Dendrometric structure and spatial distribution of Pterocarpus erinaceus Poir. in three savannah types stands in Côte d'Ivoire

Pterocarpus erinaceus is a popular tree for medicinal and fodder uses in the Sudano-Sahelian belt of West Africa. It is also used for its wood. P. erinaceus is one of the most exploited tree species in many countries in West Africa. Planks and logs have been exported towards the South-West Asian countries for ten years. This paper analysed the demographic structure, the ecological characteristics of natural stands of P. erinaceus and level of human pressure they suffer in two agro-ecological zones of Burkina Faso and Niger. Transects were installed in four  forests of which two  were in the Sahelian zone of Niger and two were in the Sudan region of Burkina Faso. Measurements and observations focused on the dendrometric parameters, soil type, vegetation type and the presence of termite mound. The traces of debarking and pruning were noted. Trenching traces have been categorized into 3 classes according to their intensity. The Sudanian zone shows higher densities than the Sahelian zone. The largest individuals of P. erinaceus (the mean diameter and the highest average height) are observed in the W regional park (57.7 ± 18.6 cm and 10.8 ± 2 m) although this park belongs to the Sahelian zone. In all areas, distribution of diameter classes are bells, characteristics of aging stands with predominance of older individuals. Dendrometric characteristics vary according to the agro-ecological zones, soil type and vegetation. Twenty-one percent of P. erinaceus inventoried in the Sahelian zone and 13% in Sudanian area are close to an anthill. P. erinaceus is a species of Sahelo-Sudanese areas, analysis of its demographic structure shows that individuals of small diameter are very poorly represented in all forests. The species is exploited much more in Sahelian zones for feed supplements. The soil type and vegetation type influence the growth of P. erinaceus. Indeed, the strongest individuals were observed on soil clay loam, sandy loam soil and woodland.   Key word: Pterocarpus erinaceus, demographic characteristics, Sahelian and Sudanian zones, Niger, Burkina Faso. &nbsp

Understanding tree species autecology and population structure supports effective conservation actions. Of particular importance are multipurpose trees that provide non-timber forest products (NTFPs). We assessed the population structures and morphologies of two species of NTFP trees in the genus Mimusops across bioclimatic zones in Benin by sampling 288 plots within 11 forests. Structural characteristics were compared between species, forests and zones. Correlations were also observed between Mimusops tree regeneration density, tree features and ecological characteristics. The density of trees ≥5 cm and of regeneration and mean tree height were higher for M. andongensis (within more protected forest) than M. kummel (in forests with access to people), while the highest mean diameter was observed for M. kummel. Tree and regeneration densities and mean height were greatest in the humid zone of Benin, whilst the largest mean diameter was obtained in the sub-humid zone. The results showed significant correlations between regeneration density and soil properties for M. andongensis but not for M. kummel. The correlations between tree morphology and soil characteristics were weak for both species. Ecological characteristics, along with the species’ functional traits and pressures, are important factors related to the observed differences between the species. All diameter classes were represented, and the population seemed more stable in the more protected forest relative to other forests. Mimusops trees with a diameter of 5–15 cm represented more than 30% of this species in most forests; this suggests, for M. kummel, whose trees flower when quite small (≥6 cm dbh), that there are sufficient reproductive trees. Thus, as a long-lived species, its populations could be maintained even with low/episodic recruitment. However, we found no regeneration in many forests and climate change could threaten populations. Therefore, it is important to investigate regeneration growth and dynamics, seed production and germination of the species in relation to the biophysical conditions and disturbances experienced by Mimusops stands.

