Defining Household Typologies Based on Cropland Use Behaviors for Rural Human-Environment Systems Simulation Research: A Case Study in Southwest China.

The dynamics of rural human-environment systems in developing countries have increasingly been attracting attention. Agent-based modeling (ABM) is a valuable simulation tool for detecting complex feedback loops in rural human-environment systems with a 'bottom-up' approach. However, such models require the prerequisite analysis of household typology to simulate households' decision-making process, where a gap exists between having accurate classification criteria and a simplified modeling framework. This study aimed to develop a household typology for two selected counties in southwest China based on multivariate analysis techniques and the classification tree method. Four categories of socioeconomic variables, including labor conditions, resource endowments, economic status, and social connections, were screened as possible factors impacting agriculture practice decisions. The results showed that household diversification in the study area was mainly determined by diversified livelihood strategies of off-farm work, livestock breeding, subsidy dependence, and traditional planting. Five distinct household types were identified: non-farm households, part-time households, livestock breed households, subsidized households, and traditional planting households. The household types were associated with specific cropland use behaviors, and their decision-making behaviors were verified with bounded rationality theory (where the maximization of profits is the primary goal). The quantitative classification criteria obtained in this study were clear and could be easily identified and used by ABMs. Our study provides a basis for further simulation of the complicated rural human-environment systems in southwest China.

How to Identify Future Priority Areas for Urban Development: An Approach of Urban Construction Land Suitability in Ecological Sensitive Areas.

The suitability of urban construction land (SUCL) is key to the appropriate utilization of land resources and represents an important foundation for regional exploration and land management. This study explores the SUCL conceptual framework by considering the theory of human-land relationships. The upper reaches of the Yangtze River were studied, a typical ecologically-sensitive area of China. The spatial pattern and control of the SUCL were determined using the improved entropy method. The results show that an area of 91 × 104 km2 was categorized as prohibited or restricted, and these categories account for 28.61% and 50.66% of the total area, respectively. Priority areas and suitable areas are mainly located in the Chengdu Plain, the urban agglomeration of southern Sichuan Province, Chongqing, and the economic corridor in the west, and the surrounding cities of Guiyang and Kunming. SUCL hotspots feature obvious spatial heterogeneity and are concentrated in Sichuan Basin and Guizhou Plateau. The SUCL is obviously constrained by the physical geography of this region. In addition, towns affected by the pole-axis effect have stronger suitability for development and construction. These findings will be very useful for land managers as they provide relevant information about urban development in mountainous areas.

Mapping regional differences in payment for ecosystem service policies to inform integrated management: Case study of the Yangtze River Economic Belt.

State and local governments consider payment for ecosystem services (PES) a valuable tool for watershed protection. However, regional differences in PES policies, which significantly influence province-scale cooperation, have been seldom documented. The interrelationships among these policies directly affect overall PES development in the Yangtze River Economic Belt (YREB). Textual analysis was used to categorize the content of PES policies in 11 provinces from 2004 to 2018. Then, we assessed these PES policies with four indicators (i.e., policy intensity, interdepartmental coordination, diversity, and duration). Finally, we analyzed the impact factors of these regional differences. The results showed that the number of PES policies increased yearly, reaching a peak in 2017. Provinces in the upper reaches had the highest policy-intensity score (7.38), followed by downstream provinces (6.39) and provinces in the middle reaches (4.52). Regarding interdepartmental coordination, the downstream areas exhibited the most interdepartment interaction (27.92%), followed by the upstream areas (20.76%) and the middle areas (19.18%). Diversity in the middle reaches was the highest (scored 4.3) while the upstream area exhibited the lowest diversity value (3.25). Downstream provinces issued PES policies the earliest, with a duration 5.52 years, followed by the upstream provinces (4.68) and middle provinces (4.28). Policy intensity was significantly correlated with fixed-asset investment, solid-waste generation, and population. The results suggest that PES in the YREB needs to be strengthened by enhancing policy consistency. In this regard, identifying regional differences in PES policies can help improve the coordination of PES policies for the whole YREB.

