Density Of Mature Trees Research Articles

Investigation of Woody Species Structure and Regeneration Status in the Central Rift Valley, Sidama Regional State, Ethiopia

Protected areas are the most commonly used tool for in situ conservation of biodiversity. Selective removal of species proposed by the local communities living surrounding the national park and grazing pressure negatively affect the composition, structure, and regeneration of woody species. Assessment of vegetation structure and regeneration status of woody species is essential for orienting management activities. The purpose of this study was to investigate the floristic composition, population structure, and regeneration status of woody species in the Loka Abaya National Park, to design conservation strategies. A total of 99, 20 m × 20 m quadrats were systematically laid along an established line transect to collect a list of woody species, abundance, height, and diameter at breast height (DBH), while five 3 m × 3 m subquadrats within the main quadrats were established to assess the regeneration status of woody species. In each quadrat, all woody species were identified, counted, and recorded. In each quadrat, all tree and shrub species higher than ≥2 m in height and ≥2 cm in diameter at breast height were measured by a calibrated wooden stick and by a caliper, respectively. Density, frequency, basal area, importance value index (IVI), height, and diameter at breast height (DBH) were used for description of vegetation structure, while the density of mature trees, saplings, and seedlings was used for assessment of regeneration status of woody species. A total of 101 woody plant species representing 40 families in 69 genera were collected, identified, and documented. Fabaceae was the most diverse family representing 16 (15.84%) species, followed by Euphorbiaceae 9 species (8.91%) and Anacardiaceae with 6 species (5.94%). Four families including Combretaceae, Moraceae, Olacaceae, and Tiliaceae were represented by 4 species each. 4 families were also represented by 3 species each, 12 families were represented by two species each, and 18 families were represented by one species. The density of trees was 831.31 individuals ha−1, while the total basal area was 73.18 m2·ha−1. D. angustifolia, C. molle, E. schimperi, R. natalensis, O. europaea L. subsp. cuspidataD. cinerea, A. brevispica, I. mitis, and E. tirucalli were ecologically important woody species. The majority (75%) of woody plant species had a less than 5% importance value index (IVI). The diameter class distribution of selected tree species demonstrated various patterns of population structure, implying the existence of different population dynamics among ecologically important tree species. The regeneration assessment results demonstrate that 32.35% had poor regeneration, 19.12% had good regeneration, 16.17% had fair regeneration, 8.82% lacked regeneration, and 14.08% appeared as newly regenerated species in the national park. The majority of woody species had a small population size, and some of them were found in specific habitats which need attention for conservation, and those woody species lack regeneration study soil seed bank and propagation methods for sustainable conservation.

The effects of fire, climate, and species composition on longleaf pine stand structure and growth rates across diverse natural communities in Florida

The longleaf pine (Pinus palustris) savanna is an endangered ecosystem within a global biodiversity hotspot. However, most studies of longleaf habitats have not considered their distinct structure and function among unique communities, which are critical for developing appropriate management strategies. We aim to assess how differences in climate, fire, and species composition interact and relate to longleaf pine densities and growth rates in distinct communities. We surveyed longleaf pine stand structure (density by size and age classes) and estimated growth rates using 516 tree cores across 5 community types (69 plots, each ≤ 160 m2). Surveys covered the range of longleaf pine in Florida, USA, including the southernmost extent of the species range, and included all communities where longleaf are dominant (sandhill, upland pine, and mesic, wet, and scrubby flatwoods). We used an NMDS ordination to classify communities by species composition. We used linear mixed-effects models to examine the effect of community type on longleaf pine density and growth rates and then used recursive partitioning and regression tree analyses to identify how climate, fire, and species composition affect density and growth rates. We found that stand structure and species composition were different across communities, with upland pine being the most species rich and having the highest density of mature trees, whereas growth rates were not statistically different across communities. Across communities, unique interactions between climate, fire, and species composition, resulted in differences in stand structure and growth rates. In general, tree and grass stage densities were best predicted by species composition and fire rather than by climate, whereas growth rates were best predicted by climate. Having included the southernmost extent of longleafs range we show that longleaf growth rates increased with higher temperatures, but this effect is reversed in dry conditions. Our results suggest that longleaf growth rates across its range will be more sensitive to current and future climate change than longleaf population density. Furthermore, while controlling competition from hardwoods has been a focus of longleaf restoration, our results suggest that species that facilitate longleaf establishment may be equally important in restoring and managing these habitats. Managers should design and apply regional and community specific plans that take into account relationships between fire and associated species composition under a changing climate, which will influence strand structure and tree growth differently in different communities.

