Change in the woody floristic composition,diversity and structure from protected to unprotected savannahs in Pendjari Biosphere Reserve (Benin,West Africa)

Savannahs are widespread vegetation type in Sudanian zone of Africa. As protected areas are often assumed to be the best way to conserve biodiversity, we assessed the effectiveness of the Pendjari Biosphere Reserve in Benin, for maintaining savannah woody species composition, diversity and structure. Square plots of 900 m² were randomly established in protected and surrounding unprotected savannahs, and all woody species (dbh ≥ 1 cm) were recorded and identified. Species composition, Importance Value Index, densities, basal area and diversity indexes were assessed in relation to conservation status. The results showed that DCA based on presence/absence species data did not separate clearly protected savannahs from unprotected ones. However, some species were prominent in unprotected savannahs while others showed the same scheme in protected ones. Diversity indexes indicated a good distribution of species in the two savannah types. The woody density showed a higher value in protected than unprotected savannah at shrub layer level. The basal area was significantly higher in the protected savannah than unprotected one at the two woody layer levels. It can be concluded that biodiversity conservation in surrounding unprotected areas should be of great importance to increase biodiversity conservation by protected area whether specific actions were implemented.     

Characterisation of alternative stable vegetation assemblages in a mesic savannah in Kenya

The phenomenon of sharp boundaries between distinctive vegetation types occurring under the same climatic conditions has often been interpreted by plant ecologists to characterise alternative stable states (ASS). The phenomenon may be relevant in explaining two strikingly different vegetation formations (broad-leaved nonspiny Combretum and fine-leaved spiny Acacia) co-occurring in mesic savannah of southeastern Kenya. We hypothesise that the two vegetation within southeastern Kenya ecosystems represent ASS whose transition may be a response to soil characteristics switch. To explore our hypothesis, we analysed empirical field data of woody species and soil characteristics from 57 plots that included 25 from Combretum and 32 from Acacia vegetation formations. We compared floristic composition and soil characteristics between the two systems and correlated edaphic statuses and vegetation states. We encountered 2,749 woody plant individuals, representing 115 species, 87 genera and 40 families. We found that the two vegetation had discrete woody species composition and soil characteristics, and also a significant species–edaphic association. The results are consistent with the ASS theory demonstrating that soil characteristics are among the important micro-environmental filters driving and maintaining woody vegetation mosaics in the tropics. Importantly, understanding ASS has ramifications for sustainable utilisation of woody plant resources in East African savannahs.     

Beyond the tropics: forest structure in a temperate forest mapped plot

Question: How do the diversity, size structure, and spatial pattern of woody species in a temperate (Mediterranean climate) forest compare to temperate and tropical forests? Location: Mixed evergreen coastal forest in the Santa Cruz Mountains, California, USA. Methods: We mapped, tagged, identified, and measured all woody stems (≥1 cm diameter) in a 6‐ha forest plot, following Center for Tropical Forest Science protocols. We compared patterns to those found in 14 tropical and 12 temperate forest plots. Results: The forest is dominated by Douglas‐fir (Pseudotsuga menziesii) and three species of Fagaceae (Quercus agrifolia, Q. parvula var. shrevei, and Lithocarpus densiflorus), and includes 31 woody species and 8180 individuals. Much of the diversity was in small‐diameter shrubs, treelets, and vines that have not been included in most other temperate forest plots because stems <5‐cm diameter had been excluded from study. The density of woody stems (1363 stems ha^?1) was lower than that in all but one tropical plot. The density of large trees (diameter ≥30 cm) and basal area were higher than in any tropical plot. Stem density and basal area were similar to most other temperate plots, but were less than in low‐diversity conifer forests. Rare species were strongly aggregated, with the degree of aggregation decreasing with abundance so that the most common species were significantly more regular than random. Conclusions: The patterns raise questions about differences in structure and dynamics between tropical and temperate forests; these need to be confirmed with additional temperate zone mapped plots that include small‐diameter individuals.     

