Bark Harvesting Research Articles

Phytochemicals from Bark Extracts and Their Applicability in the Synthesis of Thermosetting Polymers: An Overview.

This review focuses on recent research on the phytochemicals found in bark from different trees and their potential to be used as substrates for the synthesis of thermosetting resins. Recent studies about the influence of each bark harvesting step on the extracted phytochemicals, from debarking to extraction, are investigated. A comparison of bark extracts in terms of the correlation between extraction conditions and efficiency (based on the total phenolic content (TPC) and extraction yield) is presented for six groups of trees (Norway spruce, pine species, other conifers, oak species, other deciduous trees of the north temperate zone, tropical and subtropical trees) and evaluated. The evaluation revealed that there is an interesting relationship between the extraction time and the type of solvent for some types of tree bark. It was found that a relatively short extraction time and a solvent temperature close to the boiling point are favourable. The latest research on the application of bark extracts in different types of thermosetting resins is described. This review discusses the attractiveness of bark extracts in terms of functional groups and the possibilities arising from extractable phytochemicals. In addition, different approaches (selective versus holistic) and methods of application are presented and compared.

Recovery of Sterculia quadrifida R.Br. bark: A guide to sustainable bark harvesting for traditional medicine

Recovery of Sterculia quadrifida R.Br. bark: A guide to sustainable bark harvesting for traditional medicine

Evaluation of Antibacterial Efficacy of Cinnamomum Burmanii Leaf Essential Oil in Toothpaste Formulation Against Streptococcus Mutans: An Experimental Study

Background: Traditional cinnamon bark harvesting practices often discard valuable leaves, neglecting their potential benefits such as essential oil with antibacterial properties. Previous studies have highlighted the antibacterial effects of Cinnamomum burmannii leaves from Indonesia, including their potential as antibacterial agents. The study aimed to evaluate the antibacterial effect of Cinnamomum burmanii leaf essential oil in toothpaste formulation against Streptococcus mutans
 Method: This quasi-experimental study compared the antibacterial effectiveness of toothpaste containing essential oil with Streptococcus mutans cultures in Brain-heart Infusion Broth (BHIB) overnight. Six wells were created on agar plates using sterile 6 mm punches. Each well was filled with the following: Positive control (Chlorhexidine), pure essential oil, 100% essential oil toothpaste, 75% diluted essential oil toothpaste, 50% diluted essential oil toothpaste, and negative control (aquadest). The diameter of inhibition zones was measured after incubating all plates at 36°C for 24 hours.
 Result: The inhibition zone diameter was measured to evaluate the effectiveness of essential oil toothpaste against dental plaque bacteria. Non-parametric Kruskal-Wallis statistical analysis revealed no significant difference in the diameter produced between Cinnamomum zeylanicum leaf essential oil and the positive control minosep (p=0.10). However, after formulation into toothpaste, a significant decrease in effectiveness was observed (p=0.015).
 Conclusion: It can be concluded that cinnamon leaf essential oil is effective in inhibiting the growth of Streptococcus mutans bacteria. However, when formulated into toothpaste, its effectiveness decreases with lower concentrations of the toothpaste dilution.

Does tenure influence sustainable use? The ecological impacts of harvesting baobab (Adansonia digitata)

AbstractUsing the lens of the baobab tree, this paper explores the ecological outcomes of different tenurial arrangements and implications for resource sustainability. With the emergence of markets for baobab products, a central concern is to confirm whether use patterns differ across different tenure regimes and, if so, their ecological outcomes. The study is based on an ecological survey in Zimbabwe of 244 baobab trees located across three tenure regimes – communal, private and state – and also draws on interviews with key informants. The results suggest that tenure has a strong influence on the sustainability of baobab harvesting. Based on identified parameters of ecological sustainability, trees under state tenure were shown to be harvested unsustainably, and showed excessive bark harvesting, while those under private and communal tenure had fewer signs of debarking and produced more fruits, suggesting their use was more sustainable. Excessive bark harvesting was found to negatively affect fruit and bark production and, to a lesser extent, the overall health of the tree. The research illustrates that in order to understand ecologically sustainable use, an understanding of resource use patterns across different tenure regimes is crucial, suggesting the design of bespoke interventions to manage the use of natural resources in different tenure systems.

