Woody plant diversity,composition and structure in relation to environmental variables and land-cover types in Lake Wanchi watershed,central highlands of Ethiopia

Knowledge of vegetation dynamics associated with human land-use change and environmental variables is crucial for sustainable watershed management. The objective of this study was to analyse woody plant diversity in response to the effects of anthropogenic disturbances, and topographic variables in different land-cover types. Woody plants ≥5 cm diameter at breast height (DBH) were recorded from 20-by-20 m plots, those <5 cm DBH were recorded from 10-by-10 m plots, and tree seedlings were recorded in 3-by-3 m plots. Nonmetric multidimensional scaling with Bray–Curtis distance was employed to analyse woody species composition. Woody species richness was analysed using generalised linear modelling. Tree diameter-class distributions were examined for population structure. The study identified 104 woody plants belonging to 52 families, where 74.5% were indigenous and 16.7% were endemic to Ethiopia. Asteraceae, Fabaceae and Rosaceae were the most species-rich families. There was evidence for the effect of anthropogenic disturbance and elevation on woody species composition. Wetlands contained the highest woody species richness, while woody species richness declined with increasing elevation and disturbance. Evidence of good regeneration was observed in wetlands. To sustain the ecological functions and services provided by the watershed, rehabilitation of the forest and shrub-cover should be a high priority for local management authorities.     

Macrotermes mounds as sites for tree regeneration in a Sudanian woodland (Burkina Faso)

The importance of mounds created by Macrotermes subhyalinus as safe site for tree regeneration was analysed in a savannah woodland of Burkina Faso. Plantlets (height <1.5 m) were sampled and followed over an year in 72 × 4 m² quadrats located on M. subhyalinus mounds and adjacent areas. The mechanisms of regeneration and plantlet mortality were also determined. We identified three regeneration mechanisms: seedlings regenerated by seed (abundant on mounds), sprouts (abundant on adjacent areas) and root suckers (a rare case on both sites). A total of 37 species representing 17 families and 30 genera were found on all quadrats, of which 29 species were found on termite mounds and 22 species on adjacent areas. Species richness and density of plantlets at the 4 m² scale were higher on mounds than in the adjacent area (P < 0.05). Among plantlet categories, seedling density was significantly different among microhabitats (P < 0.001) and across sampling periods (P < 0.01) and, the majority of plantlet individuals appeared within the 0–25 cm height class. The mortality of plantlets and particularly seedling mortality differed significantly between microhabitats (P < 0.01) and between periods (P < 0.01), whereas more than half the variation in the death of Acacia erythrocalyx seedlings (the most abundant species) were related to the density of the live seedlings of the same species (P < 0.001). The observed mortality rate was way below 50%; plantlet density remained higher on mound during sampling periods as compared to the adjacent area. It can thus be concluded that Macrotermes termite mounds are favourable sites for the recruitments of woody plants in savannah woodlands.     

Canopy cover and tree regeneration in old-growth cove forests of the Appalachian Mountains

Relationships between canopy cover and tree regeneration were determined for various species in cove forests of the Great Smoky Mountains. Old-growth stands were sampled with six plots covering a total area of 4.8 ha. Each plot was subdivided into contiguous 10×10 m quadrats. Canopy cover overlying each of the 480 quadrats was characterized with three different indices based on visual estimates of cover. Influences of: (1) overlying cover, (2) proximate openings, and (3) total area of proximate openings on quadrat regeneration densities were determined. Most species reproducing by seed and some species reproducing by vegetative means had higher densities in quadrats with openings, but only the intolerants were highly dependent on gaps. Tsuga canadensis, a very shade-tolerant species, was one of the few species with abundant regeneration beneath dense canopy cover. In general, understory areas near gaps had somewhat higher regeneration densities than other areas with overlying cover. Several shade-tolerant species showed a positive regeneration density response to canopy openings and an ability to regenerate in gaps 0.01–0.03 ha in area. These openings were too small for intolerant species. Many species exhibited a positive response to total size of the proximate opening(s). A sharp increase in regeneration density with area of the opening(s) was evident at approximately 0.04 ha for the shade-intolerant species.     

