Destruction Of Trees Research Articles

Statutory measures for the protection and enhancement of the urban forest in Guangzhou City, China

Summary Urban-forestry management in China, due to its unique political and social environment, exists in a different legislative and administrative regime. An evaluation of the current statutory and quasistatutory administrative instruments can throw light on the status and prospects of the country’s urban-forestry programme. Guangzhou City, the largest municipality in South China, with a high green cover, was chosen for a case study. The assessment includes measures with a bearing on the planning, development, management and protection of urban trees and urban landscapes, at the national, provincial and municipal levels. Four national laws accompany a plethora of administrative documents to define an overall urban-forestry framework, and to demarcate the relevant authority and responsibility at different planes of the government hierarchy. The provincial measures play a secondary role in filling some gaps in the national legislation, with the main contributions being in allocating financial responsibilities and laying down punitive and compensatory legal procedures. Operations-related measures have been developed comprehensively at the municipal level with practical guidelines for their implementation. Special issues related to weaknesses, room for improvement, and general implications for Guangzhou and other cities are discussed. The lack of clearly defined enforcement agents and generally lax enforcement have weakened the otherwise quite comprehensive legislative measures. The widespread illegal use of urban parks for commercial and other activities by government departments has undermined statutory integrity. The continued destruction of trees due largely to government projects signifies that the relevant laws are widely disregarded and ignored by civil servants. The legal vacuum of liability related to hazardous trees needs to be promptly filled. The overwhelming domination of the government with negligible participation by citizens contrasts vividly with urban forestry in other countries and deprives the programme of the necessary popular support.

Dynamics of Salix caprea L. populations during forest regeneration after strong herbivore pressure

Abstract. Broadleaved forest communities degenerated through strong pressure from large herbivores. Relief of this pressure led to regeneration, in particular of Salix caprea and other light‐seeded pioneer trees: Populus tremula, Betula pendula and B. pubescens. This regeneration proceeded following conservation protection of degenerate stands in a nature reserve and later in Biaowiéza National Park. The emergence and development of the Salix caprea population proceeded following the expansion of Picea abies, which coincided with the period of enhanced animal pressure on the broadleaved forest. Salix caprea filled all the gaps in the tree stand after the destruction of trees and undergrowth by herbivores (in the years 1892–1915). The species also appeared abundantly in old, at the time unforested, clearings and felled areas.Here, S. caprea developed large populations with certain trees in good condition, with a growth form typical of forest trees and attaining considerable heights. The majority of trees were 50 ‐ 60 yr old at the time of death, although some individuals reached 74 yr of age. The process of extinction of the Salix population — observed over 19 yr on permanent plots with marked trees — proceeded very quickly, especially in the first decade of observation. It led to the almost complete disappearance of S. caprea from the forest communities of Biaowiéza National Park. The death of individual trees is preceded by impairment of their health and reduced annual increments in the last 4–9 years of their life.The development of populations of permanent constituents of the forest, notably Carpinus betulus, Tilia cordata, Acer platanoides and Ulmus glabra, under the canopy of light‐seeded trees, and the absence of a new generation of pioneer trees points to the end of the process of regeneration in the forest communities of BiaHwiéza National Park.

Scientists Stress Biodiversity—Human Health Links

THE DIVERSITY of life on earth is directly related to human health. As environmentalists sound warnings about the human destruction of natural habitats, the message they send does not concern just the possible extinction of some avian, mammal, botanical, or other species, but the survival of humankind itself. Physicians hardly need to be reminded of the adverse health effects of air pollution or excessive exposure to ultraviolet light. But they may be less aware of the implications for human health of the effects of global warming, or that changing patterns of precipitation can affect the spread of infectious diseases by altering the ranges of insect vectors, or that the destruction of plants and trees could reduce the sources of new medicines derived from botanical products and microorganisms. This interconnecting relationship between biological diversity ("biodiversity") and human health was the topic of a symposium held in Washington, DC, and sponsored by