Impacts of Industrialization on Plant Species Composition, Diversity, and Tree Population Structure in Tropical Moist Deciduous Forest in Bangladesh

Industrial activities have various effects on biodiversity, posing significant threats to forest ecosystems. The current study describes the species composition, taxonomic diversity, and stand structure at Bhawal Sal forest, Gazipur, Bangladesh, as they are affected by industrialization. To achieve the goal, 30 different categorized industries within the forest were considered sampling points and three distance gradient sites viz. Site-1 = Adjacent to industries (0 m), Site-2 = 160 m distance and Site-3 = 320 m distance from industries were designated as treatments. A total of 90 quadrate plots (10 m × 10 m) were taken randomly, of which 30 plots were from each site. Through forest inventory, 46 species (24 trees, 8 shrubs, 5 climbers, and 9 saplings) were recorded from three sites. The study revealed that the stand density and basal area of mature trees (257 stems ha−1 and 8.06 ± 0.60 m2·ha−1) at Site-1 were significantly lower due to diverse industrial operations than other sites. Statistically, all the biodiversity indices of mature trees; Shannon–Wiener’s index (1.72), Simpsons index (0.82), Margalef’s index (1.38), Pielou’s evenness Index (0.39) was found to be lower at proximity to industries. The lowest species richness (12) of all plants was recorded from Site-1. However, the diameter and height distributions of Site-1 comprised young (10–20 cm·dbh) to medium-sized (20.1–30 cm·dbh) trees, while the medium to large sized (>30 cm·dbh) trees was contained at Site-3 in this study. The population structure of tree species at Site-1 also showed a fluctuating curve. Overall, this study highlights that plant ecosystems and tree population structure have declined tremendously due to industrialization. Hence, the current research could be significant for developing the management framework for the disturbed deciduous forest.

Response of Pear Trees’ (Pyrus bretschneideri ‘Sinkiangensis’) Fine Roots to a Soil Water Regime of Regulated Deficit Irrigation

A field experiment was conducted to evaluate the effects of regulated deficit irrigation (RDI) on the fine root redistribution of mature pear trees in 2009 and 2010. The experiment consisted of four RDI treatments: MRDI-1 and SRDI-1, in which the trees received irrigation replacing 60% and 40% of pan evaporation (Ep) during Stage 1 (cell division stage), and MRDI-1+2 and SRDI-1+2, in which the trees received irrigation replacing 60% and 40% of Ep during Stage 1+2 (cell division and slow shoot growth stage). All the RDI-treated trees received irrigation replacing 80% of Ep (full irrigation) in other stages, and the control trees were fully irrigated during the whole growth season. The results showed that the fine root length density (RLD) of mature pear trees was reduced by water stress. The resumption of full irrigation boosted fine root growth. The RLD of the SRDI-1-treated trees in the irrigated zones recovered in early July, they maintained water and nutrient absorption during the fruit enlargement stage, and the final fruit yield was significantly improved. The RLD of trees in the irrigated zones with MRDI-1 and MRDI-1+2 recovered in July and September, respectively, but there were no significant differences in fruit yield between the MRDI-1, MRDI-1+2, and the control. This indicates that the fruit yield was not negatively or positively impacted by the redistribution of moderate water stress applied during either Stage 1 or Stage 1+2.