Riparian vegetation change in upstream and downstream reaches of three temperate rivers dammed for hydroelectric generation in British Columbia,Canada

River flow regulation by dams for hydroelectric generation has been a common practice worldwide for centuries, with diverse ecological impacts. We studied upstream and downstream reaches of three British Columbia Hydro reservoirs on the Allouette, Coquitlam, and Cheakamus Rivers to determine if riparian plant communities were affected by the dams. We determined cover of all plants in consecutive 1 m² quadrats along five to six 14 m-long belt transects in each 300 m upstream and downstream sections of these rivers. We encountered 166 plant species in a total of 448 quadrats. Differences in plant communities (abundance, species richness, diversity) amongst rivers were larger than that between the upstream versus downstream of the rivers. This suggests that any difference caused by reservoir management was within the natural range of variation found across the rivers. We found significant reductions in the occurrences of red alder and western red cedar downstream of reservoirs. The lack of regeneration of these two species may be attributable to the reduction in extremes of flow variation and lack of sediment transport due to the reservoirs. Coordinated flow management can help mitigate these downstream impacts.     

Effects of red deer on tree regeneration and growth in Aorangi Forest, Wairarapa

New Zealand forests have been substantially modified by introduced red deer over the past century. New Zealand’s indigenous forest managers need to know if regeneration of palatable tree species can be restored following control or eradication of browsing ungulates. Aorangi Forest, Wairarapa, suffered dramatic changes in forest understorey composition by the 1950s after more than seven decades of colonisation by red deer (Cervus elaphus), feral goats (Capra hircus) and pigs (Sus scrofa). Since then feral goats have been eradicated, but red deer and pigs persist throughout Aorangi Forest despite ongoing recreational hunting. This study uses data from paired fenced and unfenced plots established at seven sites in Aorangi Forest between 1981 and 1987, and re-measured in 2004, to show the effects of ungulates on tree (≥ 2 cm diameter at breast height) regeneration and growth. Our results show that browsing by red deer has prevented regeneration of kanono (Coprosma grandifolia), a highly palatable, fast-growing sub-canopy hardwood tree. Deer reduced the growth of mahoe (Melicytus ramiflorus) trees, probably by directly browsing epicormic shoots. The regeneration of other less palatable sub-canopy trees (e.g. porokaiwhiri, Hedycarya arborea), and slower-growing canopy species (e.g. hinau, Elaeocarpus dentatus and rewarewa, Knightia excelsa) appears to have been unaffected by deer browsing. Accordingly, tree species composition does not appear to have been greatly affected by browsing from deer populations in Aorangi Forest over the past two decades.     

Use of Terra Firme Forest by Caicubi Caboclos,Middle Rio Negro,Amazonas, Brazil. A Quantitative Study

Use of Terra Firme Forest by Caicubi Caboclos, Middle Rio Negro, Amazonas, Brazil. A Quantitative Study. An ethnobotanical study was carried out with caboclos from the village of Caicubi, Roraima State, Brazil. This village is located between the Rio Negro and Rio Branco. The data were collected in 1 ha of terra firme forest and involved caboclo knowledge of the tree species with individuals dbh ≥ 10 cm. A total of 11 informants between 34 to 74 years of age were interviewed. The caboclos used 185 (98%) of the 189 species analyzed. The family with the highest use value for the community was Arecaceae. The species with the highest use value was Bertholletia excelsa. Arecaceae, Lecythidaceae, and Sapotaceae showed a wide variety of uses. The uses were grouped into eight categories; those with the highest use values were firewood, technology, and construction. The mean use value for species was 1.6. The most intensely used resources in the forest were wood, leaves, spines, and exudates.     