The History of Deforestation and Afforestation in Ethiopia Prior to World War I

The History ofDeforestation and Afforestation in Ethiopia Prior to World War I Richard Pankhurst Institute of Ethiopian Studies Addis Ababa University The advent of firearms in Ethiopia, mainly in the 18th, 19th, and early 20th centuries led, as argued by the present writer elsewhere,1 to a dramatic destruction of wildlife, first in the northern and later in the southern part of the country. This can be illustrated not only from travelers' accounts, but also by the well-documented sharp increase, and later no less rapid decrease, in ivory exports. An examination of the by-no-means abundant historical records relevant to forestry seems to show that the destruction of trees, though perhaps slower, was no less significant. Deforestation In considering the long history of Ethiopian deforestation one should emphasize at the outset that there are no reliable records of the extent of the country's forests prior to recent times. The modern forestry expert H. F. Mooney has argued that Ethiopia was "densely wooded" in "ancient, and not so remote times,"2 but there is in fact no way of establishing how much of the country was actually forested, or at precisely what period and at what rate deforestation occurred. There can, however, be no gainsaying that areas of major settlement were over the centuries steadily deforested, and that the result was "ruinous," as Stanislaw Chojnacki has observed, most "especially in the©Northeast African Studies (ISSN 0740-9133) Vol. 2, No. 1 (New Series) 1995, pp. 119-133 119 120 Richard Pankhurst hilly parts of the country." Explaining the processes involved he adds: "First the hills lost their covering of forests by human action, then torrential rains did the rest: good soil was washed away on the slopes and only poor grass and some bushes remained."3 Medieval Times Deforestation, it is clear, was by no means a uniquely modern phenomenon . Wood was reportedly scarce in medieval times, particularly in the vicinity of settlements, and especially of royal and other military camps. Shortage of firewood, as well as of provisions, was reportedly a major factor leading to the institution of moving capitals, notably in the 16th and 17th centuries.4 The Florentine merchant Andrea Corsali reported in 1517 that Ethiopian monarchs of that period traveled with such large retinues and armies that the latter, because of the exhaustion of provisions, could not remain in any one place for more than four months, nor return in less than twelve years.5 The presence of so many courtiers and soldiers, it may be assumed on the basis of later evidence, led not only to acute shortages of food, but also to the significant depletion of trees cut down for timber and firewood. Some, though not necessarily very reliable, evidence of deforestation is also to be found in oral tradition. Folk memory claims that a forest on Mounts Männagäsha or Wächächa (the names of two sides of a mountain west of present-day Addis Ababa) was "devastated" in "ancient times." The tradition asserts that Emperor Ya'qob (1593-1603, 1607) ordered that the mountain be re-afforested with tidh trees (Juniperus procera ) supposedly brought from the Wofwasha forest south of Däbrä Sina, and sown in prepared patches. It is further claimed that Ya'qob then issued an edict prohibiting the cutting down of trees in this forest.6 As the Portuguese Jesuit Manoel de Almeida noted in the early 17th century, there was at that time "not much woodland" in the country, which, he added, was "not well stocked" with trees. This shortage, he declared, was "not the soil's fault," but the inhabitants,' for, "every day" the latter cut down trees "for their houses and for fuel," but "none of them," he complains, had either "the energy or the will to replant a single one."7 A century and a half later the Scottish "explorer" James Bruce told a similar tale, observing that in the vicinity of the then-capital, Gondar, The History ofDeforestation and Afforestation in Ethiopia 121 people had "everywhere extirpated the wood," and in consequence labored "under a great scarcity."8 Trees in Urban Centers While emphasizing the extent of deforestation in historic...

