Recovery after Experimental Cutting and Burning in Three Shrub Communities with Different Dominant Species

The aim of this study is to compare the recovery dynamics in three shrub communities subjected to experimental burning and cutting, and situated on an altitudinal gradient. Climatic features are different in each area, but all had the common characteristic of very homogeneous vegetation cover before the disturbances, with only one shrub species clearly dominant, a different taxon in each area, and with different regeneration strategies. The first area was a heathland dominated by Calluna vulgaris, situated at an altitude of 1600 m, with a continental climate (mean annual precipitation 1320 mm). The second area was a heathland dominated by Erica australis, located at an altitude of 1000 m (mean annual precipitation 840 mm). The third area was a Cistus ladanifer shrubland, located at 900 m altitude, with a Mediterranean climate similar to that of the previous area, but with lower mean annual precipitation (470 mm). Erica australis recovers by vegetative resprouting, but Cistus ladanifer is an obligate seeder, as is Calluna vulgaris in these areas. Each experimental disturbance was carried out over 100 m² in each area. Post-fire recovery is faster in Cistus ladanifer: 2 years after burning there was 40% cover vs. less than 20% in the other two species. However, recovery after cutting was similar for Cistus ladanifer and Erica australis. Calluna vulgaris recovers very slowly, with cover values below 20% even 10 years after both disturbances. Cover of dominant shrub species is negatively correlated with cover of herbaceous species. So different recovery of dominant species lead a different community dynamic in each area.     

The dynamics of mediterranean shrubs species over 12 years following perturbations

The response of woody species to experimental burning, cutting andploughing was studied for a period of twelve years in a shrub community in NWSpain. The treatments represent the perturbations most frequently imposed bymanon these shrub communities throughout history. The response to burning is muchfaster than the response to cutting. The response to ploughing is slower due tothe regeneration mechanism that species use: germination. In general, thedominant species, Erica australis, influences theregeneration patterns of the rest of the species, which make up the community.There is a significant increase in the cover of woody species until the fourthyear, and of herbaceous species until the third year. Subsequently,Erica australis attains dominance, returning to itsoriginal spatial occupancy and cover values, removing the herbaceous speciesandnegatively influencing the growth of woody ones like Halimiumumbellatum, Halimium alyssoides and Quercuspyrenaica. Both Erica australis andChamaespartium tridentatum regenerated by sprouting in theburnt and cut plots, and by germination in the ploughed plot.Arctostaphylos uva-ursi only recovers after burning andploughing. Halimium alyssoides, Halimium umbellatum, Ericaumbellata and Calluna vulgaris regenerate bygermination in the three plots. Differences in cover values and spatialoccupancy during the first years of succession tend to be eliminated twelveyears after treatment and most of the species tend to recover their initialcover values. These shrubland communities have a high degree of resilience dueto the strong sprouting potential of the component species.     

Effects of grazing and inundation on pasture quality and seed production in a salt marsh

During a six-year period, changes in the composition of dominant plant species of importance to foraging birds in a salt marsh on the Swedish west coast were followed inside and outside exclosures to document effects of grazing on herbage quality and seed production. Since marshes provide an important habitat for foraging geese and ducks, it was of interest to determine how cattle grazing would affect herbage production inAgrostis stolonifera andPuccinellia maritima and seed and root-tuber production inScirpus maritimus. Measurements of cover and height in permanent plots revealed that a wetter weather type favouredAgrostis, probably through reduced salinity, at the expense ofPuccinellia, which was the most favoured food of both cattle and birds.Agrostis out-competedPuccinellia when grazing pressure was low. Seed production inScirpus maritimus was reduced by cattle grazing, particularly whenPhragmites australis formed part of the vegetation. In the absence of cattle grazing, both herbage- and seed producing plants were gradually reduced, andPhragmites increased. Since high herbage consumption and high seed production are mutually exclusive, grazing rotation in combination with mowing is suggested as a management strategy.     

