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Herbivores alter plant biodiversity (species richness) in many of the world's ecosystems, but the magnitude and the direction of herbivore effects on biodiversity vary widely within and among ecosystems. One current theory predicts that herbivores enhance plant biodiversity at high productivity but have the opposite effect at low productivity. Yet, empirical support for the importance of site productivity as a mediator of these herbivore impacts is equivocal. Here, we synthesize data from 252 large-herbivore exclusion studies, spanning a 20-fold range in site productivity, to test an alternative hypothesis-that herbivore-induced changes in the competitive environment determine the response of plant biodiversity to herbivory irrespective of productivity. Under this hypothesis, when herbivores reduce the abundance (biomass, cover) of dominant species (for example, because the dominant plant is palatable), additional resources become available to support new species, thereby increasing biodiversity. By contrast, if herbivores promote high dominance by increasing the abundance of herbivory-resistant, unpalatable species, then resource availability for other species decreases reducing biodiversity. We show that herbivore-induced change in dominance, independent of site productivity or precipitation (a proxy for productivity), is the best predictor of herbivore effects on biodiversity in grassland and savannah sites. Given that most herbaceous ecosystems are dominated by one or a few species, altering the competitive environment via herbivores or by other means may be an effective strategy for conserving biodiversity in grasslands and savannahs globally.

Indicators are being sought for monitoring the ecological integrity of forests and other kinds of ecosystems. Biological measures are commonly used as indicators because of their inherent ecological importance and ability to provide insight into environmental change. Such measures are commonly based on data from sets of permanent plots in which the abundances of plant species are monitored. However, the data may be difficult to interpret, especially if corresponding information on natural and anthropogenic stressors is lacking. In this review, we examine general principles of indicator use and discuss the types of plot-based compositional measures obtained from vegetation that may be most relevant for monitoring ecological integrity. Our focus is on the ground vegetation of forested ecosystems, but the principles discussed are relevant to other vegetation types. Individual plant species, guilds, aliens, diversity indices, Ellenberg indicator values, the floristic quality assessment index, multivariate and multimetric indicators are examined, as well as concepts of threshold changes and the need for reference states. The usefulness of any given approach tends to be highly context specific. In particular, the value of using individual species as indicators is highly dependant on factors such as the character of the floristic community of interest and the types and intensities of anthropogenic stressors. Alien species are considered to be especially valuable indicators of changes in ecological integrity due to their established relationships with anthropogenic stressors, known historical state, relevance to all floristic communities, and ability to cause undesirable changes to biodiversity and ecological processes. Key words: ecological integrity, indicators, monitoring, vegetation, aliens, forests. On recherche des indicateurs pour suivre l'integrite ecologique des forets et autres types d'ecosystemes et Ton utilise generalement des mesures biologiques comme indicateurs, compte tenu de leur importance ecologique inherente et de leur capacite a fournir des indices de changements environnementaux. De telles mesures se basent generalement stir des donnees obtenues a pariir d'un reseau de places echantillons permanentes sur lesquelles on suit tin grand nombre d'especes vegetates. Cependant, les donnees peuvent demeurer difficiles a interpreter, surtout en l'absence d'informations eorrespondantes sur les agents de stress naturels ou anthropogenes. Les auteurs examinent ici les principes generaux pour l'utilisation d'indicateurs et discutent les types de mesures de la composition sur la base de places echantillons, obtenues de la vegetation, et qui peuvent s'averer les plus pertinentes pour faire le suivi de l'integrite ecologique. On met l'accent sur la vegetation du parterre des ecosyslemes lerrestres, mais les principes dont on discute sont pertinents pour d'autres types de vegetation. On examine les plantes individuelles, les regroupements, les adventices, les indices de diversite, les valeurs indicalrices de Ellenberg, l'index devaluation de la qualile floristique, les indicateurs mullivaries el mullimeiriques, les concepts de seuils de changement et les besoins pour des etats de reference. L'utilite de toute approche individuelle tend a etre etroitement liee au contexte specifique. En particulier, la valeur de l1 utilisation d'especes individuelles comme indicatrices depend etroitement de facteurs comme le type d'interet pour la communaute floristique et les types et intensites des agents stressants anthropogenes. On considere les especes adventices comme indicateurs pailiculierement valables compte tenu de leur relation etablie avec des agents stressants anthropogenes, leur historique, leur pertinence pour l'ensemble des communautes tloristiques. et leur capacite a engendrer des changements indesirables pour la biodiversite et les processus ecologiques. Mots-cles : integrite ecologique. indicateurs, monitorage. vegetation, adventices, forets. [Traduit par la Redaction], 1. Introduction Ever since Aldo Leopold's seminal reference to the 'integrity' of the biotic community (Leopold 1949), the concept of ecological integrity (EI) has received considerable attention from researchers and [...]