Clearing of native vegetation and changes to disturbance regimes have resulted in dense regeneration of native trees and shrubs in parts of Australia. The conversion of open vegetation to dense woodlands may result in changes to the composition of plant communities and ecosystem function if structure, composition and function are tightly linked. Widespread clearing of the floodplain tree Eucalyptus coolabah subsp. coolabah (coolibah), in New South Wales, Australia, has led to state and federal listings of coolibah woodland as an endangered ecological community. Dense regeneration of coolibah in the mid 1970s, however, also resulted in its listing as an ‘invasive native species’ in NSW, meaning it can be legally cleared under certain conditions. Dense regeneration could be a novel state dissimilar to the threatened community or it could represent the next generation of coolibah woodlands and may contribute to passive restoration of heavily cleared landscapes. This study investigated if dense stands are distinct from remnant woodland by comparing floristic composition of the ground-storey community and top-soil properties of four coolibah vegetation states: derived grassland, derived degraded grassland, dense regeneration and remnant woodland. Ground-storey composition was found to overlap broadly among states regardless of tree density. Most species were common to all states, although dense regeneration contained characteristic woodland species that were absent from grasslands. The carbon : nitrogen ratio of the soil was significantly higher in dense regeneration and remnant woodland than in either of the grassland states, indicating that the woody states are broadly similar in terms of nutrient cycling. The study demonstrates that structurally different vegetation states (grasslands, woodlands and dense regeneration) are not associated with distinct plant communities. The results also suggest that grazing management has a more pronounced effect on ground-storey composition of plant communities than tree density and that well managed derived grasslands and dense regeneration are floristically similar to remnant woodlands. Since dense regeneration and remnant woodlands are not floristically distinct from one another, dense regeneration could contribute to the conservation of endangered coolibah woodlands in cleared agricultural landscapes.

This study aims to assess population structure and ecological indicators of woodland vegetation dominated by Pterocarpus erinaceus and Anogeissus leiocarpa as a basis for sustainable management and conservation strategies. We sampled 34 plots each measuring 30m×30m in W National Park in Niger and analyzed structural parameters (tree density, basal area, Lorey's mean height and size class distribution) and ecological indicators (species richness, Shannon diversity index, Pielou evenness index and Importance Value Index) of woodland in general and for the two key species. Mean tree density was 752.6stems/ha and basal area was 24.5m2/ha in woodlands including 145.4stems/ha and 14.1m2/ha for A. leiocarpa and 3.3stems/ha and 0.7m2/ha for P. erinaceus. The woodland was composed of 59 tree species belonging to 34 genera and 17 families. A. leiocarpa had the highest IVI value (0.93), whereas P. erinaceus was among the species with the lowest IVI value (0.03). The mean diameter of both species was higher (24cm and 47cm for A. leiocarpa and P. erinaceus respectively) than the mean diameter in woodlands (16cm). A “reverse J” shape distribution was found for woodland in general and for A. leiocarpa, but P. erinaceus showed a left dissymmetric distribution. Findings of this study showed that urgent actions are needed for sustainable management and conservation of some key species especially P. erinaceus.

Aims: The overall objective of this study was to assess the effect of different densities of tree dominated by V. paradoxa and dendrometric parameters on the selected soil physical properties. Study Design: This study was conducted in the municipality of Sapone (12.03´N, 1.43´W) located 30 km south of Ouagadougou, Burkina Faso. Place and Duration of Study: The experimental design was made of 20 plots randomly. The studied factor was the tree density (D) in each of our plots, with 5 tree density levels being designed. The first density class (D1) was 0 trees/ha, i.e. 0 tree in the plot, the second was 16 trees/ha, i.e. 4 trees in the plot (D2), the third was 28 trees/ha, i.e. 7 trees in the plot (D3), the fourth was 36 trees/ha i.e. 9 trees in the plot (D4), and finally the fifth was 48 trees/ha i.e. 12 trees in the plot (D5). Each density class is repeated four times. In each plot, 9 subplots were set up for evaluating water infiltration, bulk density, soil moisture and texture. Study was conducted in 2023. Results: the results showed that tree densities levels affected the soil texture. The sand content in plots with trees was much higher than that in plots without trees. On the other hand, the silt and clay content was much higher in plots without tree compared to those with trees. Shea dominated tree density affected significantly soil water infiltration speed (P ≤ 0.001). The average soil infiltration rates were higher in fields with trees densities (16 trees/ha, 28 trees/ha, 36 trees/ha and 48 trees/ha) with average values between 3.02 and 3.64 L/h than those in fields without tree density (0 trees/ha) with an average value of 1.65 L/h. Conclusion: This research is a contribution to better understanding soil-plant relationships in Sub-Saharan African agroforestry parklands. It providing information on the expression of soil physical properties in the most widespread parklands according to different levels of tree densities.

