For centuries, traditional agricultural systems have contributed to food and livelihood security throughout the world. Recognizing the ecological legacy in the traditional agricultural systems may help us develop novel sustainable agriculture. We examine how rice-fish coculture (RF), which has been designated a "globally important agricultural heritage system," has been maintained for over 1,200 y in south China. A field survey demonstrated that although rice yield and rice-yield stability are similar in RF and rice monoculture (RM), RF requires 68% less pesticide and 24% less chemical fertilizer than RM. A field experiment confirmed this result. We documented that a mutually beneficial relationship between rice and fish develops in RF: Fish reduce rice pests and rice favors fish by moderating the water environment. This positive relationship between rice and fish reduces the need for pesticides in RF. Our results also indicate a complementary use of nitrogen (N) between rice and fish in RF, resulting in low N fertilizer application and low N release into the environment. These findings provide unique insights into how positive interactions and complementary use of resource between species generate emergent ecosystem properties and how modern agricultural systems might be improved by exploiting synergies between species. G lobal food security is becoming an acute problem because of the increasing world population (1), the limitation of agricultural resources (e.g., land and water) (2), and the effects of global climate change on crop production (3, 4). World agriculture currently faces great challenges in producing sufficient food while minimizing the negative environmental effects of crop cultivation.In the past 50 y, crop yields have substantially increased, mainly resulting from the use of chemical fertilizers and pesticides, the development of new crop varieties, and the improvement in cultivation methods. The heavy application of chemical fertilizers and pesticides for long periods, however, negatively affects the environment, induces pest resistance to pesticides, and increases agricultural costs (5, 6). As a consequence, modern agriculture now requires "rethinking" (1, 7), and such rethinking should include reconsideration of traditional agricultural systems (8-10).For many centuries, traditional agricultural systems have contributed to food and livelihood security throughout the world (8). Because traditional agricultural systems have been created, shaped, and maintained by generations of farmers who used management practices that were matched to local conditions, and because these systems are based on diverse species and species interactions, traditional agricultural systems reflect a successful adaptation to different environments and are rich in biological diversity (8,11,12). The recognition of the ecological legacy of these traditional agricultural systems and the integration of these unique experiences into our future farm designs could help us to develop more sustainable agriculture. In fact, stud...

Despite evidence from previous case studies showing that agronomic traits partially determine the resulting yield of different rice ( Oryza sativa L.) varieties, it remains unclear whether this is true at the ecotype level. Here, an extensive dataset of the traits of 7686 rice varieties, released in China from 1978 to 2017, was used to study the relationship between yield and other agronomic traits. We assessed the association between yield and other agronomic traits for four different rice ecotypes, i.e., indica inbred, indica hybrid, japonica inbred, and japonica hybrid. We found that associations between agronomic traits and yield were ecotype-dependent. For both the indica inbred and indica hybrid ecotypes, we found that greater values of certain traits, including the filled grain number per panicle, 1000-grain-weight, plant height, panicle length, grains per panicle, seed setting rate, long growth period, low panicle number per unit area, and low seed length/width ratio, have accounted for high grain yield. In the japonica inbred and japonica hybrid ecotypes, we found that only high panicle number per unit area and long growth period led to high grain yield. Indirectly, growth period consistently had a positive effect on yield in all ecotypes, and plant height had a positive effect on yield for the indicas and japonica inbred only. Plant height had a negative effect for the japonica hybrid. Altogether, our findings potentially have valuable implications for improving the breeds of rice ecotypes.

Because rice feeds half of the world’s population, a secure global food supply depends on sustainable rice production. Here we test whether the co-cultivation of rice and fish into one “rice-fish system” (RFS; fish refers to aquatic animals in this article) could help sustain rice production. We examined intensive and traditional RFSs that have been widely practiced in China. We found that rice yields did not decrease when fish yield was below a threshold value in each intensive RFS. Below the thresholds, moreover, fish yields in intensive RFSs can be substantially higher than those in traditional RFS without reducing rice yield. Relative to rice monoculture, the use of fertilizer-nitrogen and pesticides decreased, and the farmers’ net income increased in RFSs. The results suggest that RFSs can help sustain rice production, and suggest that development of co-culture technologies (i.e. proper field configuration for fish and rice) is necessary to achieve the sustainability.