Influence of patch geometry, post-bark-extraction-treatment on bark recovery and standardizing number of sprouts for bark harvest from coppices in Cinnamomum zeylanicumblume: implications for sustainable harvesting.

Though Cinnamomum zeylanicum is a very important commercial aromatic bark yielding and oldest known tree spice of India, there are hardly any studies to understand the nature of wound healing and bark recovery. Further, optimal number of sprouts to be retained under coppice system to maximize the bark yield per tree in C. zeylanicum is not yet standardized. The present investigation was carried out to understand the influence of patch geometry and application of post-bark-extraction-protection treatments on bark regeneration in mature trees as well as to standardize an optimal number of sprouts to be retained under coppice system to maximize the bark yield per tree. In general, wound healing in C. zeylanicum occurred from the edge of the blaze and was quicker in the narrower patch than the broader patch; application of Bordeaux paste or neem seed kernel extract on the blazed area immediately after the bark extraction, resulted in significantly higher mean percent bark recovery and higher bark oil content than control. Allowing seven coppice sprouts per stem resulted in higher dry mass of bark per plant and higher bark oil than other treatments under coppice system. The results of the study would enable formulation of management strategies specifically for sustainable bark harvesting in Cinnamomum species.

Impact of different factors degrading cork oak stands in the Mediterranean region: A case study from Algeria

In recent years, the cork oak forests that characterise the Mediterranean region have been exposed to various factors that result in their degradation. These cork oak trees, due to increasingly accentuated anthropogenic activity, undergo withering at different scales.The objective of the study is to assess the impact of various factors that degrade cork oak forests in the Mediterranean region located in northeastern Algeria, and this was achieved by prospecting 22 sampling locations. This allowed the creation of a database containing 745 trees that were observed and 27 measured variables. Different readings were then taken into consideration based on measurements and sometimes on ratings. The impact of several biotic and abiotic factors, which affect and damage the health of cork oak, was identified. These factors include in particular the infestations by xylomycetophagous insects such as Platypus cylindrus and Xyleborus sp., which can potentially infest the cork oak trees that we observed one year after bark harvesting. On the other hand, the stationary descriptors such as altitude, slope, exposure, etc., are important for the dendrometric and exploitation characteristics, but their unfavourable values do not necessarily lead to tree mortality; for example, medium to low slopes, associated with average altitudes of 600 m a.s.l., may ensure the healthiest trees like in our case study. Finally, we were able to find that certain decline factors may affect a particular category of trees, either because they are older, taller or have a large girth, or because they are subject to inadequate debarking.

Evaluation of anthropization indicators of the floristic landscapes of Kaélé hills in the Sudano-Sahelianzone of Cameroon

This work focuses on the influence of anthropogenic activities on the phytodiversity of Kaélé hills, particularly those of Lara, Boboyo and Midjivin, in the Mayo-Kani Division, Far North Region of Cameroon. The aim is to assess the effects of the exploitation of the natural resources of these hills on the ligneous plants in order to contribute to their sustainable management. Two methods were used for this study: floristic inventories and ethnobotanical survey. The inventory design consisted of three blocks (hills) which are main treatments, the hillsides which are secondary treatments and the plots which are the replications. The species were inventoried in plots of 40 x 30 m each arranged from the bottom to the top of each hill on each of the two slopes and separated by 10 m of intervals (down-up and left-right). For the ethnobotanical survey, interviews were carried out with 385 people in order to assess the importance of the resources of these hills and the activities carried out there. 2495 woody individuals were inventoried, distributed in 35 species, 29 genera and 19 families over all the three hills. The main signs of disturbances recorded are marks of cutting, bark harvesting and pruning. The anthropization index is most noticeable on species on Lara hill such as Terminalia brownii (105 individuals), Grewia bicolor (88 individuals), Ficus abutilifolia (72 individuals). On Boboyo hill, the anthropization index is most noticeable on species such as Terminalia brownii (60 individuals), Grewia bicolor (73 individuals), Ficus abutilifolia (64 individuals), and on Midjivin hill, they are Terminalia brownii (74 individuals), Ficus abutilifolia (72 individuals) and Grewia bicolor (57 individuals). The species used in the local pharmacopoeia in order of appreciation by exploiters are: Terminalia brownii (19.9%), Azadirachta indica (17.97%), Anogeissus leiocarpus (16.14%) and Croton pseudopulchellus (13.76%). Eleven species are used in crafts, amongst which the most used are Terminalia brownii (93.77%) and Grewia bicolor (83.83%). This work has shown that the floristic diversity of the Kaélé hills is under anthropogenic pressure, thus leading to the disappearance of several plant species and the fragmentation of the natural habitat of biodiversity.

