An ecophysiological model of plant-pest interactions: the role of nutrient and water availability.

Empirical studies have shown that particular irrigation/fertilization regimes can reduce pest populations in agroecosystems. This appears to promise that the ecological concept of bottom-up control can be applied to pest management. However, a conceptual framework is necessary to develop a mechanistic basis for empirical evidence. Here, we couple a mechanistic plant growth model with a pest population model. We demonstrate its utility by applying it to the peach-green aphid system. Aphids are herbivores which feed on the plant phloem, deplete plants' resources and (potentially) transmit viral diseases. The model reproduces system properties observed in field studies and shows under which conditions the diametrically opposed plant vigour and plant stress hypotheses find support. We show that the effect of fertilization/irrigation on the pest population cannot be simply reduced as positive or negative. In fact, the magnitude and direction of any effect depend on the precise level of fertilization/irrigation and on the date of observation. We show that a new synthesis of experimental data can emerge by embedding a mechanistic plant growth model, widely studied in agronomy, in a consumer-resource modelling framework, widely studied in ecology. The future challenge is to use this insight to inform practical decision making by farmers and growers

PREDICTING HABITAT DISTRIBUTION FOR FIVE RARE PLANT SPECIES WITHIN THE BLACKFOOT SWAN LANDSCAPE RESTORATION PROJECT

This study predicted rare-plant habitat at the landscape scale. Using the Maximum Entropy (MaxEnt) algorithm, relationships to and between each environmental variable were quantified for five species in the Blackfoot Swan Landscape Restoration Project (BSLRP) study area in western Montana. This project is part of a greater vegetation assessment for BSLRP that utilizes remotely sensed products for planning and management purposes. The five rare plant species studied in this analysis were common camas (Camassia quamash), clustered lady’sslipper (Cypripedium fasciculatum), western pearlflower (Heterocodon rariflorum), Howell’s gumweed (Grindelia howellii), and crested shieldfern (Dryopteris cristata). Rare plant models typically do not address dispersal mechanisms in conceptual design. This analysis built dispersal mechanisms into model design by buffering the project area based upon dispersal potential. Plant population data is typically stored as polygons in state and federal databases. This data is usually condensed into a single point before entry into modeling algorithms. This analysis addressed this issue by proportionately placing multiple points inside the polygons. In addition, this analysis considered the effects of using different regularization parameter values in MaxEnt and how it affected model performance. For one species, the efficacy of including LiDAR-derived canopy cover to enhance discrimination of understory communities and its effect on improving model performance was examined. Accuracy assessments were used to better understand predictions and statistical relationships between environmental variables. Lastly, predicted habitat maps were overlaid to identify areas of high probability habitat for multiple species across the project area. The field surveys identified thirteen new populations of plants. Overall accuracy for the predictions ranged from 26 to 69%. Comparison between predictions based upon centroids versus distributed points yielded an improved AUC and reduced standard deviation. The LiDAR data defined a narrower niche and had an improved AUC and lower standard deviation but did not lower assessed accuracy for crested shieldfern. Species distribution model studies are one way for resource managers to identify potential habitat for rare species before going into the field. They can use this information to prioritize field surveys and inform management decisions. Also, SDM studies provide information on species’ environmental associations and can be used to further understand species ecology

To what degree are philosophy and the ecological niche concept necessary in the ecological theory and conservation?

Ecology as a field produces philosophical anxiety, largely because it differs in scientific structure from classical  physics. The hypothetical deductive models of classical physics are simple and predictive; general ecological models are predictably limited, as they refer to complex, multi-causal processes. Inattention to the conceptual  structure of ecology usually imposes difficulties for the application of ecological models. Imprecise descriptions of ecological niche have obstructed the development of collective definitions, causing confusion in the literature and complicating communication between theoretical ecologists, conservationists and decision and policy-makers. Intense, unprecedented erosion of biodiversity is typical of the Anthropocene, and knowledge of ecology may provide solutions to lessen the intensification of species losses. Concerned philosophers and ecologists have characterised ecological niche theory as less useful in practice; however, some theorists maintain that is has relevant applications for conservation. Species niche modelling, for instance, has gained traction in the literature; however, there are few examples of its successful application. Philosophical analysis of the structure, precision and constraints upon the definition of a ‘niche’ may minimise the anxiety surrounding ecology, potentially facilitating communication between policy-makers and scientists within the various ecological subcultures. The results may enhance the success of conservation applications at both small and large scales