Ecological features and ranging patterns at a chimpanzee release site on Rubondo Island, Tanzania

The effect of fire intensity on soil seed bank in Mediterranean macchia

Predicting natural hyperdense regeneration after wildfires in Pinus halepensis (Mill.) forests using prefire site factors, forest structure and fire severity

SUMMARY Sampling studies in the Gouna Forest indicated that the density of tree regeneration, density and height of onderbos—Trichocladus crinitus—and basal area/ha of different tree species groups are significantly different for different aspects. The height and density of onderbos, density of regeneration, basal area of tree species groups, density of individual tree species, density of ground flora species, slope, radiation index and canopy height are all interrelated. A table is presented giving the relative frequency, density and density per cent of different tree species.

Demographic structure and population dynamics of Maremmana cattle local breed after 35 years of traditional selection

Forest ecosystems are complex dynamical systems described by attributes of composition, structure, and function. To understand and manage forest ecosystems, we are required to explain and classify their dynamic structure and spatial patterns. We investigated the spatial patterns of trees and their regenerations in a preserved area in Zagros forests of western Iran. We applied geostatistical methods to examine the spatial pattern in distribution of tree and regeneration density and diversity. Fractal analysis was also used to characterize the complexity of the spatial patterns. The results showed that the mean of tree density per plot was 10.56 (S.E. ± 0.29) individual with canopy cover being 18.1 (S.E. ± 0.96) percent per plot. The mean of regeneration density was 3.06 (S.E. ± 0.23) individual in plot. We revealed spatially structured characteristics for tree density and diversity indices through the variograms that showed the presence of spatial autocorrelation. We also found that preservation favored density and diversity of tree regeneration in this area compared to unpreserved area. We also found that fractal dimension representing the unpredictability of spatial patterns, is high for trees and regeneration. This implies that although spatial dependence in semivariograms exists, it is generally fairly weak. These results revealed the scattered and homogeneous spatial distribution of trees and their regeneration in Zagros forests. It seems that the preservation action is not yet sufficient to effect on the spatial pattern of regeneration in this area. Therefore, conservation efforts must continue to complete the recovery of regenerated forest and flourishing of their spatial structure.

Landscape and local‐scale influences are important drivers of plant community structure. However, their relative contribution and the degree to which they interact remain unclear. We quantified the extent to which landscape structure, within‐patch habitat and their confounding effects determine post‐clearing tree densities and composition in agricultural landscapes in eastern subtropical Australia. Landscape structure (incorporating habitat fragmentation and loss) and within‐patch (site) features were quantified for 60 remnant patches of Eucalyptus populnea (Myrtaceae) woodland. Tree density and species for three ecological maturity classes (regeneration, early maturity, late maturity) and local site features were assessed in one 100 × 10 m plot per patch. All but one landscape characteristic was determined within a 1.3‐km radius of plots; Euclidean nearest neighbour distance was measured inside a 5‐km radius. Variation in tree density and composition for each maturity class was partitioned into independent landscape, independent site and joint effects of landscape and site features using redundancy analysis. Independent site effects explained more variation in regeneration density and composition than pure landscape effects; significant predictors were the proportion of early and late maturity trees at a site, rainfall and the associated interaction. Conversely, landscape structure explained greater variation in early and late maturity tree density and composition than site predictors. Area of remnant native vegetation within a landscape and patch characteristics (area, shape, edge contrast) were significant predictors of early maturity tree density. However, 31% of the explained variation in early mature tree differences represented confounding influences of landscape and local variables. We suggest that within‐patch characteristics are important in influencing semi‐arid woodland tree regeneration. However, independent and confounding effects of landscape structure resulting from previous vegetation clearing may have exerted a greater historical influence on older cohorts and should be accounted for when examining woodland dynamics across a broader range of environments.

