Their Effect on the Herbaceous Plants in a Mediterranean Maquis

Plant Ecol (2009) 205:165–177 DOI 10.1007/s11258-009-9606-3

Woody species as landscape modulators: their effect on the herbaceous plants in a Mediterranean maquis

Har’el Agra Æ Gidi Ne’eman

Received: 5 July 2008 / Accepted: 14 April 2009 / Published online: 7 May 2009 Ó Springer Science+Business Media B.V. 2009

Abstract ‘‘Landscape modulators’’ are ecosystem species richness in Mediterranean ecosystems, which engineers that have an impact on community struc- is a main goal of global nature conservation policy. ture by creating patches in the landscape mosaic. Our aim was to study the effect of evergreen-trees, as Keywords Evergreen-trees Á Grazing Á landscape modulators, on herbaceous plants in a Israel Á Landscape mosaic Á Patch-type Á Mediterranean maquis system in northern Israel. We Plant functional types Á Species richness examined the effects of canopy removal and cattle grazing on species richness, plant functional types, and rare plant species in two patch-types: (1) woody—under tree canopy (or the location of a removed canopy); (2) herbaceous—in open areas Introduction with no tree canopy. Patch-type and tree removal affected species richness and plant functional types. Dense multi-stemmed, evergreen, sclerophyllous low The extreme negative effect of the woody patch-type trees are the dominant life forms constructing the on species richness disappeared soon after the Mediterranean ‘maquis’ vegetation in Mediterranean removal of the landscape modulator canopy. We type ecosystems worldwide (di Castri et al. 1981; conclude that the dominant effect of the evergreen Archibold 1995). Natural selection under Mediterra- woody landscape modulators can be regulated by nean climate shaped the Mediterranean vegetation, canopy removal and grazing for maintaining patch- but its evolution has also been affected by intensive type and landscape diversities, and consequent high human activities since prehistoric times (Naveh 1990). The first evidence of hominoid control of fire in the Middle East is found at the Gesher H. Agra Benot Ya’akov (northern Israel) prehistoric site Department of Evolutionary and Environmental Biology, 790,000 years ago (Goren-Inbar et al. 2004); this is Faculty of Science and Science Education, a milestone, marking the beginning of large-scale University of Haifa, 31905 Haifa, Israel e-mail: [email protected] human impacts on nature. Later (ca. 10,000 years ago), after the beginning of early agriculture, grazing, G. Ne’eman (&) and tree clearing significantly increased man’s effect Department of Science Education – Biology, on nature (Naveh 1990). In historical periods when Faculty of Science and Science Education, University of Haifa-Oranim, 36006 Tivon, Israel the agricultural population in Israel was dense, the e-mail: [email protected] proportion of agricultural areas was high, while that 123 166 Plant Ecol (2009) 205:165–177 covered by natural vegetation was low; but as in the environment by changing the physical structure of western Mediterranean when wars and epidemics other living or non-living materials in the system decreased human population, the natural maquis (Jones et al. 1994). ‘‘Landscape modulators’’ are recovered over wider areas (Barbero et al. 1990). ‘‘ecosystem engineers’’ that have an impact on Nowadays, dense and well-developed maquis covers community structure by creating patches in the the upper Galilee in northern Israel. Until 1948, landscape mosaic, in which the availability of traditional agriculture intensively exploited this area, resources and distribution of organisms differ from similar to the current situation across the Lebanese that of the background area (Shachak et al. 2008). border. However, the semi-humid Mediterranean Patchiness of the landscape created by landscape climate enhanced natural regeneration after the modulators induces ecological processes that affect severe disturbance. From 1964 to 1992, the tree- biodiversity in general and species diversity in cover increased from 2% to 41%, while during the particular (Shachak et al. 2008). Trees are autogenic same period the herbaceous vegetation cover landscape modulators that create landscape patchi- decreased from 56% to 24% (Carmel and Kadmon ness by their own presence and physical structure, 1999). which create local changes in the availability of some The Mediterranean basin is a global biodiversity main resources such as light, water, and soil organic hotspot; the number of endemic plant species in this matter content, thereby affecting the presence of area is ca. 13,000, the third in richness after the other species (Shachak et al. 2008). tropical South American Andes and the Sundaland in The model of Shachak et al. (2008) predicts that southeast Asia (Myers et al. 2000). In the Mediter- woody-landscape modulators affect local species ranean basin, Israel has high species richness and richness by filtering from the regional species pool endemism rate (Shmida 1984;Me´dail and Que´zel to the local assemblage. It predicts that traditional 1999). Heliophilous herbaceous plant species account human activities (tree cutting and grazing) affect for most plant diversity in Israel (Naveh and Whit- local species richness mainly through their effect on taker 1980; Sternberg et al. 2000); therefore, the the landscape modulators (Shachak et al. 2008). The natural regeneration and the expansion of the woody overall effect of the woody vegetation as landscape maquis (Carmel and Kadmon 1999) should have a modulators on the herbaceous vegetation depends on negative effect on plant species diversity. the balance between their positive and their negative Furthermore, the natural regeneration process has effects (Jones et al. 1997), which depends on already led to severe decrease in flowering and environmental conditions. A positive effect is subsequent population size of some rare species such expected in arid areas, where