Survival, growth, and escape from herbivory are determined by habitat and herbivore species for three Australian woodland plants

To understand how plant communities are structured by herbivory it is essential to investigate the roles of different herbivores and the responses of a variety of plant species in different habitats. We examined the effects of mammalian herbivores on survival and growth of transplanted seedlings of two native trees (Eucalyptus albens and Callitris glaucophylla), and one native grass (Themeda australis) in white box (E. albens) woodlands in eastern Australia over 3 years. Herbivores were manipulated using four fencing treatments that successively excluded livestock, macropods, and rabbits from woodland and grassland (cleared pasture). Survival was highest in the absence of mammalian herbivores and in woodlands, and patterns differed among plant species. Survival of T. australis was low, especially in grasslands, and mortality by overgrowth was common in ungrazed treatments. All plant species were taller in fenced plots, and differences between treatments were greater in grassland. Rabbits and livestock had the greatest influence on C. glaucophylla, while T. australis and E. albens were most affected by livestock and macropods. We used field data to parameterize stage-classified matrix models to predict escape from herbivory (escape height >100 cm) for tree species. Reduced herbivory increased the proportion of individuals reaching escape height after 15 years. Rate of escape was greater in grassland, and this faster growth appeared to counteract much of the negative impact of herbivores. While T. australis was unable to escape herbivory, larger, ungrazed individuals were more likely to flower and therefore contribute to the maintenance of the population. Our results show that habitat and herbivore species strongly influence the effect of herbivory on vegetation.     

Host habitat finding and host selection of theDrosophila parasitoidLeptopilina australis (Hymenoptera,Eucoilidae), with a comparison of the niches of EuropeanLeptopilina species

Summary Decaying petioles of giant hogweed,Heracleum mantegazzianum Sommier & Levier, are used as a breeding site by six species ofDrosophila and the drosophilidScaptomyza pallida. The most numerous parasitoid species associated with this community isLeptopilina australis. BecauseL. australis was previously unknown in western Europe, we present the characters to distinguish it form its close relativeL. clavipes. Experiments on host species selection and survival ofL. australis showed that this parasitoid mainly usesD. limbata as host. Olfactometer experiments showed thatL. australis is attracted by the odour of decaying hogweed stalks, especially when these contain larvae ofD. limbata. L. australis is also strongly attracted by the odour of stinkhorns, a habitat in which it has never been found in nature.D. phalerata is the dominant fly species in stinkhorns, and is not a host ofL. australis. We offer a possible functional explanation for this unexpected habitat choice, by showing thatD. transversa andD. kuntzei, both species found to breed in fungi, are also suitable hosts forL. australis. We also discuss habitat choice with regard to a proposed phylogeny of theLeptopilina species in temperate Europe. Finally, we discuss niche overlap ofL. australis with the otherLeptopilina species.     

Effects of controlled livestock grazing and annual prescribed fire on epigeal termite mounds in a savannah woodland in Burkina Faso

The diversity and abundance of epigeal termite mounds were investigated in response to controlled livestock grazing and annual prescribed fire in a Sudanian savannah-woodland in Tiogo State Forest. Sampling of termite mounds was carried out in 4×4 subplots of 0.25 ha in a split-plot experimental design during the rainy season in 2002. There were two main plots of which one was fenced to exclude livestock grazing and the second exposed to grazing. Each of the main plots included 4 subplots with annual prescribed fire since 1992 and 4 subplots without fire. Data were collected on the number and characteristics of termite mounds. A mean density of 698 mounds ha⁻¹ was recorded. Mounds built by Trinervitermes spp. were the most abundant followed by Cubitermes spp., Macrotermes subhyalinus and M. bellicosus. The large mound-builders Macrotermes spp. dominated the community interms of basal area (96% of the total) and above-ground volume (99%). The diversity of mound types was notaffected by livestock grazing and annual early prescribed fire (P>0.05). There was no statistical effect of livestock grazing on mound density, whereas a strong depressive effect of annual fire was observed for Trinervitermes spp. mound density (P=0.012). In this ecosystem, annual prescribed fire appeared to be the major determinant for termite mound abundance. Received 2 February 2007; revised 23 October 2007 and 21 January 2008; accepted 22 Feburary 2008.     

不同水分条件下混种密度对芦苇和反枝苋种间竞争的影响

与本地植物的种间竞争是影响外来植物能否成功入侵的关键因素之一,该研究通过受控模拟试验研究了本地植物芦苇(Phragmites australis)和外来入侵植物反枝苋(Amaranthus retroflexus)在淹水和干旱两种水分条件下混种密度(6∶2、4∶4和2∶6)对其种间竞争的影响。结果表明:(1)芦苇和反枝苋的相对产量与相对产量总和均小于1,即两种植物存在种间竞争。(2)种间竞争使芦苇和反枝苋的生长均受到了不同程度的抑制,表现在两者的株高和生物量均随着竞争者密度的增加而降低。(3)植株地上部分和地下部分的氮浓度表现出与株高和生物量相同的趋势,且在不同水分条件下存在差异。(4)芦苇和反枝苋分别在淹水和干旱环境下具有较强竞争力,但在各自较高混种密度下亦具有较强竞争力。可见,芦苇和反枝苋的种间竞争受到了水分和混种密度的影响。因此,在有反枝苋分布的湿地中,植物生长初期可通过增加土壤水分和/或增加芦苇等本地植物的种群密度以降低反枝苋的种群密度来限制其竞争能力,防止反枝苋在湿地中生长建群和扩散入侵。     

