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Resource Exploitation (resource + exploitation)
Selected AbstractsNATURAL RESOURCE EXPLOITATION UNDER COMMON PROPERTY RIGHTSNATURAL RESOURCE MODELING, Issue 1 2003MICHAEL R. CAPUTO ABSTRACT. Renewable natural resources such as ground-water, pastures and fisheries are often governed bycommon propertyrights in which members of a group jointlyown the exclusive use of the resource. We develop a formal model of a common propertycontract based on differential game theory and then use the model to examine (i) the incentives of individual users of the common resource; (ii) the resulting harvest and stock time paths; (iii) the local stabilityof the steady state; and (iv) the steadystate comparative statics. Moreover, we compare the qualitative properties of the common propertyregime to those generated under perfectlydefined private rights and open access. We show how common prop-ertyownership of natural resources can generate rent and be a second-best solution when private propertyrights are costly to establish. [source] Decadal change in wetland,woodland boundaries during the late 20th century reflects climatic trendsGLOBAL CHANGE BIOLOGY, Issue 8 2010DAVID A. KEITH Abstract Wetlands are important and restricted habitats for dependent biota and play vital roles in landscape function, hydrology and carbon sequestration. They are also likely to be one of the most sensitive components of the terrestrial biosphere to global climate change. An understanding of relationships between wetland persistence and climate is imperative for predicting, mitigating and adapting to the impacts of future climate change on wetland extent and function. We investigated whether mire wetlands had contracted, expanded or remained stable during 1960,2000. We chose a study area encompassing a regional climatic gradient in southeastern Australia, specifically to avoid confounding effects of water extraction on wetland hydrology and extent. We first characterized trends in climate by examining data from local weather stations, which showed a slight increase in precipitation and marked decline in pan evaporation over the relevant period. Remote sensing of vegetation boundaries showed a marked lateral expansion of mires during 1961,1998, and a corresponding contraction of woodland. The spatial patterns in vegetation change were consistent with the regional climatic gradient and showed a weaker co-relationship to fire history. Resource exploitation, wildland fires and autogenic mire development failed to explain the observed expansion of mire vegetation in the absence of climate change. We therefore conclude that the extent of mire wetlands is likely to be sensitive to variation in climatic moisture over decadal time scales. Late 20th-century trends in climatic moisture may be related primarily to reduced irradiance and/or reduced wind speeds. In the 21st century, however, net climatic moisture in this region is projected to decline. As mires are apparently sensitive to hydrological change, we anticipate lateral contraction of mire boundaries in coming decades as projected climatic drying eventuates. This raises concerns about the future hydrological functions, carbon storage capacity and unique biodiversity of these important ecosystems. [source] Conservation Challenges for the Austral and Neotropical America SectionCONSERVATION BIOLOGY, Issue 4 2009GERARDO CEBALLOS América Austral y Neotropical; América Latina; desarrollo de capacidades Abstract:,The Austral and Neotropical America (ANA) section of the Society for Conservation Biology includes a vast territory with some of the largest relatively pristine ecosystems in the world. With more than 573 million people, the economic growth of the region still depends strongly on natural resource exploitation and still has high rates of environmental degradation and biodiversity loss. A survey among the ANA section membership, with more than 700 members, including most of the section's prominent ecologists and conservationists, indicates that lack of capacity building for conservation, corruption, and threats such as deforestation and illegal trade of species, are among the most urgent problems that need to be addressed to improve conservation in the region. There are, however, strong universities and ecology groups taking the lead in environmental research and conservation, a most important issue to enhance the ability of the region to solve conservation and development conflicts. Resumen:,La sección América Austral y Neotropical (AAN) de la Sociedad para la Biología de la Conservación incluye un vasto territorio con unos de los ecosistemas relativamente prístinos más extensos del mundo. Con más de 573 millones de habitantes, el crecimiento económico de la región aun depende fuertemente de la explotación de recursos naturales y aún tiene altas tasas de degradación ambiental y pérdida de biodiversidad. Un sondeo de la membresía de la sección AAN, con más de 700 miembros, incluyendo la mayoría de los ecólogos y conservacionistas más prominentes de la sección, indica que la carencia de desarrollo de capacidades para la conservación, la corrupción y amenazas como la deforestación y el comercio ilegal de especies, son algunos de los