Regenerating sclerophyllous shrubby and woody vegetation on uncultivated land in the Mediterranean region is a source of browse for goats, cattle, camels, and wildlife. Traditionally, this Mediterranean shrubland was intensively grazed by mixed herds, predominantly goats that maintained an open landscape. In addition, the vegetation supplied timber for fuel and construction, as well as culinary and medicinal plants. Patches of deeper soil were cultivated, often on terraces. In recent years, goat husbandry has declined and the establishment of protected areas has favored the regeneration of a dense woodland dominated by Quercus calliprinos. Commercial beef husbandry has largely replaced the traditional management system. After initial thinning to open up the thickets, the oak woodland can sustain a viable beef herd with moderate supplementation. Appropriate management of grazing, control of the shrub component and, in some cases, soil nutrient amelioration, can lead to the development of relatively stable, open woodland with nutritious and usually attractive herbaceous patches. In addition to animal production, these rangelands have significant recreational, conservation, and landscape values that are becoming increasingly important as urbanization increases. Such landscapes provide a wide range of ecological services and are less of a fire hazard than the undisturbed regenerating successional shrub thickets. The multiple benefits of the open landscape can justify the expense of necessary interventions that cannot be borne by any single benefit.
Orna Reisman-Berman and Zalmen Henkin
We describe and quantify the process of space occupation by the dwarf shrub, Sarcopoterium spinosum, in mesic and xeric Mediterranean environments. The shrubs were sampled in fifteen 2 m x 1 m plots in an arid Mediterranean site (Lahav, northern Negev, Israel) and in a 10-m2 patch in a sub-humid Mediterranean site (Elkosh, Galilee). The results revealed three clear stages of development that follow the seedling stage (first year): "Sapling";, "Young";, and "Adult" stages, each of which contributes differently to the persistence of the individual shrub and its population in space and time. The timelines in the xeric and mesic sites were very similar, though development was more intense in the mesic site. The "Sapling" stage is characterized by rapid elongation of only a few stem axes during the first 5 years. The transition to the "Young" stage is marked by the onset of canopy expansion and the proliferation of stem axes, and during this stage clonal structures are formed, i.e., the connected ramets (stem-axes), the split proximate ramets, and the integrated ramets (layering branches with or without daughter shrubs). The "Adult" stage starts around the age of 15 years. Although only small fractions of the population survive to this age, this stage is highly viable and it is characterized by escapes from senescence, manifested in proliferation of clonal structures and canopy expansion. The minimum age for sexual reproduction observed in the field was 4 years, however, this reproduction mode varied greatly between environments and in the xeric environment, peaking was at the "Adult" stage, with 60% of this age class exhibiting sexual reproduction.
Zalmen Henkin and No'am G. Seligman
Seedling survival of the dwarf shrub Sarcopoterium spinosum growing on hilly terra rossa soil was monitored between 2000 and 2004 on forty 1 x 1-m quadrats, each of which contained a single shrub. Of the 40 shrubs, 20 (designated P+) received a dressing of super-phosphate in 1988 and 20 (designated P-) did not. After seed dispersal in 1999, the shrubs were uprooted to prevent further addition of seeds. Seed dispersal was monitored up to 50 cm from the edge of the mother shrub. There were large year-to-year differences in emergence that were not clearly related to the rainfall distribution. On the P+ quadrats the peak biomass of herbaceous vegetation was consistently greater and the number of emergent seedlings was consistently smaller than on the P- quadrats, but seedling survival was not related to differences in herbaceous biomass. Our main conclusions are: S. spinosum germination is extremely erratic from year to year; only 0.5 of an average of 8-14 seedlings m-2 that emerged, survived the first summer; these survivors had a good chance of becoming established plants; seedlings can become established in dense herbaceous vegetation; seedling dispersal was limited to 50 cm from the edge of the shrub; the current soil seed bank can maintain recruitment for at least 5 years without replenishment.
Sivan Golan, Yoni Waitz, Jotham Ziffer-Berger, Michal Barzilai, Nir Hanin, Zalmen Henkin and Oz Barazani
Germination behavior of the widespread southeastern Mediterranean shrub Sarcopoterium spinosum was conducted to assess its respond to post-fire cues. Germination experiments were conducted on 10 populations along a rainfall gradient – from productive, fuel-rich and fire-prone mesic Mediterranean populations, as well as from those in arid and fuel-poor environments. Our results indicate that post-fire cues induced germination of S. spinosum only among populations that originated from sites that are prone to wild fires. As wild-fires in this region occur mainly during the long dry season, but rarely ignited by natural factors, the adaptation to human made fires in natural populations of the southeastern Mediterranean environments is discussed.