Endangered byrophytes in Czechoslovakia— causes and present status

Problems concerning endangered bryophytes in Czechoslovakia have been discussed for at least 15 years. The main threats are air and water pollution, the use of pesticides and the destruction of habitats e.g. by exploitation and destruction of old trees. In 1983 it was decided to publish Red Data Books of endangered plant and animal taxa. Bryophytes are to be included in the fifth part, devoted to non-vascular plants. As a first step in the preparation of this book a provisional Red list of Czechoslovakia bryophytes has been prepared. This list shows that at least 6·2% of the liverworts and 1·9% of the mosses are extinct, 10·0% of the liverworts and 5·6% of the mosses are endangered and 12·5% of the liverworts and 22·4% of the mosses are vulnerable. Altogether, almost one-third of Czechoslovakia's bryophytes are now extinct or threatened. Since the Red Data Book should include only representative taxa, 40 species (11 liverworts and 29 mosses) were selected to demonstrate the various types of threat.

Impact of chronic gamma irradiation on a Mediterranean forest ecosystem in Cadarache (France)

An area of mixed forest, white oak and evergreen oak in Cadarache (southern France) has been irradiated for 18 years by a 137Cs source. The irradiation effects on the soil system were investigated at five stations along a transect, from 116 mGy h −1 to 0·3 mGy h −1, towards the source and at a control area of non-irradiated forest. The key factor was that there were no ongoing litter inputs to soils in the most irradiated area (100 to 60 mGy h −1) because of the destruction of trees and shrubs. The responses of the edaphic characteristics, biological activities and invertebrate populations of the soils indicated the existence of two main zones, one receiving litter, the second without litter input. In the latter the C and total N fluxes by respiration were significantly reduced. Chronic exposure reduced the carbon biomass and the dehydrogenase activity by around 50% and increased the amount of nitrate in the soil. The structure and composition of animal communities in the soil were changed: microarthropod density was low, ‘other mites’ were dominant. Chronic gamma irradiation had a range of direct and indirect effects. Nevertheless, the degree of disturbance was comparable to those induced by silvicultural practices or by burning. However, the chronic nature of the irradiation maintained the ecosystem under a long-term state of stress.

Evidence of widespread fungal attack on Upper Triassic trees in the southwestern U.S.A.

Certain Upper Triassic tree trunks in the southwestern U.S.A. show evidence of damage similar to that caused in tree trunks at the present day by pocket rot fungi such as Polyporus amarus Hedgc. and Heterobasidion annosum (Fries) Bref. The damaged trunks occur in a relatively thin stratum at the same horizon over a wide area in the Petrified Forest National Park, Arizona and elsewhere in the southwestern United States duting the Late Triassic. If the peculiar pattern of damage was caused, as it seems, by a pathogenic fungus then it can be compared in scale with the extensive destruction of Ulmus trees by Dutch Elm Disease [ Ophiostoma (Ceratocystis) ulmi (Buisman)] in recent years in Europe and North America.

Sustainable solutions to land use conflicts: Cattle and trees in the SADCC region

This article addresses the potential land use conflict between trees and cattle. The search for pasture frequently leads to the large-scale destruction of trees yet, paradoxically, when grazing land is under stress the retention of trees becomes ever more important to sustain the productive capacity of the land. Communal grazing is a vitally important land use in southern Africa, but it is increasingly under stress. Through a series of case studies, the article explores ways of maintaining a productive environment by turning the potential adversaries of cattle and trees into allies. To achieve this goal will require an integrated land use approach which overcomes the institutional boundaries of rangeland management, forestry, energy planning and agricultural extension.

Effect of Fire on the Availability of Hollows in Trees Used by the Common Brushtail Possum, Trichosurus Vulpecula Kerr, 1792, and the Ringtail Possum, Pseudocheirus Peregrinus Boddaerts, 1785.