woody landscape as Paeonia mascula (Ne’eman 2003), Lilium candi- modulators improve seed trapping, nutrient, moisture, dum (Oz and Dafni 1991), and probably other species and protection from browsing or trampling (Flores that cannot reproduce in heavy or semi-shaded and Jurado 2003); a negative effect is expected in the habitats. Loss of species and decrease in species more humid areas of the Mediterranean climatic zone diversity may affect stability and threaten the exis- in Israel as a result of their heavy shade (Holzapfel tence and the functioning of ecosystems (Balvanera et al. 2006; Shachak et al. 2008). et al. 2006). This emphasizes the importance of During the last several decades, woody vegetation predicting the impact of natural factors and manage- in the Mediterranean basin has been increasing at the ment regimes on biodiversity. expense of herbaceous vegetation and decrease in While the effect of the environment on organisms biodiversity (e.g., Verdu´ et al. 2000). As a result, has received much scientific attention, research on several studies documented a positive effect of organisms’ impact on their environment has broad- trimming, partial removal of the woody vegetation, ened only recently. Organisms that modify habitats or grazing on herbaceous plant diversity in Mediter- by changing the availability of resources for other ranean maquis on a relatively large scale (Hadar et al. organisms are ‘‘Ecosystem engineers’’. Autogenic 1999; Barbarl et al. 2001; Noy-Meir and Kaplan engineers (e.g., corals or trees) change their environ- 2002). ment via their own physical structure, while allogenic The current research examines, by removal and engineers (e.g., beavers or moles) modify their mild cattle grazing, the effect of the woody-landscape 123 Plant Ecol (2009) 205:165–177 167 modulator canopy on herbaceous plant species rich- 95%, of which 60% were trees, 15% shrubs, 10% ness, plant functional types, and some Israeli rare dwarf-shrubs, and 10% herbaceous plants. herbaceous plant species in two patch-types: (1) woody—under tree canopy (or the location of a Experimental design removed canopy); (2) herbaceous—in open areas with no tree canopy. Patch-type and tree removal Five blocks of 4,000 m2 were marked and divided affected species richness and plant functional types. into four plots of 1,000 m2. In November–December Our specific hypotheses were: (A) herbaceous species 2005, we randomly subjected each plot in each block richness will be lower in the woody than in the to one of the following treatments: (1) No tree herbaceous patches (Holzapfel et al. 2006); (B) removal and no grazing (NRNG), (2) no tree removal landscape modulators’ canopy removal will increase with grazing and (NRG), (3) tree removal with no herbaceous species richness (Hadar et al. 1999) grazing (RNG), and (4) tree removal with grazing mainly in the woody patches; (C) cattle grazing will (RG). In all R plots, we removed all the woody plants increase herbaceous species richness (Hadar et al. to ground level, and all the NG plots were wire- 1999; Noy-Meir and Kaplan 2002); and (D) land- fenced to exclude cattle that regularly graze at scape modulators’ canopy removal and cattle grazing moderate intensity (ca. 30 cows per km-2) in summer will have differential effects on the presence of plant in the area. functional types and individual plant species according to their specific traits (Hadar et al. 1999;Dıáz et al. 2007). Sampling A deep and comprehensive understanding of the processes by which landscape modulators affect In each plot, we located two patch-types: (1) Woody biodiversity and of the effect of the traditional plant patch—covered with an evergreen tree (Q. callipri- management treatments (tree removal and grazing) nos) canopy, or one that was covered with such a tree on these processes will assist in planning manage- prior the tree removal treatment. (2) Herbaceous ment regimes to increase biodiversity according to patch—not covered with any woody plant prior to the global nature conservation policy. tree removal, but with herbaceous vegetation in winter and spring. The patch-type per plot, which consisted of all patches of the same type (woody or herbaceous) in each plot, was our independent Materials and methods sampling unit. For each patch-type per plot, we randomly sampled 0.04 m2 quadrats, in which we The study site identified all plant species following Zohary and Feinbrun-Dothan (1966–1986), Feibrun-Dothan and The research site is located on Mt. Tziv’on (35.25°E, Danin (1991) and Danin (1998). 33.15°N), Upper Galilee, Israel; at an average altitude One of the main issues in the analysis of species of 850 m. The bedrock is limestone, the soil is terra- richness is estimating the real species richness out of rosa and average annual precipitation is 900 mm. The the number of species recorded in the samples while vegetation consists of Quercus calliprinos (60% of taking sampling effort into account (Gotelli and the trees) and Pistacia palaestina association (Zohary Colwell 2001). In a preliminary study (spring 2006), 1973), accompanied by Quercus boissieri and other we analyzed species accumulation curves of 30 deciduous tree species mainly of the Rosaceae, which sampling quadrats of 0.04 m2 for each patch-type are frequent in the Quercus–Pistacia association in per plot using the ‘EstimateS’ computer software the higher mountains (Waisel et al. 1978). The (Colwell 2005). In consequence, we fixed our sam- vegetation forms dense maquis, with patches of pling effort at 30 quadrats of 0.04 m2 for the herbaceous plants, which are green in winter and herbaceous patch-type per plot and 50 quadrats of spring but dry in summer, separating the woody 0.04 m2 for the woody patch-type per plot. All the patches. At the beginning of the experiment (October results presented here are from the second sampling 2005), the average total vegetation cover was ca. season (spring 2007). 123 168 Plant Ecol (2009) 205:165–177

