Vegetation and climate

Over the last two centuries, man's activities have caused a 30% increase in the atmospheric concentration of CO₂, with continued increases seeming inevitable. This change in CO₂ concentration will act on vegetation, both directly and indirectly through global climatic change. It is well established that, on a global scale, patterns of vegetation and climate are closely correlated. Such correlations indicate that climatic change will cause the distribution of vegetation to change. However, the use of correlations for predicting vegetation responses to climatic change is fundamentally unreliable because correlations have no mechanistic underpinning of causation. This paper outlines a mechanistic model for predicting the equilibrium state between current climate and vegetation. It is also used to indicate the sensitivity of global vegetation to the changed climate associated with a doubled CO₂—greenhouse scenario. The interpretation of this static model is discussed in terms of rates and patterns of vegetation change.     

Fatty acid composition as a dietary indicator of the invasive caprellid, Caprella mutica (Crustacea: Amphipoda)

The invasive caprellid amphipod Caprella mutica is one of the most widely dispersed marine non-native species globally. Originating in sub-boreal north-east Asia, it has now been found in both the northern and the southern hemispheres. One potential reason why this species is such a successful invader is its ability to utilise a wide variety of food sources. The contribution of different food sources to the diet of C. mutica was estimated using fatty acids as biomarkers. Caprella mutica was collected from three field sites, including sea cages stocked with Atlantic salmon Salmo salar, shellfish longlines stocked with the blue mussel Mytilus edulis and mooring lines marking the Loch Linnhe Artificial Reef (>2 km from caged finfish aquaculture), where established populations of this species are known to occur. In addition, the fatty acid compositions of C. mutica held in aquaria and either fed the microalga, Dunaliella tertiolecta, or the diatom, Phaeodactylum tricornutum, for a period of 21 days were investigated. The fatty acid composition of the diatom and the microalgal diets was also examined. The results showed that C. mutica contained high levels of polyunsaturated fatty acids, particularly 20:5(n-3); other dominant fatty acids included 18:1(n-9), 22:6(n-3) and 16:0 (in decreasing order based on abundance). Significant differences in the fatty acid profiles between caprellids fed on the microalgae and the diatom diets and between C. mutica collected from the field sites were observed. These results provide evidence that lipid biomarkers can be successfully used to provide evidence of feeding strategy for C. mutica and that the flexibility observed in this strategy may play an important role in its invasion success.     

Towards guidelines for post‐disaster vulnerability reduction in informal settlements

Although the development community has long recognised that securing land tenure and improving housing design can benefit significantly informal settlement residents, there is little research on these issues in communities exposed to natural disasters and hazards. Informal settlements often are located on land left vacant because of inherent risks, such as floodplains, and there is a long history worldwide of disasters affecting informal settlements. This research tackles the following questions: how can informal settlement vulnerabilities be reduced in a post‐disaster setting?; and what are the key issues to address in post‐disaster reconstruction? The main purpose of the paper is to develop a set of initial guidelines for post‐disaster risk reduction in informal settlements, stressing connections to tenure and housing/community design in the reconstruction process. The paper examines disaster and reconstruction responses in two disaster‐affected regions—Jimani, Dominican Republic, and Vargas State, Venezuela—where informal settlements have been hit particularly hard.     

Locus of control and farmer orientation: Effects on conservation adoption

Farmers in a southwestern Ontario watershed were surveyed to determine factors influencing their attitudes towards adoption of soil conservation practices. The majority of farmers in the watershed were internally motivated which indicates they believe that their own actions determine their successes and failures. Most respondents were also environmentally oriented. However, although many farmers in the study area have adopted crop rotations and cross-slope tillage, the adoption rate of conservation tillage is low. The survey suggests that the low adoption rate may be more a function of perceived economic risk associated with the tillage practice than lack of farmer motivation.     

The political significance of local agenda 21: The early stages of some European experience

Sustainable development, as it emerged in Agenda 21 from the Rio conference in 1992, will only be meaningful when it touches the lives of ordinary people; then it becomes a reality. Local Agenda 21 (LA21) seeks to achieve that objective. This article assesses the origins of LA21, reviews its social and political significance, and considers its prospects in the light of case study experience emerging from the UK, Germany and Norway, focusing on the role of local government as a major stakeholder in Agenda 21 (A21). The range of response to LA21 has proved to be varied. A successful transformation to a more sustainable world will require visionary political leadership, supportive administrations, networks of experience sharing, alliances with non-governmental organisations and local industry, and effective community mobilisation. All of that, in turn, requires equally supportive economic and social policy backing from national governments. This article will indicate that, not surprisingly, it is the domestic political context, nationally and locally, which in the main determines the speed and nature of response to LA21, now and in the future. By understanding and being aware of these contexts, factors impeding progress towards LA21 may be addressed, whilst at the same time retaining the diversity of response which is an essential part of local sustainability.     

