نتایج جستجو برای: habitat conditions

تعداد نتایج: 894764  

2004
ALAN B. FRANKLIN BARRY R. NOON

Habitat fragmentation is an issue of primary concern in conservation biology. However. both the concepts of habitat and fragmentation are ill-defined and often misused. We review the habitat concept and examine differences between habitat fragmentation and habitat heterogeneity, and we suggest that habitat fragmentation is both a state (or outcome) and a process. In addition, we attempt to dist...

Journal: :محیط زیست طبیعی 0
مجتبی قندلی اداره کل حفاظت محیط زیست استان سمنان افشین علیزاده استادیار دانشکده منابع طبیعی، دانشگاه تهران، ایران محمود کرمی - استاد دانشکده منابع طبیعی، دانشگاه تهران، ایران محمد کابلی استادیار دانشکده منابع طبیعی، دانشگاه تهران، ایران

kavir national park is an example of dry and desert ecosystem that is consisted of vast plains and numerous highlands. wild sheep is one of the iconic bovid in this area. understanding their habitat requirements and similarities is essential for their successful population management. we used ecological niche factor analysis approach to develop habitat suitability models for wild sheep in kavir...

2015
Johannes Radinger Christian Wolter Jochem Kail Judi Hewitt

Habitat suitability and the distinct mobility of species depict fundamental keys for explaining and understanding the distribution of river fishes. In recent years, comprehensive data on river hydromorphology has been mapped at spatial scales down to 100 m, potentially serving high resolution species-habitat models, e.g., for fish. However, the relative importance of specific hydromorphological...

2016
Scott F. Pearson Shannon M. Knapp

Habitat selection that has fitness consequences has important implications for conservation activities. For example, habitat characteristics that influence nest success in birds can be manipulated to improve habitat quality with the goal of ultimately improving reproductive success. We examined habitat selection by the threatened streaked horned lark (Eremophila alpestris strigata) at both the ...

2009
Peter A. Bisson Jason B. Dunham Gordon H. Reeves

In spite of numerous habitat restoration programs in fresh waters with an aggregate annual funding of millions of dollars, many populations of Pacific salmon remain significantly imperiled. Habitat restoration strategies that address limited environmental attributes and partial salmon life-history requirements or approaches that attempt to force aquatic habitat to conform to idealized but ecolo...

2007
Jörn Buse Boris Schröder Thorsten Assmann

Saproxylic insects are characterised by their exceptional diversity and high proportion of threatened species. No recent studies have demonstrated the validity of habitat suitability analysis for scientifically based habitat management for these species. We studied the habitat requirements of the endangered longhorn beetle Cerambyx cerdo, a species with a supposed keystone function for the sapr...

Journal: :The American naturalist 2009
Virginie Ravigné Ulf Dieckmann Isabelle Olivieri

We derive a comprehensive overview of specialization evolution based on analytical results and numerical illustrations. We study the separate and joint evolution of two critical facets of specialization-local adaptation and habitat choice-under different life cycles, modes of density regulation, variance-covariance structures, and trade-off strengths. A particular feature of our analysis is the...

2007
Tara K. Muenz Stephen P. Opsahl Stephen W. Golladay

Streams of the Flint River Basin (FRB) remain as viable habitat for many freshwater species and harbor some of the most diverse mussel assemblages in the Southeast. However, land use changes, hydrologic alterations, and declines in native fish species have adversely affected mussel diversity and abundance throughout the region. Protection of rare and sensitive mussels requires the development o...

2011
Ruchira Somaweera Jonathan K. Webb Richard Shine

Animals almost always use habitats non-randomly, but the costs and benefits of using specific habitat types remain unknown for many types of organisms. In a large lake in northwestern Australia (Lake Argyle), most hatchling (<12-month-old) freshwater crocodiles (Crocodylus johnstoni) are found in floating vegetation mats or grassy banks rather than the more widely available open banks. Mean bod...

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