Estimated herbaceous plant species richness Plant functional types

We determined and estimated the herbaceous plant Dividing plants into similar functional groups by their species richness for each patch-type per plot traits provides an additional way of estimating (N = 40) by analyzing the species accumulation biodiversity (Box 1996; Lavorel et al. 1977). The curves using the ‘Species Richness Estimators’ tool classification of species into plant functional types is of the EstimateS computer software (Colwell 2005). based on species biological traits (e.g., morphology, When sampling homogeneous habitats, non-paramet- physiology, reproduction, and phenology). For our ric methods give more accurate results than others classification into plant functional types, we used a (Brose et al. 2003). Therefore, we determined the variation of Raunkiær’s (1934) traditional division of estimated herbaceous plant species richness as the plant life forms: tree saplings, climbers, dwarf- asymptote of the average curve between the two most shrubs, annual herbs, and perennial herbs. In addition, commonly used non-parametric methods: Chao and we analyzed annual Gramineae and perennial Grami- Jackknife. Using three-way ANOVA, we analyzed neae. We excluded shrubs from the analyses because the effects of patch-type and the two treatments of their low frequency in the samples. We used (removal and grazing) on the estimated herbaceous the percentage of occurrences of each of the plant plant species richness and their interaction. Estimated functional types in each patch-type per plot (N = 40) herbaceous plant species richness data showed nor- as the dependent variable for the analyses. mal distribution (Shapiro-Wilk, P \ 0.05) for all To explore the responses of the various plant eight patch-types per plot. Species richness depends functional types relative to the three factors (patch- on the size of the area, so the initial tree-cover in each type, tree removal, and grazing), we used canonic plot may directly affect the estimated herbaceous ordination (CANOCO: ter Braak and Smilauer 1998) plant species richness. To separate this effect from for the data from all patch-types per plot. This that of our independent variables, we used the initial analysis presents both the independent and dependent tree-cover as covariate in the ANOVA model. Since variables on a single ordination plot, whose axes the ANOVA results showed a significant effect of represent two independent linear combinations that pre-treatment tree-cover on the estimated herbaceous optimally separate the functional types being tested plant species richness, we checked the correlation (ter Braak and Smilauer 1998). We used the RDA- (Pearson) between the estimated herbaceous plant type canonic ordination, which is more suitable for species richness and the initial tree-cover for each of the analysis of categorical factors. We also analyzed all eight patch-types per plot. For patch-types per the effects of the four treatments on each of the plot, where we detected a significant correlation, we functional groups separately. Since the data had non- also applied a linear regression analysis. normal distribution, even after conventional transfor- mations, and plots within each block are not independent, we used the Friedman non-parametric Mean herbaceous species richness per quadrate test for repeated measures; this test minimizes the effect of the differences among the blocks. In addition to analysis of the estimated herbaceous plant species richness at the plot scale (1,000 m2), we Rare species analyzed the mean number of herbaceous species at the smallest scale of 0.04 m2 quadrate in each patch- We analyzed the effects of patch-type and treatments type per plot (N = 40). The mean herbaceous species on rare herbaceous plant species in Israel [following richness per quadrate data showed normal distribu- Feibrun-Dothan and Danin (1991)], which were pres- tion (Shapiro-Wilk, P \ 0.05) for all eight patch- ent in more than ten samples. The rare species included types per plot. As for the estimated herbaceous plant three annual plants: Alyssum simplex, Arabis verna species richness, whenever we found significant (Cruciferae), Galium divaricatum (Rubiaceae), and correlation between the mean herbaceous species three perennial herbaceous plants: Asperula libanoti- richness per quadrate and the initial tree-cover, we ca (Rubiaceae), Crepis reuteriana (Compositae), and also applied a linear regression analysis. Brachypodium pinnatum (Gramineae). 123 Plant Ecol (2009) 205:165–177 169