problemas que requieren ser atendidos más urgentemente para mejorar la conservación en la región. Sin embargo, hay universidades y grupos ecológicos que están tomando el liderazgo en investigación ambiental y conservación, un tema importante para mejorar la habilidad de la región para resolver conflictos de conservación y desarrollo. [source] Building Peace with Conflict Diamonds?DEVELOPMENT AND CHANGE, Issue 4 2009Development in Sierra Leone, Merging Security ABSTRACT This article examines the merging of security and development agendas in primary commodity sectors, focusing on the case of peace-building reforms in Sierra Leone's diamond sector. Reformers frequently assume that reforming the diamond sector through industrializing alluvial diamond mining will reduce threats to security and development, thereby contributing to peace building. Our findings, however, suggest that the industrialization of alluvial diamond mining that has taken place in Sierra Leone has not reduced threats to security and development, as it has entailed human rights abuses and impoverishment of local communities without consolidating state fiscal revenues and trust in local authorities. This suggests alternative strategies for resource-related peace-building initiatives, which we consider at the end of the article: the decriminalization of informal economic activities; the prioritization of local livelihoods and development needs over central government fiscal priorities and foreign direct investment; and better integration between local economies and industrial resource exploitation. [source] The Spatially Splintered State: Myths and Realities in the Regulation of Marine Fisheries in Tamil Nadu, IndiaDEVELOPMENT AND CHANGE, Issue 4 2003Maarten Bavinck The spatial dimension of law is a neglected field of study. This article responds to suggestions that have been made to develop a ,geography of law', and investigates expressions of State-centred law regarding common pool natural resources. It asks how variations in law between lower-level territorial units are to be explained in situations where patterns of resource exploitation are similar and the overarching State proclaims an even approach. To explore these issues, the article focuses on a case study of Tamil Nadu marine fisheries. Comparing the reality of State regulation in different coastal districts, the author argues that the State occupies a relatively weak position vis-à-vis user groups, and strives to maximize its legitimacy by adapting to local political circumstances. The end result is a legal patchwork with strong spatial connotations. [source] Host plants and butterfly biology.ECOLOGICAL ENTOMOLOGY, Issue 1 2004Do host-plant strategies drive butterfly status? Abstract., 1.,To determine whether rarity and decline is linked to organism ecology, associations have been examined between butterfly larval host-plant competitive, stress-tolerant, ruderal (C-S-R) strategies and butterfly biology. 2.,Associations have been sought between mean C-S-R scores for larval host plants with butterfly life history, morphology and physiology variables, resource use, population attributes, geography, and conservation status. Comparisons are carried out across species and controlled for phylogenetic patterning. 3.,Butterfly biology is linked to host-plant strategies. An increasing tendency of a butterfly's host plants to a particular strategy biases that butterfly species to functionally linked life-history attributes and resource breadth and type. In turn, population attributes and geography are significantly and substantially affected by host choice and the strategies of these host plants. 4.,The greatest contrast is between butterfly species whose host plants are labelled C and R strategists and those whose host plants are labelled S strategists. Increasingly high host-plant C and R strategy scores bias butterflies to rapid development, short early stages, multivoltinism, long flight periods, early seasonal emergence, higher mobility, polyphagy, wide resource availability and biotope occupancy, open, areally expansive, patchy population structures, denser distributions, wider geographical ranges, resistance to range retractions as well as to increasing rarity in the face of environmental changes. Increasing host-plant S strategy scores have reversed tendencies, biasing those butterfly species to extended development times, fewer broods, short flight periods, smaller wing expanse and lower mobility, monophagy, restricted resource exploitation and biotope occupancy, closed, areally limited populations with typical metapopulation structures, sparse distributions, and limited geographical ranges, range retractions, and increased rarity. 5.,Species with S strategy host plants are species vulnerable to current environmental changes and species of conservation concern. [source] Allee effect in larval resource exploitation in Drosophila: an interaction among density of adults, larvae, and micro-organismsECOLOGICAL ENTOMOLOGY, Issue 5 2002Bregje Wertheim Abstract 1. Aggregation pheromones can evolve when individuals benefit from clustering. Such a situation can arise with an Allee effect, i.e. a positive relationship between individual fitness and density of conspecifics. Aggregation pheromone in Drosophila induces aggregated oviposition. The aim of the work reported here was to identify an Allee effect in the larval resource exploitation by Drosophila melanogaster, which could explain the evolution of aggregation pheromone in this species. 