Woody Species Diversity and Structure of Protected Woodlands Adjacent to Free Grazing Land Woodland at Dugda Woreda, Oromia, Ethiopia

The study was conducted in protected woodland and free graze woodland located in Dugda Woreda, Oromia state, Ethiopia. The objective of the study was to explore the floristic composition, structure, and regeneration of woody species. In the park, the vegetation ecology has not been studied up to date, which is necessary for conservation. The systematic sampling technique was used to collect vegetation and human disturbance (presence and absence) data from August to December 2017. The vegetation data were collected from 30 plots from each woodland with a size of 900 m2 (30 m × 300 m) for tree/shrub, while subplots of size 400 m2 (20 m × 20 m) for sapling, respectively, were established in the main plots. Individual tree and shrub diameters at breast height (DBH) ≥2.5 cm and height ≥ 2 m were measured using a tape meter and clinometer, respectively. Diameter at breast height (DBH), frequency, density, basal area, and importance value index (IVI) were used for vegetation structure description, while the densities of mature trees, sapling, and seedling were used for regeneration. A total of 446 individual stems from free grazed woodland and 641 individual stems from protected woodland with a DBH of ≥2.5 cm were encountered from 30 studied sample plots that are protected and free grazed woodlands. Of these, from the total woody species, 68.42% were trees and 31.57% shrubs found in protected woodland; 76.92% were trees and 23.07% shrubs found in free grazed woodland. The total basal area of the woody plant was 3.1 ± 1 m2/ha in free grazed woodland and 4.2 ± 2 m2/ha in protected woodland, calculated for 19 woody species. Fabaceae, Balanitaceae, Capparidaceae, Verbenaceae, and Boraginaceae families were the most abundant families in both woodlands. However, there is a good initiation for the conservation of the park; still, the vegetation of the park was threatened by human-induced fire following intensive farming, gold mining, and overgrazing.

Baobab (Adansonia digitata L.) population structure across different agro-ecological zones in Coastal and lower Eastern Kenya

ABSTRACT Baobab (Adansonia digitata L.) is a multipurpose wild fruit tree of sub-Saharan Africa with unknown population demographic stability. This study assessed the baobab population structure in two main growing regions of Kenya where thirty-five plots (0.5 × 3 km each) were set in two transects, along road C107 in the coastal region and B9 in the lower Eastern Kenya, covering different agro-ecological zones (AEZs). For all baobabs within a plot, position, height and diameter at breast height (DBH) were recorded, stem densities calculated and DBH size-class distribution (SCD) curves developed. In total, 599 and 1351 baobab trees were recorded in the 14 and 21 plots in the Coastal and lower Eastern regions, respectively with densities of 0.285 (±0.07 S.E.) and 0.429 (±0.07 S.E.) stems/ha, respectively. The rather dry AEZ “Lower Midland 5” had a significantly higher density of mature (p = .047) and total trees (p = .028) than the other zones. However, at regional level (coast versus eastern), there were no significant differences in the densities of juvenile, mature or total baobab trees. Negative SCD slopes obtained in the two regions indicated more trees in the smaller size classes and hence good recruitment. The results indicated stable populations in general, but local communities should be encouraged to maintain existing trees and promote the establishment of young baobabs.

Woody plant assemblage and the structure of miombo woodland along a disturbance gradient in Hurungwe, Zambezi Valley, Zimbabwe

Miombo woodlands near human settlements are under significant pressures from human activities, with negative consequences on their structure and composition. As studies are limited, we assessed the structure and species composition of a portion of miombo woodland along an increasing disturbance gradient from a national park, through a buffer zone to communal lands in northeast Zimbabwe. Five concentric plots of 2 and 11 m radii were established in each area to record woody species composition, diameter, height, basal area, density and volume as well as evidence of disturbance. Effects of site, growth stage and their interaction on vegetation diversity and structural parameters were tested using a general linear model (GLM). Principal component analysis (PCA) tested the association between species and site and ANOVA the differences in the level of disturbance across strata. Species diversity did not differ between sites except for evenness, which increased with disturbance. Evenness and richness were greater in seedlings and saplings than mature trees across sites, respectively. Sapling and mature tree diameters differed significantly between sites. Volume and density of mature trees declined with increasing disturbance while seedling densities peaked at intermediate disturbance levels (buffer zone). Tree harvesting, was more evident in the buffer zone and in the communal area relative to the national park. In contrast, fire frequency was greater in the national park and in the buffer zone relative to the communal area. The results of this study identify a true miombo woodland dominated by Brachystegia boehmii with a stable population, as illustrated by an inverse-J shape in diameter class distribution on all sites, and that these woodlands are generally resilient to disturbances, maintaining similar species composition and structure at various levels of disturbance. However, continued monitoring of disturbance levels and miombo woodland response is recommended to ensure sustainable utilisation of these resources.