We used the percentage of occurrences for each of Table 1 Three-way ANOVA testing the effects of patch-type, the species in each patch-type per plot (N = 40) as tree removal, grazing and their interaction on the estimated the dependent variable. Data analyses were similar to species richness of herbaceous plants at the plot scale, using pre-treatment tree-cover as covariate those of the plant functional types. Source df Mean FP square

Results Corrected model 8 4412.2 9.071 <0.001 Intercept 1 16857.5 34.655 <0.001 Vegetation cover Tree-cover (covariate) 1 2500.9 5.141 0.030 Grazing 1 739.5 1.520 0.227 In summer 2006, one growing season after the Removal 1 10662.8 21.920 <0.001 treatments were applied, we measured the cover of Patch-type 1 9241.6 18.999 \0.001 the vegetation along the two diagonals in each plot Grazing 9 removal 1 151.5 0.312 0.581 (ca. 90 m). In the intact (NR) plots, the average tree- Grazing 9 patch-type 1 0.400 0.001 0.977 cover was 64%, shrub cover 17%, dwarf-shrub cover Removal 9 patch-type 1 12180.1 25.040 <0.001 10%, and 9% of herbaceous vegetation. In the Grazing 9 removal 1 44.1 0.091 0.765 removal (R) plots, tree-cover was ﬁrst estimated in 9 patch-type 2005, prior tree removal, and in summer 2006, we Error 31 486.4 measured the regenerating canopies. In 2006, the Total 40 average tree-cover was 16%, shrub cover 8%, dwarf- Adjusted R squared = 0.623 shrub 10%, and 66% of herbaceous vegetation.

Estimated herbaceous plant species richness that removal affected the estimated herbaceous plant species richness only in the woody patch (Table 1; The lowest estimated herbaceous plant species rich- Fig. 1). The pre-treatment tree-cover in the plots (as a ness was in the woody patch-type in the NR plots, covariate) had a significant effect on the estimated with or without grazing (Fig. 1). Patch-type, removal herbaceous plant species richness (Table 1). Pre- and grazing, and their interaction, significantly treatment tree-cover was also negatively and signif- affected the estimated herbaceous plant species icantly correlated (Spearman) with the estimated richness with high percentage of the explained herbaceous plant species richness in the woody patch variance (Table 1). The significant interaction in the NRNG plots (r =-0.881, P = 0.049), and in between the patch-type and the removal indicated the herbaceous patch in the RG plots (r =-0.901, P = 0.037). In contrast, we found a positive (Spear- man) correlation between the estimated herbaceous

120 Herbaceous plant species richness and the initial tree-cover in the Woody woody patch in the RNG plots (r = 0.898, 100 P = 0.038). The signiﬁcant linear regression 80 (Fig. 2) allows prediction of the estimated herba- 60 ES ceous plant species richness in the patch-types per

40 plot from the pre-treatment tree-cover in any speciﬁc plot. 20

0 No removal Removal No removal Removal Mean herbaceous species richness per quadrate

No grazing Grazing Mean herbaceous species richness per quadrate was Fig. 1 Average (and SE) estimated herbaceous species rich- higher in the herbaceous patch than in the woody ness (ES) in woody and in herbaceous patches under removal, no removal, grazing or no grazing treatments, a year and a half patch, and it was relatively higher under tree-removal after treatment application. N = 5 for each column and lower under grazing. The ANOVA for the effects 123 170 Plant Ecol (2009) 205:165–177

140 12 Herbaceous GRRG, herbaceous 120 Woody y =273.000 - 2.861x 10 2 100 R = 0.748, p=0.037 8 80 XRRNG, woody woody y =32.523 + 0.884x 6 ES

