Livestock grazing has minimal effect on the species richness and diversity of semi-arid shrubland in the Western Little Karoo,South Africa

The Succulent Karoo, one of two arid biodiversity hotspots in the world, is known for its high plant species richness, but little is known about the influence of topography and how it mediates the potentially deleterious effects of grazing. Changes in vegetation species composition, cover and species diversity were examined along piosphere gradients on northerly slopes, bottomlands and low-lying plains on 45 farms. Landscapes differed in the plant speciesand life-form composition, species richness and cover, with the more species-rich, heterogeneous grassy northerly slopes distinct from the plains and bottomlands, which were dominated by Pteronia pallens, Psilocaulon junceum and Drosanthenum spp. with more annual and ephemeral species. Overall, species richness declined linearly with decreasing rangeland condition. A weak grazing effect was detected only on the north-facing slopes, where shrubs and grass decreased with intense grazing. Years of overgrazing have resulted in the widespread dominance of P. pallens, especially on the plains and bottomlands, rendering them insensitive to grazing. The current condition of the northern slopes should be maintained and managed such that palatable species can spread to more degraded areas of the landscape.     

The effects of topo-edaphic variables and cultivation on the woody vegetation of Weenen Nature Reserve,KwaZulu-Natal

The soil types and woody vegetation of Weenen Nature Reserve (WNR), KwaZulu-Natal, were described. Mispah, overlying shale, and Shortlands, overlying dolerite were the most common of 18 the soil forms encountered. Six vegetation types were identified by TWINS PAN which differed in slope, aspect, land-use history, species richness and tree density. Vegetation types ranged from species-rich, dense 'Coddia rudis-Dombeya cymosa Closed Woodland' overlying dolerite and occurring on steep north-east facing slopes that had never been cultivated, to previously cultivated, species-poor 'Acacia sieberiana Open Woodland' on flat topography, overlying shale. Ordination analyses further described the main associated floristic-environmental gradient from steep slopes supporting a high diversity of broad leaved species through to species-poor, flatter areas with an abundance of microphyllous plants. A second main gradient described was from uncultivated sites on steep slopes of usually dolerite-derived soils through to flat, previously cultivated land on shallow soils overlying shale. Topo-edaphic variables and previous cultivation, which were confounded, were therefore the main determinants of floristic variation in WNR, whereas fire had no influence. Half of the dominant woody species exhibited a reverse-J size structure, indicating relatively constant population change. A number of species had a preponderance of individuals in the smallest (0.5–1.5m height) size class, owing possibly to recruitment during the exceptional wet season of 1995/6, and/or the inability of individuals to escape the 'fire-trap'. Several, mostly Acacia, species appear to have recruited intermittently. The vegetation changes of this system will have an affect on browse availability. The woody vegetation of WNR appears to be changing in response to successional processes and management influences.     

Notes on two brief surveys of the small mammal fauna on the Rooiberg,Ladismith, southern Cape Province

Two brief(3½ days each) trapping surveys of the small mammal fauna in fynbos vegetation on the Rooiberg mountains were conducted at the beginning and end of the rodent breeding season in 1978. Four study areas were selected at different altitudes and in different vegetation types. A total of six rodent, three shrew and one small carnivore species were captured. Estimates of density and biomass are given and were found to be relatively high for fynbos communities at the end of the breeding season (March). Differences were found between the fauna inhabiting north-facing and south-facing slopes.     

Woody Vegetation Persistence and Disturbance in Central Texas Grasslands Inferred From Multidecadal Historical Aerial Photographs

Woody vegetation encroachment has been assumed to occur uniformly over the past century across the southern Great Plains of the United States. To assess this assumption, we evaluated changes in pixels classified as woody vegetation from aerial photographs from 1937 to 2004 that were acquired approximately every 13 yr for a 7 109-ha wildlife refuge located in the eastern Edwards Plateau region of central Texas. We found that the percentage of total area classified as woody vegetation changed minimally (62.0–64.2%) from 1937 to 2004. However, on average, 32% of the study area changed classification between woody vegetation and nonwoody vegetation pixels between each photograph date. To assess potential causes of woody vegetation change, we analyzed contiguous pixels with area ≤ 1 ha and area > 1 ha representing small- and large-scale disturbances, respectively. Small-scale woody vegetation pixel loss was found to be moderately low, ranging between 11.1% and 12.6% of the study area for the period of analysis, indicating relatively constant levels of canopy-level disturbance. Large-scale woody vegetation pixel loss peaked in the 1951–1964 time interval, where we identified 98 patches averaging 8.1 ha and covering 7.6% of the study area. The timing and area of these potential disturbances were correlated with drought and increased fire frequency within our study area. This methodology, which includes careful georectification and radiometric standardization of the historical photographs, can be used to detect interdecadal variability related to changes in types of disturbance over longer periods of time. This study also shows that repeated observations, such as those from aerial photographs, may be required to adequately characterize woody plant encroachment, particularly in subhumid grasslands, where disturbance and regrowth of woody plants may occur at decade time scales.     

