نتایج جستجو برای: species evenness

تعداد نتایج: 548668  

ارزانی, حسین, برهانی, مسعود, بصیری, مهدی, زارع چاهوکی, محمدعلی, فرح‌پور, مهدی,

In order to investigate the effects of range management plans on species diversity, richness and evenness in Semirum rangelands, 52 sites (28 with treated plan and 24 without treated plan) were selected. The non-parametric indices for species richness (Margalof, Menhinick, Jacknife and counting method) and species diversity (Simpson, Camargo, Smith and Wilson and modified Nee) were compared in ...

Fariba Noedoost Mohammad Jankju

Rangeland ploughing and cultivation using dry land farming crops may be amajor reason for the destruction of natural resources in the semiarid and sub-humid regionswhich may significantly change the composition and reduce the stability of the affectedcommunities. In present research, an abandoned ploughed site was compared with a nearbyreference site in the semiarid rangelands of Baharkish, Quc...

2012
Elena Rovenskaya Brian D. Fath

Using donor-controlled, bottom-up equations to describe network collapse we systematically investigate the impact each species has on the survival or extinction of other species. Short of extinction, one can determine the integrated losses experienced by the ecosystem. These losses are aggregated into system level indicators, such as entropy, average gain/loss, average time to extinction, etc. ...

2016
Daniel Yeboah Han Y.H. Chen Steve Kingston

Understanding species diversity and disturbance relationships is important for biodiversity conservation in disturbance-driven boreal forests. Species richness and evenness may respond differently with stand development following fire. Furthermore, few studies have simultaneously accounted for the influences of climate and local site conditions on species diversity. Using forest inventory data,...

2012
NATALIA NORDEN SUSAN G. LETCHER VANESSA BOUKILI NATHAN G. SWENSON ROBIN CHAZDON

To gain insight into the ecological processes driving community reassembly in disturbed ecosystems, we assessed the phylogenetic dispersion of earlyand late-successional tree species occurring in lowland forests of northeastern Costa Rica. Early-successional species were more closely related than expected by chance, whereas late-successional species tended to be less closely related than expect...

Journal: :Ecology letters 2009
Forest I Isbell H Wayne Polley Brian J Wilsey

Theory predicts that the temporal stability of productivity, measured as the ratio of the mean to the standard deviation of community biomass, increases with species richness and evenness. We used experimental species mixtures of grassland plants to test this hypothesis and identified the mechanisms involved. Additionally, we tested whether biodiversity, productivity and temporal stability were...

Journal: :Tropical life sciences research 2016
Chee Su Yin Sim Yee Kwang

Land reclamation in Penang began two decades ago and is still rampant with large reclamation projects planned to be executed in the near future. The present study provides the first information on effects of land reclamation in Penang towards the coastal macroinvertebrates. This study assessed the abundance, diversity, and evenness of coastal invertebrates assumed to be the foremost affected wh...

2015
Tarald O Kvålseth

Various properties have been advocated for biological evenness indices, with some properties being clearly desirable while others appear questionable. With a focus on such properties, this paper makes a distinction between properties that are clearly necessary and those that appear to be unnecessary or even inappropriate. Based on Euclidean distances as a criterion, conditions are introduced in...

2015
M. Choudhury

Moth species were studied from some selected districts of Assam (i.e., Cachar and Barpeta district) to determine their diversity index, species richness and evenness of Arctiidae and Geometriidae family of the moth fauna.The moths were collected by applying specialized trapping methods using UV light operating during night. Collected moth species were identified up to family-genusspecies level....

2011
Lars Gamfeldt Helmut Hillebrand

The study of the interrelationship between productivity and biodiversity is a major research field in ecology. Theory predicts that if essential resources are heterogeneously distributed across a metacommunity, single species may dominate productivity in individual metacommunity patches, but a mixture of species will maximize productivity across the whole metacommunity. It also predicts that a ...

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