Kazuharu Mizuno

Succession Processes of Alpine Vegetation in Response to Glacial Fluctuations of Tyndall Glacier, Mt. Kenya, Kenya

The Tyndall Glacier of Mt. Kenya retreated at a steady rate from the late 1950s to 1996. The first colonist species over the new till, Senecio keniophytum, advanced at a rate similar to the retreat of the glacier. The species growing near the ice-front of Tyndall Glacier colonize in tandem with retreat of the glacier. Till age and stability of land surface are important environmental factors controlling the vegetation pattern around Tyndall Glacier. Till age is affected by the glacial fluctuation. The stability of the land surface is governed by the particle-size of the surface material which is controlled by landform, geology, and past climatic conditions. The pioneer species make humus which results in improved soil condition. About 70 to 100 yr elapse from the glacial release for such large woody plants as Senecio keniodendron and Lobelia telekii to grow on the glacier foreland.

Glacial Fluctuation and Vegetation Succession on Tyndall Glacier, Mt Kenya

Abstract Dramatic changes are taking place in the glacier-covered high mountains of Africa. The glacial area on Mt Kilimanjaro is now only half as large as it was in the 1970s. The Tyndall Glacier on Mt Kenya, which retreated at approxi-retreated at approximately 3 m/yr from 1958 to 1997, retreated at about 10 m/yr from 1997 to 2002. Pioneer species such as Senecio keniophytum, Arabis alpina, mosses, lichen, and Agrostis trachyphylla have advanced over areas formerly covered by the glacier. The rate at which this vegetation migrated up the former bed of the glacier (2.1–4.6 m/yr from 1958 to 1997) is similar to the rate of glacial retreat (2.9 m/yr). In the interval from 1997 to 2002, pioneer species advanced at a rapid rate of 6.4–12.2 m/yr, while the glacier retreated at 9.8 m/yr. Rapid glacial retreat has been accompanied by rapid colonization by plants. Pioneer species improve soil conditions and make habitat suitable for other plants. If warming continues, alpine plant cover may extend all the way to mountain summits, and then eventually diminish as trees colonize the areas formerly occupied by alpine plants. Larger woody plants such as Senecio keniodendron and Lobelia telekii, which showed no obvious advance prior to 1997, have advanced quickly since that year.

LANDFORM DEVELOPMENT ALONG THE MIDDLE COURSE OF THE KUISEB RIVER IN THE NAMIB DESERT, NAMIBIA

The hyperarid to arid Namib Desert extends along the west coast of southern Africa. The Kuiseb River is one of the major ephemeral rivers originating in the interior highland, and crosses the Namib Desert. Fluvial terraces are well developed along the middle reaches of the Kuiseb River near Gobabeb, and are classifi ed into four surfaces: upper (H), middle 1 (M1), middle 2 (M2), and lower (L). Layers of calcrete are founded on the M1 and M2 surfaces, and gypcrete layers are founded on the H surface. Dead tree matter, buried by dune sand on the L surface, dates to 300±60 years BP and 550±50 years BP. The calcareous crusts on the M1 surface date to 5,300±60 years BP and 6,450±50 years BP, and those of the M2 surface date to 22,070±260 years BP. The presence of calcrete suggests that the ground water level was higher when the M1 and M2 surfaces were formed than it is at the present time. Tree size distribution on the L surface demonstrates that the L surface was also formed during a relatively wet period. It may be concluded, therefore, that these fluvial terraces record the humid periods of ca 22 ka, 5-6.5 ka, and 300-600 years BP in the catchment area of the Kuiseb River. The presence of a water-soluble gypsum crust on the H surface suggests that the paleohydrologic environment of these terrace-forming periods probably involved increased rainfall in the interior highland east of the desert.

VEGETATION SUCCESSION AND PLANT USE IN RELATION TO ENVIRONMENTAL CHANGES ALONG THE KUISEB RIVER IN THE NAMIB DESERT

The aim of this study was to clarify the relationship between environmental change and vegetational succession in the Kuiseb River area of the Namib Desert. The results reveal the following: 1. About 5000-7000 years ago, wetter conditions prevailed in the Kuiseb River basin, forming a wider riverbed than at present. 2. About 600 years ago, a low terrace formed. The low terrace was characterized by the growth of acacia trees and other vegetation, which trapped and accreted aeolian sand. 3. About 400 years ago, the trapped and accumulated sand began to form a sand dune, eventually killing the tree population. 4. At the present time, all of the buried acacia trees have died and have been replaced by salvadora bushes, which continue to trap sand and increase the size of the dune. 5. Plants such as Acacia erioloba, Faidherbia albida, and Acanthosicyos horridus are very important food sources and shade plants for the local Topnaar people and their livestock. The succession of vegetation in response to environmental change has a profound impact on life in the Kuiseb River area, owing to the harsh environmental conditions and scarce plant life in the region.