Growth and chemical composition of silver birch: Comparative study between Lithuania and Romania

The effects of different climatic conditions on growth and chemical composition of Betula pendula in geographically different European regions, Lithuania and Romania, were compared. Birch species in the entire area have a wide natural distribution, but B. pendula is commercially more important in Lithuania than in Romania. Here we evaluated tree ring width, wood density and foliar chemical composition of mature birch trees in two European regions. Trees at the Lithuanian sites had greater radial growth and wood density with no clear changes in foliar chemistry than those at the Romanian sites. Mean wood density was 600–700 kg m−3 at Lithuanian and 350–450 kg m−3 at Romanian sites. Mean width of wood ring, earlywood and latewood for Lithuanian birch trees were several times higher than the means for Romanian birch trees. We hypothesized that the main differences in birch radial growth and wood density were due to the different climatic conditions in the studied regions. Ca, K and Mg concentrations were significantly higher and Fe and Mn were lower in the birch foliage at the Lithuanian sites compared those at the Romanian sites. Overall assessment of growth showed that silver birch cultivation is more appropriate for colder climate regions and that birch growth may change in the context of a warming climate.

Woody Species Structure and Regeneration Status in Kafta Sheraro National Park Dry Forest, Tigray Region, Ethiopia

The study was conducted in Kafta Sheraro National Park (KSNP) dry woodland natural forest located in Kafta Humera and Tahitay Adiyabo weredas (districts), Western and Northwestern Zones of Tigray regional governmental state, North Ethiopia. The objective of the study was to explore the floristic composition, structure, and regeneration of woody species in the home ofLoxodonta africanaL.,Hippotragus equinus,Anthropoides virgo,Ourebia ourebi,Crocuta crocuta,Tragelaphus strepsiceros,Phacochoerus africanus, and unidentified crocodile and fish species. In the park, the vegetation ecology has not been studied up to date which is necessary for conservation. The systematic sampling technique was used to collect vegetation and human disturbance (presence and absence) data from August to December 2018. The vegetation data were collected from 161 plots each with a size of 400 m2(20 m × 20 m) for tree/shrub while subplots of size 100 m2(10 m × 10 m) and 25 m2(5 m × 5 m) for sapling and seedling, respectively, were established in the main plots. Individual tree and shrub diameter at breast height (DBH) ≥2.5 cm and height ≥ 2 m were measured using tape meter and clinometer, respectively. Diameter at breast height (DBH), frequency, density, basal area, and importance value index (IVI) were used for vegetation structure description while the density of mature trees, sapling, and seedling was used for regeneration. A total of 70 woody species (46 (65.7%) trees, 18 (25.7%) shrubs, and 6 (8.6%) tree/shrub) were identified. The total basal area and density of 79.3 ± 4.6 m2·ha−1and 466 ± 12.8 stems·ha−1, respectively, were calculated for 64 woody species. Fabaceae was the most dominant family with 16 species (22.9%) followed by Combretaceae with 8 species (11.4%). The most dominant and frequent species throughout the park wereAcacia mellifera,Combretum hartmannianum,Terminalia brownii,Balanites aegyptiaca,Dichrostachys cinerea,Acacia senegal,Acacia oerfota,Boswellia papyrifera, Ziziphus spina-christi, andAnogeissus leiocarpus. Abnormal patterns of selected woody species were dominantly identified. The regenerating status of all the woody plant species was categorized as “fair” (18.75%), “poor” (7.81%), and “none” (73.44%). There was a significant correlation between altitude, anthropogenic disturbance (grazing and fire frequency), and density of seedling, sapling, and mature trees. But there was no correlation between gold mining and regeneration population. However, there is a good initiation for the conservation of the park; still, the vegetation of the park was threatened by human-induced fire following intensive farming, gold mining, and overgrazing. Therefore, the study area was the habitat for the population of the African elephant; species with low importance value indices and lack or having few seedling and sapling stage should be prioritized for conservation, and their soil seed banks should be studied further.