60 R2 = 0.742, p=0.038 MSQ 4 40 XUNRNG, woody herbaceous y =30.822 - 0.288x 2 20 R2 = 0.701, p=0.049 0 0 020406080100 No removal Removal No removal Removal Tree cover (%) No grazing grazing Fig. 2 The relation between the estimated herbaceous species Fig. 3 Average (and SE) of the mean herbaceous species richness (ES) of each patch type per plot and the pre-treatment richness per quadrate (MSQ) in woody and in herbaceous percentage of tree-cover in the plot. Significant equations of the patches under removal, no removal, grazing and no grazing linear regressions are presented for the herbaceous and woody treatments in the second growing season after treatment patch-types under the various treatments: no tree removal with application. N = 5 for each column no grazing (NRNG), no tree removal with grazing (NRG), and removal with grazing (RG) mean herbaceous species richness per quadrate of patch-type, tree removal, grazing, and of their (Table 2), and it was negatively and significantly interaction, and on the mean herbaceous species correlated (Spearman) with the mean herbaceous richness per quadrate was significant, and the species richness per quadrate in the woody patch in percentage of explained variance was high (Table 2). the NRNG plots (r =-0.974, P \ 0.005) and in the The interaction was significant because the main NRG plots (r =-0.927, P = 0.023). Pre-treatment effect of the tree removal was in the woody patch, tree-cover was also correlated with the mean herba- while grazing had an effect mainly in the R plots ceous species richness per quadrate in the herbaceous (Table 2; Fig. 3). The pre-treatment tree-cover in the patch in the NRNG plots (r =-0.940, P = 0.018) plots (as covariate) had a significant effect on the and in the RG plots (r =-0.962, P = 0.009). The significant linear regression (Fig. 4) allows prediction of the mean herbaceous species richness per quadrate Table 2 Three-way ANOVA testing the effects of Patch-type, tree removal, grazing and their interaction on the species richness of herbaceous plants per quadrate, using pre-treatment 12 RG,GR herbaceous herbaceous tree-cover as covariate y = 15.970 - 0.122x 10 R2 = 0.900, p=0.009 Source df Mean square F P XU herbaceous 8 NRNG, herbaceous y = 13.471 - 0.102x Corrected model 8 54.867 71.184 \0.001 R2 = 0.844, 0.018 6 Intercept 1 91.764 119.055 <0.001 NRNG,XU woody woody MSQ y = 1.622 - 0.019x Tree-cover (covariate) 1 13.266 17.212 \0.001 2 4 R = 0.931, p=0.005 Grazing 1 2.505 3.250 0.081 NRG,GU woody woody Removal 1 40.143 52.081 \0.001 2 y = 1.195 - 0.011x R2 = 0.813, p=0.023 Patch-type 1 363.328 471.379 \0.001 0 0 20406080100 Grazing 9 removal 1 4.973 6.451 0.016 Tree cover (%) Grazing 9 patch-type 1 0.216 0.280 0.600 Removal 9 patch-type 1 5.237 6.794 0.014 Fig. 4 The relation between the mean herbaceous species Grazing 9 removal 1 0.010 0.014 0.908 richness per quadrate (MSQ) of each patch-type per plot and 9 patch-type the pre-treatment percentage of tree-cover in the plot. Significant equations of linear regressions are presented for Error 31 0.771 the herbaceous and woody patch-types under the various Total 40 treatments: no tree removal with no grazing (NRNG), no Adjusted R squared = 0.935 removal with grazing, (NRG), tree removal with no grazing (RNG), and removal with grazing (RG) 123 Plant Ecol (2009) 205:165–177 171 0 in all patch types per plot according to the initial pre- . 1 treatment tree-cover in any specific plot. Grazing

Plant functional types

Removal Tree saplings The canonical ordination analysis (RDA) for the data Annual herbs of all patch-types per plot (Fig. 5) exploring the Per. Gramineae distribution of the various plant functional types Ann. Gramineae Dwarf shrubs among the woody or herbaceous patch-type and their Perennial herbs No removal responses to the removal or grazing treatments was Climbing plants significant (F = 35.600, P = 0.002). The canonical function of the first (horizontal) ordination axis 0 explained 95.4%, and the functions of the two axes . No grazing 1 - together explained 99.7% of the variance in the -1.0 1.0 relations between species and environment. The first axis was mostly affected by the patch-type Fig. 6 Location of the plant functional types: annual Gram- inaeae (Ann. Gramineae), perrenial Graminaeae (Per. Grami- (r = 0.865) and thus the patch-types are located close neae), annual herbs, perennial herbs, climbing plants, dwarf- to it. Removal was the main component of the second shrubs and tree saplings, growing in the woody patch only, function (r = 0.629), and thus it is located close to marked as vectors on the canonic ordination plane (RDA), the vertical axis. Grazing is located next to axes relative to the location of the treatments: grazing, no grazing, removal and no removal (marked as triangles) origin and close to the second axis meaning it had only a small effect, and its correlation with the second axis is 0.121 (Fig. 5). The occurrence of the were strongly related to the woody patch, while tree- four functional types of herbaceous plants was mostly saplings were associated with the woody patch under related to the herbaceous patch. Dwarf-shrubs the no-removal treatment (Fig. 5). showed a similar but much weaker trend. Climbers The canonic ordination (RDA) using the plant functional types dataset only for the herbaceous patch was not significant, meaning the treatments did not 0 . have a significant effect on the occurrence of plant 1 No removal functional types in the herbaceous patch. In contrast, the same analysis for the plant functional types Herbaceous dataset of only the woody patch (Fig. 6) was highly Tree saplings Grazing significant (F = 30.638, P = 0.002). The canonical Ann. Gramineae Dwarf shrubs function of the first (horizontal) ordination axis Per. Gramineae explained 99.0% of the variance in the dataset and Perennial herbs the functions of the two axes together explained Woody 100.0% of the variance. The main component of the No grazing Annual herbs first axis was removal (r = 0.934), while grazing was Climbing plants the main component of the second function (r = 0.629) (Fig. 6). In the woody patch, the occur- Removal rence of the annual herbs and grasses was strongly 0 . 1 - and positively affected by tree-removal treatment, -1.0 1.0 while that of perennial herbs and to less extent, Fig. 5 Location of the plant functional types: annual Gram- dwarf-shrubs were also affected by the NG treatment. inaeae (Ann. Gramineae), perrenial Graminaeae(Per. Grami- The occurrence of climbers in the woody patch was neae), annual herbs, perennial herbs, climbing plants, dwarf- associated with the NG treatment, while tree saplings shrubs, and tree saplings, marked as vectors on the canonic occurred mainly in the NR plots (Fig. 6). ordination plane (RDA), relative to the location of the patch- types: woody and herbaceous, and the treatments: grazing, In the woody patch, the occurrence of all herba- removal (marked as triangles) ceous plant functional types and dwarf-shrubs was 123 172 Plant Ecol (2009) 205:165–177