Environmental Changes in Relation to Tree Death Along the Kuiseb River in the Namib Desert

The Namib Desert is located along the western coast of Namibia and is affected by the cold Benguela Current. Although forest is distributed along the Kuiseb River in the Namib Desert, many trees are almost dead in some areas. The aim of this research was to clarify the relationship between environmental changes and tree death. The results of the survey are summarized as follows: (1) Many dead trees are located on the riverbanks made of dune sand, which are about 1 m high. (2) Dead trees are located in transitional areas where a northward protrusion of the southern shore is followed by a southward protrusion of the northern shore along the course of the river, in proximity to a sand dune. (3) Floods have eroded the noses of advancing sand dunes of the upper stream and have caused tree death by depositing sand. (4) The date of tree death has been estimated between the late 1970s and the early 1980s by 14 C dating. (5) Flood days numbered 33 per year from 1962 to 1975 and 2.7 from 1976 to 1985. The remaining thick sand layer, deposited by the last fl ood, may be the cause of tree death, given that there was drastic decrease in fl oods since 1976. (6) Tree death has greatly affected peoples lives along the Kuiseb River because they depend on riverside forests as a source of shade, shelter, fuel, and food for humans and livestock.

VEGETATION SUCCESSION IN RELATION TO GLACIAL FLUCTUATION IN THE HIGH MOUNTAINS OF AFRICA

Dramatic changes are taking place in the glacier-covered high mountains of Africa. The glacier-covered area on Kilimanjaro is now only half as large as it was in the 1970s. The Tyndall Glacier on Mt. Kenya, which retreated at approx. 3 m yr -1 from 1958 to 1997, retreated at ca. 10 m yr -1 from 1997 to 2002. Pioneer species such as Senecio keniophy- tum, Arabis alpina, mosses, lichen, and Agrostis trachyphylla have advanced over areas formerly covered by the glacier. The rate at which this vegetation migrated up the former bed of the glacier (2.1-4.6 m yr -1 from 1958 to 1997) is similar to the rate of glacial retreat (2.9 m yr -1 ). In the interval from 1997 to 2002, pioneer species advanced at a rapid rate of 6.4 -12.2 m yr -1 when the glacier retreated at 9.8 m yr -1 . Rapid glacial retreat has been accompa- nied by rapid colonization by plants. Pioneer species improve soil conditions and make habi- tat suitable for other plants. If warming continues, alpine plant cover may extend all the way to mountain summits, and then eventually diminish as trees colonize the areas formerly occu- pied by the alpine plants. Larger woody plants such as Senecio keniodendron and Lobelia telekii, which showed no obvious advances before 1997, have advanced quickly since 1997.

Himalayan Nature and Tibetan Buddhist Culture in Arunachal Pradesh, India

Nature, Society and People in Monyul (Monpa Area).- Arrival of a Tibetan Prince in Monyul and Establishment of a Clan.- Taxation by the Tibetan Authorities and the Formation of Fortresses.- Tibetan Buddhism, Bon and Animism.- Forests in Monyul: Distribution and Management.- Yak Husbandry and Pastoral Communities.- Distribution of Farmland and Agricultural Communities.

The Distribution and Management of Forests in Arunachal Pradesh, India

The State of Arunachal Pradesh is located in the northeastern part of India, surrounded by the borders of Assam, Bhutan, and Tibet (China). There has been a long history of conflict over the sovereignty of this area between India and China. Foreigners were prohibited from entering the state until the 1990s and, therefore, the area has been veiled in secrecy until recently. The Monpa people, who reside in the western region, have historically deep ties with Tibet and the Tibetan Buddhist faith.

Yak Husbandry and Pastoral Communities

Yak husbandry is a crucial part of Monpa community life. These domestic animals of the Tibetan plateau and Himalayan Region, including highlands of Arunachal Pradesh have complex mating patterns. Each of a number of types of yak [g.yag] is used for a specific purpose. The relationship between the type of yak and altitude is especially important. Grazing land is produced by forest reduction. The traditional method is the application of aconite root extract to tree trunks after ring-barking, and the main method used today is simply to bark trees. Pastoral people migrate seasonally, but they typically allow yak grazing in areas around their settlements during the winter. Pastoralists never practice agriculture even in or around their winter settlements. In pastoral communities, yaks are much more than mere domestic animals: they are fundamental to the livelihood of Monpa communities. The focus of this chapter is on Monpa pastoral communities, and consideration is given to their relationship with agricultural people.

Taxation by the Tibetan Authorities and the Formation of Fortresses

The Tibetan government set up fortresses, locally called dzong [rdzong], at several locations in Monyul as administrative offices for the purpose of collecting taxes. The dzong also functioned as administrative centers for local communities. In addition, the Tibetan government constructed Tawang Monastery, which exerted an influence on many aspects of the lives of the local inhabitants. Taxes collected from local residents were used by the monastery, and a portion of the taxes was transported to Lhasa. In the early eighteenth century, two administrators dzongpon, one at Dirang and another at Taklung, were appointed for collection of tax as contribution towards the monastery etc. Since 1944, especially in 1946 just before the independence, British-ruled India tried to abolish taxation by dzongpon in the Dirang and Kalaktang areas. However, since the taxation contributed to Tawang Monastery or to locally resettled former officials, the local people themselves continued this practice until 1951. This chapter examines the types of items that were collected as taxes and how the taxes were conveyed to Tawang Monastery and Lhasa. The main focus of this chapter is on the history of the interrelationships among the local people in the Monpa area, Tawang Monastery, and the Tibetan government.