Sero-systematics ofCytisus sect.Trianthocytisus (Fabaceae)

The serological reaction of seed proteins provides evidence for a partly new systematic arrangement ofCytisus sect.Trianthocytisus and ofCytisus s.l. Proposed modifications agree with recent advances in morphological taxonomy. Sect.Trianthocytisus includes only two species,C. villosus andC. aeolicus. Its position is central within the genus, and this fact agrees with the proposed retypification ofCytisus (type species:C. villosus).C. emeriflorus, formerly included in the same section, constitutes the monospecific sect.Emeroides, which is intermediate towards the genusLembotropis. This is serologically isolated and includes onlyL. nigricans. It is confirmed thatC. sessilifolius should be removed from the genusCytisus as a monospecific genus:Cytisophyllum Lang which is closely allied toHesperolaburnum and toPodocytisus, the most primitive genera ofGenisteae.     

Effects of sowing native herbaceous species on the post-fire recovery in a heathland

Erica australis heathlands in León province (NW Spain) have high resilience to disturbances and their post-fire recovery is very fast. The risk of soil erosion is high in the first few months after fire. The aim of this study is to investigate the effects on post-fire succession of sowing grass (Agrostis capillaris and Festuca rubra) and legume (Lotus corniculatus) seeds in a heathland burned by a summer wildfire, and to determine the most suitable native herbaceous species combination for protecting the soil in the first few phases of recovery. Fifteen permanent 4 m² plots are established in the burned area; four treatments and a control (unsown) are applied, each with three replicates. Three similar unburned plots are also considered (unburned control). Total cover is significantly higher in the sown plots in relation to the control in the first few months after sowing, but there are no differences after 18 months. Lotus corniculatus appears only in the first year and has no effect on the total cover. F. rubra appears earlier than Agrostis capillaris, but decreases significantly in cover after 18 months. Shrub species have the highest cover in the control plots and the lowest in the Agrostis plots. The correspondence analysis shows that the trend for vegetation in all plots reaches similar species composition by the time of final sampling. The last sampling of sown plots shows greater similarity to the control plots than the sampling of these plots within the first year. The fast initial growth of F. rubra, together with its decrease and subsequent low cover from the second year, make it more preferable than Agrostis capillaris for purposes of soil protection. However, additional research, both species- and site-specific, is necessary, as different responses due to different post-fire conditions and pre-fire species composition can have important implications on community dynamics.     

Population genetic structure of three tree species in the mangrove genus Ceriops (Rhizophoraceae) from the Indo West Pacific

Ceriops is a viviparous mangrove with widespread species Ceriops decandra and C. tagal, and an endemic species C. australis. Genetic diversity of the three species was screened in 30 populations collected from 23 locations in the Indo West Pacific (IWP) using Inter-simple sequence repeats (ISSR) and sequences of partial nuclear gene (G3pdh) and chloroplast DNA (trnV-trnM). At the species level, the total gene diversity (Ht) revealed by ISSRs was 0.270, 0.118, and 0.089 in C. decandra, C. tagal, and C. australis, respectively. A total of six haplotypes of G3pdh and five haplotypes of trnV-trnM were recognized among the three species. Only C. decandra was detected containing more than one haplotype from each sequence data set (four G3pdh haplotypes and three trnV-trnM haplotypes). At the population level, genetic diversity of Ceriops was relatively low inferred from ISSRs (He = 0.028, 0.023, and 0.053 in C. decandra, C. tagal, and C. australis, respectively). No haplotype diversity within population was detected from any of the three species. Cluster analysis based on ISSRs identified three major geographical groups in correspond to the East Indian Ocean (EIO), South China Sea (SCS), and North Australia (NA) in both C. decandra and C. tagal. The cladogram from DNA sequences also detected the same three geographical groups in C. decandra. Analysis of molecular variance (AMOVA) revealed that most of the total variation was accounted for by differentiation between the three major geographical regions of both C. decandra and C. tagal. The significant genetic structure may result from the geological events in these regions during the recent Pleistocene glaciations. This study also provided insights into the phylogenetics of Ceriops. Yelin Huang and Fengxiao Tan contributed equally to this work.     