Increasing the amount of organic-carbon stored in the biomass of terrestrial ecosystems is an effective way to reduce the net anthropogenic emissions of greenhouse gases to the atmosphere. This can be done by conserving existing ecological reservoirs of fixed organic-carbon, maintaining or enhancing the rate of sequestration, and restoring stocks that have been depleted by past land-use practices. Most trading systems for greenhouse-gas offsets recognize the validity of projects that gain ecological offsets, and permit them to sell carbon credits in an emerging marketplace for these novel commodities. Although ecological carbon-offset projects have been criticized from a variety of perspectives, most of the supposed problems can be satisfactorily mitigated. In addition to offsetting emissions of greenhouse gases, ecological projects that accumulate carbon credits may have a strong cross-linkage to the conservation of natural values, which in itself is an important action for society to undertake. This is, however, less of a consideration for projects that are based on anthropogenic ecosystems, such as no-till agricultural systems and plantation forests, which provide relatively few benefits to native biodiversity and might even detract from that objective if developed on newly converted natural habitat. Moreover, the existing rules for carbon-offset systems exclude some kinds of ecological projects from the trading markets, even though they would result in avoided emissions or enhanced sequestration of organic-carbon. As the emerging marketplace for carbon offsets grows, it will be important to understand the co-benefits and side effects of offset projects on non-carbon values, including native biodiversity. L'augmentation des quantites de carbone organique accumulees dans la biomasse des ecosystemes terrestres constitue un moyen efficace pour reduire les emissions anthropogenes nettes de gaz a effets de serre dans I'atmosphere. On peut atteindre cet objectif en conservant les reservoirs ecologiques de carbone organique existants, en maintenant ou en augmenlani le laux de sequestration, et en restaurant les reserves qui ont ete epuisees par les utilisations passees des territoires. La plupart des systemes de compensation des gay. a effet de serre reconnaissent la validite des projets conduisanl a des compensations ecologiques el leur permettent de vendre des credits de carbone dans un marche emergent visant ces nouveaux biens marchands. Bien que les projets ecologiques de compensation du carbone aient ete critiques selon differentes perspectives, on peut mitiger de facon satisfaisante, la plupart des supposes problemes. En plus de compenser les emissions de gaz a effets de serre, les projets ecologiques qui accumulent des credits de carbone peuvent presenter des liens etroits avec la conservation de valeurs naturelles, qui en soi constituent une action importante que doit entreprendre la societe. Cependant, cette consideration s'applique moins aux projets bases sur des activites anthropogeniques comme les systemes de culture sans labour et les plantations forestieres, qui rapportent relativement peu de benefices a la biodiversite indigene et peuvent meme s'eloigner de 1'objectif, si on les applique a des habitats naturels recemment convertis, De plus, les regies existantes pour les systemes de compensation du carbone excluent certains types de projets ecologiques du marche boursier, meme s'ils pennettraient d'eviter des emissions ou augmenter la sequestration de carbone organique, A mesure que les marches emergents des compensations en carbone s'accroissent, il deviendra important de comprendre les cobenefices et les effets secondares des projets de compensation de valeurs autres que le carbone, incluant la biodiversite indigene. [Traduit par la Redaction], 1. Introduction Global climate change is now widely recognized as an issue that must be addressed if the most severe of its predicted environmental and socioeconomic impacts are to be [...]