Lowland boreal forests characterization in Algonquin Provincial Park relative to beaver (Castor canadensis) foraging and edaphic factors

Beaver (Caster canadensis) foraging and edaphic conditions can modify the vegetational characteristics of woody plant community in lowland boreal forests. Effective management of these areas requires an understanding of the relative contribution of these factors in shaping the woody plant community structure. Our objective was to quantify the effects of herbivory by beavers and edaphic conditions on woody plant community organization of lowland boreal forests surrounding beaver ponds. Woody vegetation and soils were sampled at 15 ponds occupied by beavers and one other pond abandoned by them in southern Algonquin Park, Ontario. We measured spatial variation in plant diversity, foraging rates and sapling recruitment of trees and shrubs along gradients of beaver foraging intensity and soil moisture, P, K, Mg, and pH. Beavers fed preferentially on a small number of deciduous species and the number of cut stems declined sharply with increasing distance from ponds. Conifers increased in relative dominance to deciduous species in the presence of beavers. Plant species richness and stem and basal area diversity peaked at intermediate distances (about 25 m) from ponds. Sapling recruitment by non-preferred species was positively related to foraging intensity. Total stem abundance and basal area and sapling recruitment by four preferred species (Populus tremuloides, Acer rubrum, Acer saccharum and Corylus cornuta) were negatively related to foraging intensity. However, by including Alnus rugosa and Salix bebbiana (also preferred by beavers) these patterns changed, becoming positively related to foraging intensity. There was also a pronounced gradient in soil moisture, which also decreased with distance from ponds. The other measured edaphic variables did not vary consistently with distance from ponds. Sapling recruitment in mesic versus xeric species varied consistently with hydrid conditions along the moisture gradient, such that variation in moisture also could produce the observed pattern of plant diversity. Diversity patterns changed three years after beaver abandonment of a pond, though sapling recruitment patterns in preferred and non-preferred species around the abandoned pond were similar to the occupied ponds. These observations suggest spatial variation in woody plant richness and diversity could be determined by combined effects of both herbivory (disturbance by beavers) and variable responses of different species to edaphic conditions.     

Effects of termite mounds on composition,functional types and traits of plant communities in Pendjari Biosphere Reserve (Benin,West Africa)

Understanding the role of termite mounds in biodiversity and ecosystem functioning is a priority for the management of tropical terrestrial protected areas dominated by savannahs. This study aimed to assess the effects of termite mounds on the diversity of plant functional types (PFTs) and herbaceous’ net aboveground primary productivity (NAPP) in plant communities (PCs) of the Pendjari Biosphere Reserve. PCs were identified through canonical correspondence analysis performed on 96 phytosociological ‘relevés’ realized in plots of 900 m². PFTs’ diversity was compared between savannahs and mounds’ plots using generalized linear models. In each plot, 7 m² subplots were harvested and NAPP was determined. Linear mixed models were performed to assess change in herbaceous NAPP regarding species richness, graminoids’ richness, specific leaf area and termite mounds. There is no specific plant community related to mounds. However, the occurrence of termite mounds induced an increase of woody and forbs diversity while the diversity of legumes and graminoids decreased. These diversity patterns led to decreasing of PCs’ NAPP. This study confirms that termite‐induced resource heterogeneity supports niche differentiation theory and increased savannah encroachment by woody species.     

Is the Peltogyne gracilipes monodominant forest characterised by distinct soils?

Various explanations have been put forward for monodominance in otherwise diverse tropical forests. This study assesses if the monodominance of Peltogyne gracilipes on Maraca Island in the northern Amazon can be related to edaphic factors. The basal area of P. gracilipes and the five other most common tree species on Maraca Island (Astrocaryum aculeatum, Attalea maripa, Ecclinusa guianensis, Licania kunthiana and Pradosia surinamensis) were recorded in 30 regularly-spaced 0.5 ha plots distributed over an area of 25 km², for which data on topography and concentration of mineral elements in the soil were also obtained. Stems of P. gracilipes accounted for ≥50% of the basal area in five of the plots, which we consider indicative of monodominance, whilst the highest relative basal area that any of the other species achieved in any plot was 31%. The soils data explained more of the variation in the basal area of P. gracilipes than it did for the other five species. The presence vs. absence and basal area of P. gracilipes was positively related to concentrations of magnesium (Mg), aluminium (Al), iron (Fe), phosphorus (P) and silt in the soil and to Mg:Ca ratios. These soils were found in the plots at the lowest elevations, which suggests that drainage factors may also be important. Overall, our results suggest that edaphic factors may explain, at least partially, monodominance in this Amazonian forest.     

