JME 2002 2-3
A quantitative method designated to individualize and classify vegetation units occurring in Mediterranean mosaic-likelandscapes is proposed. The method is based on the quantification of the two most basic structure parameters : Heightand coverage. According to a simple nomenclature including five height classes and three cover categories, up to fifty-five different types of vegetation structure are discriminated. The spatial assemblage of up to fifty-five types of vegeta-tion structures can be mapped with the help of a GIS. Thus, a quantitative analysis of the mosaic-like landscape of agiven region can be carried out. The distinction between monostratified, bistratified and multistratified structures typesis emphasized, as well as the ability to quantify mosaic-like landscape structural diversity.By discriminating between vegetation units occurring within Mediterranean mosaic-like landscapes according to quan-titative structure criteria, this classification method avoids the confusion resulting from the abundance of qualitativeterms used to designate Mediterranean vegetation units. Hence, this quantitative classification method makes Mediterra-nean mosaic-like landscapes directly comparable all around the Mediterranean basin.
Keywords: Cover categories, height classes, landscape structural diversity, Mediterranean vegetation unitsterminology, mosaic analysis, vegetation structure discrimination method.
Management of fuel breaksin the Israeli Mediterranean Ecosystem: thecase of Ramat Hanadiv Park
A. Perevolotsky, E. Ettinger, R. Schwartz-Tzachor, R. Yonatan
This study evaluates the effectiveness of different management alternatives – shrub removal, cattle grazing and combi-ned shrub removal and grazing – in maintaining fuel breaks in dense Mediterranean shrublands. Shrub removal+grazingproved to be the most effective treatment; it delays full recovery of woody vegetation for the longest period (~20 years).In comparison, without grazing shrubland returned to the original cover after 6 years since shrub removal. Heavy cattlegrazing for a short duration removed more than 80% of the herbaceous biomass but affected shrubs’ regeneration rate foronly 2 years. Full recovery of the shrubland under heavy cattle grazing took 7 years. Recovery dynamics is species-dependent but the dominant shrubs fully recovered both laterally and vertically within 7 years since removal. Naturalherbivory had no significant impact on the regeneration of the dominant woody species. Shrub removal is most effectiveif carried out in the spring. This study helps in laying the operational basis for an effective establishment and maintenan-ce of fuel breaks in east Mediterranean woody ecosystems.
Keywords: Mediterranean ecosystem, fire, fire/fuel breaks, fire prevention, herbivory impact, ecosystemmanagement
F. Bussotti, G. Gerosa
The influence of air pollutants on ecosystems in Europe has been studied for over two decades in the Western and Nordiccountries and in the Alps. The impacts of air pollutants on Mediterranean forest ecosystems (evergreen sclerophyllousforests and maquis) are poorly understood. The Mediterranean climate encourages the generation of high concentrationsof ozone – now recognised to be the most prevalent and damaging air pollutant to which vegetation is exposed in manyregions. In this paper, we examine the way in which many of the typical morphological and ecophysiological features ofMediterranean vegetation influence ozone impacts, plus the way in which the combination of environmental stresses towhich Mediterranean vegetation is exposed in the field affect responses to ozone. Sclerophyllous Mediterranean species(typified by leaves with dense mesophyll, little intercellular air space and containing an abundance of primary, e.g.ascorbate, and secondary metabolites, e.g. tannins and phenylpropanoids, that are capable of protecting key biomolecu-les from oxidative stress) might be expected to be hardier than their counterparts more typical of the relatively mesicenvironments of Northern and Continental Europe. Moreover, soil water shortage during the height of summer causespartial stomatal closure for lengthy periods each day. As a result, vegetation may avoid taking-up the ozone when con-centrations are at their highest. There are several confirmed reports of visible symptoms of ozone damage (chloroticmottle, necrosis, reddening etc.) on important crops and forest trees. The significance of these observations is discussed,along with the way in which ongoing changes in the Mediterranean environment may affect the future impacts of risingozone concentrations on vegetation.
