Enemy release of exotic plants from soil pathogens has been tested by examining plant-soil feedback effects in repetitive growth cycles. However, positive soil feedback may also be due to enhanced benefit from the local arbuscular mycorrhizal fungi (AMF). Few studies actually have tested pathogen effects, and none of them did so in arid savannas. In the Kalahari savanna in Botswana, we compared...

Widely-held, untested assumptions in many prairies are that high-intensity fires conducted during droughts will decrease native herbaceous species richness and lead to rapid invasions by alien species. We compared native and exotic herbaceous species richness and aboveground herbaceous biomass one year following the application of highintensity growing-season fires in Texas coastal prairie. Fir...

Questions: Is seedling emergence limited by the set of viable seeds, by incompatibility between the phenology of seed shedding and timing of mowing, or by dry weather in germination periods? Does seedling mortality fluctuate with season and weather? Location: Negrentino, southern Alps, Switzerland. Methods: Fecundity estimates of the dominant grass Bromus erectus; highly frequent counts of spon...

Broom snakeweed (snakeweed) is an aggressive native range-weed found throughout arid and semiarid areas of the western United States, that increases following disturbances such as overgrazing, drought, or wildfire. Ecologically based strategies that include controlling snakeweed and reestablishing desirable herbaceous species are needed to restore productivity and diversity to invaded areas. Th...

A common form of land degradation at the desert margins involves the rapid encroachment of woody plants into historic grasslands and the acceleration of soil erosion as a result of the loss of grass cover (Archer, 1989; Schlesinger et al., 1990). The conversion of perennial grasslands into desert scrublands has been documented worldwide (Van Auken, 2000; Ravi, 2008) and has important implicatio...

1. Biological invasion can permanently alter ecosystem structure and function. Invasive species are difficult to eradicate, so methods for constraining invasions would be ecologically valuable. We examined the potential of ecological restoration to constrain invasion of an old field by Agropyron cristatum , an introduced C 3 grass. 2. A field experiment was conducted in the northern Great Plain...

Natural ecosystems are threatened by climate change, fragmentation, and non-native species. Dispersal-limitation potentially compounds impacts of these factors on plant diversity, especially in isolated vegetation patches. Changes can impact the phenology native species distinct ways from non-natives, resulting cascading communities. Few empirical studies have examined combined effects change d...