Positive Feedback in Natural Systems

Jiang, Jiang; Post, W. M.; Travis, Curtis C.

doi:10.1007/978-3-642-82625-2

Cited by 150 publications

(100 citation statements)

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“…DeAngelis and his coworkers (7,26) have examined positive feedbacks in biological systems in detail, noting that their influence often goes unrecognized or underestimated. In general, this type of feedback between herbivores and their plant hosts would induce responses that neither organism can produce alone.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Grasshopper crop and midgut extract effects on plants: an example of reward feedback.

Dyer

Moon²,

Brown³

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

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Acid extracts and a resultant fraction from solid-phase extraction (SPE) of Romalea guttata crop and midgut tissues induce sorghum (Sorghum bicolor var. Rio) coleoptile growth in 24-h incubations an average of 49% above untreated controls. When combined with plant auxin, indole-3-acetic acid (IAA), the SPE fraction shows a synergistic reaction, yielding increases in coleoptile growth that average 295% above untreated controls and 8% above IAA standards.The interaction lowered the point of maximum sensitivity of IAA 3 orders of magnitude, resulting in a new IAA physiological set point at 10-7 g/ml. This synergism suggests that contents in animal regurgitants making their way into plant tissue during feeding may produce a positive feedback in plant growth and development following herbivory. Such a process, also known as reward feedback, may exert major controls on ecosystem-level relationships in nature.As herbivores feed on their host plants they induce a variety of changes in plant responses. These include production of defense mechanisms (1, 2) and changes in internal physiology (3, 4) and productivity (5, 6), providing overall a series of positive and negative feedback signals to the plant that can reorient its C and N distribution as well as its growth and development potential (7,8). The induction signal itself may emanate from endogenous biochemical pathways set in motion by physical damage to plant leaves (9-11) or, perhaps as likely, exogenously from biochemical messengers found in salivary and digestive systems of herbivores (12)(13)(14)(15)(16). Epidermal growth factor (EGF), a highly conserved mitogenic peptide found in salivary glands of many animal species that acts as an intracellular messenger in animal tissues (17), also affects plant cell growth, seedling development, and plant production processes (12)(13)(14)(15) peptides that induce plant responses, which in turn control production processes similar to those actions found in applications of vertebrate EGF. MATERIALS AND METHODSDuring the summers of 1992 and 1993 we collected >1000 late-instar and adult male and female Romalea grasshoppers from a park in Athens, Georgia. We kept the grasshoppers in 0.23-m3 laboratory cages in a greenhouse, fed them washed lettuce and high-protein chick starter meal for several days, and then starved them for at least 2 days to clear out their digestive tracts. We dissected the crop and midgut and froze the tissues immediately on dry ice for storage at -80°C.We extracted the tissues by a method developed for purification of bioactive polypeptides with known molecular masses of <13 kDa (20). We homogenized the frozen crops and midguts (5-25 g) in 100 ml of ice-cold 0.2 M acetic acid solution containing protease inhibitors. After centrifugation (20 min; 17,200 x g) and reextraction of the pellet twice more, we pooled the supernatant solutions ('300 ml) and lyophilized them. We rehydrated the lyophilized solutions with HPLC grade water and centrifuged them (as before) to obtain a supernatant solution or ...

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Section: Resultsmentioning

confidence: 99%

“…In general, this type of feedback between herbivores and their plant hosts would induce responses that neither organism can produce alone. Such signals may function to give at least a temporary physiological or ecological advantage to the wellbeing of the organism processing the signal (7,26). If …”

Section: Resultsmentioning

confidence: 99%

Grasshopper crop and midgut extract effects on plants: an example of reward feedback.

Dyer

Moon²,

Brown³

et al. 1995

Proc. Natl. Acad. Sci. U.S.A.

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“…In addition, because the increase in SOM decomposition that we found at elevated CO 2 could contribute to an elevated rate of increase in the atmospheric CO 2 concentration, determining the potential extent of this positive feedback in anaerobic systems worldwide and quantifying thresholds for its initiation are important for understanding future carbon-cycling dynamics (DeAngelis et al, 1986).…”

Section: Discussionmentioning

confidence: 98%

An oxygen‐mediated positive feedback between elevated carbon dioxide and soil organic matter decomposition in a simulated anaerobic wetland