Rangeland Livestock Production in Relation to Climate and Vegetation Trends in New Mexico

A large statewide historical database involving livestock numbers, vegetation cover, precipitation, air temperature, and drought frequency and severity allowed us to explore relationships between climate and rangeland livestock grazing levels and livestock productivity from 1920 to 2017. Trends in vegetation cover and livestock grazing levels from 1984 to 2017 were also explored. Our climate time series was divided into two periods, 1920 ? 1975 and 1976 ? 2017, based on an apparent accelerated increase in mean annual air temperatures that began in the mid-1970s. Both mean annual precipitation (MAP) and mean annual air temperature (MAT) differed (P ≤ 0.05) between the two periods. MAP and MAT were 9.6% and 3.4% higher in period 2 compared with period 1, respectively. From the 1920s to 2010s the livestock grazing level and weaned calf numbers fell 30% and 40%, respectively, despite a significant increase in MAP. Long-term declines in livestock grazing levels and in weaned calf numbers were significantly (P ≤ 0.05) correlated with increasing MAT (r = ? 0.34 and r = ? 0.43, respectively). No long-term trends (1984–2017) in woody or perennial herbaceous cover were detected at the level of the entire state of New Mexico. Woody plant cover dynamics for New Mexico were not related to livestock grazing levels. However, at the county level we detected a 2% increase in woody plant cover coupled with a 9% decrease in cattle animal units between 2000 and 2002 and 2015 and 2017 for 19 select counties well distributed across New Mexico. Increases in woody plant cover varied greatly among counties and were higher for eastern than western New Mexico. Both global and New Mexico data show the climate warming trend is accelerating. Our findings have relevance to several other parts of the world because New Mexico occurs at midlatitude, has varied topography and climatic conditions, and several different range vegetation types.     

Long-Term Effects of Aeration and Fire on Invasion of Exotic Grasses in Mixed-Brush Plant Communities

Invasion of exotic grasses into grasslands dominated by native plants changes fire cycles and reduces biodiversity. Brush management practices that create soil disturbance, such as aeration, may potentially result in invasion of exotic grasses and replacement of native vegetation. We tested the hypothesis that a long-term effect of aeration and prescribed burning is an increase in exotic grasses. The study was conducted at the Chaparral Wildlife Management Area in the western south Texas plains where four treatments were evaluated: aeration, warm-season burn, aeration followed by a warm-season burn, and no treatment (control). The experimental design was a randomized complete block with four replicates. We estimated percentage canopy cover of exotic grasses, native grasses, forbs, litter, bare ground, and woody and succulent plants in 2007. There was a multivariate main effect among treatments for the dependent variables absolute canopy cover of exotic grasses, native grasses, forbs, litter, and bare ground (Wilks's Lambda F_15,179.84 = 2.78, P = 0.001). Variables that contributed to the significant overall effect included litter (F_3,69 = 4.32, P = 0.008) and native grasses (F_3,69 = 6.11, P = 0.001). The multivariate main effect of treatment was significant (Wilks's Lambda F_9,180.25 = 2.04, P = 0.038) for the relative canopy cover of herbaceous species. Relative cover of exotic grasses was 31% higher (P = 0.024) in control than in the prescribed burn treatment. Native grasses relative cover was 30% higher (P = 0.003) in prescribed burn than in the control treatment. We did not detect differences among treatments in the percentage of total woody and succulent plants canopy cover (P = 0.083). Under the environmental conditions at the time of the study, aeration and/or prescribed burning do not increase exotic grasses.     

Observations on the Feeding Ecology of Impala

The distribution, habitat preference, and diet of impala in mixed wooded savanna were studied. In the wet season impala were evenly distributed through the different vegetation types and their diet was predominantly grass, but in the dry season they concentrated in areas of Acacia savanna and changed to a mainly browsing diet. The amount of grass in the diet was related to plant moisture content and recent effective rainfall. The impala selected succulent food rich in crude protein but preferred grazing to browsing when palatable grass was available. These factors and the presence of fallen Acacia pods probably attracted impala to the Acacia areas in winter.     

