly used in various research areas, including agroecosystems. This paper summarizes the basic concepts and approaches commonly used in complex network theory, and then reviews recent studies on the applications in agroecosystems of three types of common ecological networks, i.e., food webs, pollination networks and microbial co-occurrence networks. In general, agricultural intensification is considered to be a key driver of the change of agroecosystems. It causes the simplification of landscape, leads to the loss of biocontrol through cascading effect in food webs, and also reduces the complexity and connectance of soil food webs. For pollination networks, agricultural intensification impaired the robustness by reducing specialization and enhancing generality. The microbial co-occurrence networks with high connectance and low modularity generally corresponded to high efficiency in utilization of nutrients, and high resistance to crop pathogens. This review aims to show the readers the advances of ecological networks in agroecosystems and inspire the researchers to conduct their studies in a new network perspective.