Sabine Miehe

Tree endurance on the Tibetan Plateau marks the world’s highest known tree line of the Last Glacial Maximum

Because of heterogeneous topographies, high-mountain areas could harbor a significant pool of cryptic forest refugia (glacial microrefugia unrecognized by palaeodata), which, as a result of poor accessibility, have been largely overlooked. The juniper forests of the southern Tibetan Plateau, with one of the highest tree lines worldwide, are ideal for assessing the potential of high-mountain areas to harbor glacial refugia. Genetic evidence for Last Glacial Maximum (LGM) endurance of these microrefugia is presented using paternally inherited chloroplast markers. Five-hundred and ninety individuals from 102 populations of the Juniperus tibetica complex were sequenced at three polymorphic chloroplast regions. Significant interpopulation differentiation and phylogeographic structure were detected (G(ST) = 0.49, N(ST) = 0.72, N(ST) > G(ST), P < 0.01), indicating limited among-population gene flow. Of 62 haplotypes recovered, 40 were restricted to single populations. These private haplotypes and overall degrees of diversity were evenly spread among plateau and edge populations, strongly supporting the existence of LGM microrefugia throughout the present distribution range, partly well above 3500 m. These results mark the highest LGM tree lines known, illustrating the potential significance of high-mountain areas for glacial refugia. Furthermore, as the close vicinity of orographic rear-edge and leading-edge populations potentially allows gene flow, surviving populations could preserve the complete spectrum of rear-edge and leading-edge adaptations.

Highest Treeline in the Northern Hemisphere Found in Southern Tibet

Abstract Three new records of the highest treelines in the northern hemisphere are presented here, based on the definition of a “tree.” The tree species with the highest treeline in the northern hemisphere is Juniperus tibetica Kom. The highest forest stand is located at 4900 m in southeast Tibet. The highest tree stands of Juniperus indica Bertol. in the Himalaya were found in northern Bhutan at 4750 m. Information from such observations is decisive for the development of hypotheses on the limits of tree growth. We compare the present findings with findings on highest treelines in other mountain areas worldwide and draw some conclusions.

Status and dynamics of the Kobresia pygmaea ecosystem on the Tibetan plateau.

Abstract This paper provides information about the distribution, structure, and ecology of the worlds largest alpine ecosystem, the Kobresia pygmaea pastures in the southeastern Tibetan plateau. The environmental importance of these Cyperaceae mats derives from the extremely firm turf, which protects large surfaces against erosion, including the headwaters of the Huang He, Yangtze, Mekong, Salween, and Brahmaputra. The emphasis of the present article is on the climate-driven evolution and recent dynamics of these mats under the grazing impact of small mammals and livestock. Considering pedological analyses, radiocarbon datings, and results from exclosure experiments, we hypothesize that the majority of K. pygmaea mats are human-induced and replace forests, scrub, and taller grasslands. At present, the carrying capacity is increasingly exceeded, and reinforced settlement of nomads threatens this ecosystem especially in its drier part, where small mammals become strong competitors with livestock and the removal of the turf is irreversible. Examples of rehabilitation measures are given.

Sacred Forests in Tibet: Using Geographical Information Systems for Forest Rehabilitation

Abstract The treeless desertlike environments of southern Tibet are assumed to be naturally unsuitable for forests. Yet, climatic conditions do allow for the growth of indigenous trees in Lhasa and many parts of southern Tibet, even where there is no high groundwater table or irrigation. This was discovered and proven in a Sino–German research project launched in 1997. The project made an inventory of forest relics, correlated residual tree stands with climatic data, and successfully cultivated nonirrigated indigenous junipers and cypresses. The eroded semidesert landscape of southern Tibet appears to have a huge potential for reforestation. The area with a potential for tree growth was investigated using the Geographical Information System known as GRASS (Geographical Resource Analysis Support System). Reforestation measures could meet the heavy demand for timber and firewood, help combat erosion on overgrazed slopes, and restore the degraded pastures. Grazing must be excluded on reforestation plots. Simultaneously, rangelands may regenerate after overgrazing. The optimum duration of the ungrazed period varies with altitude, humidity, soil conditions, and the degree of degradation. Successional trends observed on exclosure plots suggest that the drier the climate and the lower the initial degree of herbaceous vegetation cover, the longer the ungrazed period will be beneficial for pasture regeneration. Challenges in research and practice resulting from these preliminary results are highlighted.

