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The Circular Economy – A new sustainability paradigm?

Sustainable development: a critical review

The evolving concept of ecosystem management k tie focus of much current debate To clartfi discussion and provide a framework for implementation, I trace the histor- ical development of ecosystem management, provide a working definition, and summarize dominant themes taken mm an t&ensive literature revieut. The general goal of maintaining ecological integrity is discussed along with five specific goals.- maintaining viable popu!z!ions, ecosystem representation, maintaining ecological process (i e., natural disturbance regimes), protecting evolutionary potential of species and ecosystems, and accommodating human use in light of the above short-term policy implications of ecosys- tem management for several groups of key actors (scientists, poliqnaker& managers, citixer&s) are discussed Long-term (>I00 years) poliq implications are also reviewed inch&

What Is Ecosystem Management

The three-pillar conception of (social, economic and environmental) sustainability, commonly represented by three intersecting circles with overall sustainability at the centre, has become ubiquitous. With a view of identifying the genesis and theoretical foundations of this conception, this paper reviews and discusses relevant historical sustainability literature. From this we find that there is no single point of origin of this three-pillar conception, but rather a gradual emergence from various critiques in the early academic literature of the economic status quo from both social and ecological perspectives on the one hand, and the quest to reconcile economic growth as a solution to social and ecological problems on the part of the United Nations on the other. The popular three circles diagram appears to have been first presented by Barbier (Environ Conserv 14:101, doi: 10.1017/s0376892900011449, 1987), albeit purposed towards developing nations with foci which differ from modern interpretations. The conceptualisation of three pillars seems to predate this, however. Nowhere have we found a theoretically rigorous description of the three pillars. This is thought to be in part due to the nature of the sustainability discourse arising from broadly different schools of thought historically. The absence of such a theoretically solid conception frustrates approaches towards a theoretically rigorous operationalisation of ‘sustainability’.

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Three pillars of sustainability: in search of conceptual origins

Sustainability indicators for managing community tourism

Sustainability is increasingly viewed as a desired goal of development and environmental management. This term has been used in numerous disciplines and in a variety of contexts, ranging from the concept of maximum sustainable yield in forestry and fisheries management to the vision of a sustainable society with a steady-state economy. The meaning of the term is strongly dependent on the context in which it is applied and on whether its use is based on a social, economic, or ecological perspective, Sustainability may be defined broadly or narrowly, but a useful definition must specify explicitly the context as well as the temporal and spatial scales being considered. Although societies differ in their conceptualizations of sustainability, indefinite human survival on a global scale requires certain basic support systems, which can be maintained only with a healthy environment and a stable human population. A clearer understanding of global sustainability and the development of appropriate indicators of the status of basic support systems would provide a useful framework for policy making.

Global sustainability: Toward definition

We compared seasonal trends in photosynthesis of two naturalized exotic shrubs (Rhamnus cathartica and Lonicera X bella) and two native shrubs (Cornus racemosa and Prunus serotina) in open and understory habitats in southern Wisconsin. We examined the relationships between resource availability and leaf photosynthetic performance in these four species. All four species had similar relationships between leaf nitrogen (N) content and photosynthetic rate, but the species differed in absolute leaf N content and therefore in photosynthetic rates. Maximum daily photosynthetic rates of all species were significantly correlated with leaf N content in the open habitat, but not in the understory, where low light availability was the major limitation to photosynthesis. Extended leaf longevity was important in the forest understory because it allowed shrubs to take advantage of high light availability at times when the overstory canopy was leafless. Early leaf emergence was more important than late senescence: from 27% to 35% of the annual carbon gain of P. serotina, R. cathartica, and L. X bella occurred prior to leaf emergence of C. racemosa, the species with the shortest leaf life span. Extended leaf longevity of exotic shrubs may help explain their persistence in the understory habitat, but it contributed relatively less to their annual carbon gain in the open habitat.

Ecophysiology of exotic and native shrubs in Southern Wisconsin : I. Relationship of leaf characteristics, resource availability, and phenology to seasonal patterns of carbon gain.

The widespread interest in the concept of sustainable environment and development has been accompanied by the need to develop useful systems of measurement. We discuss the use of indicators which might be used to assess such conditions. Our characteristics, or criteria, for desirable global sustainability indicators are:
 We discuss the basis of these characteristics, and examine two categories of indicators (soil erosion and population) and two specific indicators (physical quality of life index and energy imports as a percentage of consumption) for their value as sustainability measures.

Global sustainability: Toward measurement

In this study we compared the aboveground growth rates of two exotic shrubs (Rhamnus cathartica and Lonicera X bella) and two native shrubs (Cornus racemosa and Prunus serotina) that are important in southern Wisconsin hardwood forests. For all species except P. serotina, aboveground growth rates in an open habitat were greater than in an understory environment. Growth rates differed among species in the open habitat and were significantly correlated with woody production per unit leaf area. All species had greater leaf area per unit wood biomass in the understory than in the open habitat. A comparison of above-ground growth and annual carbon gain suggests much greater respiratory costs in the open habitat, especially for P. serotina. The data from this study were used to examine mechanisms of species response to different light availabilities. We found that the species that increased their production per unit leaf area in response to increased light did not increase their leaf area per unit wood biomass in response to low light, and vice versa. Production of proportionately high leaf area may be important for the growth of C. racemosa in low light.

Ecophysiology of exotic and native shrubs in Southern Wisconsin : II. Annual growth and carbon gain.

Survival and height growth of tree seedlings and rooted cuttings introduced into artificially shaded and unshaded plots in a degraded dry forest were measured at intervals for nine months. Ten tree species were selected to represent a range of ecological characteristics of the dry–forest plant community on St. John, U.S. Virgin Islands. Of three propagule types – seeds, seedlings, and rooted cuttings – introduced to field plots, seedlings survived best (52%) over the initial nine-month period. Cuttings of six species rooted successfully in a shadehouse, but only two of these species survived the nine–month field experiment. Seed germination was low, under 11% for eight of ten species tested, and four species did not germinate. Subsequent mortality of seedling recruits was moderately high. Plumeria alba was the only species for which seedling height growth was not significantly greater than cutting height growth. Shading treatment (25% of full sun) significantly increased seedling survivorship (p= 0.03) but suppressed growth slightly for some species. Shading enhanced survival of seedlings produced from broadcast seeds, but not seed germination. Mortality occurred during dry periods, apparently from drought stress. Results suggest (1) that seedling introductions are the preferred propagule type (over seeding or rooted cuttings) for ecological restoration of degraded tropical dry forests, and (2) that some level of shading is required to increase the survivorship of many dry-forest species or to avert complete mortality of some species. This study suggests that early secondary dry forest may be best restored by underplanting within the existing vegetation. Sufficient shading suitable for growth of native dry-forest trees may be attained using a nurse crop of fast-growing leguminous trees.

Becky J. Brown

Papers

Global sustainability: Toward definition

Ecophysiology of exotic and native shrubs in Southern Wisconsin : I. Relationship of leaf characteristics, resource availability, and phenology to seasonal patterns of carbon gain.

Global sustainability: Toward measurement

Ecophysiology of exotic and native shrubs in Southern Wisconsin : II. Annual growth and carbon gain.

Restoring Caribbean Dry Forests: Evaluation of Tree Propagation Techniques