Influence of bushdumps on the herbaceous understorey in a mesic Eastern Cape savanna

Abstract

Studies of the effects of woody vegetation on herbaceous vegetation in southern Africa have focused almost exclusively on savannas with isolated trees with no attention given to multi‐species bushclump savannas. The influence of multi‐species bushdumps on herbaceous vegetation was investigated in a mesic savanna in the Eastern Cape. Development of bushdumps appeared to reduce herbaceous production underneath the clumps by up to 90%. The herbaceous layer underneath the bushdumps was distinctly different to that of the open grassland and it also had slightly higher quality compared to that of grassland. Effective bush control measures are warranted if these savanna areas are to sustain beef and mutton production as is currently the case.     

Kouebeskadiging van houtagtige plante in die Suuragtige‐Gemengde Bosveld

Cold damage to woody plants in the Sourish Mixed Bushveld. An incident of damage to woody plants by cold in the Sourish Mixed Bushveld was investigated. Woody plants in eight paddocks which were subjected to long‐term grazing treatments and which gave rise to different tree densities, were examined. The most common form of damage was top kill, and these plants subsequently coppiced from the base. Four woody species, namely Dichrostachys cinerea (the dominant woody species in the area), Acacia nilotica, A. gerrardii and A. robusta were severely damaged by the cold. The greatest effect was on trees in a certain height range; 1,0–3,0 m in the case of D. cinerea and 0,5–2,0 m in the case of the Acacia species. There was a negative curvilinear relationship between the number of trees larger than 2,0 m per hectare and the percentage damage. In paddocks where the tree density was relatively low the number of tree equivalents (equivalents of a tree 1,5 m high) was reduced by as much as 30%.     

Effect of long-term exclusion of fire and herbivory on the soils and vegetation of sour grassland

The effect of long-term exclusion of fire and herbivory, as mediated by aspect, on soils and the structure, composition, and diversity of vegetation was investigated in Döhne Sourveld (34 years), Piet-Retief Sourveld (45 years) and Southern Tall Grassveld (49 years). Exclusion had no effect on the soil chemistry of the surface 15 cm of soil in Dohne and Piet Retief Sourveld. Exclusion promoted the ingress of woody elements, including heath-like species, but the extent of ingress was related to water availability (rainfall, aspect), proximity of propagules, duration of protection, and accidental fires. Alien invasive woody species, in particular Acacia mearnsii established at all sites. Woody species were mostly bird- or wind dispersed, some had no known nearby population, although some Acacia species were herbivore-dispersed. The wettest grassland, Piet Retief Sourveld on a southern aspect, was transformed to a shrubland matrix (mainly Helichrysum splendidum) with tree clumps of forest precursor species (Rhus dentata, Halleria lucida, Myrsine africana, Buddleja salviifolia, Leucosidea sericea) and A. mearnsii. A species-rich grassland on the northern aspect had become dominated by tall Hyparrhenia rufa, with scattered shrubs of L. sericea and Helichrysum rogulosum. The southern aspect exclosure in Döhne Sourveld had developed an A. mearnsii - B. salviifolia savanna, with Cymbopogon excavatus, Themeda triandra and Tristachya leucothrix as common grasses. The northern aspect exclosure on Döhne Sourveld maintained a grassland character, although heath-like elements (Stoebe vulgaris, Erica aspalanthifolia) established. Protection of the Southern Tall Grassveld promoted an open savanna of exotic and indigenous Acacia and broadleaf species, an increase in life forms including the succulent Aloe maculata, and the transformation of a T. triandra - T. leucothrix sward to an Aristida junciformis sward. Ferns benefitted from exclusion of fire and herbivory. Fire and herbivory rather than soil properties would seem the primary determinants of the structure of sour grasslands.     

Veldherwinning langs paaie

The results of a trial to study the effects of periodic burning, or complete resting, on the vegetation and some soil characteristics of semi‐arid Acacia nigrescens/Combretum apiculatum savanna in eastern Botswana are discussed. Plots of 1,2 ha were burned at intervals of O (no burn control), 1,2,3,4 and 5 years from 1958 to 1980. In 1981 these were assessed for bush density by species and by height classes, for grass basal cover and botanical composition, and for soil properties. Bush density increased with increasing burning interval but complete resting suppressed seedling development. All burned plots were visibly more open than the rested plot and hence fire appears to offer the possibility of a low cost means of bush control. The changes in soil properties, grass cover and botanical composition resulting from low frequency burns were small.     