Effects of Different Wetland Plant Species on Fresh Unweathered Sulphidic Mine Tailings

Vegetation cover with two Eriophorum species on old unweathered sulphidic mine tailings has earlier been found to reduce the element levels and to prevent production of acidity in drainage water. The present study aims to find out if Carex rostrata Stokes, Eriophorum angustifolium Honck. and Phragmites australis (Cav.) Steud. had other effects on metal and As release in fresh unweathered sulphidic mine tailings, if the species showed different effects and if this depended on plant mechanisms such as O₂, carbonate or organic acid release. Plants were grown in pots with fresh sulphidic mine tailings for 13 months. Arsenic, Cd, Cu, Fe, Pb, Zn, pH, SO ₄ ²⁻ , alkalinity and organic acids in the drainage water as well as metals and As in roots and shoot and O₂ and redox potential in pore water were analysed. The tailings weathered slowly due to high buffering capacity thus no pH decrease was found and therefore similar buffering effects by plants as shown in the previous investigation could not be found. The plants increased the total release of metals and As from the tailings. The release did not depend on carbonate or organic acid release from plants. However, the Fe and As release was due to changed redox potential, caused by O₂ release, and high concentration of Fe and As was found in plant roots. Phragmites australis released more As and Fe but less Cd than E. angustifolium and C. rostrata which make P. australis not suitable for plant establishment on sulphidic mine tailings containing high levels of As. Plants did take up the elements and the lowest translocation of elements to the shoot was found in P. australis while the highest in E. angustifolium.     

Enhancement of photosynthesis in post-disturbance resprouts of two co-occurring Mediterranean <Emphasis Type="Italic">Erica</Emphasis> species

The higher growth rates of resprouting shoots compared with those of mature plants in resprouter woody species are supported by higher rates of photosynthesis and transpiration. In this contribution we hypothesize that species with higher resprouting vigour will show a larger enhancement of photosynthesis in resprouting shoots. We test this hypothesis by comparing gas exchange and leaf parameters between resprouting and mature plants in Erica scoparia and E. australis. These two Erica species co-occur in Mediterranean heathlands of the Strait of Gibraltar. Erica scoparia has a higher rate of post-disturbance starch recovery than E. australis, which makes it more resistant to recurrent disturbance. We tested the hypothesis that enhancement of photosynthesis and water use characteristics of resprouting shoots compared with mature plants should be more pronounced in E. scoparia. In both species, resprouts had higher efficiency in the use of light and higher maximum net photosynthesis than mature shoots. However, contrary to expectations, differences in the photosynthetic performance between resprouts and mature plant shoots were larger in E. australis. Higher root to shoot ratios in resprouting E. australis plants, determined by their slower above-ground recovery, together with stronger demand from carbon sinks might explain this result.     

Ramet size equalisation in a clonal plant,Phragmites australis

The influence of shading from older generations of dead culms (standing litter) on density, growth rate and development of size structure at the ramet level was investigated in a pure stand of Phragmites australis by experimental neutral shading of plots after removal of standing litter. Initial differences in height distribution between autumn and spring cohorts disappeared in the course of shoot growth. The Gini coefficients of shoot heights and estimated shoot weights indicated that the size structure of the shoots became more equal with increasing mean size in both shaded and unshaded plots. Relative growth rate for height (RHGR) and weight of individual shoots was negatively related to shoot size during the early and presumably storage-dependent growth period, suggesting a strong support for growth of smaller shoots. No etiolation was indicated by mean or maximum height in shaded and unshaded plots, or by the relationship between shoot height and weight. Mean shoot density was significantly lower in shaded than in unshaded plots in one of two shade treatment years. A regression model indicated a small but significant effect of shoot density on the approximately linear relationship between RHGR and the logarithm of height. The growth rate of small shoots was slightly larger at low than at high shoot density. Therefore, it is suggested that the shade from standing litter in P. australis stands can decrease shoot natality in the spring cohort, and thereby increase the support to fewer small shoots.     