Faloak (Sterculia quadrifida R.Br.) bark harvesting for curing hepatitis in Kupang City: Herbal medicine in the urban environment

Trees in an urban environment play an important role. Studies have shown that the presence of trees can improve human physical and mental health. People in Kupang, Nusa Tenggara Timur Province, Indonesia, harvest Sterculia quadrifida R.Br. (faloak) bark for medicinal decoction for hepatitis and energy booster. Hepatitis cases in Kupang City continue to increase, from 40 cases in 2016 to 147 cases in 2017 and 220 cases in 2018. This study aimed to assess S. quadrifida bark harvesting intensity and its utilization in Kupang City. This study was conducted in five sub-districts in Kupang, namely Alak, Kelapa Lima, Kota Raja, Maulafa, and Oebobo. In each district, 20 faloak trees were selected to be observed. Parameters observed included: diameter, height, trees that were recently debarked and have recovered bark, distance from the road, and the presence of seedlings around the tree. The data were tabulated and analyzed descriptively. There were 98 trees observed because, in Kota Raja, only 18 faloak trees were found. The recently debarked trees in Kota Raja, Alak, and Maulafa were 54.12%, 49%, and 41.05%, respectively. Meanwhile, trees with recovered bark were found mainly in Kelapa Lima (50%), Oebobo (38.95%), and Kota Raja (31%). Most debarked faloak trees were those closest to roads and settlements with a diameter ranging from 10.38 to 89.17 cm. The distance from the road to the trees was 1-203 m. A large number of debarked faloak trees indicates a high demand for faloak bark.

The Ethnobotany and Chemistry of South African Meliaceae: A Review

Meliaceae are widely distributed across the world in tropical or subtropical climates and are of considerable ethnobotanical importance as sources of traditional medicine and cosmetics. This comprehensive review summarizes the ethnobotanical uses and chemistry of 12 South African species, belonging to six genera: Ekebergia, Nymania, Entandrophragma, Pseudobersama, Trichilia, and Turraea. Eight of the species have ethnomedicinal records, classified into 17 major disease categories. The ethnomedicinal uses comprise 85 ailments dominated by gastrointestinal complaints, followed by gynaecological and obstetrics related problems. Chemical records were found for 10 species, which describe nine classes of compounds. In nearly all South African Meliaceae, limonoids are the predominant constituents while triterpenes, sterols, and coumarins are also common. The widest range of use-records and medicinal applications are found with the two most chemically diverse species, Ekebergia capensis and Trichilia emetica. Of the chemical compounds identified in the various plant organs of the 10 species of South African Meliaceae for which data are available, 42% was found in bark and 17% in seeds. Roots represent 35% and bark 33% of the organs that are used medicinally, and they are typically prepared as decoctions or infusions. Root and bark harvesting are destructive so that it may be important to examine the chemistry of plant parts such as wild-crafted leaves and fruits.