Factors Affecting the Distribution of Wild Ungulates on a Ranch in Kenya. Preliminary Report

This paper gives a preliminary report on the factors affecting the distribution of wild ungulates on a ranch in Kenya. The study covers only one phase of an overall project on the compatabfiity of wild and domestic ungulates. The major factors considered are vegetation, water, fire, cattle grazing, hunting and animal behaviour. These factors are related to five major wild ungulate species which occur on Akira - Coke's hartebeest (kongoni), Grant's gazelle, Thomson's gazelle, eland and giraffe.

The major influence on wild ungulate densities and distribution was vegetation. The condition of vegetation was determined by rainfall, fire and grazing intensities. Generally game populations increased with cattle populations which indicated that vegetation conditions were improving during the period of this study. Overgrazing was generally detrimental to all species except to the Thomson's gazelle which was attracted to short grass areas around water, bomas and overgrazed sites. Kongoni were found usually in tall grass areas while Grant's gazelle were not as selective as Thomson's gazelle or eland. Giraffe were confined mostly to Acacia communities and eland, though found in grassland, were most frequently in high bush country where the variety of shrubs was greater.

The effects of other factors on each of the ungulates are also presented. The interrelationships of all factors are being considered as the study continues.     

Effect of Prosopis (mesquite) invasion and clearing on vegetation cover in semi-arid Nama Karoo rangeland,South Africa

The Nama-Karoo is the largest of the three biomes that comprise the semi-arid Karoo-Namib ecoregion of southern Africa. Large tracts of Nama-Karoo rangeland have been invaded by alien leguminous trees of the genus Prosopis. We assessed the impact of Prosopis invasion and clearing on vegetation cover in heavily grazed Nama-Karoo rangeland on two sheep farms in the Beaufort West district of the Western Cape province of South Africa. Our results suggest that, below critical threshold cover levels, Prosopis trees do not affect indigenous vegetation and add to overall rangeland vegetation cover. However, once Prosopis cover exceeds critical thresholds, the trees begin to negatively impact on indigenous vegetation (especially grasses) and overall vegetation cover. In addition, our data suggest that vegetation cover recovers after Prosopis clearing, being temporarily higher than pre-invasion levels possibly as a result of enhanced post-invasion soil fertility. Lastly, our results suggest that Prosopis trees reduce rangeland erosion potential at low cover and increase it after they exceed critical threshold cover. Information about thresholds of Prosopis impact can be used to direct clearing efforts for maximum benefit when resources are limited.     

Factors Affecting Nest Success and Predator Assemblage of Breeding Birds in Semiarid Grasslands

Woody encroachment has influenced wildlife distributions and, thus, predator-prey dynamics, for many taxa in North American grasslands. In 2015 and 2016, we examined how vegetative characteristics influenced avian nest predator assemblages and nest predation rates in semiarid grasslands of south Texas, where encroachment of woody plant species is common. We monitored 253 nests of 17 bird species and deployed infrared cameras at 107 nest sites within four vegetation types at our study sites. We also used data from a concurrent, multispecies monitoring project within our study area to assess predator activity within these same vegetation types. We divided bird species into four nest types based on nest shape and size (i.e., small, medium, and large cup-shaped nests and exposed nests with little structure). We then used logistic regression to examine relationships between shrub cover, concealment, and distance to edge and the probability of nest success and predation by snakes. We observed a significant decrease in nest success of our medium-sized, cup-shaped nest type when shrub cover increased at the nest site, indicating small increases in shrub cover (≈ 10%) could have substantial impacts on birds using this nest type. Snakes were our primary predator at camera-monitored nests (59%), and snake activity increased by 6.7% with every 10% increase in shrub cover at the nest site. Mesomammalian and large mammalian predators were most active in vegetation types predominated by herbaceous cover, small mammals were most active in vegetation types predominated by woody cover, and snake activity was highly variable. Predator activity did not reflect predator identity at camera-monitored nests, suggesting that potential nest predator activity may not accurately reflect the risk of nest predation. Results of our study will help inform management of bird species using semiarid grasslands affected by woody encroachment and offer recommendations for improved nest success.     