2. It is hypothesised that an Allee effect in D. melanogaster larvae arises from an increased efficiency of a group of larvae to temper fungal growth on their feeding substrate. To test this hypothesis, standard apple substrates were infested with specified numbers of larvae, and their survival and development were monitored. A potential beneficial effect of the presence of adult flies was also investigated by incubating a varying number of adults on the substrate before introducing the larvae. Adults inoculate substrates with yeast, on which the larvae feed. 3. Fungal growth was related negatively to larval survival and the size of the emerging flies. Although the fungal growth on the substrate was largely reduced at increased larval densities, the measurements of fitness components indicated no Allee effect between larval densities and larval fitness, but rather indicated larval competition. 4. In contrast, increased adult densities on the substrates prior to larval development yielded higher survival of the larvae, larger emerging flies, and also reduced fungal growth on the substrates. Hence, adults enhanced the quality of the larval substrate and significant benefits of aggregated oviposition in fruit flies were shown. Experiments with synthetic pheromone indicated that the aggregation pheromone itself did not contribute directly to the quality of the larval resource. 5. The interaction among adults, micro-organisms, and larval growth is discussed in relation to the consequences for total fitness. [source] Interspecific competition among urban cockroach speciesENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2004Stéphane Boyer Abstract The aim of this study was to quantify and to compare the effects of intraspecific and interspecific competition among pairs of urban cockroaches [Blatta orientalis L., Periplaneta americana (L.), and Periplaneta australasiae Fabricius (Dictyoptera: Blattodea)] in relation to the limitation of resources such as shelter or food. Our approach was to assess whether the presence of one species affected the resource exploitation of another. A reduction in access to shelters or to food for one species revealed dominant/subordination relationships among species and induced spatial segregation in shelters and temporal segregation during food exploitation. The fragmentation of available resources facilitated spatial segregation and the access of more individuals of the subordinate species. Individuals of each species were aware of the presence of non-conspecifics. The outcome of interspecific competition under laboratory conditions should help us to understand how segregated spatial distributions occur under natural conditions in urban areas. [source] Medieval environmental impacts and feedbacks: The lowland floodplains of England and WalesGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2010John Lewin Because of their varying channel styles (braided, meandering, and anastomosing) medieval lowland floodplains in England and Wales provided varying opportunities for defense, settlement, river crossing, and resource exploitation. In turn, these activities altered the character of channels and floodplains, with medieval and later development obscuring the former variety of floodplains themselves. The changing nature of river floodplains is reviewed using archaeological, documentary, and geomorphological evidence. Anastomosing channels and floodplain wetlands have now all but disappeared but were formerly of considerable significance; also discussed are interactions involving flooding, fording, bridging, modifications to channels and their dimensions, and those arising from accelerated soil erosion,most of which peaked in the medieval period when floodplains were significantly transformed. Deliberately or inadvertently, dynamic floodplain landforms were interactively involved with human development during a critical time period in a totality of ways not previously fully identified. © 2010 Wiley Periodicals, Inc. [source] Food provision to nestlings in the Hoopoe Upupa epops: implications for the conservation of a small endangered population in the Swiss AlpsIBIS, Issue 1 2001JÉRÔME FOURNIER In an attempt to recognize the possible ecological causes of the decline of a population of Hoopoes Upupa epops in the Swiss Alps, we collected data on resource exploitation. The prey provisioned to nestlings by parents was investigated at four breeding sites using photographs (n = 4353, 80% of which enabled prey identification). Molecrickets Gryllotalpa gryllotalpa and Lepidoptera (larvae and pupae) were dominant in nestling diet (93% frequency; 97% biomass). Although Molecrickets were provisioned less frequently (26%) than Lepidoptera (67%), they represented 68% of the total biomass (vs 29% for Lepidoptera). There was an overall negative relationship between the proportion of Molecricket biomass in the diet and the parents' feeding rate, whereas a comparison between broods showed that a higher