Woody plants' diversity,structural analysis and regeneration status of Wof Washa natural forest,North‐east Ethiopia

Wof‐Washa forest is one of the few remaining dry Afromontane forests in the central plateau of Ethiopia. Woody species composition, structure and regeneration patterns of this forest were studied to generate information essential for formulating feasible management options for the forest. Vegetation data were collected from 64 quadrats of size 20 m × 20 m, 10 m × 10 m and 5 m × 5 m for tree/shrub, sapling and seedling, respectively, laid systematically along transects. A total of 62 woody species belonging to 54 genera and 40 families were recorded. Rosaceae was the most diverse family with five (12.5%) species followed by Anacardiaceae, Euphorbiaceae and Myrsinaceae with three (7.5%) species each. Tree/shrub, sapling and seedling densities were 699, 1178 and 7618.7 individuals/ha. About 56.7% of the importance value index was contributed by Juniperus procera, Maytenus arbutifolia, Podocarpus falcatus and Ilex mitis. Vegetation classification resulted in five plant communities: Ilex mitis – Maytenus obscura, Galiniera saxifraga – Maesa lanceolata, Juniperus procera – Erica arborea, Podocapus falcatus – Allophylus abyssinicus and Pittosporum viridiflorum – Polycias fulva community types. Regeneration status of all the woody plant species was categorized as ‘Good’ (28%), ‘Fair’ (19%), ‘Poor’ (8%), ‘None’ (40%) and ‘New’ (5%).     

Variation in structural diversity and regeneration potential of tree species in different tropical forest types of Similipal Biosphere Reserve,Eastern India

Understanding the regeneration potential of tree species in natural forest ecosystems is crucial to deliver suitable management practices for conservation of biodiversity. We studied the variation in structural diversity and regeneration potential of tree species in three different tropical forest types, namely: Dry Deciduous forest (DDF), Moist Deciduous forest (MDF) and Semi-evergreen forest (SEF) of Similipal Biosphere Reserve (SBR), Eastern India. Random sample plots were laid for studying the diversity and distribution pattern of tree, sapling, and seedling stages of the tree species. A total of 84 species belong to 73 genera and 35 families were recorded from the study area. The highest species richness was reported for tree (54 species) in DDF, sapling (24 species) in MDF and seedling (22 species each) in SEF and DDF. The overall density of trees with GBH (Girth at Breast Height) ≥ 10 cm was 881 individuals/ha. The regeneration potential of tree species was poor in DDF (39%) where as it was fair in SEF (43%) and MDF (49%). Most of the dominant tree species at each forest type performed good regeneration. The species such as Ehretia laevis Roxb., Bridelia retusa (L.)A.Juss., Mitragyna parviflora (Roxb.) Korth., Terminalia tomentosa Wight & Arn., Terminalia chebula Retz., Terminalia bellirica (Gaertn.) Roxb.etc. had either no regeneration or poor regeneration potential need immediate attention for conservation measures. The diversity of standing trees did not correlate with seedling or sapling diversity in all the cases but there was significant correlation among seedling and sapling diversity found in DDF (r = 0.67, p ≤ 0.05) and SEF (r = 0.83, p ≤ 0.05). Further, the diversity of tree species increased with their age (trees > saplings > seedlings) and the stem density decreased with their age (trees < saplings < seedlings) in all three forest types. The results of our study would be helpful in understanding the structural attributes, diversity and regeneration potential of different tropical forest types of India for their better conservation and management.     

Regeneration of indigenous trees in Mgahinga Gorilla National Park, Uganda

This study examines the regeneration of indigenous tree species in the formerly encroached area in Mgahinga Gorilla National Park (MGNP), south‐western Uganda. Before gazetting in 1992, MGNP had basically been agricultural land for well over 50 years. The distribution of exotic vegetation was established using a Geographical Positioning System receiver and indigenous vegetation was sampled by establishment of quadrats along transect lines. Observations indicated that approximately 2% of the old cropland was covered by exotic woodlots. Black wattle (Acacia mearnsii) and Eucalyptus trees were found to be the most widely distributed and Pinus patula the least distributed species in the park. Species numbers of indigenous trees (n = 26) were high in the old cropland, compared with twelve species observed in exotic woodlots. The natural forest supported the highest (75%) stem density and the lowest (4%) stem density was recorded in exotic woodlots. Seedling class (< 2 cm, d.b.h.) accounted for the majority of juveniles, with the lowest stem density (1350 seedlings ha^?1) recorded in exotic woodlots compared with 6609 seedlings ha^?1 in the old cropland and 24,625 seedlings ha^?1 in the natural forest. The levels of tree diversity and stocking characteristics recorded under the exotic species suggest that a low diverse community of native species may exploit this environment.     

