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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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The spread of a wild plant pathogen is driven by the road network     
 Elina Numminen  and Anna-Liisa Laine. 2020

Spatial analyses of pathogen occurrence in their natural surroundings entail unique opportunities for assessing in vivo drivers of disease epidemiology. Such studies are however confronted by the complexity of the landscape driving epidemic spread and disease persistence. Since relevant information on how the landscape influences epidemiological dynamics is rarely available, simple spatial models of spread are often used. In the current study we demonstrate both how more complex transmission pathways could be incorpoted to epidemiological analyses and how this can offer novel insights into understanding disease spread across the landscape. Our study is focused on Podosphaera plantaginis, a powdery mildew pathogen that transmits from one host plant to another by wind-dispersed spores. Its host populations often reside next to roads and thus we hypothesize that the road network influences the epidemiology of P. plantaginis. To analyse the impact of roads on the transmission dynamics, we consider a spatial dataset on the presence-absence records on the pathogen collected from a fragmented landscape of host populations. Using both mechanistic transmission modeling and statistical modeling with road-network summary statistics as predictors, we conclude the evident role of the road network in the progression of the epidemics: a phenomena which is manifested both in the enhanced transmission along the roads and in infections typically occurring at the central hub locations of the road network. We also demonstrate how the road network affects the spread of the pathogen using simulations. Jointly our results highlight how human alteration of natural landscapes may increase disease spread.

The two computed centrality measures, betweenness (A) and closeness (B), for the considered host populations, computed based on their projection to the closest point in the road network. The correlation between the Euclidean- and shortest distance by road for a random set of pairs of host populations (C) and the relationship between the computed betweenness summary-statistic and the presence and absence of pathogen in different years (D). The roadmaps in the background were created using data produced by National Land Survey of Finland.

https://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1007703

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How we eat determines to a considerable extent how the world is used. 

Wendel Berry
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Holobiont Evolution - Joan Roughgarden

 

A  parasitic Trissolcus wasps lurks among a clutch of stinkbug eggs in an Ecuadorian cloud forest.
Photo: Alex Wild(@Myrmecos)

The Book of Thel

By William Blake 

 

THEL'S MOTTO
Does the Eagle know what is in the pit?
Or wilt thou go ask the Mole:
Can Wisdom be put in a silver rod?
Or Love in a golden bowl?

I

The daughters of Mne Seraphim led round their sunny flocks.

All but the youngest; she in paleness sought the secret air. 

To fade away like morning beauty from her mortal day: 

Down by the river of Adona her soft voice is heard: 

And thus her gentle lamentation falls like morning dew. 

O life of this our spring! why fades the lotus of the water?

Why fade these children of the spring? born but to smile & fall. 

Ah! Thel is like a watry bow. and like a parting cloud. 

Like a reflection in a glass. like shadows in the water. 

Like dreams of infants. like a smile upon an infants face,

Like the doves voice, like transient day, like music in the air; 

Ah! gentle may I lay me down, and gentle rest my head,

And gentle sleep the sleep of death. and gentle hear the voice

Of him that walketh in the garden in the evening time.

The Lilly of the valley breathing in the humble grass

Answer'd the lovely maid and said: I am a watry weed,

And I am very small, and love to dwell in lowly vales;

So weak, the gilded butterfly scarce perches on my head. 

Yet I am visited from heaven and he that smiles on all. 

Walks in the valley. and each morn over me spreads his hand 

Saying, rejoice thou humble grass, thou new-born lilly flower,

Thou gentle maid of silent valleys. and of modest brooks;

For thou shalt be clothed in light, and fed with morning manna: 

Till summers heat melts thee beside the fountains and the springs

To flourish in eternal vales: then why should Thel complain, 

Why should the mistress of the vales of Har, utter a sigh. 

She ceasd & smild in tears, then sat down in her silver shrine.

Thel answered. O thou little virgin of the peaceful valley. 

Giving to those that cannot crave, the voiceless, the o'ertired. 

Thy breath doth nourish the innocent lamb, he smells thy milky garments,

He crops thy flowers. while thou sittest smiling in his face,

Wiping his mild and meekin mouth from all contagious taints.

Thy wine doth purify the golden honey, thy perfume,

Which thou dost scatter on every little blade of grass that springs,

Revives the milked cow, & tames the fire-breathing steed.

But Thel is like a faint cloud kindled at the rising sun:

I vanish from my pearly throne, and who shall find my place?"

"Queen of the vales," the Lily answered, "ask the tender cloud,

And it shall tell thee why it glitters in the morning sky,

And why it scatters its bright beauty thro' the humid air.

Descend, O little cloud, & hover before the eyes of Thel."

The Cloud descended, and the Lily bowd her modest head,

And went to mind her numerous charge among the verdant grass.