Structural and floristic characteristics of some monodominant and adjacent mixed rainforests in New Caledonia

Nothofagus spp. dominate the upper canopy of some rainforests on ultramafic soils in New Caledonia. These monodominant forests typically occur within, or contiguous with, larger areas of mixed‐canopy rainforest. In this study the structure, diversity and composition of six Nothofagus‐dominated plots were investigated, and comparisons were made with three adjacent mixed rainforest plots. Stand density and basal area (all stems ≥ 1.3 m high) in the Nothofagus plots were in the range 16,056–27,550 stems/ha and 43.1–69.9 m²/ha, respectively. There was no significant difference (P ≥ 0.05) in total stand density or basal area between the paired Nothofagus and mixed rainforests, but there were consistently fewer trees and less basal area of trees ≥ 40 cm d.b.h. in the Nothofagus forests. Species richness, species diversity (Shannon‐Wiener, based on basal area) and equitability (based on basal area) of trees ≥ 20 cm d.b.h. on 0.1 ha Nothofagus plots were in the range 4–17, 0.96–3.76 and 0.45–0.87, respectively. No significant differences (P ≥ 0.05) were recorded in these three parameters between the paired Nothofagus and mixed rainforests, although species diversity was consistently lower in the paired Nothofagus forests. Comparison of dominance by density and basal area indicated that although the uppermost canopy of the Nothofagus forests was dominated by Nothofagus (70–95%), the basal area and density contribution was ≤ 55% except at Col de Yaté (≈ 85%). Analysis of similarity indicated no significant difference in stand composition of trees ≥ 20 cm d.b.h. (following removal of Nothofagus from the data set) between Nothofagus and mixed rainforests using basal area, density or presence‐absence data. It is concluded that the Nothofagus‐dominated forests differ from the adjacent mixed rainforests mainly by (1) dominance of the uppermost canopy, without necessarily dominance of the stand by basal area or density, and (2) the smaller basal area contributed by large trees (all species).     

Long‐term directional changes in upland Quercus forests throughout Oklahoma,USA

Questions: (1) How have the composition and structure of undisturbed upland Quercus forests changed over 50 years across a large region and moisture gradient; (2) What factors are associated with long‐term and broad‐scale changes in these forests? Location: Oklahoma, USA. Methods: We re‐sampled 30 forest stands originally sampled in the 1950s across a large geographical area and compared basal area, tree density, and sapling density between the sampling periods using paired t‐tests, CCA, and DCA. We examined vegetation dynamics in the context of drought indices compiled for the sample period. Results: Total and Quercus stellata basal area and tree density increased, but Q. stellata and Q. marilandica sapling density decreased. Juniperus virginiana and woody species richness increased for all measures. DCA indicated that re‐sampled stands generally changed from Q. stellata–Q. marilandica‐dominated forests to forests with greater woody species richness and more J. virginiana. Q. stellata remained a dominant tree species; otherwise, composition shifted towards mesophytic and invasive woody species. Measurements taken in the 1950s immediately followed a major drought; whereas subsequent decades were significantly moister. Conclusions: Fire exclusion and drought may have played an important role in driving changes towards lower dominance by Quercus, increased importance of mesophytic and invasive species, and greater woody species richness. These phenomena are similar to those found in Quercus‐dominated forests throughout the northern hemisphere.     

Effects of Forest Use on Aphyllophoraceous Fungal Community Structure in Sarawak, Malaysia

Aphyllophoraceous fungi are expected to reflect changes in the environmental conditions caused by forest use. To reveal the effects of forest uses on the fungal community structure, we performed a 3‐month survey of aphyllophoraceous species in five forest types (undisturbed primary forest, isolated patches of primary forest, old and young fallow forest, and rubber plantations) in Sarawak, Malaysia in 2005. We used a canonical correspondence analysis (CCA) to reveal the relationships between fungal community composition and the environmental variables (canopy openness, soil water potential, amount and composition of coarse woody debris, litter mass, basal area, plant species composition). A total of 155 samples from 67 species were collected during the study period. The fungal species density represented by the number of species in a transect differed significantly among forest types. The fungal species density increased significantly with increasing number of pieces of coarse woody debris (CWD), but decreased significantly with increasing the scores of second axis of principal component analysis (PCA) for plant species composition. In the CCA ordination, automatic forward selection revealed that only the number of pieces of CWD significantly affected the fungal species composition. The occurrences of Flabellophora licmophora, Coriolopsis retropicta, Microporus vernicipes, and Amauroderma subrugosum were positively correlated with the number of pieces of CWD. Our study clearly demonstrated that forest use negatively affected aphyllophoraceous fungal diversity and suggest that the quantity of CWD would be an important determinant of fungal diversity and composition.     