Large-Scale Patterns of Quercus ilex, Quercus suber, and Quercus pyrenaica Regeneration in Central-Western Spain

In Central-Western Spain, forests and woodlands composed of Quercus sp. support outstanding levels of biodiversity, but there is increasing concern about their long-term persistence due to a lack of regeneration. We hypothesize that this regenerative lack is operating on a large geographic scale; that there are differences in the abundance of regeneration between three oak species; that oak regeneration is governed mainly by forest management and structure; and that shrubs act as important physical protectors of seedlings and saplings. We analyzed whether densities of oak seedlings and saplings in several size classes were related to stand-structure, understory, and physiographic variables potentially affecting regeneration. Data collected at a regional level (1 km × 1 km grid) by the Spanish Forest Inventory were evaluated from 2,816 plots. Results revealed that regeneration failure was common for all size categories, from small seedlings to large saplings, and for the three oak species studied, especially the evergreens. Of the Quercus ilex, Q. suber, and Q. pyrenaica plots studied, 49%, 62%, and 20% were lacking any small seedlings, and 82%, 96%, and 56% did not have any large saplings, respectively. Regeneration was positively correlated with tree cover and density, especially of small and medium-sized trees, and negatively correlated with the presence of large trees, indicating that regeneration failure is mostly associated with more open, uniform, and/or aged woodlands. Regeneration densities of Q. ilex and Q. suber were positively correlated with all understory variables, suggesting that the presence of pioneer shrubs represent a major safe site for early tree recruitment, independent from specific shrub species.     

Viability of ecological processes in small Afromontane forest patches in South Africa

Abstract The conservation of biodiversity is dependent on protecting ecosystem‐level processes. We investigated the effects of fragment size and habitat edge on the relative functioning of three ecological processes – decomposition, predation and regeneration of trees – in small Afromontane forests in KwaZulu‐Natal, South Africa. Ten sampling stations were placed in each of four forest categories: the interior of three large indigenous forest fragments (100 m from the edge), the edges of these large fragments, 10 small indigenous fragments (<1 ha) and 10 small exotic woodlands (<0.5 ha). Fragment size and edge effects did not affect the abundance of the amphipod Talitriator africana, a litter decomposer, and overall dung beetle abundance and species richness significantly. Bird egg predation was marginally greater at large patch edges compared with the other forest categories, while seed predation did not differ among forest categories. Tree seedling assemblage composition did not differ significantly among large patch interiors and edges, and small indigenous fragments. Sapling and canopy assemblage composition each differed significantly among these three indigenous forest categories. Thus, while tree recruitment was not negatively affected by patch size or distance from the edge, conditions in small fragments and at edges appear to affect the composition of advanced tree regeneration. These ecological processes in Afromontane forests appear to be resilient to fragmentation effects. We speculate that this is because the organisms in these forests have evolved under fragmented conditions. Repeated extreme changes in climate and vegetation over the Pleistocene have acted as significant distribution and ecological extinction filters on these southern hemisphere forest biota, resulting in fauna and flora that are potentially resilient to contemporary fragmentation effects. We argue that because small patches and habitat edges appear to be ecologically viable they should be included in future conservation decisions.     