Abstract: Aquatic plants are important components of many freshwater ecosystems. In this review we examine natural and anthropogenic influences on the distribution and abundance of aquatic plants, and develop a [...]

The history of development of the concept of ecological design (or eco-design) is described, and key influences and antecedents are introduced. Seven principles of ecological design are advanced: (1) the need to meet the inherent needs of humans and their economy; (2) the requirement to sustain the integrity of the structure and function of both natural and managed ecosystems; (3) the appropriateness of emulating the inherent designs of nature in anthropogenic management systems; (4) the need to make progress to a sustainable economy through greater reliance on renewable resources and more focus on recycling, reusing, and efficient use of materials and energy; (5) the use of ecological economics (or full-cost accounting) to comprehensively take resource depletion and environmental damage into consideration and thereby address issues of natural debt; (6) the need to conserve natural ecosystems and indigenous biodiversity at viable levels; and (7) the desirability of increasing environmental literacy to build social support for sustainable development, resource conservation, and protection of the natural world. Examples are presented of the recent application of the principles of eco-design to the planning and management of human communities, industrial parks and networks, architectural practice, and products. The principles and practices of eco-design have much to contribute to the urgent need to make rapid and tangible progress towards a sustainable human economy. [ABSTRACT FROM AUTHOR]

At a high arctic lowland on Ellesmere Island, heath communities dominated by Cassiope tetragona were widespread, and occurred in a variety of habitats that differred in time of snowmelt, relative site moisture, soil thaw depth, and air and soil temperature. Cover, standing crop, and production were dominated by woody plants, notably Cassiope tetragona and Dryas integrifolia. The Cassiope-dominated heaths were similar in composition to those at other Canadian high arctic localities, but were less similar to localities in Greenland and Spitzbergen. Compositional relationships among Cassiope-dominated heaths in different habitats at the study site may be largely determined by two interrelated environmental factors, time of snowmelt and site moisture. Aboveground vascular plant biomass was concentrated near the ground surface, resulting in simple vertical structure that takes advantage of relatively warm soil and air temperatures in summer, and a protective snow cover in winter, Aboveground vascular plant standing crop was largely comprised of attached dead tissue, and there were equal proportions of above- and belowground biomass. Low community production was due to dominance by long-lived, slow-growing species, and to short growing seasons and cold temperatures. Overall character of Cassiope-dominated heaths reflects the conservative, stress tolerant growth strategy of the dominant species. Cassiope tetragona. [ABSTRACT FROM AUTHOR]

The Greater Fundy Ecosystem (GFE) project is an attempt to design and implement a plan to manage a landscape on an ecologically sustainable basis. The overall aim is to protect ecological structures, functions and processes while providing sustainable flows of goods and services for people. A key element of the GFE project is the integration of a protected area into its regional landscape as a single greater ecosystem. At the core of the GFE project is Fundy National Park (FNP), a small (206 km2) national park located on the upper Bayof Fundy in New Brunswick, Canada. The landscape surrounding the park is managed mainly for industrial forestry, often to the park boundary. The contrast between the park and adjacent landscape led to concerns that the ecological integrity of FNP was being affected and that these stresses should be defined and, if needed mitigated. During ourresearch and the development of guidelines related to the maintenance of forest biodiversity, it became apparent that successful implementation of an ecologically sustainable landscape relies on several keythings. These include: a landscape-level appreciation of ecological process; stand-scale application of best-management practices; a political climate that supports change in forest management practices; and a vehicle for stakeholders to work for change. The Fundy Model Forest, one of ten such sites in Canada, was the vehicle that allowed partners to reach a comfortable balance of objectives with values for the environment and economy. Fundy National Park represented a benchmark for conducting comparative research of the impacts of industrial forestry and 'natural' forest. In our work we found that the large protected area was instrumental in distributing the perceived costs of biodiversity over an ecologically-defined forestry operation. Industrial forest managers were more willing to, adopt objective-based guidelines than restrictive practice-based rules. The process of making science [ABSTRACT FROM AUTHOR]