provisioning activity did not lead to an increase in the biomass supplied to the chicks. A diet based on Molecrickets therefore appears to be energetically advantageous. As Molecrickets are a traditional prey of Hoopoes in central Europe, this might be relevant to other populations. In the study area, Molecrickets occur only on the intensively cultivated plain, whereas the majority of Hoopoe pairs nest at various altitudes on the foothills adjacent to the plain as the latter provides at present almost no suitable nesting sites. Hoopoes breeding higher up on the foothills seem to experience greater provisioning costs and have, on average, lower breeding success. Providing nest sites on the plain is the main conservation measure proposed for the local Hoopoe population. Further attention should also be paid to Molecrickets as these may be crucial for Hoopoes. [source] Joint spectrum and power optimization in the design of the UMTS satellite componentINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2001Ernestina Cianca Abstract The paper provides a power and spectrum joint analysis of the universal mobile telecommunications system (UMTS) satellite component, based on the wideband code division multiple access (W-CDMA) air interface. In fact, power and spectral efficiency may become highly conflicting requirements in a satellite system and a trade-off analysis is needed to drive a proper dimensioning of the satellite. The proposed approach allows a dimensioning of the satellite component either in terms of orbit and power budget or in terms of additional capacity for the terrestrial section, for specified orbit and power limitations. The impact of candidate frequency bands, orbit type and diversity on both spectral and power requirements of the satellite component is evaluated. For given traffic requirements, power-vs-spectrum trade-off is proposed which ensures a proper resources utilization. The efficiency evaluation accounts for: beams overlapping, ortho gonality, voice activity factor, diversity and cross-polarization frequency reuse. Perfect power control is assumed and the effect of the excess power required by the shadowed users is accounted for in the interference calculation. Furthermore, still in the frame of a proper resource exploitation, a possible optimization of capacity through the use of unpaired bands in the two link directions is analysed. Copyright © 2001 John Wiley & Sons, Ltd. [source] Diversity,stability relationships in multitrophic systems: an empirical explorationJOURNAL OF ANIMAL ECOLOGY, Issue 5 2003Priyanga Amarasekare Summary 1The relationship between diversity and stability is crucial in understanding the dynamics of multitrophic interactions. There are two basic hypotheses about the causal link between diversity and stability. The first is that fluctuations in resource abundance allow consumer coexistence, thus increasing diversity at the consumer trophic level (resource variability hypothesis). The second is that interactions between coexisting consumer species reduce consumer efficiency and dampen population fluctuations, thus increasing consumer,resource stability (consumer efficiency hypothesis). 2The two hypotheses lead to three comparative predictions: (i) fluctuations should be greater (resource variability) or smaller (consumer efficiency) in resource populations with coexisting consumer species, compared to those invaded only by the consumer species superior at resource exploitation; (ii) average resource abundance should be greater (resource variability) or smaller (consumer efficiency) in resource populations with greater fluctuations; and (iii) removal of the consumer species inferior at resource exploitation should increase or not affect resource population fluctuations (resource variability), or always increase them (consumer efficiency). 3I tested these predictions with data from a host,multiparasitoid community: the harlequin bug (Murgantia histrionica) and two specialist parasitoids (Trissolcus murgantiae and Ooencyrtus johnsonii) that attack the bug's eggs. 4Local host populations with coexisting parasitoids exhibited smaller fluctuations and greater average abundance compared to those with just Trissolcus, the species superior at host exploitation. Local populations that lost Ooencyrtus, the species inferior at host exploitation, exhibited an increase in host population fluctuations compared to those that did not. 5The results contradict the expectations of the resource variability hypothesis, suggesting that host population fluctuations are unlikely to be driving parasitoid coexistence. They are consistent with the consumer efficiency hypothesis, that interactions between coexisting parasitoid species dampens host population fluctuations. I discuss the implications of these results as well as possible caveats. [source] Mechanisms of functional response and resource exploitation in browsing roe deerJOURNAL OF ANIMAL ECOLOGY, Issue 5 2002Andrew W. Illius Summary 1The functional responses of roe deer were examined using 11 plant species. A technique to discriminate between encounter- and handling-limited processes was used, and it can be concluded that the functional response applicable to patch browsing by roe deer is governed not by the rate of encounter but by the rate of oral processing. 