Multiple canopy opening effects on recruited saplings in a typhoon-disturbed tropical rainforest,Taiwan

To investigate the influence of multiple canopy openings on the composition and diversity of recruited saplings in a forest frequently disturbed by typhoons. We conducted tree-by-tree censuses (diameter at breast height ≥ 1 cm) and mapped gaps (canopy height < 5 m) in 1993, 2000, 2008, and 2013 in a tropical mountain zonal foothill evergreen broad-leaved forest in Nanjenshan Nature Reserve, Taiwan. We analyzed the composition and diversity of recruited saplings within a 2.1 ha plot (840 sampling quadrats (5 m × 5 m)) with variable numbers of canopy openings recorded during the study period. Composition of recruited saplings was dissimilar between quadrats that stayed opened and those that stayed closed throughout the study period (pairwise similarity estimates C₀₂ = 0.52, 95% CI = 0.38–0.66). The quadrats under closed canopy had high diversity when weighting rare species (species richness), whereas quadrats with one or two gap opening records during the past 20 years had high diversity when weighting the abundance of species. Although canopy openings provided establishment conditions for saplings of some shade-intolerant species, due to the nature of small gap size, such habitats do not favor the dominance of shade-intolerant species. Even in a frequently disturbed forest, species composition and richness of recruited saplings were mainly contributed by shade-tolerant species. Although multiple canopy openings facilitated the establishment of shade-intolerant species, species diversity in the study forests is possibly mainly mediated by coexistence mechanisms of those shade-tolerant species rather than light-gap-related species strategies.     

Diversity and biovolume of tree species in natural forest ecosystem in the bitumen-producing area of ondo state,Nigeria: a baseline study

Tree species diversity, biovolume and forest stand structure were investigated in natural forest ecosystem located around some selected communities in the bitumen-producing area of Ondo state, Nigeria. Two forest reserves and four free areas distributed in 4 Local Government Areas (LGA) of the state were selected for data collection, out of the total 6 LGAs in the bitumen belt of the state. The two forest reserves are Oluwa FR at Legge in Odigbo LGA and Eba Island FR in Ese-Odo LGA while the four free areas are located close to each of Omotoso community (Odigbo LGA), Ode-Aye community (Okitipupa), Igbo-Egunrin community (Ilaje) and Igbotako community (Okitipupa). Eight plots of equal size (20 × 20 m) were located in each of the selected location, using systematic line transect sampling design. In each plot, all living trees with dbh ≥ 10 cm were identified with their botanical names and their dbhs were also measured. The results of the study reveal that there were ninety nine (99) tropical hardwood timber species (range: 21 to 48 species per selected forest). These species were distributed among twenty nine (29) families. While Funtumia elastica has the highest population distribution across the selected communities’ forest, Euphorbiaceae was the dominant family in the entire area. Although there was a moderate variation in the biodiversity indices among the selected communities’ forest, the Shannon-Weiner diversity index of H¹ = 4.02 and species evenness of E = 0.88 were obtained for the entire study area. Tree density summing up to 2,740 trees/6 ha varied moderately, with a range of 361–609 tree/ha, among the communities. Though most of the trees encountered belonged to the lowest diameter size class, the mean basal area and biovolume were 26.69 m²/ha and 262.36 m³/ha respectively. Recommendations guiding the decision on the allocation of the communities’ forest to the bitumen exploratory industries are made and the need for good forest management of the prospective area of bitumen exploration of Ondo state is emphasized. This is to prevent the imminent loss of biological diversity that would eventually accompany the exploration.     

Biodiversity loss in Appalachian headwater streams (Kentucky,USA): Plecoptera and Trichoptera communities