Bark harvesting by human population shapes tree allometry in an economically important species of the Brazilian savanna

Theoretical models of allometric scaling provide an important framework for understanding and predicting how and why the morphology and function of organisms vary with scale. However, the predictions of ‘universal’ scaling models for vascular plants do not consider different environments and disturbance types which can reduce the predictive power of these models. One important source of disturbance in tropical regions is the harvesting of non-timber forest products, such as leaves, flowers, resins and barks. In this context, we examine the influence of bark harvesting and different light environments on scaling of the height and diameter of Himatanthus drasticus (Apocynaceae), an economically important tree species harvested by several local communities living in the Brazilian savanna. By considering this species as a model system and using Bayesian regression, we show that bark harvesting modifies tree allometry and that the empirical scaling exponents diverge from the theoretical predictions. In addition, the results of a mechanistic model of tree growth revealed that bark harvesting affects tree height and that this effect varies independently of the light environment. On the other hand, trees with higher bark harvesting levels presented lower height growth rates when compared to trees without bark harvesting or those with<50% of bark harvesting. Our results highlight the importance of including bark harvesting as a source of disturbance that can cause differences between the observed scaling relationships and those predicted by theoretical models. Finally, from the management perspective, we observed that high levels of bark harvesting could compromise the plant height growth of the debarked trees. Therefore, our recommendation for the management of this species is that the previously defined limits of 50% of bark harvesting should be maintained to avoid the negative effects of harvesting on the tree height over time.

Sustaining Medicinal Barks: Survival and Bark Regeneration of Amphipterygium adstringens (Anacardiaceae), a Tropical Tree under Experimental Debarking

Commercial harvests can threaten tree species harvested for their bark. Amphipterygium adstringens is a dioecious tree, endemic to the tropical dry forests of Mexico, where it is intensively harvested for its medicinal bark. Limited information hinders developing sustainable management strategies for A. adstringens. We assessed bark regeneration for male and female trees, and evaluated the effect of tree sex and diameter, debarking treatments and cutting seasons on bark regeneration and tree survival rates. Bark regeneration was higher for wet season harvested trees (vs. dry), regardless of their sex. Bark regeneration was higher on female than on male trees. There were significant interactions of harvest season, harvest treatment and tree sex diameter on bark regeneration and survival. Overall, the highest bark regeneration rates occurred in female trees with ≥20.1 cm diameter that were wet season harvested with a 50% debarking intensity. Consequently, wet season and intermediate intensity harvests appear to foster sound management, but we recommend against targeting exclusively a single demographic group (i.e., large female trees) due to potential negative impacts on species demography and bark supply. A grounded strategy for sustaining bark harvest would also need to take into account relevant aspects of local socio-ecological context, including harvest interactions with other land uses.

Forest product harvesting in the Eastern Cape, South Africa: Impacts on habitat structure

The Eastern Cape Province harbours 46% of South Africa’s remaining indigenous forest cover, and is one of the country’s poorest and least developed provinces. Forest resources thus represent a vital component of rural livelihoods in this region. Consequently, forest management policies aim to balance the needs of resource users with the ecological integrity of forest ecosystems. In a recent study, forest bird ranges were shown to have declined in the Eastern Cape over the past 20 years, despite increases in forest cover over the same time period, indicating that habitat degradation may be driving forest bird losses. Given that harvesting of forest products represents the primary human disturbance in forests in the Eastern Cape today, insight is needed regarding the link between resource use and habitat modification. We report on effects of harvesting of three key forest products – poles, timber and medicinal bark – on habitat structure at the ground, understorey and canopy layers in indigenous forests in the province. Harvest activities had considerable impacts on habitat structure, depending on the nature and extent of harvesting. Bark and timber harvesting resulted in canopy gaps, whereas pole harvesting reduced tree density, resulting in understorey gaps. Overall, harvest activities increased the frequency of canopy disturbance, and density of understorey layer foliage. Unsustainable bark harvesting practices increased the mortality rate of canopy trees, thereby increasing dead wood availability. By providing insight into human-mediated habitat modification in forests of the Eastern Cape, this study contributes to the development of ecologically informed sustainable resource management policies.&#x0D; Significance:&#x0D; &#x0D; Unregulated harvesting of forest products in state-managed indigenous forests of the Eastern Cape results in habitat modification.&#x0D; The nature and extent of habitat modification is dependent on the type and intensity of resource use, indicating that resource use may be sustainably managed.&#x0D; Timber and medicinal bark harvesting activities result in canopy disturbances, thereby altering natural canopy gap dynamics, with concomitant impacts on understorey habitat structure.&#x0D; Changes in forest habitat structure associated with high levels of resource use are likely to have ramifying effects on forest biodiversity.&#x0D;

