abstract. rangeland vegetation dynamics encompass all processes of changes in vegetation composition and structure over time. investigating the rangeland ecosystem dynamics makes it possible to determine the effects of climatic and management conditions on qualitative and quantitative changes of the vegetation in a specific period of time. accordingly, data collection and measurements for evalu...

Closed canopy vegetation often prevents the colonization of plant species. Therefore the majority of plant species are expected to appear at the initial phase of post-agricultural succession in mesic forest environment with moderate levels of resources. This hypothesis was tested with data from the BuellSmall Successional Study, NJ, USA, one of the longest continuous fine-scale studies of old-f...

Large-scale field patterns are a fundamental source of inferences on processes responsible for variation in species richness among habitats. We examined species richness of larval amphibian communities in 37 ponds over seven years on the Univ. of Michigan’s E. S. George Reserve. Ordination of the community incidence matrix indicated a strong major axis of variation in species associations that ...

wheat, cv. alvand, under late sowing condition and comparison with conventional sowing date was investigated in a field experiment in 2009-2010. the factors were seven levels of priming by sa, including control or untreated seeds, 400, 800, 1200, 1600, 2000 and 2400 µm sa and two sowing dates including conventional sowing date (23 october) and late sowing (22 november). results showed that prim...

Shrubs are the largest plant life form in tundra ecosystems; therefore, any changes in the abundance of shrubs will feedback to influence biodiversity, ecosystem function, and climate. The snow-shrub hypothesis asserts that shrub canopies trap snow and insulate soils in winter, increasing the rates of nutrient cycling to create a positive feedback to shrub expansion. However, previous work has ...

introduction soil is one of the most valuable national resources that can be wasted by erosion phenomenon. therefore, prevention of soil erosion is universally considered. erosion is a process by which soil particles are separated from their original context and can be moved to another location. rill erosion is a kind of water erosion in which detachment and movement of soil particles can be af...

This study investigated the effects of human trampling on cover, diversity and species richness in an alpine heath ecosystem in northern Sweden. We tested the hypothesis that proximity to trails decreases plant cover, diversity and species richness of the canopy and the understory. We found a significant decrease in plant cover with proximity to the trail for the understory, but not for the can...

Anthemis L. is a genus of aromatic flowering plants in the family Asteraceae and is native to Iran. In this research, 62 accessions of four chamomile species including Anthemis tinctoria, A. triumfetti, A. haussknechtii and A. pseudocotula were evaluated for morphological traits. Four experiments were conducted using a randomized complete block design with three replications at the Research Ins...

The desirable structure of longleaf pine forests, which generally includes a relatively open canopy of pines, very few woody stems in the mid-story, and a well-developed, herbaceous ground layer, provides critical habitat for flora and fauna and contributes to ecosystem function. Current efforts to restore longleaf pine to upland sites dominated by second-growth loblolly pine require informatio...

Plant canopy structure can strongly affect crop functions such as yield and stress tolerance, and canopy size is an important aspect of canopy structure. Manual assessment of canopy size is laborious and imprecise, and cannot measure multi-dimensional traits such as projected leaf area and canopy volume. Field-based high throughput phenotyping systems with imaging capabilities can rapidly acqui...