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A mediodía, la banda de langostas volaba ya a sus anchas sobre el pueblo y formaban una nube gruesa y densa. El cielo se había vuelto amarillo y el sol había desaparecido. El ruido que se oía lo causaba el frotamiento de las alas de las langostas, y, al escucharlo, uno podía imaginarse la batalla que iban a librar esas bestias y daba miedo.
Mo Yan. El clan de los herbívoros (Shicao jiazu).
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Theoretical Clues for Agroecological Transitions: The Conuco Legacy and the Monoculture Trap
Diego Griffon, Maria-Josefina Hernandez and David Ramírez
The multiple ecological crisis that we are facing forces us to ponder the transition toward sustainable agricultural systems. Two key uncertainties need to be unveiled in addressing this problem; first, we need to identify the general features of alternative models that make them sustainable, and second, we need to explore how to build them from the (flawed) existing systems. In this work we explore these two questions using an ethnoecological and theoretical approach. In the exploration of alternative models, we evaluate an ancestral farming system, the conuco, characterized by, (i) the use of the ecological succession to constantly renew its properties, (ii) the increase of its biodiversity over time (in the horizontal and vertical components), and (iii) the self-regulation of the associated populations. Next, we characterize the topology of ecological networks of agroecosystems along the transition from a monoculture to a conuco-like agroecological system. We use topologies obtained from field information of conventional and agroecological systems as starting and arrival points. To model the dynamics of the systems and numerically simulate the transitions, we use a model based on Generalized Lotka-Volterra equations, where all types of population interactions are represented, with outcomes based on a density-dependent conditionality. The results highlight the relevance of increasing the connectance and diminishing the degree centrality of the conventional systems networks to promote their sustainability. Finally, we propose that the transitions between the monoculture and the agroecological systems could be figuratively interpreted as a cusp catastrophe, where the two systems are understood as alternative stable states and the path from one to the other cannot be reverted by just reversing the values of the control parameter. That is, once a system is in either of these states there is a tendency to stay and a resistance to move away from it. This implies that in the process of transition from a monoculture to a multi-diverse system, it is prudent not to despair if there are no immediate improvements in the performance of the system because once a certain point is reached, the system may experience an abrupt improvement.
https://www.frontiersin.org/articles/10.3389/fsufs.2021.529271/full
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How much of the world's food do smallholders produce?
Ricciardi et al., 2018.
The widely reported claim that smallholders produce 70–80% of the world’s food has been a linchpin of agricultural development policy despite limited empirical evidence. Recent empirical attempts to reinvestigate this number have lacked raw data on how much food smallholders produce, and have relied on model assumptions with unknown biases and with limited spatial and commodity coverage. We examine variations in crop production by farm size using a newly-compiled global sample of subnational level microdata and agricultural censuses covering more countries (n=55) and crop types (n=154) than assessed to date. We estimate that farms under 2ha globally produce 28–31% of total crop production and 30–34% of food supply on 24% of gross agricultural area. Farms under 2ha devote a greater proportion of their production to food, and account for greater crop diversity, while farms over 1000ha have the greatest proportion of post-harvest loss.
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Soil multitrophic network complexity enhances the link between biodiversity and multifunctionality in agricultural systems
Jiao et al., 2021
Belowground biodiversity supports multiple ecosystem functions and services that humans rely on. However, there is a dearth of studies exploring the determinants of the biodiversity–ecosystem function (BEF) relationships, particularly in intensely managed agricultural ecosystems. Here, we reported significant and positive relationships between soil biodiversity of multiple organism groups and multiple ecosystem functions in 228 agricultural fields, relating to crop yield, nutrient provisioning, element cycling, and pathogen control. The relationships were influenced by the types of organisms, that soil phylotypes with larger sizes or at higher trophic levels, e.g., invertebrates or protist predators, appeared to exhibit weaker or no BEF relationships when compared to those with smaller sizes or at lower trophic levels, e.g. archaea, bacteria, fungi, and protist phototrophs. Particularly, we highlighted the role of soil network complexity, reflected by co-occurrence patterns among multitrophic-level organisms, in enhancing the link between soil biodiversity and ecosystem functions. Our results represent a significant advance in forecasting the impacts of belowground multitrophic organisms on ecosystem functions in agricultural systems, and suggest that soil multitrophic network complexity should be considered a key factor in enhancing ecosystem productivity and sustainability under land-use intensification.
https://onlinelibrary.wiley.com/doi/10.1111/gcb.15917
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A complex network framework for the efficiency and resilience trade-off in global food trade
Deniz Berfin Karakoc and Megan Konar, 2021
Global food trade is crucial for food security and availability. Trade is typically optimized to promote efficiency, whereas resilience is increasingly being recognized as another important objective. However, it is not clear if prioritizing resilience comes at the expense of efficiency or if the two objectives can be promoted simultaneously. We develop a complex network framework to assess the relationship between resilience and efficiency of food trade for the last half century. There is a competitive relationship between efficiency and resilience when only network topology is considered. However, a cooperative relationship between efficiency and resilience exists when the intensity of trade connections is accounted for. Policy makers can use this framework to evaluate the relationship between efficiency and resilience in critical supply chains.
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