Search results for "cost"

Optimal contract length for biodiversity conservation under conservation budget constraint

2014

We examine the optimal length of a contract period in a conservation program with payments for ecosystem services aiming at protecting biodiversity on privately owned forests. The government chooses the number of stands and the length of contracts so as to maximize biodiversity benefits under a binding conservation budget. We examine the implication of two alternative budgets: a separate budget for each period (periodic budget) or one budget that to be used in all periods (intertemporal budget). The impact of the budget type shows up in the fact that with intertemporal budget choice set is larger and more high quality stands are available for contracting. Based on theoretical characterizati…

2020

Marine and coastal activities are closely interrelated, and conflicts among different sectors can undermine management and conservation objectives. Governance systems for fisheries, power generation, irrigation, aquaculture, marine biodiversity conservation, and other coastal and maritime activities are typically organized to manage conflicts within sectors, rather than across them. Based on the discussions around eight case studies presented at a workshop held in Brest in June 2019, this paper explores institutional approaches to move beyond managing conflicts within a sector. We primarily focus on cases where the groups and sectors involved are heterogeneous in terms of: the jurisdiction …

Assessing the indirect and long-term ecological impacts of innovation in agriculture is a real challenge: the GM example

2003

All innovation in agriculture constitutes a significant and complex ecological disturbance, even if limited to a single and simple action. Indeed, whatever the nature and objective of the action, a large number of ecological processes are affected and numerous discontinuities may occur within the agro-ecosystem, in both time and space. As the GMO example illustrates, it is not sufficient to focus on direct effect of innovation, it is necessary to forecast mid- and long-term impacts of innovation with respect to the environment. Modelling phenomena appear then to be a key element to achieve this goal.

The cost-effectiveness of using raptor nest sites to identify areas with high species richness of other taxa

2016

Abstract Given the limited resources available for conservation, it is important that the areas to preserve are selected in a cost effective manner. However, the cost effectiveness of the surrogate species strategy (the use of information on one or more species to identify areas of value for other species for which there is no, or more limited, available information) has seldom been evaluated. In this study, we investigate the opportunity cost of setting aside breeding sites of two forest raptor species (the surrogate species) by evaluating their individual and combined contribution to preserve diversity of polypores (wood-decaying fungi) and birds against the contributions of previously es…

Mechanisms of shrub encroachment into Northern Chihuahuan Desert grasslands and impacts of climate change investigated using a cellular automata model

2016

Arid and semiarid grasslands of southwestern North America have changed dramatically over the last 150 years as a result of woody plant encroachment. Overgrazing, reduced fire frequency, and climate change are known drivers of woody plant encroachment into grasslands. In this study, relatively sim- ple algorithms for encroachment factors (i.e., grazing, grassland fires, and seed dispersal by grazers) are proposed and implemented in the ecohydrological Cellular-Automata Tree Grass Shrub Simulator (CAT- GraSS). CATGraSS is used in a 7.3 km 2 rectangular domain located in central New Mexico along a zone of grassland to shrubland transition, where shrub encroachment is currently active. CATGraS…

Flexible timing of reproductive effort as an alternative mating tactic in black grouse (Lyrurus tetrix) males

2016

Alternative reproductive tactics often take the form of dichotomous behavioural phenotypes. Focusing attention on such obvious dichotomy means that flexible patterns of behaviour within tactics is largely ignored. Using a long-term dataset of black grouse (Lyrurus tetrix) lek behaviours, we tested whether there were fine-scale differences in reproductive effort (lek attendance, fighting rates) and whether these were related to age and phenotype. Yearling males increased their lek attendance and fighting rate to a peak when adult male effort was declining. Adults and yearlings allocated reproductive effort according to their body mass but this was unrelated to differences in timing of effort…

Whistling is metabolically cheap for communicating bottlenose dolphins (Tursiops truncatus)

2020

Toothed whales depend on sound for communication and foraging, making them potentially vulnerable to acoustic masking from increasing anthropogenic noise. Masking effects may be ameliorated by higher amplitudes or rates of calling, but such acoustic compensation mechanisms may incur energetic costs if sound production is expensive. The costs of whistling in bottlenose dolphins (Tursiops truncatus) have been reported to be much higher (20-50% of resting metabolic rate, RMR) than theoretical predictions (0.5-1% of RMR). Here we address this dichotomy by measuring the change in the resting O2 consumption rate (V̇O2), a proxy for RMR, in three post-absorptive bottlenose dolphins during whistlin…

Inferring species interactions from ecological survey data: A mechanistic approach to predict quantitative food webs of seed feeding by carabid beetl…

2021

Abstract Ecological networks are valuable for ecosystem analysis but their use is often limited by a lack of data because many types of ecological interaction, for example, predation, are short‐lived and difficult to observe or detect. While there are different methods for inferring the presence of interactions, they have rarely been used to predict the interaction strengths that are required to construct weighted, or quantitative, ecological networks.Here, we develop a trait‐based approach suitable for inferring weighted networks, that is, with varying interaction strengths. We developed the method for seed‐feeding carabid ground beetles (Coleoptera: Carabidae) although the principles can …

Rocking of rigid block on nonlinear flexible foundation

2017

Abstract The two prime models used currently to describe rocking of rigid bodies, the Housner’s model and the Winkler foundation model, can capture some of the salient features of the physics of this important problem. These two models involve either null or linear interaction between the block and the foundation. Hopefully, some additional aspects of the problem can be captured by an enhanced nonlinear model for the base-foundation interaction. In this regard, what it is adopted in this paper is the Hunt and Crossley’s nonlinear impact force model in which the impact/contact force is represented by springs in parallel with nonlinear dampers. In this regard, a proper mathematical formulatio…

Preliminary design process for an adaptive winglet

2017

In the framework of Clean Sky 2 Airgreen 2 GRA ITD project, this paper deals with the design process of a morphing winglet for a regional aircraft. By improving A/C aerodynamic efficiency in off-design flight conditions, the morphing winglet is expected to operate during long (cruise) and short (climb and descent) mission phases to reduce aircraft drag and optimize lift distribution, while providing augmented roll and yaw control capability. The mechanical system is designed to face different flight situations by a proper action on the movable parts represented by two independent and asynchronous control surfaces with variable camber and differential settings. A set of suitable electromecha…