Characteristics of trees used for shelter during the day by brushtail and ringtail possums were identified in a study in open forest dominated by Eucalyptus marginata and E. calophylla in the Perup Fauna Nature Reserve, SW Western Australia. The effect of high-intensity fire on the availability of trees used by the possums was studied by comparing a burnt area (36 ha) with an unburnt area (22 ha) one and 32 months after the fire. Suitable hollows were used by possums regardless of the species, condition, height or size of the tree. Hollows deeper than 1 m were used significantly more frequently than shallow ones. Hollows of suitable size appear to develop in E. marginata when trees reach a mean age of about 300 yr, and in E. calophylla when trees reached a mean age of about 200 yr. The average age of trees inhabited by possums could be as high as 500 yr for E. marginata and 400 yr for E. calophylla. About 3 trees/ha were used by possums for diurnal refuge; the distribution of these trees was random. Fire of high intensity (1000-1400 kW/m) destroyed 38% of the trees previously inhabited by possums; the damage to other inhabited trees was related to their condition and the intensity of fire. In the longer term, high-intensity fire increased the rate of formation of hollows by direct excavation or by providing new sites for fungal and termite infestation. Thirty-two months after the fire, the average age of trees containing suitable hollows was estimated to be about 100 yr less than before the fire because of the destruction of older trees and the formation of new hollows, or the deepening of existing ones, in younger trees.

Local programs in the United States for preventing the destruction of trees on private land

Adoption of municipal ordinances regulating the removal of trees on private property is a recent phenomenon in the U.S.A. Some ordinances regulate the removal of ordinary trees above a specified size in designated areas. Others regulate the removal of trees that are special because of their age, unusual size, beauty, historic association, or because they are part of an environmentally endangered natural forest community. Most programs suffer from limited coverage, exempting major land uses, small and even medium size trees. Permit approval rates are high, but many permits are granted only after plans have been improved. There have been few court tests. Current regulatory programs do not take into account the special characteristics of a municipality's topography, existing mature stands, and patterns of buildings and open space. Regulations should be preceded by landscape analysis and a municipal landscape plan for retaining trees and planting new ones in municipal-scale patterns that will be most effective in attaining energy, environmental, and scenic goals. The municipal landscape plan could be translated into regulations through an overlay to the zoning map. Effective implemention would require incentives and education in addition to enforcement of the regulations. Research is needed to provide standards for determining amounts, locations, and nature of plantings to achieve desired microclimate moderation, noise attenuation, and scenic benefits.

Occurrences of Ceratocystis ulmi in Norway1

Norway (in contrast to Denmark and Sweden) has so far had only a few outbreaks of Dutch elm disease, all in the southern part of Norway (cities of Oslo and Drammen) on one or a few Ulmus glabra trees in city parks, not far from harbours and railways. Scolytus laevis endemic to Norway is the only potential vector found in the diseased trees. Transmission of the fungus through root grafts cannot be disregarded. The fungus is currently considered a dangerous foreign organism in Norway, subject to treatment according to the Norwegian phytosanitary regulations. Control measures, aiming at eradication, have been applied in all known cases of attack. Removal and destruction of diseased trees, stump treatment with herbicide, and covering of stumps with soil, have apparently been successful measures.

A general assessment of the environmental impact of refugees in Somalia with attention to the refugee agricultural programme

This paper attempts to examine the broad features of Somalia's harsh physical environment into which several hundreds of thousands of refugees, with mainly a nomadic or semi-nomadic life style and culture, dramatically descended six years ago. The thirty-six rural camps in which at least half of them live are described as is the refugee agricultural programme which is training several thousand families so that they may be "self-supporting." The four regions where the camps are located are each briefly summarized in terms of their soils, their climates, their natural vegetation, and the type of agriculture which the refugee farmers practice. A more detailed analysis is then given on the following critical environmental concerns: Vegetation and erosion on refugee farms, the growing problem of refugee livestock, the destruction of trees, and irrigation practices and salinity on refugee farms. The paper concludes with an argument to preserve Somalia's environment from careless and destructive exploitation, which is leading towards desertification, and calls for an in-depth study of the situation.