Short Communication: Population structure and habitat characteristics of Goniothalamus macrophyllus in Bukit Pembarisan forest, West Java, Indonesia

Abstract. Adhya I, Widodo P, Kusmana C, Sudiana E, Widhiono I, Supartono T. 2020. Short Communication: Population structure and habitat characteristics of Goniothalamus macrophyllus in Bukit Pembarisan forest, West Java, Indonesia. Biodiversitas 21: 1130-1135. Goniothalamus macrophyllus (Blume) Hook.f. &amp; Thomson is a forest species with important medicinal value and widely used by many local communities. Excessive harvesting of this species has led to population decline and may lead to extinction. The aims of this research was to investigate population structure, habitat characteristics and environmental factors affecting local densities of G. macrophyllus in Bukit Pembarisan forest, Kuningan District, West Java, Indonesia. Purposive sampling was conducted at 17 locations during November 2017 to March 2018. The result showed that the population structure in the study area was dominated by seedlings (95% of the total number of individuals), followed by saplings (4%) and poles (0.1%). Seedlings, saplings, and poles were found growing across a wide elevational range (432-1,273 m asl.), at temperatures of 19-25°C, relative humidity of 80-90%, and soil pH of 4.61-6.46. The multiple regression analysis showed that soil nitrogen and soil pH affected seedling density, whereas soil clay content affected pole density. Our findings indicate that G. macrophyllus preferred acidic soils with high nitrogen and high clay content. We therefore recommend that future conservation efforts include the maintenance of existing poles, a prohibition on bark harvesting, and encouraging use of the leaves, rather than bark, for medicinal applications among consumers of G. macrophyllus.

Vulnerability of baobab (Adansonia digitata L.) to human disturbances and climate change in western Tigray, Ethiopia: Conservation concerns and priorities

The increasing rate of land use intensification and the rising evidence of climate change impacts raise concerns about the viability of valued non-timber forest product (NTFP)-providing trees. This calls for the assessment of the current status and future trajectories of their populations. Using population data collected from three land-use types (e.g., grazing lands, riverine areas and natural forest) in western Tigray, we evaluated the vulnerability of the multipurpose baobab tree (Adansonia digitata L.) to human disturbances and climate change. The study was based on the premises that integrating ecological science with modeling tools and local knowledge would enhance the overall effectiveness of conservation strategies and community support. Therefore, based on field-based inventory, ecological niche modeling and a socioeconomic study, we characterized and mapped baobab current and future population distribution and documented local knowledge on the uses and management of the species. The characterization of the population structure showed that baobab stands were denser with larger-sized and taller trees in riverine areas and natural forest compared to grazing lands, suggesting adverse effects of human disturbances on its populations. Moreover, positively skewed size-class distributions with negative slopes in all land-use types indicated a low recruitment of juvenile trees to the adult stage. Climate change simulations using Maximum Entropy Algorithm (Maxent) revealed that future temperature increases would lead to significant reductions (41–100%) in baobab suitable habitats due to range contraction. The intensive harvesting of baobab leaves, branches and bark and lack of conversation practices as indicated by local communities, in combination with the risk of local extinction under future climate warming constitute serious threats for the viability of the species in western Tigray. The results suggest immediate interventions, such as planting baobab at up to 65 m higher in altitude, designing appropriate leaf and bark harvest strategies and protecting seedlings from livestock, will help guarantee the persistence of the species populations.