Rapid urbanization is resulting in large-scale land-use conversion and the impact on ecosystem services value is a key issue for sustainability-particularly in China-a global urbanization hotspot. Impacts of land-use change on ecosystem services value in China have been varied, ranging from strong decreases to modest increases, suggesting that bespoke analyses are required to support local and regional planning for sustainability. We quantified land-use change and valued the impact on ecosystem services from 1990 -2010 in the rapidly urbanizing Guangzhou-Foshan Metropolitan Area, southern China. We quantified land-use change from Landsat satellite imagery and calculated the value of ecosystem services using the well-established unit-value transfer method. Over one quarter of the study area changed land-use between 1990 and 2010 with Built-up, Orchard, and Waterbody land-uses expanding, and Cropland and Forestland contracting. However, the net decline in ecosystem services value was only 4.4% (US$201.5 million). This modest overall decline masked more complex and extreme dynamics in the value of individual ecosystem services. Substantial declines in the value of gas regulation (US$115.4 million, -28%) soil formation and retention (US$90.5 million, -16%), and climate regulation (US$44.6 million, -8%), while waste treatment (US$68.5 million, +10%) and recreation and culture (US$45.7 million, +12%) increased in value. Decision analysis is required to support land-use planning to ensure the sustainability of ecosystem services for the wellbeing of the people of Guangzhou-Foshan and other rapidly urbanizing areas in China and globally.

No abstract

Supply and demand dynamic effects on scarcity value Highlights:• We present a new model of how changes in supply and demand affect ES scarcity value • GFMA land-use changed 25%, population doubled, wealth up 7-fold from 1990-2010• ES scarcity value increased >6-fold driven by unmet demand • Local private-good ES replaced with substitute inputs with little price impact • Large growth in scarcity value for public-good ES with few good substitutes Abstract 25We present a new model for quantifying the effects of changes in supply and demand on the 26 scarcity value of ecosystem services under land-use change. We demonstrate its application by 27 assessing the impact of rapid urbanization in the Guangzhou-Foshan Metropolitan Area (GFMA) 28 in southern China from 1990 to 2010. Supply and demand curves were developed for both private-good and public-good ecosystem services based on published price elasticities. Change in ecosystem services supply was calculated using a well-established unit-value transfer method 31 and change in demand was calculated as a function of population, wealth, and income elasticity.Naïve assessment (i.e. ignoring supply and demand effects on scarcity value) found a small (-4.4%) decrease in the value of physical supply of ecosystem services from US$4.631 billion in 1990 to US$4.430 billion in 2010. When the effects of changes in supply and demand were considered, the scarcity value of ecosystem services increased dramatically to US$33.774 billion (+629%) in 2010 driven by a strong increase in demand especially for public-good type services with poor substitutes, combined with a slightly reduced supply. A renewed focus on land-use planning to ensure the sustainability of increasingly valuable ecosystem services for the wellbeing of burgeoning urban populations.

Understanding determinants of the invasiveness and ecological impacts of alien species is amongst the most sought-after and urgent research questions in ecology. Several studies have shown the value of comparing the functional responses (FRs) of alien and native predators towards native prey, however, the technique is under-explored with herbivorous alien species and as a predictor of invasiveness as distinct from ecological impact. Here, in China, we conducted a mesocosm experiment to compare the FRs among three herbivorous snail species: the golden apple snail, Pomacea canaliculata, a highly invasive and high impact alien listed in “100 of the World's Worst Invasive Alien Species”; Planorbarius corneus, a non-invasive, low impact alien; and the Chinese native snail, Bellamya aeruginosa, when feeding on four locally occurring plant species. Further, by using a numerical response equation, we modelled the population dynamics of the snail consumers. For standard FR parameters, we found that the invasive and damaging alien snail had the highest “attack rates” a, shortest “handling times” h and also the highest estimated maximum feeding rates, 1/hT, whereas the native species had the lowest attack rates, longest handling times and lowest maximum feeding rates. The non-invasive, low impact alien species had consistently intermediate FR parameters. The invasive alien species had higher population growth potential than the native snail species, whilst that of the non-invasive alien species was intermediate. Thus, while the comparative FR approach has been proposed as a reliable method for predicting the ecological impacts of invasive predators, our results further suggest that comparative FRs could extend to predict the invasiveness and ecological impacts of alien herbivores and should be explored in other taxa and trophic groups to determine the general utility of the approach.

Wedelia trilobata (L.) Hitchc., an ornamental groundcover plant introduced to areas around the world from Central America, has become invasive in many regions. To increase understanding of its geographic distribution and potential extent of spread, two presence-only niche-based modeling approaches (Maxent and GARP) were employed to create models based on occurrence records from its: (1) native range only and (2) full range (native and invasive). Models were then projected globally to identify areas vulnerable to W. trilobata invasion. W. trilobata prefers hot and humid environments and can occur in areas with different environmental conditions than experienced in its native range. Based on native and full occurrence points, GARP and Maxent models produced consistent distributional maps of W. trilobata, although Maxent model results were more conservative. When used to estimate the global invasive distribution of the species, both modeling approaches projected the species to occur in Africa. The GARP full model succeeded in predicting the known occurrences in Australia, while the other models failed to identify favorable habitats in this region. Given the rapid spread of W. trilobata and the serious risk of this species poses to local ecosystems, practical strategies to prevent the establishment and expansion of this species should be sought.