Keywords: ozone, Mediterranean ecosystems, foliar injuries, critical levels, Pinus halepensis, evergreensclerophyllous vegetation.
Y. Carmel and Z. Naveh
Two central concepts in ecology, the concept of ecosystem and the concept of landscape, are presented as distinct para-digms, i.e. convenient approaches around which to organizing one’s view of the world. In view of insights gained fromthe General Systems Theory, we discuss these two concepts as middle number systems, elucidating similarities as wellas vast differences between them. Recent studies of the Mediterranean ecological system of Mt. Meron are presented toexemplify the way each of these concepts affects our perceptions, research, and models, and especially our prescriptionsfor land planning and management.The ecosystem approach focuses on organisms, populations, and on energy/matter cycles only. Humans and anthropoge-nic elements are viewed as external, disturbing factors. Ecosystem borders are vaguely defined. In contrast, our landsca-pe concept is transdisciplinary, and focuses on the entirety of biotic elements, including humans and their culture. Itsbasic elements are concrete pieces of land, well defined in space, along various scales. Currently, the landscape approach(as we describe it) is seldom reflected in planning and management prescribed by ecologists. It has, however, uniqueadvantages for land planning and management. Ecological models of landscape are inherently spatially-explicit, andtypically incorporate anthropogenic impacts as integral parts of the model. Recommendations relate to specific areas (asopposed to general reference to optimal habitat composition). This approach emphasizes the conservation of culturalelements as well as ecological values. Each one of the two approaches to land planning and management has its ownindispensable value in applying wise management to the intricate natural systems. What is needed today is a transdisci-plinary cooperation of ecologists and landscape planners for the progression of ecological planning as a new, hybridrealm combining ecology and planning, nature and culture, holistic and analytic approaches.
Effects of inter- and intra-slope contrasts at ‘Evolution Canyon’, Israel,on a gall aphid and its natural enemies
A. Eitam, T. Pavlícek, L. Blaustein and E. Nevo
We use the aphid Aploneura lentisci as a model to test the hypothesis that abiotic stress is the dominant factor shapingecological contrasts between and within the slopes of ‘Evolution Canyon’, Mt. Carmel, Israel. Aploneura lentisci formsgalls on Pistacia lentiscus, one of only a few woody plant species common to both slopes. Gall densities were nearly ten-fold greater on the hotter, drier south-facing slope (SFS), but there were no statistically significant intra-slope differencesin gall abundance. The large inter-slope difference is consistent with the hypothesis that there is an indirect effect of abioticstress on A. lentisci, i.e., that P. lentiscus is less resistant to the aphid on the more stressful SFS. However, the most likelyexplanation is the greater abundance on the SFS of both primary and secondary hosts (P. lentiscus and roots of grasses,respectively). No statistically significant inter- or intra-slope differences in gall size or in abundance of parasitoids andpredators were observed, except for a decrease in the abundance of parasitoids with elevation on the SFS. The latter isconsistent with a direct negative effect of abiotic stress, which is greatest on the higher elevations of this slope.
