Negar Ahmadian

Tarbiat Modares University | TMU · Department of Range Science

Perennial plants create productive and biodiverse hotspots, known as fertile islands, beneath their canopies. These hotspots largely determine the structure and functioning of drylands worldwide. Despite their ubiquity, the factors controlling fertile islands under conditions of contrasting grazing by livestock, the most prevalent land use in dryla...

Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that in...

Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that in...

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we...

In this study, we aim to evaluate the diversity of vascular plants and lichens coexisting in Artemisia sieberi dominated landscapes of northern Iran. Specifically, we wanted to unveil to what extent Artemisia plant cover and soil features affected species diversity and composition of annuals and lichens growing beneath them, and if annual plants an...

Biological soil crusts (BSC) play a crucial role in arid ecosystem functioning, yet the effect of their properties (e.g. whether they are dominated by mosses and lichens) on the germination has rarely been investigated. Here, we analysed the effects of intact, dead and removed moss or lichen BSC on seed germination of Stipa caucasica, a key species...

Research in environmental science relies heavily on global climatic grids derived from estimates of air temperature at around 2 meter above ground1-3. These climatic grids however fail to reflect conditions near and below the soil surface, where critical ecosystem functions such as soil carbon storage are controlled and most biodiversity resides4-8...

A water-soluble polysaccharide was isolated from Tornabea scutellifera and fractionated using a DAEA Sepharose FF column to evaluate its capacity to stimulate natural killer (NK) cells and macrophages. Neutral sugars (71.8–93.5%) constituted the major part of crude polysaccharides and fractions (TSF 1 and TSF 2 ) with relatively lower levels of pro...

Abstract 1- INTRODUCTION Soil erosion is one of the most destructive processes of arid and semi-arid areas, which leads to desertification in a large area of the region. In windy areas, the wind in the region increases the probability of wind erosion. Soil moisture and soil temperature are the two effective factors in soil erosion control. Vegetati...

Abstract Biological soil crusts greatly affect the surface properties of the soil, which in turn may also alter the germination of the seeds of vascular plants. The aim of this study was to investigate the effect of moss on germination of five dominant species of Golestan National Park. At the beginning of the experiment, the seeds of five dominant...

Patchy vegetation is the main characteristic of arid and semi-arid lands. Gaps between patches in some cases are covered with biological soil crust such as lichens and these crusts have important ecological roles such as influence on germination and plant survival. In this research, effects of lichens as an important biological crust on the germina...