Search results for "ecological"
showing 10 items of 1263 documents
Dietary and Temporal Niche Differentiation in Tropical Ants-Can They Explain Local Ant Coexistence?
2014
How species with similar ecological requirements avoid competitive exclusion remains contentious, especially in the species-rich tropics. Niche differentiation has been proposed as a major mechanism for species coexistence. However, different niche dimensions must be studied simultaneously to assess their combined effects on diversity and composition of a community. In most terrestrial ecosystems, ants are among the most abundant and ubiquitous animals. Since they display direct, aggressive competition and often competitively displace subordinate species from resources, niche differentiation may be especially relevant among ants. We studied temporal and trophic niche differentiation in a gr…
Plant facilitation and phylogenetics
2013
The relationship between facilitation and evolutionary ecology is poorly understood. We review five issues elucidating how the phylogenetic relatedness of species provides insight into the role of facilitation in community assembly: (a) Are the facilitative interactions more common between species that differ in a regeneration niche? (b) Are facilitative interactions more common between distantly related species? (c) Do communities governed by facilitation (rather than competition) have higher phylogenetic diversity? (d) As facilitated juvenile plants mature, do they compete with their nurses more often if they are closely related to them? (e) How does the phylogenetic signature in a commun…
Ecological approach and community education as promoters of the social development of reform school students
1995
ABSTRACT New models of operation are being sought for Finnish reform school education traditionally based on segregation. This article deals with the possibilities of applying the ecological approach and community education to support the socialization of reform school students. The aim is to describe the participation of the students in one Finnish reform school, as well as their expressed need to join in the production system, cultural system, contact system and the decision‐making system of society. This article presents part of a larger project carried out at the University of Jyvaskyla in Finland. In the research project a three‐part division in the description into an ideal state, a r…
Phytoplankton equilibrium phases during thermal stratification in a deep subtropical reservoir
2008
SUMMARY 1. Equilibrium and non-equilibrium hypotheses have often been used to explain observations in community ecology. Published case studies have demonstrated that steady state phytoplankton assemblages are more likely to occur in deep lakes than in shallow mixed ones. 2. Phytoplankton seasonal succession was studied by weekly sampling in Faxinal Reservoir (S Brazil), a subtropical deep, clear, warm monomictic and slightly eutrophic reservoir. This study demonstrated an alternation of steady and non-steady state phases of phytoplankton assemblages with different dominant species during the steady states. 3. During the studied period, three steady states were identified with different dom…
Dynamics of two competing species in the presence of Lévy noise sources
2010
We consider a Lotka-Volterra system of two competing species subject to multiplicative alpha-stable Lévy noise. The interaction parameter between the species is a random process which obeys a stochastic differential equation with a generalized bistable potential in the presence both of a periodic driving term and an additive alpha-stable Lévy noise. We study the species dynamics, which is characterized by two different regimes, exclusion of one species and coexistence of both. We find quasi-periodic oscillations and stochastic resonance phenomenon in the dynamics of the competing species, analysing the role of the Lévy noise sources.
The spatial pattern of a forest ecosystem
1998
Abstract Statistical analysis of stands of trees as a whole need suitable methods of spatial statistics. Obviously, trees within a stand affect development and survival of their neighbours. They interact and therefore have to be considered as a system of dependent random variates from an unknown stochastic process. One such statistical model which considers the spatial dependence among trees in a forest and their characteristics is a marked point process. The `points', called events in spatial statistics, are the tree positions and the `marks' are tree characteristics such as crown lengths or tree species. A minimal prerequisite for any serious attempt to model an observed pattern is to tes…
The Economic Impact of Restricted Water Supply: a Computable General Equilibrium Analysis
2007
Water problems are typically studied at the level of the river catchment. About 70% of all water is used for agriculture, and agricultural products are traded internationally. A full understanding of water use is impossible without understanding the international market for food and related products, such as textiles. The water embedded in commodities is called virtual water. Based on a general equilibrium model, we offer a method for investigating the role of water resources and water scarcity in the context of international trade. We run five alternative scenarios, analyzing the effects of water scarcity due to reduced availability of groundwater. This can be a consequence of physical con…
Network measures in animal social network analysis : Their strengths, limits, interpretations and uses
2020
International audience; We provide an overview of the most commonly used social network measures in animal research for static networks or time‐aggregated networks. For each of these measures, we provide clear explanations as to what they measure, we describe their respective variants, we underline the necessity to consider these variants according to the research question addressed, and we indicate considerations that have not been taken so far. We provide a guideline indicating how to use them depending on the data collection protocol, the social system studied and the research question addressed. Finally, we inform about the existent gaps and remaining challenges in the use of several va…
Universal design as resilient urban space plan strategy. New scenarios for environmental resources’ sustainable management
2021
Nowadays, urban framework, stressed by the growing anthropic pressure and its constantly evolving use requests is split by uneven structures, contexts, users and patchy needs, which come out to be inefficient and ineffective in access and management. This fact is directly connected both with morph-functional structure of urban texture and its continuous changing trends. The most important consequences of this situation are some negative effects that produce entropy, mistaken anthropic space uses, ecological networks decrease and most of all a substantial urban life quality reduction connected with mobility problems and non-resilient spaces' use at the different plan scales. These elements m…
Colonization of eurasian jay Garrulus glandarius (L.) and holm oaks Quercus ilex (L.): the establishment of ecological interactions in urban areas.
2016
Here we describe the relationship between holm oak seedling diffusion and jay recolonization in an urban orchard.