Conceptual decision-making framework for the sustainable harvesting of forest and woodland species for medicinal tree bark in southern Africa

Tree bark is widely used in traditional medicine in southern Africa. The growing demand for medicinal bark requires scientifically sound harvest systems for sustainable use. A conceptual framework and decision matrix are presented to aid forest managers in selecting the most appropriate system for the sustainable harvesting of particular species. The conceptual framework is based on the results of experimental bark harvesting of selected forest and woodland tree species in southern Africa, where tree response to bark stripping was assessed. The extent and rate of bark regrowth and the susceptibility of the exposed wood to fungal and insect damage, are of particular importance to assess harvest options. The decision matrix groups species based on tree response to bark stripping, and identifies the most appropriate harvest option for a particular species. Species-specific harvest prescriptions are formulated and alternatives to strip harvesting are identified where avoidance is advised. The conceptual framework and decision matrix were applied to forest woodland species on which experimental bark harvesting was conducted in Malawi, South Africa and Zambia. Of the 22 species studied, 10 have the potential for strip harvesting, based on extent of bark regrowth and susceptibility to fungal and insect damage. These were assessed further in terms of prescriptions for strip harvesting. For the remainder, full-tree harvesting in a single-tree selection system would be the most viable harvest option. Alternatives to strip and full-tree harvesting are also discussed.

Informal forest product harvesting in the Eastern Cape, South Africa: A recent assessment

Forest management in many developing nations aims to balance the needs of resource users and the ecological integrity of indigenous forests, in terms of both biodiversity conservation and ecosystem services, particularly carbon sequestration. While South Africa has legislated management policies to achieve this, implementation has been lacking, resulting in concern that unregulated resource use is compromising forest biodiversity. However, there is little information regarding resource use since these regulations were promulgated a decade ago. This study reports on the current nature and extent of forest product harvesting in the Eastern Cape, South Africa, which contains just under half of the country's indigenous forests. Extraction rates and target species of key products, namely poles, timber and bark, were assessed across six forests, representing five forest types. Harvest intensities indicated low to moderate levels of use, but there was considerable variation in levels of resource use at the forest-scale, illustrating the importance of site-specific assessments. Furthermore, resource use was species-specific, indicating that sustainability is dependent on the ecology of preferred species. Of concern was widespread commercial-scale bark harvesting; and relatively high timber extraction from a Pondoland scarp forest, a threatened forest type. We urge implementation of existing regulations, which distinguish between subsistence and commercial use; and commensurate capacitation of the new Department of Environment, Forestry and Fisheries. In the case of timber and bark, we recommend licencing of the de facto commercial harvesting taking place in order to promote regulation.

The impacts of bark harvesting on a population of Encephalartos transvenosus (Limpopo cycad), in Limpopo Province, South Africa

Cycads are the most threatened group of plants in the world and there are a wide range of ecological and anthropological forces responsible for the extinction risk of these taxa. South Africa is a global hotspot of cycad diversity and the country’s cycads are facing high extinction risk. In this study we sampled a population (n=34) of Encephalartos transvenosus Stapf &amp; Burtt Davy, a cycad species endemic to Limpopo Province, South Africa. The population was located on the Soutpansberg mountain range in the Mutale local municipality. A survey was conducted to quantify the threats to the population. Forty-seven percent of the plants had been damaged by bark harvesting for traditional medicine, and the population showed a mortality rate of 9%. We recommend further studies at a range of Encephalartos transvenosus populations to provide a broader understanding of impacts of harvesting and population trends. We also recommend community based initiatives to enhance the protection of this species in the communities in which they are found.

Genetic characterization of fragmented populations of Cinchona officinalis L. (Rubiaceae), a threatened tree of the northern Andean cloud forests

Cinchona officinalis L., a tree species endemic to the cloud forests of the northern Tropical Andes, has suffered from historical bark harvesting for extraction of antimalarial compounds and has also experienced recent demographic losses from high rates of deforestation. Most remnant populations are found in severely degraded habitat on the edges of pastures while a minority are protected in private reserves. The goals of our research were to assess the genetic diversities of fragmented populations of C. officinalis in the Loja province of southern Ecuador, characterize their phylogeographic distribution with respect to the region’s complex topography, and identify priority populations for conservation. Five nuclear microsatellite loci and the chloroplast rps16 intron were used to analyze six populations. Moderate levels of genetic diversity were found in all populations although the more remote southern population (Angashcola) had slightly higher heterozygosity and allelic richness. There were no indications of recent genetic bottlenecks although an rps16 intron haplotype was fixed in four populations. Genetic distance analysis based on microsatellite data placed the four easternmost populations in the same clade while the Angashcola population was the most divergent. Also, the most frequent rps16 intron haplotype in Angashcola was not found in any other population. Although each of the studied populations should be protected from further deforestation and agricultural expansion, the Angashcola population deserves highest conservation priority.

