نتایج جستجو برای: diversity indices

تعداد نتایج: 268614  

2014
Robert C. Szava-Kovats Meelis Pärtel Jack Anthony Gilbert

Ecologists have developed an abundance of conceptions and mathematical expressions to define β-diversity, the link between local (α) and regional-scale (γ) richness, in order to characterize patterns of biodiversity along ecological (i.e., spatial and environmental) gradients. These patterns are often realized by regression of β-diversity indices against one or more ecological gradients. This p...

2006
Karline soetaert

Diversity indices, although designed for comparative purposes, often cannot be used as such, due to their sample-size dependence. I t is argued here that this dependence is more pronounced in h~gh divers~ty than in low diversity assemblages and that indices more sensitive to rarer species require larger sample sizes to estimate diversity with reasonable precision than indices which put more wei...

نیکوی, مهرداد, همرنگ, نازنین, پوربابائی, حسن,

  Information about gaps and their sizes distribution is useful for protecting herbaceous diversity. This study was conducted to investigate the effect of gap size on herbaceous species diversity in oriental beech (Fagus orientalis Lipsky.) stand in Asalem, Guilan province. For this study, fifteen gaps in small, medium, and large sizes were randomly selected. Then, herbaceous species were ident...

ژورنال: مرتع 2022

Railway construction is one of the important activities in the development of any country and in developing countries, the need for roads is one of the main axes of development. Railway construction operations can effect on desert rangelands around railway. This study investigates the effects of Yazd-Eghlid railway construction on vegetation diversity and richness in  the rangelands of Kalmand-...

Journal: :Applied and environmental microbiology 2007
Christopher B Blackwood Deborah Hudleston Donald R Zak Jeffrey S Buyer

Ecological diversity indices are frequently applied to molecular profiling methods, such as terminal restriction fragment length polymorphism (T-RFLP), in order to compare diversity among microbial communities. We performed simulations to determine whether diversity indices calculated from T-RFLP profiles could reflect the true diversity of the underlying communities despite potential analytica...

2015
Jari Oksanen

This document explains diversity related methods in vegan. The methods are briefly described, and the equations used them are given often in more detail than in their help pages. The methods discussed include common diversity indices and rarefaction, families of diversity indices, species abundance models, species accumulation models and beta diversity, extrapolated richness and probability of ...

 Communities or ecosystems with higher biodiversity also have higher levels of ecosystem function and services, so the relationship between functional diversity and sustainability of plant communities is essential to predict ecosystem functioning. The aim of the present study was to investigate the relationship between carbon stocks and different species diversity and functional indices as well...

Plant diversity and vegetation distribution in an area are related to the soil physical and chemical properties. The knowledge of relationships between species diversityand soil parameteris essential for sustainable ecosystem management. This study was conducted to investigate the relationships between soil factors and species diversity indices in the protected rangelands of Lashgardar, Malayer...

Reduction of species diversity which is a significant threat to the earth has been found more important and has attracted attention among ecologists over recent years. This research was carried out to determine the relationships between plant species diversity indices and soil properties by multivariate regression methods in Jamilabad region, Baft, Kerman province, Iran in 2016. Different sites...

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