Wolf

Drake

Erickson

et al. 2007

Global Change Biology

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We examined the effects of elevated atmospheric CO 2 on soil carbon decomposition in an experimental anaerobic wetland system. Pots containing either bare C 4 -derived soil or the C 3 sedge Scirpus olneyi planted in C 4 -derived soil were incubated in greenhouse chambers at either ambient or twice-ambient atmospheric CO 2 . We measured CO 2 flux from each pot, quantified soil organic matter (SOM) mineralization using d 13 C, and determined root and shoot biomass. SOM mineralization increased in response to elevated CO 2 by 83-218% (Po0.0001). In addition, soil redox potential was significantly and positively correlated with root biomass (P 5 0.003). Our results (1) show that there is a positive feedback between elevated atmospheric CO 2 concentrations and wetland SOM decomposition and (2) suggest that this process is mediated by the release of oxygen from the roots of wetland plants. Because this feedback may occur in any wetland system, including peatlands, these results suggest a limitation on the size of the carbon sink presented by anaerobic wetland soils in a future elevated-CO 2 atmosphere.

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“…Although the majority of conceptual models of community structure are either explicitly or implicitly based on competition, a large body of empirical evidence and theory has accrued supporting positive interactions, such as facilitation, as another important and general phenomenon affecting plant distributions, productivity, diversity, and reproduction (Hunter and Aarssen, 1988;DeAngelis et al, 1986;Brooker et al, 2008;Bulleri et al, 2008). Positive interactions are incredibly diverse and have a welldocumented influence on ecosystems.…”

Section: Facilitation and Restoration Ecologymentioning

confidence: 99%

Nucleation in tropical ecological restoration

Reis

Bechara

Tres

2010

Sci. agric. (Piracicaba, Braz.)

123

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Ecological theories of facilitation and nucleation are proposed as a basis for environmental restoration in tropical ecosystems. The main goal of this paper is to present restoration techniques based on the concept of nucleation, in which small nuclei of vegetation are established within a degraded land. The nucleation techniques (artificial shelters for animals, planting of herbaceous shrub life forms, soil and seed bank translocation, seed rain translocation, soil and seed rain translocation's seedling set, artificial perches, planting of native trees in groups, and ecological stepping-stones with functional groups) promote the landscape connectivity on two flows: inward: receiver connectivity and outward: donor connectivity. The nuclei development represents an alternative for restoration by prioritizing the natural processes of succession. This methodology appears to take long to generate vegetation corresponding to tropical climates, but is fundamental in the formation of communities capable of acting, in the future, as a new functional nuclei within the current fragmented landscape. This strategy also encourages greater integration between the theories and projects of ecological restoration for the development of human resources and to benefit the restoration practitioner. Key words: facilitation, succession, heterogeneity, landscape connectivity, degraded areas A Nucleação na restauração ecológica de ecossistemas tropicais RESUMO: As teorias ecológicas da facilitação e nucleação são propostas como base para a restauração ambiental de ecossistemas tropicais. Nesse "Ponto de Vista" apresentam-se técnicas de restauração fundamentadas no conceito de nucleação, onde pequenos núcleos de vegetação são implantados em uma área degradada. As técnicas de nucleação (abrigos artificiais para animais, plantio de espécies herbáceo-arbustivas, transposição de solo e banco de sementes, transposição de chuva de sementes, blocos de mudas procedentes de transposição de solo e chuva de sementes, poleiros artificiais, plantio de árvores nativas em grupos de Anderson, e trampolins ecológicos com grupos funcionais) promovem a conectividade da paisagem sob dois fluxos: interno: conectividade recebedora; e externo: conectividade doadora. O desenvolvimento dos núcleos representa uma alternativa de restauração que prioriza os processos de sucessão natural. A restauração através das técnicas de nucleação pode parecer muito lenta para atingir uma vegetação que corresponda ao clima tropical, porém representa uma base para a constituição de comunidades que, no futuro, poderão potencialmente atuar como novos núcleos funcionais dentro da atual paisagem fragmentada. Encoraja-se maior integração entre teorias ecológicas e projetos de restauração para desenvolvimento de recursos humanos e formação de restauradores ecológicos. Palavras-chave: facilitação, sucessão, heterogeneidade, conectividade da paisagem, áreas degradadas

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Positive Feedback in Natural Systems

Abstract: This book is an argument for greater research attention to natural systems with positive feedback. Positive feedback is defined in a straightforward way as "deviation amplifying" feedback, and the book describes examples from a variety of fields.

Cited by 150 publications

References 0 publications

Grasshopper crop and midgut extract effects on plants: an example of reward feedback.

Grasshopper crop and midgut extract effects on plants: an example of reward feedback.

An oxygen‐mediated positive feedback between elevated carbon dioxide and soil organic matter decomposition in a simulated anaerobic wetland

Nucleation in tropical ecological restoration

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