Nest-density distribution patterns in a yellow-legged gull archipelago colony

The nest density distribution of yellow-legged gulls Larus cachinnans was investigated on the large Marseille archipelago colony (south-east France) which houses c. 18 000 breeding pairs. The study was performed at two investigation scales, including both mean nesting density on the nine study islands and density distribution within 171 sampling plots. The mean nesting density on each island was negatively correlated with island surface area and with the distance from the initial colony location (south-east end of the archipelago). No significant correlation was found with the other island parameters analysed (maximum elevation, shape index and distance from continent). A partial least squares regression performed between denstiy data from 171 500 m² sampling plots and environmental variables showed that the mostly explaining factors were island isolation and percentage of rocks in the plots (positive correlation), and distance of the island from the south-east end of the archipelago, island area, distance from plot to seaside and percentage of stone in the plots (negative correlation). Thus in our case, vegetation parameters (cover and height) were not influencial factors in nest density distribution.     

Short-term study of effects of fertilisation and cutting treatments on the vegetation dynamics of mountain heathlands in Spain

The influence of management and nutrient availability on the vegetation dynamics of heathlands characterised by Calluna vulgaris and Erica tetralix were studied in three mountain sites in Northern Spain. A total of 90 plots (1 m² each) received different combinations of cutting and twice the estimated background atmospheric deposition of nitrogen (56 kg ha⁻¹ yr⁻¹). One of the two dominant ericaceous species was selectively cut by hand at ground level and their regeneration compared in the presence or absence of the other. The results after 2 years showed significant effects of the fertiliser on the vegetation cover, mainly by favouring perennial herbaceous species. There were less noteworthy effects on the number of flowers and on the annual growth of the ericaceous species. It is concluded that, in the short term, increased nutrients alone, at twice the estimated current atmospheric deposition for the area, will not alter significantly the composition of the mountain heathlands. However, once the stands reach the mature phase, the capacity of the community to regenerate after a severe disturbance diminishes. A drastic impact, such as cutting may not result in re-growth of the same shrub species but in replacement by herbaceous species, which will also benefit from the increased nutrients.     

阔叶丰花草对荔枝园杂草群落特征及物种多样性的影响

【目的】明确阔叶丰花草在荔枝园定植对杂草群落特征及物种多样性的影响,为阔叶丰花草在果园应用提供参考依据。【方法】通过调查广东茂名高州荔枝国家现代农业产业园的荔枝园中90个有、无阔叶丰花草样方中杂草群落组成、群落高度以及物种多样性,探究阔叶丰花草定植对荔枝园杂草群落结构及物种多样性的影响。【结果】阔叶丰花草在荔枝园定植后,杂草种类减少,由对照样方的42种减少到试验样方的30种;杂草群落结构显著改变,牛筋草、白花鬼针草等恶性杂草重要值降低,薇甘菊、香附子、火炭母等杂草消失;阔叶丰花草的重要值与杂草群落高度和物种多样性指数为显著性负相关(P0.001),且均呈显著三项式回归关系。阔叶花草在荔枝园定植后可建立结构较为单一,且低矮的杂草群落。【结论】阔叶丰花草有望成为荔枝园生草的有益草种。     

Successful biological control of mist flower (Ageratina riparia) in New Zealand: Agent establishment, impact and benefits to the native flora

The white smut fungus (Entyloma ageratinae) and the gall fly (Procecidochares alani) were released in New Zealand in 1998 and 2001 respectively to suppress mist flower (Ageratina riparia). The fungus established and spread rapidly, crossing 80 km of sea to Great Barrier Island within 2 years. The mean number of P. alani galls increased exponentially to 1.96/stem at release sites, but dispersal was slow. The impact of the biocontrol agents was monitored once annually from 1998/99 to 2003/04, at up to 51 sites in the North Island. The mean percentage of live leaves infected with fungus rapidly reached nearly 60%. Maximum plant height declined significantly. In heavy infestations, mean percentage cover of mist flower declined from 81 to 1.5%. Galls were only recorded towards the end of the impact study, and at low mean numbers. As mist flower declined, the species richness and mean percentage cover of native plants increased. In contrast, the species richness and mean percentage cover of exotic plants (excluding mist flower) did not change significantly. Many plant species colonizing the plots were important native mid- or late-successional shrubs or trees. With few exceptions, the exotic plant species common in the plots were not weeds that appeared to threaten native forest habitats. There was only a weak “replacement weed effect” from the potentially serious invader African club moss (Selaginella kraussiana). These data, together with reports of reduced threats to rare endemic plants from mist flower, suggest this rapid, well-monitored weed biocontrol program was very successful.     