The impacts of elephant, giraffe and fire upon the Acacia tortilis woodlands of the Serengeti

SummaryThe reduction in canopy cover of the Seronera woodlands since the mid‐ 1960s can be largely attributed to the destruction of mature Acacia tortilis trees by elephants. The development of the tree regeneration that has colonized the gaps in the mature canopy is being suppressed by giraffe browsing and periodic burning. A simple model is presented which simulates these impacts upon the dynamics of the A. tortilis population. Height‐specific impact rates of these three agents are quantified. Between 1968 and 1977, mature trees were lost at a mean annual rate of some 6%, although this figure showed considerable annual variation (13.5‐2%). Combinations of impact rates, simulating possible natural developments within the Serengeti woodlands, are programmed into the model to assess their effects upon the tree population structure. The results suggest that measures to promote regeneration development (fire protection and/or giraffe culling) are more effective in the long‐term to encourage mature canopy recovery than are measures to reduce mature tree mortality (elephant culling). The management implications of these results are considered, and their extrapolation to other wildlife conservation areas experiencing similar declines in mature canopy woodland is discussed. It is suggested that the effects of the combination of low elephant densities and high giraffe densities prevalent in the Serengeti produce a dynamic system in which the woodland structure oscillates between mature canopy and open regeneration‐grassland phases. The woodland structure desired by Park management to ensure continuity of mature tree canopy represents an unstable transitional stage between these two phases.RésuméLa réduction du couvert végétal dans les forêts de Seronera depuis les années 1965–1970 peut être largement attribuée ai la destruction des Acacia tortilis par les éléphants. Le développement de la régénération des arbres ayant colonisé les espaces libres du couvert végétal est anihilé par le broutage des girafes et les incendies saisonniers. On présente un modeile simple qui simule ces impacts sur la dynamique de population de Acacia tortilis. Pour ces trois facteurs, les taux d'impact spécifique de la hauteur sont quantifiés. Entre 1968 et 1977, le taux de perte

The detection of plum pox virus in Prunus species by enzyme‐linked immunosorbent assay (ELISA)

SUMMARYPlum pox virus (PPV) was detected by ELISA throughout the year in extracts of root, bark, fruit, flowers and leaves of Prunus species; extracts from healthy plants gave negligible background reactions. In the summer, ELISA values obtained with extracts from infected leaves were variable but samples extracted at 1:50 (w/v) could have been diluted a further five to 110 times before reaching the limit of detection. Using a single antiserum the virus was detected in several hundred trees, suggesting that there was little antigenic variation.PPV was unevenly distributed in leaves and shoots and commonly occurred in only a few branches of an infected tree although it was frequently present in suckers growing from the roots. Virus was detected in the only three trees known to be infected in random leaf samples taken from 530 1‐yr‐old trees, but some infected trees were missed in samples taken from older trees and from a 7‐yr‐old rootstock hedge. The main practical use of ELISA for PPV is therefore as a sensitive and highly reliable confirmatory test which greatly facilitates control of the disease by the prompt destruction of infected trees.

Apricot Decline Today and Tomorrow

AbstractFor many years, the causes of apricot decline have remained a matter of controversy. It may now be considered that this early destruction of trees is a result of the joint action of 6 different parasites, which particularly, if not exclusively, attack apricot: 4 fungi, 1 bacterium and 1 mycoplasm‐like organism. Each parasite, per se, is able to destroy trees in a good condition of growth. Some other fungi and some insects may also adversely affect apricot, as they do other fruit species. The development of each disease depends on particular agrotechnical and environmental conditions.As no curative methods are available, control consists of preventive methods. These must be formulated and applied so as to avoid favouring the development of one parasite when preventing that of another.International co‐operative research is required to cope with difficulties in acquiring the necessary data, particularly in the field of disease resistance.

The frequency and extent of uncontrolled grass fires in the Rwenzori National Park, Uganda

SummaryThe area of grassland affected by uncontrolled fires was recorded in the Rwenzori National Park for each dry season between July 1970 and July 1973 with the exception of the January 1973 season. The seasonal total of burnt grassland rose to a peak of 32 7% in January 1971 but there was then a marked decline to a negligible level in July 1971. This was followed by a further steady rise which by July 1973 had reached to within 3% of the previous peak. 13 4% of the park was burnt at least once a year on average, and 55 3% was burnt at some time or other during the 3 years. Burning was not uniformly distributed throughout the park and four regions at high risk from fire are identified for particular attention should a fire control policy be introduced. The need for a controlled burning policy is emphasized particularly in view of the destruction of trees which is taking place through the agency of elephants.