Fig. 7 The average (and 100 SE) occurrence percentage (A) of the plant functional NRNG RNG NRG RG types: Annual herbs, 80 perennial herbs, tree saplings, dwarf-shrubs, climbing plants, annual 60 graminaeae and perennial gramineae, in the various 40 treatment plots: no removal, no grazing (NRGR), Occurrence (%) removal and no grazing 20 (RNG), grazing, no removal (NRG), grazing and removal (RG), in the woody 0 patch-type (a) and in the herbaceous patch-type (b). 100 N = 5 for each column (B)

40 Occurrence (%)

0 Annual Perennial Tree Dwarf Climbing Annual Perennial herbs herbs saplings shrubs plants Gramineae Gramineae 0 higher in RG and RNG plots than in the NRG and . No grazing 1 NRNG plots (Fig. 7). In woody patch, the effect of the treatments on the occurrence of annual herbs was No removal 2 signiﬁcant (Friedman, v3 = 13.560, P = 0.004), as it 2 was on perennial herbs (v3 = 9.612, P = 0.022) and Woody 2 annual grasses (v3 = 14.739, P = 0.002). In contrast, A. libanotica A. simplex in the herbaceous patch, the mean occurrence of C. reuteriana perennial grasses was higher in the RNG plots than in G. divaricatum the RG plots (Fig. 7), but this difference was not A. verna signiﬁcant (Friedman, P [ 0.05); likewise, the effects B. pinnatum Herbaceous of the treatments on all other plant functional types in Removal the herbaceous patch. 0 . Grazing 1 Rare species - -1.0 1.0

The distribution of the rare species (in Israel) was Fig. 8 Location of the rare plant species (in Israel): Alys- signiﬁcantly (F = 2,272, P = 0.004) affected by the sum simplex, Arabis verna, Asperula libanotica, Brachypodi- woody or herbaceous patch-types and by the removal um pinnatum, Crepis reuteriana, and Galium divaricatum or grazing treatments tested by (RDA) canonical (marked as vectors) on the canonic ordination plane (RDA), relative to the location of the patch-types: woody and ordination analysis for the full dataset of all patch- herbaceous, and the location of the treatments: grazing, no types per plot (Fig. 8). The canonical function of the grazing, removal and no removal (marked as triangles) 123 Plant Ecol (2009) 205:165–177 173

