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Volver a la naturaleza es limpiarnos  

Carl Jung
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Agroecological Transitions: A Mathematical Perspective on a Transdisciplinary Problem
Theresa Wei Ying Ong and Wenying Liao

In the face of climate change, rising hunger and mass extinctions, scholars stress the need to transition food systems from fossil fuel-dependent conventional farms to agroecological alternatives that can store carbon, improve food security and harbor biodiversity. Theory provides a systematic approach for organizing knowledge on agroecological transitions across the natural and social sciences and summarizing the primary needs of future research. This paper reviews the socio-ecological literature related to agroecological transitions from a mathematical perspective that is derived from complex systems and critical transition theory. We organize the literature according to mathematically tractable concepts, including syndromes of production, agents, barriers and drivers of change that operate across three major frameworks of analysis: socio-ecological, socio-technological and social norms and networks. Our approach embeds the current agroecological transition theory within a critical transition framework that considers the stability of peasant and capitalist syndromes in response to various inhibitors and drivers of change. We find that the majority of our theoretical knowledge of food systems change is derived from the social sciences and limited primarily to examples from the Americas. Our work suggests a need for broader regional representations of change and transdisciplinary work aimed at better understanding how biophysical factors collide with socio-political conditions to hinder or reverse food systems change. Though scale and context are important considerations, we find that theory can generate general mechanisms that link separate case studies. For example, drivers of food systems change that shift balances between the costs and benefits of peasant and capitalist modes of production may be particularly important for explaining poverty and gilded traps in agriculture. We discuss this and other lessons learned from taking a theoretical perspective on agroecological transitions.

Conceptual diagram of key agents and interactions in the transformation of food systems. Key decision-making agents include farmers, consumers, markets and institutions (bolded). We identify three main frameworks used to study agroecological transitions in the literature: (1) socio-ecological, (2) socio-technological, and (3) social norms and networks frameworks. The third framework describes the structure of interactions of the first two frameworks. The three frameworks are also connected through analyses of interactions amongst farmers, consumers and markets (dashed circle). Their behaviors influence one another and spur changes in both the environmental sustainability or degradation and technological development of farming practices. We highlight three main areas of research on agroecological transitions within these frameworks: synergies and trade-offs in ecosystem services, technological and structural lock-ins, and social norms and network structure.

https://www.frontiersin.org/articles/10.3389/fsufs.2020.00091/full

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I took a walk in the woods and came out taller than the trees.

Henry David Thoreau 
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Global synthesis of the effectiveness of flower strips and hedgerows on pest control, pollination services and crop yield
Albrecht et al., 2020

Floral plantings are promoted to foster ecological intensification of agriculture through provisioning of ecosystem services. However, a comprehensive assessment of the effectiveness of different floral plantings, their characteristics and consequences for crop yield across global regions is lacking. Here we quantified the impacts of flower strips and hedgerows on pest control and pollination services in adjacent crops using a global dataset of 529 sites. Flower strips, but not hedgerows, enhanced pest control services in adjacent fields by 16% on average. However, effects on crop pollination and yield were more variable. Our synthesis identifies several important drivers of variability in effectiveness of plantings: pollination services declined exponentially with distance from plantings, and perennial and older flower strips with higher flowering plant diversity enhanced pollination more effectively. These findings provide promising pathways to optimize floral plantings to more effectively contribute to ecosystem service delivery and ecological intensification of agriculture in the future.

Forest plot showing effects of flower strips and hedgerows on pollination and pest control service provisioning in adjacent crops compared to control crops without adjacent floral plantings. Squares illustrate predicted mean effects (z-score estimates), bars show 95% confidence intervals (CIs). On average, pest control services were enhanced by 16% (z-score: 0.25) in fields with adjacent flower strip compared to control fields.

https://bit.ly/2Z2D33E
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Information arms race explains plant-herbivore chemical communication in ecological communities      
Zu et al., 2020

Plants emit an extraordinary diversity of chemicals that provide information about their identity and mediate their interactions with insects. However, most studies of this have focused on a few model species in controlled environments, limiting our capacity to understand plant-insect chemical communication in ecological communities. Here, by integrating information theory with ecological and evolutionary theories, we show that a stable information structure of plant volatile organic compounds (VOCs) can emerge from a conflicting information process between plants and herbivores. We corroborate this information “arms race” theory with field data recording plant-VOC associations and plant-herbivore interactions in a tropical dry forest. We reveal that plant VOC redundancy and herbivore specialization can be explained by a conflicting information transfer. Information-based communication approaches can increase our understanding of species interactions across trophic levels.

https://science.sciencemag.org/content/368/6497/1377
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Orchid 
Robert Mapplethorpe, 1987.

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...an echo from the past returning from deep in the forest.

Haruki Murakami 

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Co-cropping with three phytoremediation crops influences rhizosphere microbiome community in contaminated soil

N.J.B.Brereton, et al., 2020

Phytoremediation of contaminated soils using monoculture and co-cropping.

Festuca arundinacea, Salix miyabeana and Medicago sativa were compared.

Differential abundance analysis of highly resolved rhizosphere microbiomes.

Co-cropped pairs had more rhizosphere-associated bacteria than their monocultures.

Phytoremediation adaptability could be improved by increased ecosystem services.

Human industrial activities have left millions of hectares of land polluted with trace element metals and persistent organic pollutants (POPs) around the world. Although contaminated sites are environmentally damaging, high economic costs often discourage soil remediation efforts. Phytoremediation is a potential green technology solution but can be challenging due to the diversity of anthropogenic contaminants. Co-cropping could provide improved tolerance to diverse soil challenges by taking advantage of distinct crop capabilities. Co-cropping of three species with potentially complementary functions, Festuca arundinacea, Salix miyabeana and Medicago sativa, perform well on diversely contaminated soils. Here, rhizosphere microbiomes of each crop in monoculture and in all co-cropping combinations were compared using 16S rRNA gene amplification, sequencing and differential abundance analysis. The hyperaccumulating F. arundinacea rhizosphere microbiome included putative plant growth promoting bacteria (PGPB) and metal tolerance species, such as Rhizorhapis suberifaciens, Cellvibrio fibrivorans and Pseudomonas lini. The rhizosphere microbiome of the fast-growing tree S. miyabeana included diverse taxa involved in POP degradation, including the species Phenylobacterium panacis. The well-characterised nitrogen-fixing M. sativa microbiome species, Sinorhizobium meliloti, was identified alongside others involved in nutrient acquisition and putative yet-to-be-cultured Candidatus saccharibacteria (TM7-1 group). The majority of differentially abundant rhizosphere-associated bacterial species were maintained in co-cropping pairs, with pairs having higher numbers of differentially abundant taxa than monocultures in all cases. This was not the case when all three crops were co-cropped, where most host-specific bacterial species were not detected as differentially abundant, indicating the potential for reduced rhizosphere functionality. The crops cultivated in pairs here retained rhizosphere microbiome bacteria involved in these monoculture ecosystem services of plant growth promotion, POP tolerance and degradation, and improved nutrient acquisition. These findings provide a promising outlook of the potential for complementary co-cropping strategies for phytoremediation of the multifaceted anthropogenic pollution which can disastrously affect soils around the world.

https://www.sciencedirect.com/science/article/pii/S0048969719350594 

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If we throw mother nature out the window, she comes back in the door with a pitchfork. 

Masanobu Fukuoka 
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