Modelling and simulating change in reforesting mountain landscapes using a social-ecological framework

Natural reforestation of European mountain landscapes raises major environmental and societal issues. With local stakeholders in the Pyrenees National Park area (France), we studied agricultural landscape colonisation by ash (Fraxinus excelsior) to enlighten its impacts on biodiversity and other landscape functions of importance for the valley socio-economics. The study comprised an integrated assessment of land-use and land-cover change (LUCC) since the 1950s, and a scenario analysis of alternative future policy. We combined knowledge and methods from landscape ecology, land change and agricultural sciences, and a set of coordinated field studies to capture interactions and feedback in the local landscape/land-use system. Our results elicited the hierarchically-nested relationships between social and ecological processes. Agricultural change played a preeminent role in the spatial and temporal patterns of LUCC. Landscape colonisation by ash at the parcel level of organisation was merely controlled by grassland management, and in fact depended on the farmer's land management at the whole-farm level. LUCC patterns at the landscape level depended to a great extent on interactions between farm household behaviours and the spatial arrangement of landholdings within the landscape mosaic. Our results stressed the need to represent the local SES function at a fine scale to adequately capture scenarios of change in landscape functions. These findings orientated our modelling choices in the building an agent-based model for LUCC simulation (SMASH - Spatialized Multi-Agent System of landscape colonization by ASH). We discuss our method and results with reference to topical issues in interdisciplinary research into the sustainability of multifunctional landscapes

Forest floor vegetation in Sweden

In boreal forests, dwarf-shrubs (Vaccinium spp.) often dominate the forest floor and are key-stone species in ecosystems due to their importance for nutrient cycling and as a major food source for herbivores. Forestry affects the vegetation both directly through management and indirectly by altering the forest structure. Forest fertilization with N at the end of the rotation period is a common practice in Swedish boreal forests. Even higher timber production can be achieved if fertilization with multi-nutrient fertilizer is applied early in the rotation period, but the effects on forest floor vegetation have not been studied. The objectives of this thesis were to increase knowledge regarding how 1) intensive fertilization in young forest affects forest floor vegetation; 2) background deposition of N influences the effects of N addition; and 3) to relate observed changes in common species abundances to changes in forest structure. Fertilization decreased the abundance of many common forest plant species while only few species increased (I). Surprisingly, also species known as nitrophilous decreased in abundance. Paper I shows that the decrease in availability of light induced by fertilization is a crucial factor behind this change. Consequently, fertilization reduced both species richness, species diversity and the between site (β) diversity (II). In areas where the background N deposition was low (4 kg ha-1 yr-1), the effects of N addition were larger than in areas with intermediate (16 kg ha-1 yr-1) deposition (III). Key-stone species among the forest floor vegetation of boreal Sweden (e.g. Vaccinium myrtillus) were found to decrease in abundance (IV). These species are strongly dependent on aspects of forest structure, such as forest density and age, and likewise, temporal changes in species abundance coincided with corresponding changes in forest structure (IV). In conclusion, in large parts of Sweden the prevailing forest management is incompatible with a productive forest floor vegetation possessing a high diversity of plant species, and this situation will only be exacerbated by more intensive use of fertilization regimes. To avoid associated cascading effects from the decreased abundance of key-stone species, forestry intensity needs to be relaxed on the landscape level which would likely result in a considerable loss of timber production. Compensation for this loss through intensified forestry on other areas would indicate the need for altered forest zoning

Eco‐Holonic 4.0 Circular Business Model to Conceptualize Sustainable Value Chain Towards Digital Transition