first (horizontal) ordination axis explained 79.5% of NRG plots. C. reuteriana was the only rare species the variance, and the two axes together explained present in all treatments’ plots, more in RNG than in 97.3%. The main components of the first axis, which NRNG plots. G. divaricatum was totally absent from were located close to it, were the woody or herba- the woody patch. ceous patch-types (r = 0.611), while removal was In the herbaceous patch, treatments significantly the main component of the second axis (r = 0.295) affected the occurrence of C. reuteriana (Friedman, 2 (Fig. 8). A. libanotica was the only rare species that v3 = 8.022, P = 0.046), which was present mainly in occurred more in the woody patch, in the no-removal, NRG and no NRNG plots, less in RNG and still less no-grazing plots (Fig. 8). The other rare species in RG plots (Fig. 9). We found no significant effects occurred more in the herbaceous patch: A. verna and for the other rare species (Friedman, P [ 0.05), but B. pinnatum mainly in the tree removal and grazed the following trends could be observed (Fig. 9): plots, and A. simplex and C. reuteriana mainly in the A. simplex was present mainly in NRNG plots and no-removal and no-grazing plots. less in RNG and RG plots. A. verna was present In the woody patch, none of the four treatments mainly in RG plots but less in NRNG and NRG plots. had a significant effect (Friedman, P [ 0.05) on any B. pinnatum was present mainly in RG plots, less in of the six rare species, but the following tendencies NRG and NRNG plots, and not at all in RNG plots. could be observed (Fig. 9). A. simplex was present A. libanotica was present mainly in NRNG plots and only in NRNG plots, A. verna only in RG plots, and less in RNG, RG and NRG plots. G. divaricatum, B. pinnatum only in RG and RNG plots. The which was absent from the woody patch, was present occurrence of A. libanotica was lower in NRNG in the herbaceous patch mainly in NRNG, RNG and and RG plots than in RNG plots and absent from NRG, and less in RG plots.

Fig. 9 Average (and SE) 20 percentage occurrence of 18 (A) the rare plant species (in 16 Israel): Alyssum simplex, NRNG RNG NRG RG Arabis verna, 14 Asperula libanotica, 12 Brachypodium pinnatum, Crepis reuteriana, and 10 Galium divaricatum, in the 8

various treatment plots: no Occurrence (%) 6 removal, no grazing 4 (NRGR), removal and no grazing (RNG), grazing, no 2 removal (NRG), grazing 0 and removal (RG), in the woody patch-type (a) and in 20 the herbaceous patch-type 18 (B) (b). N = 5 for each column 16 14 12 10 8

Occurrence (%) 6 4 2 0 Alyssum Arabis verna Galium Asperula Crepis Brachypodium simplex divaricatum libanotica reuteriana pinnatum 123 174 Plant Ecol (2009) 205:165–177