II

"O little Cloud," the virgin said, "I charge thee tell to me,

Why thou complainest not when in one hour thou fade away:

Then we shall seek thee but not find; ah, Thel is like to Thee.

I pass away, yet I complain, and no one hears my voice."

The Cloud then shew'd his golden head & his bright form emerg'd,

Hovering and glittering on the air before the face of Thel.

"O virgin, know'st thou not our steeds drink of the golden springs

Where Luvah doth renew his horses? Look'st thou on my youth,

And fearest thou because I vanish and am seen no more,

Nothing remains? O maid, I tell thee, when I pass away,

It is to tenfold life, to love, to peace, and raptures holy:

Unseen descending, weigh my light wings upon balmy flowers,

And court the fair eyed dew, to take me to her shining tent:

The weeping virgin trembling kneels before the risen sun,

Till we arise link'd in a golden band, and never part,

But walk united, bearing food to all our tender flowers."

"Dost thou O little Cloud? I fear that I am not like thee;

For I walk through the vales of Har and smell the sweetest flowers,

But I feed not the little flowers; I hear the warbling birds,

But I feed not the warbling birds; they fly and seek their food;

But Thel delights in these no more, because I fade away,

And all shall say, 'Without a use this shining woman liv'd,

Or did she only live to be at death the food of worms?'"

The Cloud reclind upon his airy throne and answer'd thus:

"Then if thou art the food of worms, O virgin of the skies,

How great thy use, how great thy blessing! Every thing that lives

Lives not alone, nor for itself; fear not, and I will call

The weak worm from its lowly bed, and thou shalt hear its voice.

Come forth, worm of the silent valley, to thy pensive queen."

The helpless worm arose, and sat upon the Lily's leaf,

And the bright Cloud saild on, to find his partner in the vale.

III

Then Thel astonish'd view'd the Worm upon its dewy bed.

"Art thou a Worm? Image of weakness, art thou but a Worm?

I see thee like an infant wrapped in the Lily's leaf;

Ah, weep not, little voice, thou can'st not speak, but thou can'st weep.

Is this a Worm? I see thee lay helpless & naked, weeping,

And none to answer, none to cherish thee with mother's smiles."

The Clod of Clay heard the Worm's voice, & raisd her pitying head;

She bow'd over the weeping infant, and her life exhal'd

In milky fondness; then on Thel she fix'd her humble eyes.

"O beauty of the vales of Har! we live not for ourselves;

Thou seest me the meanest thing, and so I am indeed;

My bosom of itself is cold, and of itself is dark,

But he that loves the lowly, pours his oil upon my head,

And kisses me, and binds his nuptial bands around my breast,

And says: 'Thou mother of my children, I have loved thee

And I have given thee a crown that none can take away.'

But how this is, sweet maid, I know not, and I cannot know;

I ponder, and I cannot ponder; yet I live and love."

The daughter of beauty wip'd her pitying tears with her white veil,

And said: "Alas! I knew not this, and therefore did I weep.

That God would love a Worm, I knew, and punish the evil foot

That, wilful, bruis'd its helpless form; but that he cherish'd it

With milk and oil I never knew; and therefore did I weep,

And I complaind in the mild air, because I fade away,

And lay me down in thy cold bed, and leave my shining lot."

"Queen of the vales," the matron Clay answered, "I heard thy sighs,

And all thy moans flew o'er my roof, but I have call'd them down.

Wilt thou, O Queen, enter my house? 'tis given thee to enter

And to return: fear nothing, enter with thy virgin feet."

IV

The eternal gates' terrific porter lifted the northern bar:

Thel enter'd in & saw the secrets of the land unknown.

She saw the couches of the dead, & where the fibrous roots

Of every heart on earth infixes deep its restless twists:

A land of sorrows & of tears where never smile was seen.

She wanderd in the land of clouds thro' valleys dark, listning

Dolours & lamentations; waiting oft beside a dewy grave,

She stood in silence, listning to the voices of the ground,

Till to her own grave plot she came, & there she sat down,

And heard this voice of sorrow breathed from the hollow pit:

"Why cannot the Ear be closed to its own destruction?

Or the glistning Eye to the poison of a smile?

Why are Eyelids stord with arrows ready drawn,

Where a thousand fighting men in ambush lie?

Or an Eye of gifts & graces, show'ring fruits and coined gold?

Why a Tongue impress'd with honey from every wind?

Why an Ear, a whirlpool fierce to draw creations in?

Why a Nostril wide inhaling terror, trembling, and affright?

Why a tender curb upon the youthful burning boy?

Why a little curtain of flesh on the bed of our desire?"

The Virgin started from her seat, & with a shriek

Fled back unhinderd till she came into the vales of Har.