Bird Diversity Patterns along Urbanization Gradients: Some Recommendations for Landscape Planner

Birds in an urban area often being used to indicate the quality of the city. The objective of this study was to analyze the response of birds to different intensities of urban-rural change. The high variation of house size and arrangement within housing clusters in the residential area of Sentul City (Bogor, West Java) was used as a model to mimic urbanization gradients in a city landscape. Five housing clusters were selected to represent the degree of urbanization gradients. Build to unbuild land ratio and density of mature trees were used to designate urbanization gradients in the chosen observation sites. Birds were observed using a standard point count method. Bird diversity was the highest in low urbanization (33 species) and diminishing in the higher urbanization grades (15 species). Sites with the highest urbanization rate still able to function as bird habitat, although the species number was low. The persistent bird species against urban-rural were mostly insectivores, nectarivores, and granivores (seed-eaters), while species that we’re unable to cope with urbanization were generally raptors, bush dependent species (e.g. babbler group) and thick canopy dependent species (e.g. green pigeon). The results indicate that (i) there is a negative relationship between degree of urbanization and bird species persistence in urban areas; (ii) efforts for bird conservation should not only focus on regreening but also be directed toward plant functional diversity to accommodate more diverse birds; (iii) urban landscape planner should consider maintaining or creating patch(es) of semi-nature areas as a refuge habitat for birds and other city-persistent species.

Effects of species and environmental factors on browsing frequency of young trees in mountain forests affected by natural disturbances

We analyzed the effects of natural disturbances on relationships between forest regeneration and ungulate browsing. Specifically, we asked if natural disturbances affect preferences of ungulate herbivores towards tree species and size classes; and how local and landscape-scale environmental factors affect spatial patterns of ungulate browsing in disturbed forest ecosystems. Our research was conducted in the Tatra National Park, a mountain range affected by large-scale intense disturbances over the last few decades. We used field data collected in a network of regularly distributed 600 circular sample plots where young trees were recorded and examined for browsing signs. Using forage ratio, the Ivlev’s electivity index and chi square tests, we found that the preferences of wild ungulates were similar to those known from undisturbed forests. Our analyses showed preference for deciduous species, especially rowan, sycamore maple and goat willow. The most common species, Norway spruce was strongly avoided by browsing ungulates. Short saplings from 0.5 m to 1.3 m tall were the most browsed size class. Effects of environmental variables on browsing were analyzed with zero-inflated negative binomial models. The occurrence of browsing was positively related to the total number of young trees and mature tree mortality. This suggests the influence of disturbances on spatial patterns of browsing pressure. The browsing frequency (number of browsed individuals per plot) was affected by mature tree mortality and densities of young palatable trees, including silver fir, sycamore maple and rowan. Elevation, geology, soil type, and potential solar radiation did not show any significant influence on the browsing frequency. Browsing frequency was also positively related to the distance to roads and hiking trails, indicating the role of human pressure upon the behaviour of ungulate herbivores. In addition, we analyzed the effects of accumulation of coarse woody debris (CWD) on browsing frequency and found this relationship to be nonlinear. Analysis for all tree species revealed that at low levels of CWD, the browsing frequency increased with CWD accumulation as a consequence of forest regeneration. However, a large amount of CWD (>25 m3) resulted in a decrease in browsing frequency, and this relationship was species-specific.

Structure and regeneration status of woody species in the Munessa Forest, Southern Ethiopia

This study evaluates the structure and regeneration status of woody species in the Munessa Forest, a dry Afromontane forest in southern Ethiopia. Vegetation data were collected using a systematic sampling method. Density and distribution of seedlings, saplings and mature trees were assessed along an altitudinal gradient using quadrats of different sizes. The number of individuals, frequencies, heights and DBH of species > 1 m and DBH > 2.5 cm were recorded in altitudinal bands of 100 m. Analysis of the vegetation structure shows that the density of woody species decreases as DBH and height class increases. Basal area of stems with DBH > 2.5 cm was 53.4 m2 ha−1. Population structure and regeneration patterns indicate a significant degradation of the forest due to anthropogenic disturbances. Regeneration was better for less valuable woody species than for species with economic and ecological value. This suggests a discontinuous recruitment of these species due to selective cutting of middle and higher diameter classes. Therefore, enrichment planting of high value, endangered species is necessary to maintain them as part of this forest. There is a need to develop and implement an effective forest management plan for sustainable use of these forest resources.