Polyethylene glycol influences feeding behaviour of dairy goats browsing on bushland with different herbage cover

The effects of supplemental polyethylene glycol (PEG) on feeding behaviour, diet composition, intake and milk production were studied in late lactating Sarda goats browsing on a lentisk-based bushland with different herbage cover. The goats were allotted to two groups that browsed 7 h daily on 2 plots characterised by different cover proportions of woody and herbaceous species. These proportions were 90% woody vs. 10% herbaceous species in one plot (W — woody, close bushland with low herbage cover) and 70% woody vs. 30% herbaceous species in the other plot (H — herbaceous, open bushland with high herbage cover). Each group was divided into two sub-groups: one fed with 50 g day^− 1 of PEG 4000 MW (PEG⁺) and the other receiving no PEG supplementation (PEG⁻). The feeding behaviour was different between groups; goats in herbaceous plot (H-goats), had a longer grazing time, expressed as percentage of total observation time than the counterparts (64% vs. 58%, P < 0.05). The intake was not affected by the treatments. The percentage of the species eaten by the goats was different in the two groups: H-goats ate more herbaceous and less woody species than goats in woody plot (W-goats). In each group the PEG tended to affect the botanical composition of the diet. PEG dosed goats ate more tanniferous species than control counterparts (P = 0.12). The average daily milk production was 473, 591, 541 and 589 ml, respectively in W-PEG^−, W-PEG⁺, H-PEG⁻ and H-PEG⁺ sub-groups with significant effect of herbage cover × PEG dose interaction (P < 0.05). The milk urea was affected by herbage cover (P < 0.001) and PEG supplementation (P < 0.001). In conclusion, the effect of PEG is strictly dependent on pasture composition. In open bushland, featured by moderate woody cover, the effect of PEG is more intense on diet selection, due to its marked post-ingestive effects. In close bushland, characterised by high proportion of tanniferous species prevails the efficacy of PEG as a performance booster.     

Infiltration,Runoff, and Sediment Yield in Response to Western Juniper Encroachment in Southeast Oregon

Infiltration was measured in a western juniper (Juniperus occidentalis Hook.) watershed to characterize the hydrologic processes associated with landscape position. Infiltration rate, runoff, and sediment content were measured with the use of a small-plot rainfall simulator. Study sites were located in each of the four primary aspects (north, south, east, and west). Research sites were located in two ecological sites—South Slopes 12–16 PZ and North Slopes 12–16 PZ. Within aspect, plots were located in three juniper cover levels: high (> 22%), moderate (13%–16%), and low (<3%) juniper canopy cover. During rainfall simulation, water was applied at a 10.2-cm · h⁻¹ rate, levels comparable to an infrequent, short-duration, high-intensity precipitation event. Runoff was measured at 5-min intervals for 60 min. Comparing canopy cover levels, steady-state infiltration rates on control plots (9.0 cm · h⁻¹) was 68% greater than high juniper cover sites (2.87 cm · h⁻¹) and 34% greater than moderate juniper cover sites (5.97 cm · h⁻¹) on south-facing slopes. On north-facing slopes, no differences in infiltration rates were observed between juniper cover levels, demonstrating differential hydrologic responses associated with ecological site. Generally, all water applied to control plots infiltrated. Highest infiltration rates were positively associated with increased surface litter and shrub cover. In addition, depth of water within the soil profile was lowest in high juniper cover plots. This suggests that less water is available to sustain understory and intercanopy plant growth in areas with high juniper cover. Accelerated runoff and erosion in juniper dominated sites (high level) across east-, west-, and south- facing slopes can lead to extensive degradation to the hydrology of those sites. These data suggest that sustained hydrologic processes are achieved with reduced western juniper canopy cover.     

Quantified range condition assessment of open Camelthorn savanna along a degradation gradient

Measurements were taken at 20 different sites in a relatively homogenous area of open Camelthorn savanna in eastern Namibia. Ordination of grass species composition did not provide a good degradation gradient, due to domination by different species of annual grasses at many of the sites. However a centred PCA ordination of perennial grass species indicated a degradation gradient. This gradient was used to allocate a range condition score to each site, which was then correlated with other measurements. The range condition score did not correlate well with mulch cover, basal cover, proportion of bare soil, above-ground grass biomass, proportion of moribund grass, proportion of seedlings amongst the perennial grasses, density of woody plants lower than O.5m and canopy cover of browsable woody plants over 0.5m tall. A weak correlation (r² = 0.68, p<0.0001, n = 20) was obtained through a power trend line with woody canopy cover of only the bush thickening species. A better correlation (r² = 0.90, p<0.0001, n = 20) was obtained with mean distance from sampling point to the nearest perennial grass. This may therefore be an appropriate indicator to include in range condition score for such types of savanna.     