Changes in the plant community of a Brazilian grassland savannah after 22 years of invasion by Pinus elliottii Engelm

Abstract

Background: The invasion by Pinus elliottii is one of the most serious threats to the remaining native cerrado vegetation in São Paulo State, Brazil, causing biodiversity losses yet to be evaluated. We conducted a study in an area where P. elliottii began establishing in 1988.

Aims: To estimate diversity losses in the plant community and to understand the floristic and structural changes resulting from pine tree invasion of grassland savannah.

Methods: All plants taller than 50 cm were sampled in 35 plots (64 m² each) within an area densely invaded by P. elliottii and in 10 plots in non-invaded grassland savannah. Density, species richness, diversity, ground cover and spatial distribution were compared by Wilcoxon tests, non-metric multidimensional scaling and Payandeh indices.

Results: Twenty-two years after the arrival of the first invasive trees (founders), the grassland savannah has become a dense pine forest with 12,455 individuals ha^?1, a basal area of 26.44 m² ha^?1, a sparse native woody understory comprised of 16 species (H'?=?0.44), density of 1210 individuals ha^?1 and the herbaceous layer totally absent.

Conclusions: Invasion by Pinus elliottii has completely changed the structure of the grassland savannah and caused severe plant diversity losses. Native species surviving the invasion in the understory do not typically represent the previous composition and functional traits of the native vegetation.     

Recovery of floristic diversity and basal area in natural forest regeneration and planted plots in a Costa Rican wet forest

When compared to planted reforestation, natural unassisted regeneration is often reported to result in slow recovery of biomass and biodiversity, especially early in succession. In some cases, naturally regenerating forests are not comparable to the community structure of primary forests after many decades. However, direct comparison of the outcomes of tropical forest restoration and natural regeneration is hindered by differences in metrics of forest recovery, inconsistency in land use histories, and dissimilarities in experimental design. We present the results of a replicated reforestation experiment comparing natural regeneration and polyculture tree planting at multiple diversity levels (3, 6, 9, or 12 native tree species), with uniform land use history and initial edaphic conditions. We compare the recovery of basal area and floristic diversity in these treatments after 5 yr of succession. Total basal area was higher in planted plots than in naturally regenerating plots, but it but did not vary among the different planted diversity levels. The basal area of woody recruits did not differ among treatments. The diversity of woody recruits increased substantially over time but did not vary among planting treatments. Species composition trajectories showed directional turnover over time, with no consistent differences among treatments. The convergence of restoration trajectories and similarity of floristic community diversity and composition across all treatments, after only 5 yr, provides evidence of the viability of natural regeneration for rapid restoration of forest biodiversity.     

Vegetation patterns and environmental gradients in tropical dry forests of the northern Yucatan Peninsula

Patterns of plant species composition and their relationships to soil and topographic variables were investigated in tropical dry forests across the north central Yucatan, Mexico. Seven sites were studied in the oldest accessible forests along a 200–km transect oriented northwest to southeast; an eighth site was located in a little‐disturbed area located 75 km northeast of the transect. Two of the sites were on Mayan ruins. All sites were sampled using 9–24, 10m × 20m plots (<n= 132) for woody stems ≥ 3.0 cm diameter breast height. The important natural forest species were Bursera simaruba, Caesalpinia gaumeri, Gymnopodium floribundum, Piscidia piscipula, and Thouinia paucidentata. The two most important woody species in ruin woodlands were Brosimum alicastrum and Croton lundellii. Forest plots (n=108) had 17 species on average, ruin plots (n= 24) nine species. Mean basal area of stems at the forest plots (20.7 m².ha^‐1) was lower than in ruin plots (28.4 m².ha^‐1). Detrended Correspondence Analysis generally placed plots by site along the geographic transect. Natural forest plots and sites were separated from the plots on ruin sites. The five soil and topographic variables (slope, soil depth, percent surface rock, soil pH, total soil organic matter) differed significantly among sites. Plot values were correlated with DCA axe scores. Intersite floristic variation reflects an overall west to east environmental gradient affected by climate.     