Rôle de la banque de graines du sol dans la régénération des forêts denses humides d’Afrique centrale

La présente thèse s’intéresse aux moteurs de la régénération des forêts denses humides tropicales d’Afrique, plus particulièrement au rôle joué par la banque de graines du sol dans cette régénération. Plus spécifiquement, l’étude vise à : évaluer l’abondance et la composition floristique de la banque de graines du sol de deux types de forêt reposant sur des sols différents ; quantifier l’abondance de la banque de graines du sol d’une essence commerciale importante, le tali (Erythrophleum suaveolens) et étudier les facteurs intervenant dans la levée de dormance de ses graines ; évaluer la capacité du système d’imagerie hyperspectrale proche infrarouge à discriminer des graines de deux espèces sœurs, E. suaveolens et E. ivorense. Les résultats montrent que la densité et la composition floristique de la banque de graines du sol varient significativement selon les types de forêt et de sol. Les taxons pionniers sont largement majoritaires dans les deux cas, mais sont mieux représentés dans la banque du sol de la forêt à Celtis (vieille forêt secondaire) que dans le sol de la forêt à Manilkara (forêt mature). Tous taxons confondus, la similarité floristique entre la banque de graines du sol et la végétation environnante est relativement faible quel que soit le type forestier. Cependant, cette similarité s’avère nettement plus importante en ne considérant que les taxons pionniers. Seulement trois espèces de bois d’œuvre ont été observées dans la banque du sol : Nauclea diderrichii, Staudtia kamerunensis et Erythrophleum suaveolens. E. suaveolens, le tali, est une des espèces les plus exploitées d’Afrique centrale. L’évaluation de l’abondance des graines de l’espèce au sein des deux types de forêt révèle une densité plus élevée en forêt à Celtis qu’en forêt à Manilkara, où les graines sont quasi inexistantes bien que les densités d’arbres en âge de reproduction ainsi que les structures diamétriques, soient similaires entre sites. Différentes hypothèses ont été émises pour expliquer ce résultat, la plus probable étant liée à la structure de végétation différente entre les sites. Les canopées des individus vivant dans la forêt à Manilkara seraient davantage dominées et fructifieraient moins fréquemment que dans la forêt à Celtis. La longévité des graines étudiées par spectroscopie de masse par accélérateur révèle que ces semences de tali, viables et enfouies dans le sol, seraient âgées d’environ dix ans. Le système d’imagerie hyperspectrale proche infrarouge s’est avéré efficace dans la distinction des graines d’E. suaveolens et E. ivorense, ce qui ouvre d’intéressantes perspectives quant à l’utilisation de cette technique pour étudier la banque de graines du sol.

Status, structure and environmental variations in semi-arid mangroves of India

The semi-arid mangroves of the Gulf of Kachchh, the largest ecosystems on the west coast of India, are poorly studied in terms of vegetation structure and environmental parameters in spite of their conservation significance. Therefore, it is necessary to document the structural features of these mangroves in view of ongoing coastal industrial development. Mangrove forest structure in 10 locations on the northern and southern coasts of the Gulf of Kachchh were assessed using the line intercept transect method. Descriptions included density of young and mature age classes, tree heights, diameters at breast height (DBH) and aboveground biomass, along with seven significant environmental variables. Mature tree densities ranged from 350 to 1567 ind. ha−1, while average height and girth at breast height ranged from 1.0 to 6.8 m and 3.0 to 137.0 cm, respectively. The majority of trees (55.6%) were in ≤ 1.8 m height class followed by a 1.9 to 2.4 m class (25.1%). DBH was most often in class 2 cm or lower than that. Among the canopy index classes, more trees were recorded in class ≤ 2 cm. The regeneration density was greater than the recruitment class. This study indicates that the poor structural attributes of Avicennia marina Vierth. var. acutissima Stapf and Mold dominated mangroves are largely due to aridity induced by scarce and erratic rainfall and high soil and water salinities. The results should be valuable in conserving and sustainably managing these mangroves in the face of developmental activities.