Keywords: Alophia combustella, elevation, Fordini, Hordeum spontaneum, Monoctonia pistaciaecola, Pa-lumbina guerinii, plant apparency, wild barley
V.P. Papanastasis, S. Kyriakakis and G. Kazakis
There is a growing concern about the negative impact of livestock overgrazing on biodiversity of ecosystems in the Medi-terranean region, particularly in the mountain areas where several rare or endemic species are usually found. This concernis aggravated by the fact that overgrazing is very often associated with wildfires set by the shepherds themselves to sup-press undesirable to animals vegetation. In this paper, the relation between plant diversity and overgrazing with or withoutburning was investigated on Psilorites mountain of Crete at an average altitude of 1200 m. The study included grasslandsand phryganic ecosystems that are communally grazed by sheep and goats for 6-7 months during the summer period at anaverage stocking rate of 4.6 sheep/ha/year which is at least four times higher than grazing capacity. In addition, they arefrequently burned by the shepherds. In May 1996, 30 representative sites were selected, subjected to only overgrazing or tocombined overgrazing and burning. In each site, 0.50 x 0.50 m each, were taken where the number of species and theirabundance were measured. Subsequently, the species richness and equitability were calculated. In the phryganic ecosy-stems, it was found that the overgrazed sites produced slightly higher species richness compared with the protected sites(20 vs. 18 species per quadrat respectively) as well as equitability (0.46 vs. 0.45 respectively) but this increase was notstatistically significant. On the contrary, overgrazed and burned sites had significantly lower values of species richness andevenness compared with the sites subjected to only overgrazing (17 vs. 20 species per quadrat and 0.43 vs. 0.46 index ofequitability). An opposite effect of overgrazing was found in grasslands where overgrazed sites produced significantlylower species richness compared to the protected ones (13 vs. 15 species per quadrat) as well as equitability (0.39 vs. 0.42).These results suggest that overgrazing had a negative impact on plant diversity of grasslands but in phryganic ecosystemsovergrazing was negative only when combined with burning.
Keywords: Crete, endemic species, grasslands, life forms, phryganic ecosystems, Psilorites mountain
G. Garfì, M. Barbero, L. Tessier
Zelkova sicula Di Pasquale, Garfì et Quézel is a relic of the European Tertiary flora, presently found in sub-optimalenvironmental conditions.In order to elucidate the processes underlying the adaptive ability and the persistence of this species within the currenthabitat, architecture and growth patterns were investigated through observations and records of growth features. Stemanalysis on 13 samples was performed to define height growth dynamics and growth form. Branching structure was alsostudied, based on some quantitative parameters of the first-order axes (e.g.: total number, age, length, etc.). Resultssuggest that the architectural model of Z. sicula can be referred to Troll’s model. The great reiterative ability, which is atypical feature of this model, allows Zelkova to rapidly repair crown damage or stem decline following traumatic eventssuch as severe water stress. Analysis of the height growth curve showed that under the present-day environmental con-ditions Z. sicula exhibits the growth form of a small shrub. This habit most likely reflects phenotypic plasticity resultingfrom an adaptive strategy to a high-stress environment, as it is often found in plants living out of optimal range limits.Anomalies in the morphometric structure of the crown were also observed. This probably depends on the repeatedrelease of reiterative shoots following the loss of apical meristems, in response to even moderate water stress or persi-stent browsing disturbances.The different reiterative responses of Z. sicula surely reveal a notable adjustment ability, which has a basic significancein the point of view of its conservation in the present habitat. On the other hand, frequent recurrence of reiterationimplies high energetic costs, negatively affecting global growth and/or phenological phases such as flowering.
Keywords: branching structure, grazing, growth form, reiteration, stem analysis, water stress.
Th. Karyotis, A. Panagopoulos, D. Pateras, A. Panoras, N. Danalatos, C. Angelakis and C. Kosmas
The Plain of Thessaly, central Greece, is characterised by the presence of a large number of different alluvial soils, many ofwhich are highly productive. Irrigated land has increased considerably over the last three decades and this was succededdue to mechanisation, implementation of new productive varieties and the application of fertilisers succeeded this. Intensi-fication of agriculture however, in conjunction with the lack of a rational water resources management scheme, led topronounced groundwater overexploitation evidenced by head decline that recently has reached alarming levels. In parallel,nitrogen fertiliser’s use has increased and caused groundwater quality deterioration and also eutrophication in the RiverPinios estuary. An Action Plan aiming to ground and surface water protection from nitrates pollution has been elaborated inorder to meet the Greek particularities. Under this Plan a reduction of at least 15-20% nitrogen fertiliser application wassuggested. This decrease may be achieved implemented through a set of measures amongst which are the nitrogen’s effec-tiveness increase, the introduction of new irrigation techniques, the cultivation of the suitable crop varieties, as well as bymeans of financial incentives.
Keywords: nitrates, vulnerable zone, soil classes, pollution, groundwater