2The large differences between plant species were due to variations in both parameters of the functional response: h , the time lost in biting, and Rmax , the maximum processing rate. Removing the thorns from three of the species affected these parameters differently, according to the size and density of thorns. 3Animals took larger bites from larger patches (branches), and bite mass declined as patch exploitation progressed, implying that animals were selecting the larger items to eat first. It was demonstrated experimentally that depletion of the larger bites does occur first, and it was concluded that prey selection is an important component of herbivore foraging behaviour. 4The gain curves for deer feeding on the different plant species are calculated as being virtually linear. Patch depression did not, in general, occur because increasing bite rate compensated for declining bite mass. Our mechanistic approach is contrasted with other approaches to describing the gain curve in the literature. 5A priori and empirical grounds are presented for rejecting the hypothesis that resource exploitation by browsing mammals is governed by optimal patch use. Diet optimization, involving a trade-off between diet quality and quantity, offers a better explanation of herbivore foraging behaviour. [source] Applied issues with predators and predation: editor's introductionJOURNAL OF APPLIED ECOLOGY, Issue 2 2002S. J. Ormerod Summary 1,The effects of predation are among the most pervasive in ecology. As parasitoids, parasites, grazers or top carnivores, predators have large influences on the distribution, density, dynamics and evolved traits of other organisms. Effects scale-up to influence community attributes such as species coexistence and ecosystems processes such as production or trophic cascades. 2,Increasingly, however, some of the largest predation issues fall clearly within the scope of applied ecology. They include instances where, due to their ecological attributes and trophic position: (i) predators are valuable to nature conservation, as biocontrol agents, as natural enemies, or as grazers used in rangeland or ecosystem management; (ii) natural or introduced predators are viewed negatively due to effects on conservation, agriculture, forestry, hunting or disease transmission; (iii) predators are affected by human activities such as resource exploitation, or from exposure to factors such as biomagnified pollutants and disturbance; (iv) predators are controversial because different groups view them as either desirable or undesirable. 3,In all these cases, ecologists have a pivotal rôle in facilitating appropriate management. For valued predators, this involves developing sufficient ecological understanding to optimize habitat, increase prey abundance or to reinforce, establish or reintroduce desirable species. For predators considered undesirable, management can involve direct control. In other cases, predation and its consequences can be mitigated by deterrent, exclusion, supplementary feeding, habitat management to favour prey, predator swamping, or by compensating losses financially. These latter strategies are often used where predators are themselves considered too valuable to remove or control. 4,This collection of seven papers illustrates many of these themes by examining contrasting aspects of the applied ecology of Eurasian lynx; by further probing the interaction between predatory birds and red grouse; by exploring the effects of weather on biocontrol; and by illustrating effects on plant species where grazing or seed predation play a dominant rôle. 5,A key lesson from these and other recent papers in the Journal of Applied Ecology is that the successful management of predators depends invariably on understanding adequately the exact ecological context in which predator,prey interactions take place and in which problems arise. With predator-related issues growing rather than diminishing, ecologists will need sufficient resources to maintain current research if they are to provide the understanding required to offer and evaluate sound management. [source] Genetic and morphometric differentiation among island populations of two Norops lizards (Reptilia: Sauria: Polychrotidae) on independently colonized islands of the Islas de Bahia (Honduras)JOURNAL OF BIOGEOGRAPHY, Issue 7 2007C. F. C. Klütsch Abstract Aim, Anole lizards (Reptilia: Sauria: Polychrotidae) display remarkable morphological and genetic differentiation between island populations. Morphological differences between islands are probably due to both adaptive (e.g. differential resource exploitation and intra- or interspecific competition) and non-adaptive differentiation in allopatry. Anoles are well known for their extreme diversity and rapid adaptive speciation on islands. The main aim of this study was to use tests of morphological and genetic differentiation to investigate the population structure and colonization history of islands of the Islas de Bahia, off the coast of Honduras. Location, Five populations of Norops bicaorum and Norops lemurinus were sampled, four from islands of the Islas de Bahia and one from the mainland of Honduras. Methods, Body size