Alan Hamilton

Increasing carbon storage in intact African tropical forests

The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide. The role of tropical forests is critical because they are carbon-dense and highly productive. Inventory plots across Amazonia show that old-growth forests have increased in carbon storage over recent decades, but the response of one-third of the world’s tropical forests in Africa is largely unknown owing to an absence of spatially extensive observation networks. Here we report data from a ten-country network of long-term monitoring plots in African tropical forests. We find that across 79 plots (163 ha) above-ground carbon storage in live trees increased by 0.63 Mg C ha-1 yr-1 between 1968 and 2007 (95% confidence interval (CI), 0.22–0.94; mean interval, 1987–96). Extrapolation to unmeasured forest components (live roots, small trees, necromass) and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr-1 (CI, 0.15–0.43). These reported changes in carbon storage are similar to those reported for Amazonian forests per unit area, providing evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon. Indeed, combining all standardized inventory data from this study and from tropical America and Asia together yields a comparable figure of 0.49 Mg C ha-1 yr-1 (n = 156; 562 ha; CI, 0.29–0.66; mean interval, 1987–97). This indicates a carbon sink of 1.3 Pg C yr-1 (CI, 0.8–1.6) across all tropical forests during recent decades. Taxon-specific analyses of African inventory and other data suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks, as some theory and models predict.

Deforestation in Uganda

A study of the gradual destruction of Ugandas extensive forest. The author traces the process and analyzes its causes from the first introduction of agriculture to the appropriation of national forest reserves by private individuals in the Amin years. He documents the developments that have turned Karamoja from a well-wooded land into one of the worlds most disastrous famine areas, and reduced the forest cover and wildlife habitat to a mere fraction of its former extent.

Comparative homegarden medical ethnobotany of Naxi healers and farmers in Northwestern Yunnan, China

BackgroundHomegardens are ecologically and culturally important systems for cultivating medicinal plants for wellbeing by healers and farmers in Naxi communities of the Sino Himalayan region. The cultivation of medicinal plants in Naxi communities and associated ethnomedical knowledge base for maintaining and utilizing these resources is at risk with expanded commercialization of natural resources, development policies and rapid socio-economic change in China. Research is needed to understand the medicinal plant species maintained in Naxi homegardens, their use and contribution to community wellbeing, and how these practices and knowledge base varies between Naxi healers and farmers in order to develop plans for biodiversity conservation and preservation of ethnomedical practices. The main objective of this study is to document and compare medicinal plant species in Naxi homegardens and associated ethnomedical knowledge between Naxi healers and farmers.MethodsEthnobotanical homegarden surveys were conducted with three Naxi healers and 28 farmer households in two Naxi communities in Lijiang Prefecture in Northwest Yunnan Province of China. Surveys included inventories of medicinal plants in homegardens and semi-structured interviews with homegarden managers to document traditional medicinal uses of inventoried plants. Inventoried plants were classified into 13 ‘usage categories’ of medical condition groupings that impact a system of the body. Finally, plant species richness was calculated for each homegarden and species richness was compared between healers and farmers as well as between study sites using a Least Square Means Tukey HSD function.ResultsEthnobotanical surveys at the study sites found that 13% of households rely exclusively on traditional Naxi medicine, 26% exclusively use Western medicine and 61% use a combination of traditional Naxi and Western medicine. A total of 106 medicinal plants were inventoried in Naxi homegardens representing 50 botanical families. Over 85% of inventoried medicinal plants were herbaceous. The most represented families were Asteraceae (12.8%), Ranunculaceae (8.3%), Apiaceae (8.3%), and Polygonaceae (7.3%). The primary medical functions of inventoried plants were to treat inflammation (73 species), circulatory system disorders (62), nervous system disorders (41), detoxification (39), digestive system disorders (33), muscular-skeletal system disorders (26), genitourinary system disorders (26), skin conditions (23), respiratory systems disorders (22), and cold and flu (20). Local herbal experts maintained greater medicinal plant species richness in their homegardens compared to local farmers as well as had greater knowledge of medicinal functions of plants. Healers maintained medicinal plants primarily for healing while farmer households maintained approximately 90% of the medicinal plants in their homegardens for commercialization and the remaining for household healthcare.ConclusionsThis study highlights the importance of biodiversity and traditional ecological and medical knowledge for human wellbeing and livelihoods in Naxi communities. Conservation efforts and policies are necessary to preserve the ecological and cultural base that maintains medicinal plant use by both healers and farmers in Naxi homegardens of the Sino Himalayan region.