Planning priority conservation areas for biodiversity under climate change in topographically complex areas: A case study in Sichuan province, China.

Identifying priority conservation areas plays a significant role in conserving biodiversity under climate change, but uncertainties create challenges for conservation planning. To reduce uncertainties in the conservation planning framework, we developed an adaptation index to assess the effect of topographic complexity on species adaptation to climate change, which was incorporated into the conservation framework as conservation costs. Meanwhile, the species distributions were predicted by the Maxent model, and the priority conservation areas were optimized during different periods in Sichuan province by the Marxan model. Our results showed that the effect of topographic complexity was critical for species adaptation, but the adaptation index decreased with the temperature increase. Based on the conservation targets and costs, the distributions of priority conservation areas were mainly concentrated in mountainous areas around the Sichuan Basin where may be robust to the adaptation to climate change. In the future, the distributions of priority conservation areas had no evident changes, accounting for about 26% and 28% of the study areas. Moreover, most species habitats could be conserved in terms of conservation targets in these priority conservation areas. Therefore, our approach could achieve biodiversity conservation goals and be highly practical. More importantly, quantifying the effect of topography also is critical for options for planning conservation areas in response to climate change.

[Dynamic Process of Nitrogen and Phosphorus Export and Loss Load in an Intensive Orchard with Ridge and Furrow Plantation in the Three Gorges Reservoir Area].

To comprehend the runoff load of nitrogen (N) and phosphorus (P) and the impact on the receiving river in an agricultural area with an intensive orchard plantation and a longitudinal ridge and furrow morphology in the Three Gorges Reservoir Area, the runoff and N and P concentrations were dynamically monitored in a typical citrus orchard catchment in Wanzhou Country, Chongqing, China. The results showed that the nutrient concentration in runoff water from the intensive citrus planting catchment was very high. The average annual event mean concentrations (EMC) were 9.31 mg·L-1 for total nitrogen (TN), 8.11 mg·L-1 for dissolved nitrogen (DN), 5.66 mg·L-1 for nitrate nitrogen (NN), 0.51 mg·L-1 for ammonium nitrogen (AN), 0.87 mg·L-1 for total phosphorus, 0.56 mg·L-1 for solved phosphorus (DP), and 0.32 mg·L-1 for particulate phosphorus (DP). In addition, the annual loss loads were 13.43, 12.20, 8.77, 0.75, 1.26, 0.84, and 0.42 kg·(hm2·a)-1 for TN, DN, NN, AN, TP, DP, and PP, respectively. The annual average concentrations of TN and TP were 8.49 mg·L-1 and 0.87 mg·L-1, respectively, which exceeded the category V values of the surface water quality standards (GB3838-2002) by 4.25 times and 2.2 times, respectively, and also exceeded the internationally recognized thresholds for the eutrophication of waterbodies. The TN and TP loss load from storm runoff was one of the main reasons for the degradation of the river water quality, thus suggesting the need to treat surface runoff and control runoff nutrient losses, especially during the first storm events after fertilization. During two typical long-duration springtime rainfall events after fertilization, the loads of nitrate nitrogen (NN) and dissolved phosphorus (DP) were 4.94 kg·hm-2 and 0.28 kg·hm-2, respectively, which accounted for 92.90% and 64.69% of the total annual TN and TP loss loads, respectively. The loads of NN and DP in a short-duration high-intensity rainfall event were 0.52 and 0.05 kg·hm-2 respectively, which accounted for 65.92% and 74.88% of the total annual TN and TP loss loads, respectively. The DN and DP were the main forms of nitrogen and phosphorus losses from the intensive citrus orchard with a longitudinal ridge and furrow morphology. Meanwhile, the catchment showed a significant first-flush phenomenon during a typical rainfall event, with a total of 58.0%, 57.0%, 58.5%, 79.0%, 62.0%, 63.5%, and 60.0% of the mass of TN, DN, NN, AN, TP, DP, and PP in the initial 20% of the runoff, respectively. Hence, controlling the surface runoff at the early runoff stage plays an important role in reducing nutrient losses.

