• Leaf gas exchange responses to elevated CO 2 and N are presented for 13 perennial species, representing four functional groups: C 3 grasses, C 4 grasses, legumes, and nonleguminous forbs. Understanding how CO 2 and N effects interact is important to predict plant community response to global change. • Plants were field-grown in monoculture under current ambient and elevated (560 μ mol mol − 1...

There is increasing interest in the analysis of annual growth rings in the secondary root xylem of perennial forbs (herb-chronology). Therefore, we need to verify whether these growth rings are always formed annually. To investigate the formation of root rings we performed common garden experiments at two distinct sites in Switzerland. We grew nine unrelated forb species from seed and subjected...

As pinyon–juniper (specifically, Pinus monophylla and Juniperus osteosperma) woodlands in the western United States increase in distribution and density, understory growth declines and the occurrence of crown fires increases, leaving mountainsides open to both soil erosion and invasion by exotic species. We examined if the loss in understory cover that occurred with increasing tree cover was re...

Abstract. The purpose of this study was to investigate vegetation dynamics and range conditions considering the climatic conditions and soil properties in Haftooman, Khoor and Biabanak deserts, Iran. For this purpose, after determining vegetation types and the associated species, the type of rangeland utilization, grazing season, the livestock type, the other relevant information, vegetation da...

Mandates for biofuel and renewable electricity are creating incentives for biomass production in agricultural landscapes of the Upper Midwest. Different bioenergy crops are expected to vary in their effects on biodiversity and ecosystem services. Here, we use data from the North American Breeding Bird Survey to forecast the impact of potential bioenergy crops on avian species richness and the n...

Fresh forages are an important natural source of vitamins and fatty acids in ruminant diets, and their concentrations in forage species are important for the quality of animal-derived foods such as dairy and meat products. The aims of this study were to obtain novel information on vitamins and fatty acids (FA) in a variety of forage legumes and non-legume forb species compared to a grass-clover...

The dynamics of invasive species may depend on their abilities to compete for resources and exploit disturbances relative to the abilities of native species. We test this hypothesis and explore its implications for the restoration of native ecosystems in one of the most dramatic ecological invasions worldwide, the replacement of native perennial grasses by exotic annual grasses and forbs in 9.2...

The study of the exclosure effects on the vegetation changes undergrazing and non-grazing conditions in the rangeland areas has particularimportance in the rangeland improvement and revivification projects. Theresearch was accomplished in semi-steppe KhoyBilehvar area, from 1999 to2005. Vegetation cover was annually measured within fixed plots during transact.The results showed that during nine...

Pinus-Juniperus L. (Piñon-juniper) woodlands of the western United States have expanded in area nearly 10-fold since the late 1800's. Juniperus occidentalis ssp. occidentalis Hook. (western juniper) dominance in sagebrush steppe has several negative consequences, including reductions in herbaceous production and diversity, decreased wildlife habitat, and higher erosion and runoff potentials. Pr...