TY  - JOUR
A1  - Petru, Martina
A1  - Menges, Eric
T1  - Seedling establishment in natural and experimental Florida scrub gaps
N2  - Gaps are often important microhabitats for recruitment of herbaceous plants. In the Florida scrub, fires create gaps by top-killing resprouting shrubs. These natural gaps are aboveground gaps (without aboveground vegetation) that may also be complete gaps (if belowground roots and rhizomes are absent). Within three types of gaps (natural gaps, experimental aboveground and experimental complete gaps), we studied seedling recruitment and survival of spontaneous species and seven sown herbs for two years. We created aboveground gaps by clipping vegetation and complete gaps by removing shrub roots and rhizomes. These gaps occurred in two Florida scrub habitats: rosemary scrub and scrubby flatwoods. We also explored factors that can affect recruitment patterns in gaps, such as soil moisture, root water retention and light availability. In addition, we tested effects of supplemental watering on sown seeds in the field since drought in 2000 and 2001 suppressed natural seedling recruitment. The watering treatment increased recruitment in all types of gaps. Over half of all gaps were colonized, but there were few seedlings. Recruitment was highest in watered, complete gaps in scrubby flatwoods, where the soil moisture levels were higher and light levels lower than in the other gap types. Seedlings of a single spontaneously recruited species (Lechea deckertii) were more abundant than sown species. Locally common gap specialists were more abundant than generalists. Because many of these gap specialists are endangered plant species, understanding how disturbances create microsites for their regeneration is critical for conservation and management of the Florida scrub ecosystem. In small-scale conservation projects, artificially created gaps may substitute for post-fire gaps when prescribed burning is impossible.
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Petru, Martina
A1  - Tielbörger, Katja
A1  - Belkin, Ruthie
A1  - Sternberg, Marcelo
A1  - Jeltsch, Florian
T1  - Life history variation in an annual plant under two opposing environmental constraints along an aridity gradient
N2  - Environmental gradients represent an ideal framework for studying adaptive variation in the life history of plant species. However, on very steep gradients, largely contrasting conditions at the two gradient ends often limit the distribution of the same species across the whole range of environmental conditions. Here, we study phenotypic variation in a winter annual crucifer Biscutella didyma persisting along a steep gradient of increasing rainfall in Israel. In particular, we explored whether the life history at the arid end of the gradient indicates adaptations to drought and unpredictable conditions, while adaptations to the highly competitive environment prevail at the mesic Mediterranean end. We examined several morphological and reproductive traits in four natural populations and in populations cultivated in standard common environment. Plants from arid environments were faster in phenological development, more branched in architecture and tended to maximize reproduction, while the Mediterranean plants invested mainly in vertical vegetative growth. Differences between cultivation and field in diaspore production were very large for arid populations as opposed to Mediterranean ones, indicating a larger potential to increase reproduction under favorable conditions. Our overall findings indicate two strongly opposing selective forces at the two extremes of the aridity gradient, which result in contrasting strategies within the studied annual plant species
Y1  - 2006
UR  - http://www3.interscience.wiley.com/journal/117966123/home
U6  - https://doi.org/10.1111/j.2005.0906-7590.04310.x
ER  -