and weight differentiation were measured in order to test for significant differences between sexes and populations. In addition, individuals were genotyped using the amplified fragment length polymorphism technique. Bayesian model-based and assignment/exclusion methods were used to study genetic differentiation between island and mainland populations and to test colonization hypotheses. Results, Assignment tests suggested migration from the mainland to the Cayos Cochinos, and from there independently to both Utila and Roatán, whereas migration between Utila and Roatán was lacking. Migration from the mainland to Utila was inferred, but was much less frequent. Morphologically, individuals from Utila appeared to be significantly different in comparison with all other localities. Significant differentiation between males of Roatán and the mainland was found in body size, whereas no significant difference was detected between the mainland and the Cayos Cochinos. Main conclusions, Significant genetic and morphological differentiation was found among populations. A stepping-stone model for colonization, in combination with an independent migration to Utila and Roatán, was suggested by assignment tests and was compatible with the observed morphological differentiation. [source] Land-use and cover changes (1988,2002) around budongo forest reserve, NW Uganda: implications for forest and woodland sustainabilityLAND DEGRADATION AND DEVELOPMENT, Issue 6 2008E. N. Mwavu Abstract Land-use and cover changes around Budongo Forest Reserve (BFR) were analysed from multi-temporal LandSat images (1988 and 2002) and associated field-based studies in 2003,2004. Three major land-use and cover classes: forest/woodland, sugarcane plantations and grassland/shifting-cultivation/settlements were clearly discriminated. The area under sugarcane cultivation increased over 17-fold, from 690,ha in 1988 to 12729,ha in 2002, with a concomitant loss of about 4680,ha (8·2 per cent) of forest/woodland, mainly on the southern boundary of BFR. Land-use and cover changes were a result of (a) agricultural expansion, (b) increasing human population, exacerbated by large influxes of refugees, (c) conflicts of interest and political interference in the management of BFR and (d) unclear land tenure. Agriculture is the main land-use practice and source of income to local people, with commercial sugarcane and tobacco as the primary cash crops. Individual smallholder sugarcane plantations covered distances ranging from 30 to 1440,m along the BFR edge, with no buffer zone, resulting in direct conflicts between farmers and forest wild animals. There is an ever-increasing need for more land for agricultural expansion, resulting in continued loss of forest/woodland on private/communal lands and encroachment into BFR. This unsustainable agricultural expansion and the local people's perception of BFR as an obstacle to agriculture, threatens the conservation of its threatened wild plants (e.g. Raphia farinifera) and the endangered chimpanzees. Therefore, their sustainable management for both development and conservation will require strong and incorruptible institutions that will seek a balance between resource exploitation and conservation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Development policies and tropical deforestation in the southern Yucatán peninsula: centralized and decentralized approachesLAND DEGRADATION AND DEVELOPMENT, Issue 6 2003P. Klepeis Abstract It is well established that for multiple biophysical contexts there are legacies of past government policies in present land conditions. Despite this recognition, however, investigation of ongoing tropical deforestation dynamics often de-emphasizes the past. The case of the southern Yucatán peninsula demonstrates the need for historical analysis in identifying key drivers of deforestation. The most important land-use changes in the region over the past 100 years are connected to shifts in national development policies. These shifts represent tensions between centralized and decentralized approaches to land management,as represented by the policies of Presidents Díaz (1876,1910) and Cárdenas (1934,40),that persisted throughout the 20th century. The legacies of these reoccurring development strategies include depleted hardwood reserves, large areas of permanently cleared forest, a complicated system of land allocation, and long-standing tensions between economic, social welfare, and environmental conservation goals. These findings suggest that while centralized and decentralized approaches to development both focus on natural resource exploitation, the rates of deforestation tend to be faster, the patterns of forest clearing more pronounced, and land-use decision making less democratic under systems of centralized control. These conclusions hold implications for land-use decision making today. Copyright © 2003 John Wiley & Sons, Ltd. [source] The Plant's Capacity in Regulating Resource DemandPLANT BIOLOGY, Issue 6 2005R. Matyssek Abstract: Regulation of resource allocation in plants is the key to integrate understanding of metabolism and resource flux across the whole plant. The challenge is to understand trade-offs as plants balance allocation between different and