Pterocarpus erinaceus is an arborescent deciduous legume tree of African savannas and dry forests growing in natural stands in the sudanian zone in Benin. An inventory of trees in the P. erinaceus dominated communities was carried out in order to describe their structure in tree-savannah and woodland, on the basis of some dendrometric parameters such as the diameter, the height, the basal area, the bark factor etc. The measurements have been done in 400 circular plots of 15 m of radius, in Ouémé Supérieur and Wari-Maro forest reserves. The results showed that the tree-density of the stands was higher in tree-savannas than inthe woodlands whereas the mean height and the mean diameter of P. erinaceus trees and of the whole stands obtained their highest values in woodlands. Furthermore, the two targeted forest reserves (Ouémé supérieur and Wari-Maro) have similar values for the dendrometric parameters. The diameter structure of P. erinaceus revealed the abundance of trees with mean diameter whereas trees with small or high diameter were scarce. The overall stand has an «i-shaped» structure, showing an uneven-aged and mixed species nature of the stands. Moreover, the height-diameter relationship of P. erinaceus was logarithmic with a R-square value of 37 % and 16 % in tree-savanna and woodland, respectively. Pterocarpus erinaceus est une Légumineuse arborescente des forêts claires et savanes arborées d’Afrique, croissant en peuplements naturels dans les zones soudaniennes au Bénin. Un inventaire des arbres dansces formations naturelles à dominance de P. erinaceus a été effectué afin de décrire leur structure, sur la base des paramètres dendrométriques comme la hauteur, le diamètre, la surface terrière, le facteurd’écorce, etc. Les mesures du diamètre et de la hauteur des arbres ont été réalisées dans 400 placettes circulaires de 15 mètres de rayon, situées dans les forêts claires et savanes arborées des forêts classéesde l’Ouémé Supérieur et de Wari-Maro. Les résultats obtenus permettent de noter que la densité du peuplement est plus élevée dans les formations de savane (169,4 arbres/ha) alors que la hauteur moyenneet le diamètre moyen de tous les arbres et spécifiquement de P. erinaceus présentent des valeurs significativement plus élevées en forêt. Par ailleurs, les deux forêts étudiées (Ouémé Supérieur et Wari-Maro) présentent des valeurs similaires pour les paramètres dendrométriques calculés. La structure en diamètre de P. erinaceus révèle une relative stabilité du peuplement avec une abondance des individus dediamètre moyen et une rareté des individus de faibles ou gros diamètres. L’ensemble du peuplement présente une structure en « i », caractéristique d’une nature inéquienne et multispécifique. La hauteur deP. erinaceus peut être exprimée en fonction du diamètre à 1,30 m du sol, dans les peuplements de savane et de forêt par des équations logarithmiques avec des coefficients de détermination de 37 % et 16 %respectivement en savane arborée et forêt claire.

AimImpacts of different global change drivers are altering the performance of plant species worldwide. However, these pressures usually differ across the species' distribution range. To properly assess the combined effect of global change at species level, we need to evaluate its consequences across their complete distribution. We focused on recent decline in Cork oak (Quercus suber L.) populations given its high ecological and economic relevance.LocationWe selected 10 different sites (and two populations per site) separated about one degree in latitude across the core distribution of Q. suber, following a transcontinental aridity gradient.MethodsTo evaluate the current trends in population dynamics across the species' distribution and the factors implied on population decline, we evaluated the effect of latitude, aridity, pathogens (Phytophthora cinnamomi), stand density and tree size on seed and crop size, demographic structure, dominance of recruitment bank, defoliation and mortality.ResultsWe found an increase in seed weight as latitude decreased, with a homogeneous low crop size across the complete distribution. Demographic structure was determined by latitude, precipitation and pathogen abundance. We detected a trend towards reduced sapling densities towards the southern edge of the distribution, with a demographic structure dominated by old trees. The low sapling density at the southern edge translates into a loss of dominance with respect to other woody species, suggesting an alteration of community structure in the mid‐term future. Tree density, precipitation and pathogen abundance determined tree mortality across the species distribution, with a higher abundance of pathogens in central‐latitude populations.Main conclusionsOur results allow the early detection of declining trends and the evaluation of the main risks for species' conservation, suggesting potential for range displacement of the species driven by the recruitment failure at the southern edge of the distribution and a likely range expansion at northern populations.

In Mediterranean drylands microclimate affects more tree seedlings than adult trees