Cattle and Weedy Shrubs as Restoration Tools of Tropical Montane Rainforest

Over the last 150 years, a large proportion of forests in Latin America have been converted to pastures. When these pastures are abandoned, grasses may slow re‐establishment of woody species and limit forest regeneration. In this study, we explored the use of cattle in facilitating the establishment of woody vegetation in Colombian montane pastures, dominated by the African grasses Pennisetum clandestinum (Kikuyo) and Melinis minutiflora (Yaraguá). First, we described woody and herbaceous vegetation in grazed and non‐grazed pastures. Second, we tested the effect of grazing and seed addition on the establishment and growth of woody species. We also determined if the effect of grazing was different in P. clandestinum and M. minutiflora pastures. We found that low stocking density of cattle greatly increased density, number of branches per individual (a measure of “shrubiness”), and basal area of woody species, but also reduced woody plant species richness and diversity. In the grazed area, the shrubs Baccharis latifolia (Chilca) and Salvia sp. (Salvia) were the most abundant. The combined effect of grazing and shading from the shrubs reduced herbaceous vegetation by 52 to 92%. In the grazing/seed addition experiment, grazing increased establishment of woody seedlings, particularly of the shrub Verbesina arborea (camargo), but the largest effect was seed addition. Where grasses are an important barrier to regeneration, grazing can facilitate the establishment of shrubs that create a microhabitat more suitable for the establishment of montane forest tree species.     

Composition of Woody Species in a Dynamicforest–woodland–savannah Mosaic in Uganda: Implications for Conservation and Management

Forest–woodland–savannah mosaics are a common feature in the East African landscape. For the conservation of the woody species that occur in such landscapes, the species patterns and the factors that maintain it need to be understood. We studied the woody species distribution in a forest–woodland–savannah mosaic in Budongo Forest Reserve, Uganda. The existing vegetation gradients were analyzed using data from a total of 591 plots of 400 or 500 m² each. Remotely sensed data was used to explore current vegetation cover and the gradients there in for the whole area. A clear species gradient exists in the study area ranging from forest, where there is least disturbance, to wooded grassland, where frequent fire disturbance occurs. Most species are not limited to a specific part of the gradient although many show a maximum abundance at some point along the gradient. Fire and accessibility to the protected area were closely related to variation in species composition along the ordination axis with species like Cynometra alexandri and Uvariopsis congensis occurring at one end of the gradient and Combretum guenzi and Lonchocarpus laxiflorus at the other. The vegetation cover classes identified in the area differed in diversity, density and, especially, basal area. All vegetation cover classes, except open woodland, had indicator species. Diospyros abyssinica, Uvariopsis congensis, Holoptelea grandis and all Celtis species were the indicator species for the forest class, Terminalia velutina and Albizia grandbracteata for closed woodland, Grewia mollis and Combretum mole for very open woodland and Lonchocarpus laxiflorus, Grewia bicolor and Combretum guenzi for the wooded grassland class. Eleven of the species occurred in all cover classes and most of the species that occurred in more than one vegetation cover class showed peak abundance in a specific cover class. Species composition in the study area changes gradually from forest to savannah. Along the gradient, the cover classes are distinguishable in terms of species composition and vegetation structure. These classes are, however, interrelated in species composition. For conservation of the full range of the species within this East African landscape, the mosaic has to be managed as an integrated whole. Burning should be varied over the area with the forest not being burnt at all and the wooded grassland burnt regularly. The different vegetation types that occur between these two extremes should be maintained using a varied fire regime.     

Legacy of thinning on woody species composition and structure in southern Appalachian Mountain hardwood forests: restoration implications

In the Appalachian Mountains, Liriodendron tulipifera monocultures are widespread, with these forests lacking both species and structural diversity. In this study, we developed models that described the effects of thinning treatments, conducted almost 60 years ago, on the density, composition, and functional identity of the woody understory in L. tulipifera forests. The woody understory of these thinned L. tulipifera forests was diverse, with the small seedling (<1.4 m), large seedling (≥1.4 m and <2.54 cm dbh), and sapling (≥2.54 and <12.7 cm) layers possessing 38, 32, and 23 species, respectively. Although model performance was low to moderate (r² = 0.05–0.40), we found that legacy effects, alone or in combination with environmental variables, explained, in part, the variability associated with the density, composition, and functional identity of the small seedling, large seedling, and sapling size classes, with the relative influence of legacy versus environmental effects varying by metric and size class. Post-thinning basal area and/or percent of basal area removed were not the primary legacy effects influencing the woody understory. Instead, legacy effects associated with species composition of the overstory before and/or after thinning along with average stem diameter post-thinning, variation in stem diameter post-thinning, and age at the time of thinning were more influential than density or thinning intensity. This study provides evidence that conserving species diversity during forest management activities can have positive long-term effects on composition and function of the woody understory and increase restoration potential.     