Resistance of three co-occurring resprouter Erica species to highly frequent disturbance

The resistance to experimental, highly frequent disturbance has been analysed in three congeneric, strong-resprouter species (Erica australis, E. scoparia and E. arborea) that co-occur in heath-dominated communities of the northern side of the Strait of Gibraltar, southern Spain. To do so, mature individuals of the three species from a long undisturbed location were clipped at the ground level every sixth month during two years. The relationship between the resprouted biomass dry weight (as indicative of the resprouting vigour) and the upper surface area of the lignotuber along the experiment was established separately for each species at each clipping event by means of linear regressions analysis. The resprouting vigour of the three species was compared by means of independent one-way ANOVAs within each clipping event. Resprouting vigour decreased after recurrent clippings in the three species. Nevertheless, significant differences between species in this loss of resprouting vigour were detected, being E. scoparia the most resistant to the experimental, highly frequent clipping. It is concluded that experimental levels of recurrent disturbance may help to find out differences in resilience within similar (taxonomically, morfologically and/or ecologically), strong-resprouter plant species. Considering the history of forestry management in the nothern side of the Strait of Gibraltar, differences in this regard between the three Erica species may contribute to explain their somewhat segregated ecological distribution in this region.     

扎龙湿地不同生境芦苇功能性状变异及其对土壤因子的响应

物种的遗传特征和外在环境条件的差异共同决定了植物功能性状的表达,植物功能性状可以反映物种对环境条件的适应策略。采用大样本抽样调查与统计分析方法,比较研究扎龙湿地4种生境（盐碱生境、旱生生境、湿生生境和水生生境）芦苇分株和叶功能性状,分析不同生境芦苇功能性状的分异规律及其对土壤因子的响应。结果表明：（1）不同生境芦苇功能性状均表现出中等程度变异。其中分株和叶性状均以盐碱生境最低（P<0.05）,分株及除叶面积和比叶面积以外的叶性状均以水生生境最高;株高和株重在种群内的变异系数为15.96%-48.61%和38.65%-87.82%,种群间的变异系数为46.58%和66.39%;叶性状在种群内的变异系数为13.21%-72.37%,种群间的变异系数为26.46%-57.03%;（2）不同生境芦苇功能性状间存在协同变化特征。芦苇的株高、株重、叶长、叶宽、叶面积和叶重之间均呈极显著正相关关系（P<0.01）,比叶面积与其他性状的相关性因生境不同存在一定变化;（3）不同生境芦苇的原位土壤因子表现出异质性特征,芦苇功能性状的变异是含水量、pH、有机质和速效氮等土壤因子综合作用的结果。其中含水量、有机质和速效氮为正向驱动,而pH为负向驱动。因此,芦苇通过自我调节功能性状更好地适应不同的生存环境,局域尺度不同生境的土壤因子是引起芦苇功能性状产生分异的导因。     

Long-term impacts of goat browsing on bush-clump dynamics in a semi-arid subtropical savanna

The effects of 16 years of continuous browsing by goats in a South African savanna at stocking rates intended for bush control were compared with plots unbrowsed for the same period of time. Differences in bush-clump density, structure and species composition were recorded. Bush-clump density did not differ between browsed and unbrowsed plots. Within individual bush-clumps, browsing was shown to impact more on structure than species composition, with smaller, shorter bush-clumps, containing fewer species but much greater stem-densities. Although species presence/absence was little affected by browsing, many species showed differences in abundance, growth and location within browsed and unbrowsed bush-clumps. Species reduced in abundance in browsed plots included Cussonia spicata, Ehretia rigida, Grewia occidentalis, Jasminum angulare and Senecio linifolius. Several species showed reduced growth in browsed plots, particularly those located at bush-clump edges. The relatively unpreferred Aloe ferox was a notable exception. Although browsing had little effect on the composition of the main clump founding species, emergents or late arrivals, there were twice as many single plants in browsed plots and emergence of several species was restricted to the middle of bush-clumps. Comparison of our findings with aerial photographic evidence and other literature suggest that browsing alone is unlikely to significantly reduce scrub cover, although it can clearly control further expansion. Combinations of fire and browsing, rather than one factor alone, are considered likely to act fastest and most effectively to significantly reduce or remove scrub cover altogether.