Plant and Small Vertebrate Composition and Diversity 36–39 Years After Root Plowing

Root plowing is a common management practice to reduce woody vegetation and increase herbaceous forage for livestock on rangelands. Our objective was to test the hypotheses that four decades after sites are root plowed they have 1) lower plant species diversity, less heterogeneity, greater percent canopy cover of exotic grasses; and 2) lower abundance and diversity of amphibians, reptiles, and small mammals, compared to sites that were not disturbed by root plowing. Pairs of 4-ha sites were selected for sampling: in each pair of sites, one was root plowed in 1965 and another was not disturbed by root plowing (untreated). We estimated canopy cover of woody and herbaceous vegetation during summer 2003 and canopy cover of herbaceous vegetation during spring 2004. We trapped small mammals and herpetofauna in pitfall traps during late spring and summer 2001–2004. Species diversity and richness of woody plants were less on root-plowed than on untreated sites; however, herbaceous plant and animal species did not differ greatly between treatments. Evenness of woody vegetation was less on root-plowed sites, in part because woody legumes were more abundant. Abundance of small mammals and herpetofauna varied with annual rainfall more than it varied with root plowing. Although structural differences existed between vegetation communities, secondary succession of vegetation reestablishing after root plowing appears to be leading to convergence in plant and small animal species composition with untreated sites.     

Comparison of Ground-Measured and Image-Classified Mesquite (Prosopis glandulosa) Canopy Cover

Remote sensing has long been recognized as a rapid, inexpensive, nondestructive, and synoptic technique to study rangeland vegetation and soils. With respect to the worldwide phenomenon of woody plant invasion on many grasslands and rangelands, there is increasing interest in accurate and cost-effective quantification of woody plant cover and distribution over large land areas. Our objectives were to 1) investigate the relationship between ground-measured and image-classified honey mesquite (Prosopis glandulosa Torr.) canopy cover at three sites in north Texas using high spatial resolution (0.67-m) aerial images, and 2) examine the suitability of aerial images with different spatial resolutions (0.67-m, 1-m, and 2-m) for accurate estimation of mesquite canopy cover. The line intercept method and supervised maximum likelihood classifier were used to measure mesquite cover on the ground and on images, respectively. Images all were taken in September when mesquite foliage was photosynthetically active and most herbaceous vegetation was dormant. The results indicated that there were robust agreements between classified and ground-measured mesquite cover at all three sites with the coefficients of determination (r²) ≥ 0.95. Accuracy of lower spatial resolution images ranged from r² = 0.89–0.93, with the 2-m spatial resolution image on one of the sites at r² = 0.89. For all sites, the overall, producer's, and user's accuracies, and kappa statistics were 92% and 97%, 91% and 99%, 85% and 96%, and 0.82 and 0.95 for 2-m and 0.67-m spatial resolution images, respectively. Results showed that images at all three spatial resolution levels were effective for estimating mesquite cover over large and remote or inaccessible areas.     

Cattle Grazing Fails to Control Shrub Encroachment in Mediterranean Landscapes

The Common Agricultural Policy supports the use of free-ranging cattle herds to control woody encroachment and fire hazards in Europe. There is, however, little empirical evidence about the effectiveness of extensive grazing to preserve open landscapes in the Mediterranean Basin. In this work, we evaluated the effects of extensive beef cattle grazing on the vegetation structure in a Mediterranean ecosystem using a twofold framework: 1) analyzing temporal changes in the forest, shrub, and grassland cover in areas under different grazing pressures for 16 yr (1993 ? 2009) and 2) studying diet selection to assess the impact of cattle on the local Mediterranean vegetation. Our landscape structure analyses revealed a remarkable change in land cover over the study period. However, woody community dynamics seemed to be more related to natural vegetation succession than to cattle effects. Extensive grazing seemed to preserve grasslands but only at high stocking rates. On the other hand, the diet analyses supported the lack of a role for cattle in encroachment control. Beef cattle diets were based on herbaceous plants (59%) with lower contribution of woody ones (41%). Cattle only showed a significant preference (P < 0.05) for few woody species (Erica multiflora, Olea europaea, Quercus ilex, and Rosmarinus officinalis), mostly at high-density stocking rates. Hence, our results support the idea that extensive cattle grazing alone exerts a negligible effect on shrub encroachment and thus on the risk of fire in the studied Mediterranean area. We urge a redesign of current research to truly integrate extensive cattle grazing as High Nature Value farming in European policies to successfully meet its putative goals, such as shrub encroachment control and wildfire risk prevention.