There is at present enough ecological understanding of Mediterranean ecosystems to provide legitimacy for active management and intervention in these environments. One of the principal threats to biodiversity in Mediterranean environments is posed by the successional processes that turn the landscape into a dense, close stand of woody vegetation, prone to burning. Active management aimed to control the closing up process is required; it should be considered at several levels—species, populations, communities, and ecosystems—and should be applied according to well-defined management/conservation goals. Biodiversity, especially in the animal populations and the herbaceous community, is an expression of the landscape structure, which, in turn, is modulated principally by the woody vegetation. Therefore, a management scheme based on multiscale functional patchiness is required. Scientists, especially landscape ecologists, should provide the required information on the relations between the woody formation and biodiversity and should participate in the management decision-making process.
AVI PEREVOLOTSKY and YIGAL HAIMOV
This paper examines the structural response to disturbance of two common species, Quercus calliprinos and Phillyrea latifolia, in a dry Mediterranean woodland in Israel. Disturbance was represented by (a) a continuous diffuse effect as a result of browsing during a 5-year period, (b) a discontinuous concentrated disturbance caused by a single massive thinning and pruning treatment, and (c) a combination of thinning and browsing. Q. calliprinos responded to browsing by increasing leaf toughness and the number and sharpness of leaf spines. Leaf shape was also affected. P. latifolia, on the other hand, showed much less structural adaptations, but responded to both continuous and discontinuous disturbance by intensive shoot regrowth. It appears that while Q. calliprinos has developed complex defense mechanisms to continuous disturbance such as browsing, P. latifolia has employed a different strategy which may be better adapted to massive concentrated disturbance (wood cutting, fire), since under such conditions rapid “recapture” of space by vigorous lateral growth can be an advantage. It is concluded that different defense strategies can point to the dominant disturbance sources against which they have been developed. The multiple-source disturbance so typical of the Mediterranean ecosystems (heavy grazing, frequent fires, and wood cutting) is a probable reason for the coexistence of two distinct defense strategies within the same woodland stands. Other differences (tannin content, tree regrowth pattern) also support this hypothesis.
Avi Perevolotsky and Efrat Sheffer
Natural and semi-natural landscapes usually serve varied land uses, including grazing, forestry, recreation, and nature or biodiversity protection. In most cases areas with differing land uses are managed by different agencies, with differing perspectives, goals, and operating methodologies. In his teaching, Imanuel Noy-Meir emphasized the ecological basis of the management of principal land-use practices (forests, rangelands, nature reserves) in Mediterranean Israel, and advocated ecological thinking to achieve better management and to minimize inter-agency conflicts. We propose a broader framework for integrated management of multiple uses by adoption of a landscape perspective that cuts across administrative lines. The reasoning for taking such an approach is based on the newly developing understanding of the impact of dynamic processes that occur spontaneously on a large scale in Mediterranean Israel. Landscape-scale interactions—oak woodland succession and pine colonization—may interfere or even conflict with some management goals set by the agencies involved. Attempts to mitigate these interactions may be very costly or ineffective. We propose coordinated management, planning, and implementation, based on common ecological criteria. We base this paper on observations and on perceptions gained from analyzing landscape dynamics of the predominant ecosystems in Mediterranean Israel: dense oak woodland and planted pine forests. The small size of Israel and the consequently small size of different land-use units, as well as their close proximity to each other, call for coordination of the organizational perspectives that relate at present independently to the various units. The new perspective should be broader, regional, landscape-oriented, and should take into consideration ecological processes that integrate neighboring units. As a first step, all agencies involved should accept the pine-oak interaction and dynamics as part of the local succession and should adapt their management schemes accordingly.
Avi Perevolotsky and Efrat Sheffer
Forest management (silviculture) is a long-established applied science, but also a field whose sustainability and ecological implications have been questioned. In this paper, we present the basic features of commercial forestry together with a review of novel approaches for ecologically oriented forestry. The "new forestry" advocates for multiple-species and structurally complex forests, and is directed toward a diverse array of objectives (ecosystem function, biodiversity conservation, wildlife habitats, visual quality, nutrient recycling, water retention, soil productivity, carbon sequestration, and amenity values), in addition to the provision of classic economic forestry commodities.In temperate forests, economic goals have not been abandoned. The challenge in these systems is to develop a new silvicultural approach that will keep forests sustainable and also fulfill their traditional timber production function. In Israel, the majority of forests are not economic in the traditional sense; therefore, the shift toward more ecological management should be easier. We discuss the applicability of ecological forestry to Israeli forests, suggesting ways by which forest management can be adapted for the new forestry objectives. The scientific community can aid this process by providing technical expertise to help bridge knowledge gaps. We hope that this discussion will help to create some common ground for discussions between conservationists and foresters in Israel in years to come.