Roads disrupt rodent scatter-hoarding seed-dispersal services: implication for forest regeneration

Currently, 43% of the world's terrestrial surface is within five kilometres of a road, and therefore understanding how road networks impact species and ecosystem processes is highly relevant to applied conservation ecology. Among various effects on wildlife, roads can disrupt the interaction between plants and their animal-mediated seed dispersers, compromising plant community composition and regeneration. Here, using the Chinese beech (Fagus engleriana) nut-rodent system, we quantified the extent to which rodent functions on seed dispersal were modified in habitats adjacent to roads. Compared to transects 200 m from the road, we observed approximately nine times greater seed dispersal effectiveness at transects 10 m proximity to the road and six times greater at 100 m from the road. Associated with this, high densities of seedlings, saplings and mature trees occurred closer to the road, suggesting that the road effect zone may facilitate plant recruitment. However, road proximity resulted in shorter nut dispersal distances, which did not support a benefit to plant recruitment. These counteractive effects may be caused by modified rodent behaviour in the vicinity of the road, and also by effects on rodent distribution and activity in relation to road-side habitat structure and environmental pressure. Crucially, no tagged seeds were dispersed across the road, implying that it imposed a barrier effect on animal-mediated seed dispersal and plant recruitment. We conclude that the ever-expanding effect of roads on zoochorous seed dispersal may ultimately cause profound changes in the structure of plant communities across diverse ecosystems, on a global scale.

The larger, the better? Effects of delayed diameter-limit cutting on old-growth attributes and saproxylic beetle diversity in temperate oak forests

Intensive management implies harvesting large, old trees, which reduces the old-growth attributes. This negatively affects biodiversity, especially saproxylic beetles. In managed temperate oak forests, rotation extension induced by increasing the diameter threshold of final harvest by about 10 cm compared to conventional practices (i.e. DBH around 70 cm) might mitigate this negative effect. Here, we used a gradient of the proportion of overmature trees (DBH ≥ 80 cm) among mature trees (DBH ≥ 70 cm) across plots of high oak French forests to test the potential effect of increasing diameter threshold on (1) structural features and (2) species composition and diversity of saproxylic beetles communities. We assessed deadwood and microhabitats availability (i.e. volume/density and diversity) and canopy openness in 81 1-ha plots across eleven French forests. Results highlighted that a larger proportion of overmature trees, for a given density of mature trees, had limited effects on structural features: only cavities density showed a significant positive response, with no cascading effect on cavicolous beetles. Moreover, the proportion of overmature trees had no significant effect on the composition of saproxylic beetles communities (and ecological variables altogether explained only 17% of the composition inertia). By contrast, mature tree density enhanced microhabitat density and indirectly increased the abundance of rare species. Thus, shifting DBH from 70 to 80 cm in high oak forest could have no or limited effect on saproxylic beetles conservation. Improved strategies might rather stem from combining (1) longer rotation extension and (2) less intensive management practices in extended rotation stands.

Vegetation community and factors that affect the woody species composition of riparian forests growing in an urbanizing landscape along the Chao Phraya River, central Thailand

Improved knowledge of the environmental factors that affect woody composition is urgently required for species conservation in riparian zones of urbanizing landscapes. We investigated the environmental factors influencing tree abundance and regeneration in diverse forest types growing in the riparian area of an urbanizing landscape along the Chao Phraya River. We established 252 0.1-ha circular plots in remnant forest patches along 372km of the river. Cluster analysis was applied to classify the forest types. The relationships between environmental variables and tree abundance were assessed with ordination analysis, and generalized linear models were used to assess seedling/sapling abundance. The cluster analysis revealed five forest types, including floodplain forest with three sub-forest types, swamp forest, and mangrove forest. The ordination indicated that tree abundance in the floodplain forest was positively affected by distance to the ocean and the proportion of forested area. Swamp forest was positively influenced by the proportion of urbanized area and mean rainfall. Mangrove forest was negatively related to distance to the river. Seedling/sapling abundance of the dominant species in the floodplain forests was positively affected by lowland plain topography and negatively affected by the proportion of urbanized area, whereas swamp and mangrove forest species were positively influenced by the proportion of urbanized area and estuarine topography. Mature tree density influenced seedling/sapling abundance of all forest types. Tree abundance and regeneration of the riparian landscape was prevented by the urbanized area, floodplain, estuarine topography, and mature tree densities in remnant forests. These results suggest that remnant forest patches of conserved riparian forests along the urbanized landscape of the Chao Phraya River must be protected and the factors determining their colonization must be considered to enhance restoration practices.