The Tsavo and the Elephants

In 1966 the Ford Foundation made a grant of £78,000 to finance a three-year research project in the Tsavo National Park in Kenya. The big problem to be investigated was the vast and increasing numbers of elephants which were said to be destroying the park by their wholesale destruction of trees. A research programme was started, involving the killing of large numbers of elephants. This aroused considerable controversy, and in May 1968 the Director and a research ecologist resigned. Research has, however, continued under the direction of the author, who is Botanist Warden, aided by a zoologist, both of whom joined the project later in 1968, and a count of the elephants in 1969 showed that they had not increased at all since 1965. Dr Glover's account of the work that is being done, the findings so far, and the changes in the park itself explains why it is important that the work should continue, and for this new funds must be found.

The Tsavo Elephants

The Ford Foundation has made a grant of £70,000 for research into the elephant problem in the Tsavo National Park in Kenya, which has become acute. In recent years the number of elephants has increased rapidly to some 15,000, and the widespread destruction of trees in the park is generally attributed to them. Are they destroying the habitat? If so, what should be done? One suggestion is to cull up to 5,000 of them. In this article, based on an interview with “Africana” and reprinted by kind permission, Dr Harthoorn of the University College, Nairobi, suggests that some of the tree destruction could be the result of excessive burning, and that until the effects of keeping fire out of the Tsavo have been studied, massive killings of elephants should not be attempted.

SOME PRELIMINARY OBSERVATIONS ON THE FOOD OF ELEPHANT IN THE TSAVO ROYAL NATIONAL PARK (EAST) OF KENYA

SummaryThe background to this study is discussed. In the last five years elephant have caused a change in vegetation from dense bush to open country over large regions near the permanent water supplies in the Tsavo Royal National Park (East) of Kenya. Much destruction has also been caused, or aggravated, by fire. (See Map 1).In the 1961 drought, rhinoceros appeared to have suffered from competition with elephant for food, to the point of starvation, but there did not seem to be serious competition in normal dry seasons, such as 1962. In the drought the destruction of trees and bushes by elephant occurred to a far greater extent than during the dry season of 1962.The records of plants eaten apply specifically only to the areas where the data were collected (see Map 2), but probably in a more general manner to the Park as a whole. These plants, with their observed relative importance, are listed in Appendix I. It is emphasised that this study is as yet only in a preliminary stage, and should continue for several years, before final conclusions can be drawn.Elephant were found to eat a few plants in bulk at a particular time, such as grasses, creepers and herbs, along with smaller quantities of other materiai such as bark and leaves. Grasses were always of varying importance. Bark and leaves formed a larger proportion of the food in the dry season than in the rains, but were always eaten to some degree. The plant species of which the feeds were composed varied seasonally and annually. Certain apparently suitable plants were not eaten.Many food plants were analysed, and a few of these results are briefly mentioned. It appears possible that the eating of bark is a search for calcium, as the barks consumed are very rich in this mineral. Feeding behaviour is briefly described.

The role of arboricides in bush and forest eradication

AbstractThis paper is in two parts: in the first the literature on the development and present usage of arboricides is reviewed; in the second some experimental work carried out in Africa during recent years is briefly described.The most widely used arboricide for the destruction of individual trees is sodium arsenite; promising non‐poisonous substitutes are ammonium sulphamate and synthetic plant‐growth regulators based on phenoxyacetic acid. These growth regulators are also being used successfully in certain instances for the treatment of unwanted trees or scrub, both in land clearing and in forestry operations. The control of mesquite (Prosopis spp.) in Texas and of woody vegetation on road verges in the U.S.A. generally are outstanding examples.The experimental work in Africa has been mainly concerned with the initial evaluation of arboricides and defoliants as part of the general problem of tsetse‐fly control. The results have shown that the synthetic growth‐regulators are promising for certain applications. Further work is in progress.