Reduced recruitment of blue oak (Quercus douglasii) seedlings in California grasslands and woodlands may result from shifts in seasonal soil water availability coincident with replacement of the native perennial herbaceous community by Mediterranean annuals. We used a combination of container and field experiments to examine the interrelationships between soil water potential, herbaceous neighb...

The distribution and dynamics of plant populations depend on the recruitment of young individuals, which is influenced by seed production, animal seed dispersal, dispersal distance, and the deposition of seeds in favourable places for seed germination/ establishment and seedling survival. In particular, seeds dispersed over long distances will likely encounter new environmental conditions that ...

The endemic New Caledonian conifer Agathis ovata occurs as an emergent tree in fire-prone shrublands (maquis), and fire-sensitive rainforest. Growth, survivorship and recruitment over 5 yr were compared for populations from forest and maquis on ultramafic substrates in New Caledonia to investigate whether demographic behaviour varied in response to the strongly contrasting forest and shrubland ...

poplar trees are becoming extremely important as fast growing species due to the increasing need for wood and decreasing productivity of some lands in iran. the present study aimed to find the effect of canopy of poplar clones as one of the most important effective factors on soil properties compared to the distances inter-row trees. five poplar clones and species included: populus euramericana...

Early-successional vegetation is often a major factor that limits recovery of tropical forest in abandoned pastures by outcompeting seedlings of forest trees. The goal of this study was to compare the effects of aboveand below-ground competition of pasture grasses and shrubs on the growth of tree seedlings in abandoned tropical pasture in Costa Rica. Seedlings of Calophyllum brasiliense were pl...

A profusion of fruit forms implies that seed dispersal plays a central role in plant ecology, yet the chance that an individual seed will ultimately produce a reproductive adult is low to infinitesimal. Extremely high variance in survival implies that variations in fruit production or transitions from seed to seedling will contribute little to population growth. The hey issue is that variance i...

This study documents tree mortality in Big Bend National Park in Texas in response to the most acute one-year drought on record, which occurred following a five-day winter freeze. I estimated changes in forest stand structure and species composition due to freezing and drought in the Chisos Mountains of Big Bend National Park using permanent monitoring plot data. The drought killed over half (6...

were exposed to two concentrations of atmospheric CO2 (365 or 720 μmol mol) in combination with two N treatments (40 or 400 kg N ha year) and two irrigation treatments (target values of −0.5 or −1.5 MPa xylem pressure potential) in opentop chambers from March 1993 through November 1994. Irrigation treatments were imposed after seedling establishment (i.e., 19 weeks after planting). Seedlings we...