New records of pleurocarpous mosses for Africa and Uganda

BP. The afroalpine region (> 3500 m a.s.l.) of the Ruwenzori receives more than 2000 mm precipitation (some is snow) annually (Osmaston, 1996), while the corresponding figure for Mt Elgon is around 1000 mm (Wesche, 2002). Consequently, bryophyte growth is much more luxuriant in the Ruwenzori, mainly in ericaceous vegetation, afroalpine bogs and tussock grasslands. The latter are, however, much more common on Mt Elgon. The expedition of S. and G. Miehe explored the Ruwenzori Mts for 18 days in March 1997 following the main trail around Lakes Bujuku and Kitandara. A follow-up expedition has not been possible so far, since the park was closed due to political unrest shortly afterwards and has remained so ever since. Sampling was concentrated in the upper montane and ericaceous vegetation, where bryophytes and lichens were collected, but identifications are still not completed. The high altitude vegetation of Mt Elgon was sampled during a 15-month survey that concentrated on the vascular plant vegetation (Wesche, 2002). Bryophytes and lichens

The Kobresia pygmaea ecosystem of the Tibetan highlands – Origin, functioning and degradation of the world's largest pastoral alpine ecosystem: Kobresia pastures of Tibet

With 450,000 km2Kobresia (syn. Carex) pygmaea dominated pastures in the eastern Tibetan highlands are the worlds largest pastoral alpine ecosystem forming a durable turf cover at 3000-6000 m a.s.l. Kobresias resilience and competitiveness is based on dwarf habit, predominantly below-ground allocation of photo assimilates, mixture of seed production and clonal growth, and high genetic diversity. Kobresia growth is co-limited by livestock-mediated nutrient withdrawal and, in the drier parts of the plateau, low rainfall during the short and cold growing season. Overstocking has caused pasture degradation and soil deterioration over most parts of the Tibetan highlands and is the basis for this man-made ecosystem. Natural autocyclic processes of turf destruction and soil erosion are initiated through polygonal turf cover cracking, and accelerated by soil-dwelling endemic small mammals in the absence of predators. The major consequences of vegetation cover deterioration include the release of large amounts of C, earlier diurnal formation of clouds, and decreased surface temperatures. These effects decrease the recovery potential of Kobresia pastures and make them more vulnerable to anthropogenic pressure and climate change. Traditional migratory rangeland management was sustainable over millennia, and possibly still offers the best strategy to conserve and possibly increase C stocks in the Kobresia turf.

Obituary: Dr. Dr. h. c. Hans-Juergen von Maydell (24 June 1932–11 July 2010)

Dr. Dr. h. c. Hans-Juergen von Maydell, Professor of World Forestry at the then Federal Research Organization (BFH) in Reinbek–Hamburg died after long illness on 11 July 2010 at his home near Hamburg, Germany. He leaves behind his wife, children and grandchildren. To his family we express our sincere condolences. Hans-Juergen Baron Maydell was born in Reval, Estonia, on 24 June 1932. Towards the end of World War II he fled westwards with his family who lost not only land and material goods, but also several family members on the way. He worked his way through high school and after graduation registered as forestry student at the Faculty of Forestry at Freiburg. He wrote a thesis on small dimension wood in the timber markets department and was promoted to Ph.D. in Natural Sciences in 1958. His work in Freiburg ended in 1968 when he was offered an assignment by FAO in Ghana. In 1969 the Institute of World Forestry, University of Hamburg offered him the post of assistant professor of world forestry with teaching responsibilities in forest geography, forest policy and timber trade practices. As a result of his frequent missions to developing countries, mostly in semi-arid Africa, he concluded that to fight poverty effectively traditional solutions to natural resources use and land management needed research and re-orientation. It may be assumed that personal hardship suffered influenced his conviction that people often dispose of untapped spiritual and physical resources when convinced to try new methods for improving their living conditions. Maydell was at his argumentations best when challenged by farmers with the question: ‘‘and can we eat your trees’’, as a response to Maydells request that farmers should dedicate a small lot from their subsistence millet fields for tree planting. In this and similar situations his extraordinary communication abilities and fighting spirit in motivating colleagues, students or farmers to accept challenges and overcome hindrances were legendary. He succeeded in convincing the German Government represented by GTZ, to support his projects with financial contributions and by seconding qualified staff. To mitigate wood energy shortages he promoted plantations to provide energy wood to towns and settlements. Plantations with selected species were begun in the north of Burkina Faso, in the Gambia and around deep well sites in Senegal. His interest in forestry and forest industries development in Eastern Europe never ceased. With his long-time assistant and translator, Stan Cejchan, he Kay F. Panzer formerly as Senior Researcher, Institute of World Forestry, Federal Research Organization (BFH), Hamburg, Germany.