An ecological footprint approach for cropland use sustainability based on multi-objective optimization modelling.

Croplands are heterogeneous in productivity and their sustainable use holds a prominent place in supporting a virtual society-economy-ecology-environment circle. This study developed a model for the evaluation of cropland use sustainability by integrating the revised ecological footprint model with multi-objective optimization. The model enabled to gain insights into changes of the supply-demand balance of cropland use ecologically from a planning perspective, and also enables policy makers to determine the optimal patterns of cropland use in order to reconcile contradictions between multiple dimensions in agroecosystems, such as resource utilization, economy, society, and environment. The model was demonstrated by solving a real-world problem of cropland use management in Heilongjiang Province, northeast China. Results of demonstration were found to be satisfactory for generating sustainable cropland use patterns in promoting the equilibrium of water use efficiency, net economic benefit, land resource allocation equity, and greenhouse gas emissions. Then, whether various cropland use patterns were ecologically safe based on crop ecological footprint and crop ecological carrying capacity were determined. The status and scenario-based trend of cropland use sustainability provided alternatives for policy makers to allocate cropland efficiently and sustainably. The model is applicable for similar planting-centered regions with limited land and water resources.

Assessment of the ecosystem services provided by ponds in hilly areas.

Ponds are an important ecosystem in rural landscapes. They play an important role in water retention, aquatic products supply and biodiversity conservation. By using a questionnaire-based survey of rural households in a small watershed in the Three Gorges Reservoir area, we analyzed the distribution of ponds, their size and current status. The Integrated Valuation of Environmental Services and Tradeoffs (InVEST) model was used to evaluate the regulation, provision and culture services of the ponds. We found that pond density was high throughout hilly areas. About 20 ponds were within an area of 1 km2. They were mainly distributed in the middle and lower parts of the basin. The presence of such a large number of ponds was considered remarkable. Water retention was the primary ecosystem service. On average, each pond contained about 4500 mm depth of water, which was 10 times that of the surrounding forest. However, with the transformation of agriculture in mountainous areas, the irrigation and domestic water services provided by ponds have declined. In recent years, ponds have been used predominantly for fish farming and leisure services. Aquaculture and multi-function ponds accounted for 54.55% and 27.7% of the surveyed ponds, respectively. Multi-function ponds consumed more water, but fish farming ponds were the most economically valuable. Due to weak environmental management and the decreasing economic value of ponds, it is necessary to conduct ecological management of ponds in accordance with societal changes in mountainous areas and to promote the protection and use of ponds.

Enhanced citric acid production by a yeast Yarrowia lipolytica over-expressing a pyruvate carboxylase gene.

In this study, after the expression of a pyruvate carboxylase gene (PYC) cloned from Meyerozyma guilliermondii in a marine-derived yeast Yarrowia lipolytica SWJ-1b, a transformant PG86 obtained had much higher PYC activity than Y. lipolytica SWJ-1b. At the same time, the PYC gene expression and citric acid (CA) production by the transformant PG86 were also greatly enhanced. When glucose concentration in the medium was 60.0 g L(-1), CA concentration formed by the transformant PG86 was 34.02 g L(-1), leading to a CA yield of 0.57 g g(-1) of glucose. During a 10-L fed-batch fermentation, the final concentration of CA was 101.0 ± 1.3 g L(-1), the yield was 0.89 g g(-1) of glucose, the productivity was 0.42 g L(-1) h(-1) and only 5.93 g L(-1) reducing sugar was left in the fermented medium within 240 h of the fed-batch fermentation. HPLC analysis showed that most of the fermentation products were CA.