Gidi Ne’eman, Avi Shmida and Avi Perevolotsky
RACHEL SCHWARTZ-TZACHOR, IDO IZHAKI and AVI PEREVOLOTSKY
Although many studies indicate a relation between global warming and variation in spatial and temporal butterfly distribution, detailed studies are lacking on the importance of local climatic factors on butterfly community composition. We studied the relation between climatic factors and seasonality on butterfly community composition in a Mediterranean climate-type region. The butterfly diversity measures were mainly affected by maximum daily radiation, minimum daily relative humidity, and temperature variables. We suggest extending butterfly monitoring at Long Term Ecological Research stations in Israel, which will allow separating the effect of climatic changes and/or change in local factors on butterfly community composition.
Yagil Osem, Irit Konsens, Avi Perevolotsky and Jaime Kigel
The regeneration and patch dynamics of Sarcopoterium spinosum shrubs may have profound effects on rangeland productivity in Mediterranean semiarid shrublands. Yet little is known about the role of the soil seed bank in seedling recruitment of S. spinosum and whether grazing has any effect on the size and spatial distribution of its seed bank and seedling emergence. We studied the effects of sheep grazing on the soil seed bank and seedling emergence of S. spinosum in a Mediterranean semiarid shrubland in the northern Negev Desert in Israel. The variation in density of the seed bank in autumn and of seedling emergence in the spring was measured during two years, beneath shrub canopies and in the open space matrix, inside and outside exclosures that prevented sheep grazing. Seed density beneath the shrubs ranged between 2000 and 3000 seeds m-2, and was about ten times as great as that in the adjacent open space patches. Moreover, beneath the shrubs, the proportion of the autumn seed bank that emerged as seedlings in the spring was three times as great as in the open space patches. Grazing caused a 60% increase in soil seed bank density beneath the shrub canopy but had no effect on the seed bank in the open space patches. Variation in spring seedling density between grazing treatments and patch types was strongly related to the availability of seeds in the previous autumn.
Amir I. Arnon, Eugene D. Ungar, Tal Svoray, Moshe Shachak, Joshua Blankman and Avi Perevolotsky
Ecosystems of mixed woody and herbaceous vegetation are under increasing pressure and threat from human activity and global climate changes. Many processes that shape these ecosystems remain poorly understood despite their large geographic extent, the services they provide, and their importance for wildlife and livestock. Some of these processes occur simultaneously on small and large scales; therefore their study requires methodologies that combine high spatial resolution with large spatial extent. In this study, we explored the phenomenon of rings—"circlets"—of relatively dense herbaceous biomass that seem to occur around patches of Sarcopoterium spinosum in the semiarid northern Negev. We developed a novel, non-destructive method to estimate herbaceous biomass at a high spatial resolution, over an area of 1500 m2. Steps in the study process included: low-altitude aerial photography, image rectification, delineation of shrub patches, computation of herbaceous biomass in the intershrub area, and analysis of herbaceous biomass as a function of distance from the nearest shrub. Our results confirmed the existence of circlets, and we estimated their width to be approximately 10 cm. Herbaceous biomass at the peak of the green season was approximately 40% greater in the circlet than in the remainder of the intershrub area. Circlets are probably an important feature of the ecosystem; since they covered ca. 20% of the intershrub area, their contribution to primary (herbaceous) production at the ecosystem level, and, in turn, to secondary production, is substantial. We discuss possible mechanisms in the creation of circlets, as well as the possible implications of circlets for range management and improvement.
Einav Mayzlish-Gati, Margareta Walczak, Alon Singer, Tomer Faraj, Sivan Golan, Dikla Lifshitz, Dana Bar, Yair Ur, Dafna Carmeli, Ran Lotan, Ofra Fridman, Alma Daniel, Yael Sade, Avi Perevolotsky, Rivka Hadas and Oz Barazani
Israel is a geographically small and relatively new state (founded in 1948) with high population density, industrial development and economic growth, all of which negatively affect the environment, particularly biodiversity. There is, however, a growing awareness in the country of the need for environmental and biodiversity protection. The Israel Nature and Parks Authority (INPA), the official body legally responsible for protecting natural habitats, biodiversity and ecosystems in Israel, established a program to protect and conserve the endangered, near-threatened and very rare (ENtR) plants listed in the Israel Red Data Book of flora at risk. In this communication, we describe the ex-situ conservation strategies of the Israel Gene Bank (IGB) within this program. The IGB has expanded its role in the conservation of ENtR species from only ex-situ seed conservation to active involvement in whole-plant conservation and reintroducing ENtR species back into nature. In the past 10 years, 1289 accessions belonging to 68% of the species in the Red List were collected to form the IGB core collection of endangered and rare species. The germination unit of the IGB developed 198 new protocols and propagated 87 different ENtR species.