Mixed-severity natural disturbances promote the occurrence of an endangered umbrella species in primary forests

Abstract Primary forests are characterized by high vertical and horizontal stand diversity, which provides habitat for a diverse range of species with complex habitat requirements. Detailed knowledge of related ecological processes and habitat development of primary forest species are essential to inform forest management and biodiversity conservation decisions, but relationships are not well documented. We collected dendrochronological data and inventoried numerous structural elements in permanent plots throughout the primary temperate forests within the Carpathian Mountains. We fit and compared multiple predictive models to quantify the importance of 200 years of natural disturbance dynamics on the occurrence probability of an umbrella species – the capercaillie (Tetrao urogallus). We showed that a mixed-severity disturbance regime ranging from low through moderate to high severity disturbances is required to generate diverse forest habitats suitable for capercaillie. The variation in natural disturbance severity and its timing promoted key structural habitat elements, such as low natural regeneration density, low mature tree density, high ground vegetation cover, availability of forest gaps, and abundance of standing deadwood. This study demonstrates the importance of natural disturbance in maintaining the variety of conditions necessary to support primary forest specialist species. Managers of protected areas should be mindful that natural disturbances generate habitat for the capercaillie in mountain Norway spruce forests. Further intervention is unnecessary. Conservation planning and forest reserve design should shift focus to the large-scale spatial requirements needed to ensure that a wide range of forest developmental phases are represented in protected areas.

Wildfire in boreal forest catchments influences leaf litter subsidies and consumer communities in streams: Implications for riparian management strategies

Applying the emerging paradigm of emulation of natural disturbances (END) to forest management requires understanding of how the riparian-aquatic interface responds to natural forest disturbances. A comparison of riparian forest condition and stream function was conducted across boreal, headwater streams with wildfire, harvest with minimum 30m riparian buffers, and reference forested catchment histories. We assessed riparian vegetation characteristics, leaf litter inputs to streams, instream leaf litter decomposition rates using leaf packs, and aquatic macroinvertebrates that colonized the leaf packs. Riparian shrub and juvenile woody-stem community structure was significantly more taxonomically rich and compositionally different at fire than reference sites. Mature tree densities at reference sites were 1.7× and 4× higher than at harvested and fire, respectively. Leaf litter input from riparian forests to streams was significantly greater and compositionally dissimilar at fire compared to harvested and reference sites. Although decomposition of speckled alder (Alnus icana ssp. rugosa) in the leaf packs did not differ significantly among study reaches, the aquatic invertebrate communities found in the leaf packs at fire sites were characterized by significantly higher taxa richness and unique shredder taxa. Detectable differences in riparian forest condition and instream processes suggest that forest management under the END paradigm could sustain ecosystem services (the support of aquatic biodiversity) by inducing riparian forest succession, enhancing leaf litter inputs and organic matter processing, and promoting riparian habitat complexity.

京都市の大規模都市林におけるシイ類，アラカシおよびシラカシ実生の成長特性

We set up 1055 quadrats (1055m2) on the forest floor in Tadasu-No-Mori forest, a large-scale mature urban forest in Kyoto city, to clarify the growth characteristics, recruitment, relative height growth rate and mortality of seedlings of three evergreen Fagaceae species, Castanopsis spp, Quercus glauca and Q. myrsinifolia. We recognized the differences in growth characteristics of seedlings among the species. Q. glauca showed high recruitment rates. It seems to be because the individual density of mature trees of Q. glauca was highest in this forest. Recruitment rates of C. spp and Q. myrsinifolia seedlings were relatively high, when the individual density of the mother trees which is located near, was high. Although C. spp seedlings showed higher growth rate than other two species, mortality rate of C. spp seedlings were relatively high. In contrast, mortality rate of Q. myrsinifolia seedlings were relatively low. It indicates that the individual density of Q. myrsinifolia might increase than other two species in this site in the long term. In order to conserve the original vegetation of Tadasu-No-Mori forest, the deciduous broad-leaved forest dominated by Aphananthe aspera, Celtis sinensis and Zelkova serrata and to suppress the regeneration of Q. myrsinifolia, it is necessary to maintain the population density of the mature trees of Q. myrsinifolia low.