Discussion or indirectly prevented the infiltration of herbaceous species from the regional pool to enter the woody patch Species richness (Shachak et al. 2008). In the small quadrate scale, patch-type was the main Our results show for the first time that an extremely factor that affected species richness (Table 2), and not short time (a year and a half) was enough for the its interaction with tree removal, as was in the case for herbaceous plants to populate the removed wood species richness at the plot scale. This was probably patches to a similar degree of species richness as in the because one year after tree removal the woody patches herbaceous patches. As predicted by our hypotheses (A had still a low herbaceous plant density that kept species and B), species richness was higher in the herbaceous richness lower than in the herbaceous patches at the than in the woody patch-type, and the removal of small scale. The interaction between grazing and tree landscape modulators’ tree canopy significantly removal also significantly affected species richness and affected species richness. However, contrary our the quadrate scale but not at the plot scale, because the hypothesis (C), under the moderate grazing intensity negative effect of grazing was only in the tree removal which is typical to maquis areas in the upper Galilee, plots (Fig. 4). This was probably because the cows we found no effect of grazing on the estimated preferred to feed on the herbaceous vegetation and herbaceous plant species richness (Fig. 1; Table 1). young growing fresh foliage of the regenerating trees The interaction between patch-type and tree removal rather than on the mature foliage of the trees in the no was the main factor affecting species richness because tree removal plots (Perevolotsky and Pollak 2001). tree-removal affected species richness only in the Species richness at the quadrate scale, unlike at the plot woody patch, and patch-type affected species richness scale, was lower in the tree removal with grazing than in only in the unremoved plots (Table 1; Fig. 1). Follow- tree removal with no grazing plots (Figs. 1, 3). This was ing tree-removal, numerous new species infiltrated the probably the result of the activity of wild boars, which former woody patches and dramatically increased the focused on the herbaceous patches; wild boars turned estimated herbaceous plant species richness. A similar the soil upside down, thereby decreased the density of increase in herbaceous species richness was reported the herbaceous plants. This thinning negatively earlier (Hadar et al. 1999; Barbarl et al. 2001; Noy- affected the number of species in the small quadrate Meir and Kaplan 2002). scale but not in the large plot scale. The results demonstrate the crucial role of landscape modulator canopy in modulation of landscape by Plant functional types the woody plant. Pre-treatment tree-cover was a major factor affecting species richness at the plot scale The differential responses of plant functional types to (1,000 m2) (Table 1), even in the herbaceous patch in patch-type and treatments confirmed our hypothesis grazed and tree removal plots (GR), species richness (D). The occurrence of all the herbaceous functional was negatively related to the pre-treatment tree-cover types was lower in the woody than in the herbaceous (Fig. 2). Pre-treatment tree-cover also negative patch-type, which is in concert with earlier results from affected species richness at the small quadrate scale similar Mediterranean maquis (Holzapfel et al. 2006). (Fig. 4; Table 2). This was because as the tree-cover The woody patch also had a negative effect on dwarf- percentage increased, the total area of the herbaceous shrubs; as expected, the tree saplings and climbers were patches decreases, and consequently, probably due to found mostly in the woody patch (Fig. 5). The occur- the relations between size of the sampled area and rence of herbaceous plants was much higher in the species richness. Due to the same reason, species woody patches in the tree-removal plots than in the NR richness in the woody patches in the no grazing with plots (Fig. 7), because landscape modulator canopies tree removal plots was positively related to the pre- directly (physical barrier) or indirectly (sunlight filter- treatment tree-cover (Fig. 2; Table 1). The pre-treat- ing etc.) prevented entering of new species and their ment tree-cover negatively affected species richness at establishment in the woody patch. Grazing negatively the plot and the square scales in the woody patches in affected the occurrence of annual herbs in the woody the no removal no grazing plots because of the filtering patch only in the tree removal plots, where grazing had role of landscape modulator canopies’, which directly a higher impact (Fig 7). We have neither good 123 Plant Ecol (2009) 205:165–177 175 explanation why tree removal slightly affected the that the effect of the landscape modulators on the occurrence of the perennial herbs and grasses in the herbaceous vegetation in this system is mediated herbaceous patches (Fig. 7), nor do we have an mainly by the role of the tree canopy as a filter of explanation for the positive effect of grazing on the dispersal units and as a sunlight screener (Shachak occurrence of tree saplings (Figs. 6, 7). et al. 2008), and is not due to root competition In one growing season, tree removal caused a (Callaway and Walker 1997) or enriching the ground dramatic decrease in the occurrence of tree saplings with organic matter (Munõz et al.2007). in the woody patch (Fig. 7). The reason is the limited Since grazing had a significant negative effect on re- spatial dispersal of seeds of trees (mostly oaks), their growing of the landscape modulators’ canopy (Agra short viability, and their consequent absence from 2007), we expect a long-term negative effect of cattle soil seed bank. Competition with the large number of grazing on the size and spatial structure of the woody herbaceous plants that re-occupied the woody patch patches following clear cutting, and a consequent soon after tree removal explains the absence of positive effect on herbaceous plant richness. In contrast, establishment of saplings from nearby trees. Occur- we found no evidence of the expected (Perevolotsky and rence of the climbers was higher in the woody patch; Pollak 2001) difference between grazed and none- it was negatively affected by grazing but not by tree grazed plots. Extremely high and continuous grazing removal (Figs. 6, 7). The spatial relation between the pressure is needed to reduce landscape modulator climbing plants and the woody patch is due to the canopy and decrease the area of the woody patch dispersal of their seeds by birds eating their juicy (Gutman et al. 2000). We conclude that traditional cattle fruits (Izhaki et al. 1991). The negative effect of grazing can be used as an effective biodiversity grazing on the climbers is cows’ differential food management tool, mainly after removal or intensive preference; due to their morphology, climbing plants trimming of landscape modulator tree canopy. tend to suffer more damage from the grazing cattle Preservation of woody and herbaceous patches, (Hadar et al. 1999; Lavorel et al. 1999). side-by-side, is essential for maintaining a high herbaceous plant biodiversity. The differential Rare species responses of the various plant functional types and the examined rare species to the treatments demon- As expected (hypothesis D), patch-type and treatments strate their possible use as management tools for the differentially affected the occurrence of rare species, maintenance of high diversity in general and conser- indicating differences in their traits and unique niches. vation of some rare species in particular. Intelligent For example, A. simplex occurred in herbaceous patch use of various active management tools (Perevolotsky in NRNG plots, A. libanotica in the woody patch in 2005) is needed for maintaining landscape diversity, RNG plots, and A. verna and B. pinnatum mainly in coexistence of various successional stages of the the herbaceous patch in the RG plots (Fig. 8, 9). The woody landscape modulators, and patch-types side- general common goal of management in nature by-side for the maintenance of the high biodiversity reserves is keeping or increasing diversity. However, level in Mediterranean ecosystems, which is a main while managing to increase plant diversity, rare plants goal of current nature conservation policy. can be adversely affected. Discovering the responses of the rare plant species to tree removal and grazing Acknowledgments We thank the Israel Science Foundation provides the land managers with a tool to predict their and the Eshkol Fund, Israel Ministry of Science, for their financial support, the Nature and Park Authority for their responses to future management regimes. permission to establish the LTER plots, to A. Amitay for his help in establishing the research plots, to A. Shmida for his help in plant identification, and to M. Shachack and two Conclusions anonymous reviewers for their comments.

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