The purpose of this paper is to conceptualize a circular business model based on an Eco-Holonic Architecture, through the integration of circular economy and holonic principles. A conceptual model is developed to manage the complexity of integrating circular economy principles, digital transformation, and tools and frameworks for sustainability into business models. The proposed architecture is multilevel and multiscale in order to achieve the instantiation of the sustainable value chain in any territory. The architecture promotes the incorporation of circular economy and holonic principles into new circular business models. This integrated perspective of business model can support the design and upgrade of the manufacturing companies in their respective industrial sectors. The conceptual model proposed is based on activity theory that considers the interactions between technical and social systems and allows the mitigation of the metabolic rift that exists between natural and social metabolism. This study contributes to the existing literature on circular economy, circular business models and activity theory by considering holonic paradigm concerns, which have not been explored yet. This research also offers a unique holonic architecture of circular business model by considering different levels, relationships, dynamism and contextualization (territory) aspects

The Eroding Artificial/Natural Distinction: Some Consequences for Ecology and Economics

Since Thomas Kuhn’s The Structure of Scientific Revolutions (1962), historians and philosophers of science have paid increasing attention to the implications of disciplinarity. In this chapter we consider restrictions posed to interdisciplinary exchange between ecology and economics that result from a particular kind of commitment to the ideal of disciplinary purity, that is, that each discipline is defined by an appropriate, unique set of objects, methods, theories, and aims. We argue that, when it comes to the objects of study in ecology and economics, ideas of disciplinary purity have been underwritten by the artificial-natural distinction. We then problematize this distinction, and thus disciplinary purity, both conceptually and empirically. Conceptually, the distinction is no longer tenable. Empirically, recent interdisciplinary research has shown the epistemological and policy-oriented benefits of dealing with models which explicitly link anthropogenic (i.e., “artificial”) and non-anthropogenic factors (i.e., “natural”). We conclude that, in the current age of the Anthropocene, it is to be expected that without interdisciplinary exchange, ecology and economics may relinquish global relevance because the distinct and separate systems to which each “pure” science was originally made to apply will only diminish over time

Experimenting with ecosystem interaction networks in search of threshold potentials in real-world marine ecosystems

Thresholds profoundly affect our understanding and management of ecosystem dynamics, but we have yet to develop practical techniques to assess the risk that thresholds will be crossed. Combining ecological knowledge of critical system interdependencies with a large-scale experiment, we tested for breaks in the ecosystem interaction network to identify threshold potential in real-world ecosystem dynamics. Our experiment with the bivalves Macomona liliana and Austrovenus stutchburyi on marine sandflats in New Zealand demonstrated that reductions in incident sunlight changed the interaction network between sediment biogeochemical fluxes, productivity, and macrofauna. By demonstrating loss of positive feedbacks and changes in the architecture of the network, we provide mechanistic evidence that stressors lead to break points in dynamics, which theory predicts predispose a system to a critical transition

Resilience of New Zealand indigenous forest fragments to impacts of livestock and pest mammals

A number of factors have combined to diminish ecosystem integrity in New Zealand indigenous lowland forest fragments surrounded by intensively grazed pasture. Livestock grazing, mammalian pests, adventive weeds and altered nutrient input regimes are important drivers compounding the changes in fragment structure and function due to historical deforestation and fragmentation. We used qualitative systems modelling and empirical data from Beilschmiedia tawa dominated lowland forest fragments in the Waikato Region to explore the relevance of two common resilience paradigms – engineering resilience and ecological resilience – for addressing the conservation management of forest fragments into the future. Grazing by livestock and foraging/predation by introduced mammalian pests both have direct detrimental impacts on key structural and functional attributes of forest fragments. Release from these perturbations through fencing and pest control leads to partial or full recovery of some key indicators (i.e. increased indigenous plant regeneration and cover, increased invertebrate populations and litter mass, decreased soil fertility and increased nesting success) relative to levels seen in larger forest systems over a range of timescales. These changes indicate that forest fragments do show resilience consistent with adopting an engineering resilience paradigm for conservation management, in the landscape context studied. The relevance of the ecological resilience paradigm in these ecosystems is obscured by limited data. We characterise forest fragment dynamics in terms of changes in indigenous species occupancy and functional dominance, and present a conceptual model for the management of forest fragment ecosystems