conflicting demands, e.g., for staying competitive with neighbours and ensuring defence against parasites. Related hypothesis evaluation can, however, produce equivocal results. Overcoming deficits in understanding underlying mechanisms is achieved through integrated experimentation and modelling the various spatio-temporal scaling levels, from genetic control and cell metabolism towards resource flux at the stand level. An integrated, interdisciplinary research concept on herbaceous and woody plants and its outcome to date are used, while drawing attention to currently available knowledge. This assessment is based on resource allocation as driven through plant-pathogen and plant-mycorrhizosphere interaction, as well as competition with neighbouring plants in stands, conceiving such biotic interactions as a "unity" in the control of allocation. Biotic interaction may diminish or foster effects of abiotic stress on allocation, as changes in allocation do not necessarily result from metabolic re-adjustment but may obey allometric rules during ontogeny. Focus is required on host-pathogen interaction under variable resource supply and disturbance, including effects of competition and mycorrhization. Cost/benefit relationships in balancing resource investments versus gains turned out to be fundamental in quantifying competitiveness when related to the space, which is subject to competitive resource exploitation. A space-related view of defence as a form of prevention of decline in competitiveness may promote conversion of resource turnover across the different kinds of biotic interaction, given their capacity in jointly controlling whole plant resource allocation. [source] Faunal migration in late-glacial central Italy: implications for human resource exploitation,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2008Maura Pellegrini The hunter-gatherer transhumance model presents foragers as specialised hunters of migratory ungulates, which moved seasonally between coastal lowlands and interior uplands. We studied six animal teeth of horse (Equus hydruntinus) and red deer (Cervus elaphus) from four different archaeological sites: the Grotta di Vado all'Arancio, Grotta di Settecannelle, Grotta Polesini and Grotta di Pozzo, in central Italy to test whether the migratory patterns and seasonal variations recorded in their teeth were consistent with expectations of the transhumance model for this region during the late Upper Palaeolithic. Sequential sub-samples of enamel were analysed from each tooth for oxygen, carbon and strontium isotope ratios to reconstruct mobility and yearly seasonal variations. The results show little evidence that these animals were moving over different geological terrains throughout the year, although small variations in Sr isotope ratios and concentrations were detected that corresponded to probable seasonal variations as shown by variability in oxygen isotope sequences. The results do, however, demonstrate that Cervus elaphus and Equus hydruntinus had different ranging behaviours, with the former moving over wider areas than the latter. This methodology produces results appropriate to assess animal migratory behaviour and, in turn, to test the consistency of proposed models of hunter-gatherer subsistence and mobility strategies. Copyright © 2008 John Wiley & Sons, Ltd. [source] An ecosystem modelling approach to deriving viable harvest strategies for multispecies management of the Northern Gulf of CaliforniaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2009Diego Lercari Abstract 1.An ecosystem analysis was developed focusing on resource exploitation and biodiversity conservation for the Northern Gulf of California. The main tools employed were a trophic ecosystem model and time dynamic simulations. 2.The ecosystem was represented by an Ecopath model that included 34 functional groups, from primary producers to top predators. It included relevant species in the area such as commercially important shrimp (e.g. Litopenaeus stylirostris) and highly endangered species (Phocoena sinus and Totoaba macdonaldi). 3.Temporal simulations of changing fishing effort allowed the evaluation of fishing impact on the ecosystem components and, particularly, on protected species. Formal optimization methods were applied with the purpose of searching viable temporal patterns of fishing effort that might minimize social, economic and conservationist conflicts in the area. 4.The results of those simulations showed the capability of the model to represent reference temporal series of relative biomass. The search for viable fishing strategies resulted in effort allocation consistent with those proposed by other studies; that is, a decrease in the industrial shrimp fleet (35,65%), a decrease in the gillnet fishing fleet (52,57%), and an increase of the artisanal shrimp fishery (63,222%). 5.The main conflicts in the Northern Gulf of California seem to take place between social and conservation interests, while the economic and ecological benefits seem to be relatively independent. The next steps towards conflict resolution and ecosystem management should consider the design and operation of MPAs already established in the region. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||