History of Forests and Climate

Mankind has greatly altered the distribution and characteristics of tropical forests in Africa (Hall and Swaine, 1981). Forest margins have shrunk with the spread of agriculture and burning, while forest composition and structure have been influenced even in apparently remote places by past settlement or collection of forest products. In a soil survey in apparently pristine or near-pristine forest on the East Usambara Mountains, Tanzania, charcoal was found at almost all sites, pottery was encountered in two, and one soil pit even passed through house foundations (Hamilton and Bensted-Smith, 1989). This is not particularly unusual. Ecologists who have walked many kilometres into apparently natural forest often report similar signs of former human occupation (although it is noted that in some cases charcoal could have originated from natural fires).

Mire sediments in East Africa

Summary Mires (peat-forming systems) are very localized within East Africa, being concentrated in areas of higher rainfall and lower temperature. The main centre is the high ground of the wetter part of the Western Rift, in southwestern Uganda, Rwanda, Burundi and probably Zaire. Peat-forming species include trees, such as Erica and Syzygium, sedges and Sphagnum. Mire stratigraphy is very variable between sites, reflecting a diversity of environmental contexts. Many changes in the characteristics of mire sediments in particular profiles appear to be related to climatic events. Some recent changes in mire vegetation are the result of human influence.

History and conservation of wild and cultivated plant diversity in Uganda： forest species and banana varieties as case studies

The history of wild and cultivated plant diversity in Uganda is reviewed, taking forest species and bananas as examples. Palynological research into past human influences on forests is reassessed. The evidence suggests that crops were first introduced into the country at about 1000 BCE, farming communities practicing slash and burn agriculture started to significantly influence the floristic composition of forests during the 1st millennium BCE and there was a major episode of forest reduction at about 1000 CE related to socio-economic change. Bananas were probably introduced in the early centuries CE. The colonial era from 1894 saw the introduction of new concepts of land ownership and the establishment of forest reserves and agricultural stations. Forests and banana diversity are currently under threat, Uganda having a very high rate of deforestation and endemic banana varieties proving susceptible to introduced pests and diseases. It is suggested that, under these circumstances, conservationists take an opportunistic approach to field engagement, making use of favourable local conditions as they arise. Partnerships should be sought with elements of society concerned with sustainable use, provision of ecosystem services and cultural survival to widen the social base of plant conservation. International organisations involved in conservation of plant genetic resources and wild plant species should collaborate with one another to develop the conceptual basis of plant conservation, to make it more relevant to countries like Uganda.

Botanical aspects of eco-civilisation construction

The concept of eco-civilisation refers to the need for human affairs to be contained within the limits set by nature. Plants play such fundamental roles in the functioning of ecosystems and economies that due attention must be given to them for eco-civilisation to be achieved. Species are the basic functional units of the plant world and, taking a long term perspective, their conservation with their genetic diversity should be a primary objective in eco-civilisation construction. However, standard procedures used for plant conservation have met with only limited success. Therefore, plant conservationists need social allies to boost their efforts – referring to elements of society whose primary interests in eco-civilisation construction are different, but whose efforts, if successful, will bring benefits to plant conservation too. Potential allies can be identified using an ecosystem system services framework showing how benefits received from the delivery of ecosystem services overlap with those that favour conservation of plant diversity. The concept of eco-civilisation was adopted officially in China in 2014 as a principle guiding its future development. A project at Ludian, Yunnan Province, is used to show the relationships between an ecosystem services framework and a conservation initiative.