Response of bird functional diversity to forest product harvesting in the Eastern Cape, South Africa

The ecological impact of forest product harvesting is poorly understood despite the reliance of millions of impoverished households on forest resources. As birds are indicators of environmental change and essential for the function and regeneration of forest ecosystems, this study aimed to assess the response of bird species richness and functional diversity to unregulated forest product harvesting, to illuminate the impact of harvest disturbances on forest biodiversity. Five forest ecotypes in the Eastern Cape Province, South Africa were sampled by means of circular plots in which bird communities, habitat structure and harvest intensities of sub-canopy trees harvested for poles, canopy trees harvested for timber, and bark harvested for medicinal use, were recorded. Generalized linear models (GLMs) were used to assess the response of bird diversity to harvesting activities measured on a continuous scale, and forest ecotype. Correlations between feeding traits and environmental variables relating to habitat structure and harvest disturbances were investigated using RLQ and fourth-corner analysis to better understand which traits were sensitive to harvest disturbances. Results indicated that forest ecotype was an important driver of variation in species richness and functional diversity. Additionally, harvesting disturbances negatively affected two measures of functional diversity, while species richness and functional richness were unaffected by harvesting. Specifically, functional evenness was negatively affected by timber harvesting, while functional dispersion declined in response to pole and bark harvesting. Bird traits relating to feeding ecology (i.e. primary diet and foraging strategy) were associated with habitat structure and harvest disturbances, indicating that harvest activities affected community structure. Specifically, frugivores and granivores were negatively affected by pole and bark harvesting respectively, while omnivorous species were positively affected by these harvest activities. Conversely, timber harvesting negatively affected omnivores, and positively affected nectarivores. Bark and timber harvesting, which resulted in canopy gaps, negatively affected species which forage in the understory or on the forest floor, while pole harvesting, which reduced tree abundance but not canopy cover, negatively affected canopy-foraging species. These results suggest that current unregulated forest product harvesting in the Eastern Cape may negatively affect forest productivity and ecosystem functioning. Specifically, this is the first study to measure the effects of harvesting of poles and medicinal bark on the functional diversity of avian forest communities.

Climate, rather than human disturbance, is the main driver of age-specific mortality trajectories in a tropical tree

Environmental and anthropogenic stressors can interact (e.g., drought, harvest or herbivory) to shape plant demography and evolutionary strategies with implications for sustainable resource management plans. Harvest or recurrent biomass removal can act as a selective force. However, our understanding of how harvest and changes in climate can synergistically shape plant evolutionary strategies is limited. We used age-from-stage matrix modeling to investigate how chronic anthropogenic disturbance (severe foliage and bark harvest) affects age-specific mortality trajectories of a tropical tree, Khaya senegalensis in two contrasting climatic regions (dry versus moist) in West Africa. We then developed a stochastic model to test if changes in disturbance regime and the environmental conditions in which a cohort is born may alter stochastic age-specific mortality rates. The effect of harvest on age-specific mortality trajectories was modest and only noticeable in the moist region. Age-specific mortality trajectories differed significantly between regions. In the moist region, mortality rates decreased with age for the first 30 years of life to a minimum rate and then increased gradually after to reach an old age mortality plateau. In the dry region, mortality rates decreased with age to reach a plateau asymptotically. This difference in age-specific mortality trajectory is due to a greater delay in reaching reproductive size/age in the dry region. Our findings underscore intraspecific variation in age-specific mortality schedules and indicate that climatic effect may override the impact of anthropogenic activities on plant demography. Harvest, by favoring fast life stage transition to reproductive stages, can buffer the effect of drought.