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Natural regeneration that occurs in the understory of Mediterranean pine monocultures provides the basis for the transition of these simply structured systems toward a more complex and sustainable state. However, the course and consequences of this process, and its relationships with environmental and silvicultural variables, are still inadequately understood. We investigated the relationship between rainfall amount and understory woody vegetation (UWV) structure in mature (40-50 year) Pinus halepensis plantations in the Mediterranean zone of Israel, where rainfall ranges from 280 mm/year in the south to 900 mm/year in the north. We measured abundance, diversity and species composition on south-and northfacing slopes, in forest sites distributed along the rainfall gradient. UWV abundance, as measured by cover percentage and height, increased with rainfall amount along the entire gradient (2-113% and 0.1-3.4 m, respectively), more rapidly on north-facing slopes. Species composition varied along the rainfall gradient, with ranges of species occurrences corresponding to those in unforested habitats. The relationship between rainfall and UWV species richness was positive throughout most of the rainfall gradient, possibly with a shift in pattern at the highest rainfall levels. UWV richness increased sharply with increasing abundance, up to a certain point with no further increase in richness as abundance increased further. We concluded that UWV structure in the studied forest environment and climatic range is strongly determined by rainfall and suggested that the design and management of Mediterranean forests should focus more on optimizing water availability for the various components.

Question The importance of silvicultural site preparation techniques in determining vegetation succession is increasingly recognized. We studied the effects of mechanical site preparation (MSP) on post‐fire vegetation regeneration within reforested sites in Mediterranean Israel. Location Upper Galilee region, Israel. Methods Vegetation cover and composition, ruderal species colonization and pine regeneration were monitored in four reforested sites for 3 yr following wildland fires that burned mature Pinus brutia and P. halepensis plantations. In each reforested site, a 50 m × 50 m monitoring area was assigned and measurements were conducted within five subplots (2 m × 50 m) encompassing three MSP patch types: ploughed patches (P), unploughed patches (UP) and planting mounds (M) that combined ploughing, pit digging and wood‐chip mulching. Results Recovery of vegetation cover (excluding pines) was rapid. The MSP patch type significantly affected vegetation cover in the first spring following the fire: cover was lowest on M, intermediate on P and highest on UP. However, these differences became minor by the third spring following the fire. Total woody species richness was not affected by MSP patch type, although there were minor effects on relative abundance of woody species. Two ruderal species were found, but their abundance became untraceable by the third year. Patterns of MSP effects on pine regeneration were similar for P. halepensis and P. brutia. Density of emerging seedlings of both pine species during the first year following the fire was significantly affected by MSP patch type: lower in P and M than in UP by more than 50% and 90%, respectively. However, emergence and/or survival during the following 2 yr was higher in P and M than in UP, with overall outcome of pine regeneration still about 50% lower in P and M than in UP. Conclusions The MSP treatments had only a minor, short‐term effect on post‐fire regeneration and colonization of vegetation, except for pine recruitment, which was more severely affected.