Government and academic studies indicate that many streams in the Appalachian Mountains have degraded biological communities stemming from a variety of regional landuses. Headwater stonefly (Plecoptera) and caddisfly (Trichoptera) assemblages were assessed between 1999 and 2004 in relation to pervasive landuse disturbances (coal mining and residential) in mountainous areas of eastern Kentucky, USA. Indicator metrics (richness, abundance, tolerance, and an observed/expected (O/E) null model) were compared among 94 sites with different land use pressures including least disturbed reference, residential, mining, and mixed mining and residential categories. Thirty-three stonefly species from 26 genera and 9 families were identified; Leuctra, Acroneuria, Haploperla, and Isoperla comprised the core genera that commonly decreased with disturbance. Caddisflies were represented by 48 species, 32 genera, and 14 families. Core caddisfly genera (Neophylax, Pycnopsyche, Rhyacophila, Lepidostoma, and Wormaldia) were extirpated from most disturbed sites. Species richness was significantly higher at reference sites and reference site mean tolerance value was lowest compared to all other categories; relative abundance of both orders was variable between disturbance groups. Non-metric multidimensional scaling (for riffle-dwelling stonefly and caddisfly genera) clustered reference sites distinctly from most other sites. The O/E index was highly correlated with individual habitat and chemical stressors (pH, conductivity) and on average, it estimated ~ 70% loss of common stoneflies and caddisflies across all disturbed landuse categories. Expected plecopteran and trichopteran communities were radically altered in streams draining mining and residential disturbance. Long-term impacts incurred by both landuses will continue to depress these vulnerable indigenous fauna.     

Tree heterogeneity,resource availability,and larger scale processes regulating arboreal ant species richness

Abstract Processes acting on different spatial and temporal scales may influence local species richness. Ant communities are usually described as interactive and therefore determined by local processes. In this paper we tested two hypotheses linked to the question of why there is local variation in arboreal ant species richness in the Brazilian savanna (‘cerrado’). The hypotheses are: (i) there is a positive relationship between ant species richness and tree species richness, used as a surrogate of heterogeneity; and (ii) there is a positive relationship between ant species richness and tree density, used as a surrogate of resource availability. Arboreal ants were sampled in two cerrado sites in Brazil using baited pitfall traps and manual sampling, in quadrats of 20 m × 50 m. Ant species richness in each quadrat was used as the response variable in regression tests, using tree species richness and tree density as explanatory variables. Ant species richness responded positively to tree species richness and density. Sampling site also influenced ant species richness, and the relationship between tree density and tree species richness was also positive and significant. Tree species richness may have influenced ant species richness through three processes: (i) increasing the variety of resources and allowing the existence of a higher number of specialist species; (ii) increasing the amount of resources to generalist species; and (iii) some other unmeasured factor may have influenced both ant and tree species richness. Tree density may also have influenced ant species richness through three processes: (i) increasing the amount of resources and allowing a higher ant species richness; (ii) changing habitat conditions and dominance hierarchies in ant communities; and (iii) increasing the area and causing a species–area pattern. Processes acting on larger scales, such as disturbance, altitude and evolutionary histories, as well as sampling effect may have caused the difference between sites.     

Patterns of Ephemeroptera taxa loss in Appalachian headwater streams (Kentucky,USA)

Mayflies (Insecta: Ephemeroptera) are common inhabitants of streams throughout the Appalachian Mountains. Headwater mayfly assemblages were evaluated with respect to regional landuse disturbances (coal mining and residential) in eastern Kentucky, USA. Estimates of mayfly taxa richness and relative abundance were compared at 92 sites represented by least-disturbed reference (REF; n = 44), residential only (RESID; n = 14), mixed residential and mining (MINED/RESID; n = 14), and mining only (MINED; n = 20) landuse categories. A total of 48 species from 27 genera and 9 families were identified; Ephemerella, Epeorus, Ameletus, Cinygmula, and Paraleptophlebia comprised the core 5 genera most frequently encountered at REF sites. These same genera (among others) were often reduced or extirpated from other landuse categories. Mean mayfly richness and relative abundance were significantly higher at REF sites compared to all other categories; MINED sites had significantly lower metric values compared to RESID and MINED/RESID sites. Relative mayfly abundance was most strongly correlated to specific conductance (r = 0.72) compared to total habitat score (r = 0.59), but relationships varied depending on landuse category. Non-metric multidimensional scaling (for mayfly taxa) and principal components analysis (for environmental variables) separated REF sites strongly from most other sites. The results indicate that expected mayfly communities are disappearing from streams where mining disturbance and residential development has occurred and because of the long-term impacts incurred by both landuses, recovery is uncertain.     