Soil Moisture Data Assimilation Using Support Vector Machines and Ensemble Kalman Filter1

Abstract: A hybrid data assimilation (DA) methodology that combines two state‐of‐the‐art techniques, support vector machines (SVMs) and ensemble Kalman filter (EnKF), is applied for soil moisture DA in this work. The SVM methodology provides a statistically sound and robust approach to solving the inverse problem, and thus to building statistical models. EnKF is an extension of the Kalman Filter (KF), a well‐known tool in prediction updating. In the present research, ground measurements were used to build a SVM‐type soil moisture predictor. Subsequent observations and their statistics were assimilated to update predictions from the SVM model by coupling it with EnKF. In this way, both model predictions and ground data, as well as their statistics, are fused thus minimizing the prediction error and making the predictions and observations statistically consistent. The results are shown for two approaches; one in which update is done at every time step and the other which assumes that data is only available at alternate time steps (in window of 10 time steps) and hence update is performed at those occasions. The SVM‐EnKF coupling is shown to improve soil moisture forecasts in an example using data from the Soil Climate Analysis Network site at Ames, Iowa.     

Sexual voyeurs and copiers: social copying and the audience effect on male mate choice in the guppy

In most mating systems, males and females are commonly within signalling and receiving distance of conspecifics during courtship and mating activities. Although it is well known that females who observe sexual interactions between conspecifics will use public information obtained from these interactions when making their own mating decisions, much less is known about whether males use this type of information in making mating decisions. We used the Trinidadian guppy (Poecilia reticulata) to test whether males use public information to (i) copy the apparent mate choice of another male and (ii) modify their mating preference for a given female in the presence of one or two sexual rivals (potential copiers). We show that males use public information to copy the mate choice of other males and that males alter their mating preferences in response to the presence of an audience of sexual rivals, but find no evidence of a stronger audience effect when the number of sexual rivals increases. Collectively, these results indicate that males pay attention to their immediate social environment in making mating decisions and suggest that they avoid having another male copy their mate choice by weakening or even reversing their initial mating preference in the presence of eavesdropping male sexual competitors. Our findings highlight the importance of social context and public information in male mate-choice decisions and have implications for the evolution of male mating preferences and of social information use in populations.     

Putting transdisciplinarity into practice: a mixed mode procedure for stakeholder participation in natural resource management

The definition of management actions in natural resource management requires the integration of all types of knowledge involved. An appropriate approach for such a challenge is the ideal of transdisciplinarity. A transdisciplinary process can be considered “consultative” when knowledge is simply gathered and collated, or “participatory” when knowledge integration is undertaken collectively. In this paper, we present a mixed mode procedure (i.e., using interviews, questionnaires, and group discussions) that empirically demonstrates the difference between consultative and participatory transdisciplinary processes. The mixed mode procedure is used for identifying the most relevant problems occurring in the coastal system of Praia da Vitória bay, Azores, Portugal. This mixed mode procedure is likely to be useful for other studies, because the results highlight the need to promote face-to-face interaction at the earliest opportunity, and because it allows an understanding to be gained of social learning processes, the influence of power, and participant behaviour during interaction with others.     

Mangrove recruitment after forest disturbance is facilitated by herbaceous species in the Caribbean.

Plant communities along tropical coastlines are often affected by natural and human disturbances, but little is known about factors influencing recovery. We focused on mangrove forests, which are among the most threatened ecosystems globally, to examine how facilitation by herbaceous vegetation might improve forest restoration after disturbance. We specifically investigated whether recovery of mangrove forests in harsh environments is accelerated by nurse plants and whether the beneficial effects are species-specific. Quantification of standardized effects allowed comparisons across performance parameters and over time for: (1) net effect of each herbaceous species on mangrove survival and growth, (2) effects of pre- and post-establishment factors associated with each herbaceous species, and (3) need for artificial planting to enhance growth or survival of mangrove seedlings. Mangrove recruitment in a clear-cut forest in Belize was accelerated by the presence of Sesuvium portulacastrum (succulent forb) and Distichlis spicata (grass), two coastal species common throughout the Caribbean region. The net effect of herbaceous vegetation was positive, but the magnitude of effects on mangrove survival and growth differed by species. Because of differences in their vegetative structure and other features, species effects on mangroves also varied by mechanism: (1) trapping of dispersing propagules (both species), (2) structural support of the seedling (Distichlis), and/or (3) promotion of survival (Sesuviumn) or growth (Distichlis) through amelioration of soil conditions (temperature, aeration). Artificial planting had a stronger positive effect on mangrove survival than did edaphic conditions, but planting enhanced mangrove growth more in Sesuvium than in Distichlis patches. Our study indicates that beneficial species might be selected based on features that provide multiple positive effects and that species comparisons may be improved using standardized effects. Our findings are not only relevant to the coastal environments found in the Caribbean region, but our assessment methods may be useful for developing site-specific information to restore disturbed mangrove forests worldwide, especially given the large pool of mangrove associates (>45 genera) available for screening.