Liana habitat associations and community structure in a Bornean lowland tropical forest

Lianas (woody vines) contribute substantially to the diversity and structure of most tropical forests, yet little is known about the importance of habitat specialization in maintaining tropical liana diversity and the causes of variation among forests in liana abundance and species composition. We examined habitat associations, species diversity, species composition, and community structure of lianas at Sepilok Forest Reserve, Sabah, Malaysia in northeastern Borneo among three soil types that give rise to three distinct forest types of lowland tropical rain forest: alluvial, sandstone hill, and kerangas (heath) forest. Alluvial soils are more nutrient rich and have higher soil moisture than sandstone soils, whereas kerangas soils are the most nutrient poor and drought prone. Lianas ≥0.5-cm in diameter were measured, tagged, and identified to species in three square 0.25-ha plots in each forest type. The number of lianas ≥0.5 cm did not differ significantly among forest types and averaged 1348 lianas ha⁻¹, but mean liana stem diameter, basal area, estimated biomass, species richness, and Fisher’s diversity index were all greater for plots in alluvial than sandstone or kerangas forests. Liana species composition also differed greatly among the three habitats, with 71% of species showing significant positive or negative habitat associations. Sandstone forests were intermediate to alluvial and kerangas forests in most aspects of liana community structure and composition, and fewer species showed significant habitat associations with this forest type. Ranking of forest types with respect to liana density, biomass, and diversity matches the ranking in soil fertility and water availability (alluvial > sandstone hill > kerangas). These results suggest that edaphic factors play an important role in maintaining liana species diversity and structuring liana communities.     

Population structure and succession in temperate forests of southwestern Japan

In the temperate forests of southwestern Japan, the population density of woody plants in the community increases in the early stage of secondary succession, reaches a peak in the old oak-chestnut forest, and decreases towards the climax beech forest. The species richness and diversity of woody plants also show a trend similar to that of the population density. The canopy-tree population decreases in the course of the succession while the basal area increases, showing a self-thinning process. The species richness, diversity and population density of herbaceous plants are much influenced by the dominance of the bamboo, Sasa palmata. The life-history traits of trees, lower trees and shrubs are discussed in relation to their shoot system, reproductive pattern and successional processes.     

Plant species diversity and tree population structure of a humid tropical forest in Tamil Nadu, India

Vegetation structure and species composition of tropical ecosystems were studied through nine transects at Veerapuli and Kalamalai reserve forests in the Western Ghats of Tamil Nadu, India. Species diversity, dominance, species richness and evenness indices of plant communities and also population structure of woody plants were enumerated. A total of 244 species (183 genera and 76 families) were recorded. Species richness (number of species) were 82,142 and 96 species per 0.3 ha respectively for the study areas of low-elevation forest (LEF), mid-elevation forest (MEF) and high elevation forest (HEF). Species diversity indices were greater in MEF compared to the other two forests except juveniles. In contrast, greater dominance value indices were recorded in LEF than other forests. Density and basal area of the MEF were twice greater than the LEF, while HEF showed greater tree density and low basal area when compared to LEF. The stem density and species richness (number of species) decreased with increased size classes of trees observed in the present study indicated good regeneration status. Population structure of juveniles and seedlings also reflects good regeneration status. Terminalia paniculata (IVI of 99.9) and Hopea parviflora (IVI of 103.8) were dominant tree species respectively in LEF and MEF whereas in HEF Agrostistachys meeboldii (63.65), Cullenia excelsa (63.67) and Drypetes oblongifolia (39.67) share the dominance. Past damage (anthropogenic perturbation) may be one of the reasons for single species dominance in LEF and MEF. Occurrence of alien species such as Eupatorium odoratum and Ageratum conyzoides also indicated the past disturbance in LEF. The variations in plant diversity and population structure are largely due to anthropogenic perturbation and other abiotic factors.     

Floristic composition,structure and regeneration status of Masha forest,south‐west Ethiopia

The natural forest of Masha was studied to determine the species composition and population structure of woody species in the area. A total of 130 plant species belonging 61 families were recorded, in which family Acanthaceae was represented by 11 species followed by Rubiaceae (10) and Asteraceae (9). The composition and population structure of woody species, with diameter at breast height (DBH) >2.5 cm and height >2 m, and their regeneration were assessed in 65 sample plots of 400 m² each. The density for trees and shrubs with DBH >2.5 cm was 1681 ind.ha^?1, and the basal area of the study area was 142.6 m² ha^?1. Four community types were recognized. This forest is of international and national conservation importance given its high biodiversity. Managing the remaining forest would be an appropriate option for sustainable management of biodiversity.