Shift of Conifer Boreal Forest to Lichen–Heath Parkland Caused by Successive Stand Disturbances

In the southern boreal forest (Québec, Canada), tree harvesting is a major disturbance affecting the dominant black spruce (Picea mariana) stands already suffering from naturally recurrent insect and fire disturbances. Although recovery of the spruce forest after an insect infestation or a fire is possible under current site conditions, it is less likely when both types of disturbance occur during a short period of time. The addition of yet another disturbance, such as tree harvesting, can thus have catastrophic consequences. We analyzed the impact of three successive disturbances—tree harvesting, insect infestation, and fire—on the regeneration of boreal spruce–moss forests within a period of approximately 50 years. The spruce forests were harvested in the 1940s and the 1950s. Recovery from the logging consisted of advance regeneration (spruce layers less than 1 m high that were left intact during clear-cuts), which was burned in 1991. The vegetation cover (mostly heath and lichen species) and soil conditions (acidic, nutrient-poor podzolic soils developed from coarse materials) of the postfire sites that we studied were similar. Stand structure and tree regeneration were documented from large quadrats (0.25 ha) using age, size, and tree ring data from postlogged and postfire spruce. At an early stage of development, the growing advance regeneration was damaged by insect defoliators in the late 1970s and the mid-1980s, and several trees died a few years before the 1991 fire. The successive disturbances considerably reduced the number of seed-bearers, leading to the collapse of postfire regeneration and a shift to parkland. Through a successional trajectory far from the expected trend for boreal forests influenced by single disturbance, the shift resulted in the formation of divergent plant communities. The development of divergent communities at the landscape scale is generally overlooked due to their small size. They indicate, however, the weak resilience of boreal forests faced with cascading perturbations, which are likely to increase in intensively logged areas.     

Structure of ant assemblages on street trees in urban Busan,Korea

Street trees planted in urban areas are one of the smallest urban green habitats; however, their role as a valuable refuge for local biota is poorly understood. The aim of this study was to investigate urban street trees as habitat for ants. We found ants on 195 (92%) of 211 street trees studied. Seventeen ant species were collected from five tree species. The two most common ant species were Tetramorium tsushimae (on 112 trees) and Lasius japonicus (on 93 trees). The number of ant species found per tree ranged from 0 to 5, with a mean of 1.55 ± 0.92. The species composition differed significantly among tree species. Nine ant species (Camponotus vitiosus, Lasius alienus, L. japonicus, Nylanderia flavipes, Crematogaster matsumurai, Crematogaster vagula, Monomorium intrudens, T. tsushimae, and Brachyponera chinensis) nested on the trees, mostly in the root zone. Nests were found on 150 trees but were relatively rare on trees with diameter at breast height of less than 40 cm.     

Lowland rainforests in southern Taiwan and Lanyu,at the northern border of Paleotropics and under the influence of monsoon wind

In order to reveal the characteristics of the vegetation affected by monsoons at the northern border of Paleotropics, a tree-by-tree census was conducted in the lowland forests in the southernmost Taiwan (Nanjenshan) and an adjacent islet (Lanyu). The census recorded a total of 109,060 individuals (≥1-cm diameter at breast height) belonging to 255 vascular tree species in 1330 quadrats (10 × 10 m). Two-way Indicator Species Analysis first classified forest types into two groups, Lanyu and Nanjenshan, reflecting biogeographical differences. Five subgroups were further classified, showing correlations with topographic position indices. Forests located on wind-exposed slopes, regardless of elevations, were characterised by low canopy height, high stem density, high proportion of small stems, and high proportion of warm-temperate-related species, compared with the wind-sheltered communities. However, there were no significant differences in basal area and species diversity. In comparison with other tropical forests, our forests are characterised by high stem density, low diversity and a lack of the pan-Paleotropical dominant Dipterocarpaceae. In conclusion, vegetation in the studied regions not only showed a transition characteristic between Paleotropics and Holarctic Kingdoms in terms of composition, but also showed differentiations caused by their biogeographical history and the interaction between topographic positions and wind stress from monsoons.