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1.
The relationship between growth indices and renewal rates of the Siberian larch (Larix sibiricaLedeb.) stands that have grown at the timberline in the Kuznetsk Ala Tau mountains during the past 350 years was analyzed. The age generations of larch were formed in the 1640s, 1660s, 1680s, 1700s, 1720s, 1740s, 1760s–1770s, 1800s–1810s, 1850s, 1870s–1880s, 1900s, 1920s, and 1930s–1940s. It was shown that the formation of these age generations coincided with 10- to 30-year periods of increased growth of larch and improved temperature conditions in summer.  相似文献   

2.
Former dredging sites were studied in the taiga zone of the Amur region (in Khabarovsk Krai). The involvement of Larix cajanderi in plant succession on dredging waste dumps was revealed. Some morphological-anatomical parameters of L. cajanderi needles were compared in trees growing on the dumps and in adjacent open larch stands on waterlogged peaty soils.__________Translated from Ekologiya, No. 4, 2005, pp. 259–263.Original Russian Text Copyright © 2005 by Osipov, Burundukova.  相似文献   

3.
The morphology and development are described for Siberian stone pine (Pinus sibiricaDu Tour) growing at the timberline in the Western Sayan Mountains. Throughout ontogeny, these plants have a short stem trailing in an approximately horizontal direction. Maximal longevity and viability are characteristic of basal branches, which are able to root and produce vegetative generations. This allows these plants to be classified with the procumbent tree life form, in which the clones of most adaptive genotypes not only survive under extreme environmental conditions, but can also reproduce vegetatively.  相似文献   

4.
5.
Seasonal and long-term dynamics of heterotrophic plankton in the Bay of Novorossiisk are discussed. It is shown that specific variation in the biomass of nanoheterotrophs and infusoria is associated with the processes of anthropogenic water eutrophication. The biomass of infusoria has increased ten times and that of zooflagellates two times since 1985–1986. Infusoria of the genera Strombidium, Strobilidium, and Mesodiniumare dominant in the protozoan plankton. The annual average level of Oligotrichadevelopment in the bay is characteristic of eutrophic water bodies (112–417 mg/m3); in the spring–summer season, however, it may increase to 500–1034 mg/m3. In the part of the bay near the port, which is exposed to a strong anthropogenic impact, the biomass of ciliate protozoa can reach 2 g/m3.  相似文献   

6.
The structure of the crown and branching; the growth, development, and ontogeny of branches; and organogenesis and growth of female shoots in the model Siberian stone pine trees were studied in four types of habitats at the timberline in the central Altai Mountains (1700–2170 m a.s.l.). The results provided evidence that the ecological forms of trees appear due to changes in the pattern of branching as well as to the decreased rate of vegetative (primarily apical) growth. The diameter of the shoot pith is one of the most variable characters reflecting the deterioration of environmental conditions at higher elevations.  相似文献   

7.
Delivering on the Promise of Agroforestry   总被引:1,自引:0,他引:1  
Agroforestry – the traditional practice of growing trees on farms for the benefit of the farm family and for the environment – was brought from the realm of indigenous knowledge into the forefront of agricultural research less than two decades ago. It was promoted widely as a sustainability-enhancing practice that combines the best attributes of forestry and agriculture. Based on principles of natural resource management and process-oriented research, agroforestry is now recognized as an applied science, that is instrumental in assuring food security, reducing poverty and enhancing ecosystem resilience at the scale of thousands of smallholder farmers in the tropics.Trees on farms provide both products and services: they yield food, fuelwood, fodder, timber and medicines, which farm families can use at home or take to market to bring in much-needed cash; they replenish organic matter and nutrient levels in soils and they help control erosion and conserve water. The International Centre for Research in Agroforestry, and its partners, are working to integrate the functions of trees with policy and institutional improvements that aim at facilitating wide-scale adoption by farmers.Two examples described in this paper are replenishing soil fertility in sub-Saharan Africa using short-term improved tree and shrub fallows and the results of agroforestry research to support significant land tenure policy in southeast Asia.Although just one option in sustainable land-use, science-based agroforestry has the potential to produce economically, socially and environmentally sound results for the billions of people who depend on this ancient practice and modern science.  相似文献   

8.
The results of long-term studies on plutonium distribution in the atmospheric air and plants in the area surrounding the Mayak Production Association in the years 1976–1995 are summarized. Data are presented on the changes in plutonium concentration in the air overtime at some points located in the survey zone and the impact zone of the industrial enterprise as compared to those in the control region. In addition, data on the changes in air plutonium concentration depending on the season and direction of wind are presented; the ratios between plutonium concentrations in the air and the fallout are analyzed.Translated from Ekologiya, No. 1, 2005, pp. 20–25.Original Russian Text Copyright © 2005 by Chudin, Shcherbakova, Maslovskii, Kocheva, Iovlev, Denisenko, Demin, Mamin, Chebotina.  相似文献   

9.
The expansion of so-called evergreen conifers (EGCs), including Siberian stone pine, spruce, and fir, along the transect oriented from the boundary of the larch-dominated zone (LDZ; mixed forests of the Yenisei Ridge) to its center has been studied. The normalized dispersal coefficient calculated as K i = (n i N i )/(n i + N i ), where n i and N i are the relative numbers of the ith species in the undergrowth and the upper layer, respectively, serves as an indicator of the expansion. It has been found that the K i values for EGCs (and birch) are higher than the K i of larch even in the zone absolutely dominated by larch, where the relative numbers of EGCs in the upper layer is less than 1%. The EGC undergrowth has mainly been formed during the past 20–30 years, which is correlated with the trend of summer temperatures The spread of EGCs in the LDZ depends on the frequency of forest fires. The decrease in the time intervals between fires in the 20th century to 65 years (versus 100 years in the 19th century) may have prevented the expansion of competing species in the LDZ. The results obtained indicate that EGCs and birch penetrate into the zone traditionally dominated by larch, which is related to climatic changes during the past three decades. At the same time, tree stand density is increasing in the forest-tundra ecotone, and larch is spreading further into the tundra zone.__________Translated from Ekologiya, No. 3, 2005, pp. 186–193.Original Russian Text Copyright © 2005 by Kharuk, Dvinskaya, Ranson, Im.  相似文献   

10.
Coconut trees growing on atolls of the Bikini Islands are on the margin of K deficiency because the concentration of exchangeable K in coral soil is very low, ranging from only 20 to 80 mg kg−1. When provided with additional K, coconut trees absorb large quantities of K and this uptake of K significantly alters the patterns of distribution of 137Cs within the plant. Following a single K fertilization event, mean total K in trunks of K-treated trees is 5.6 times greater than in trunks of control trees. In contrast, 137Cs concentration in trunks of K-treated and control trees is statistically the same while 137Cs is significantly lower in edible fruits of K-treated trees. Within one year after fertilization (one rainy season), K concentration in soil is back to naturally low concentrations. However, the tissue concentrations of K in treated trees stays very high internally in the trees for years while 137Cs concentration in treated trees remains very low in all tree compartments except for the trunk. Potassium fertilization did not change soil Cs availability.  相似文献   

11.
Local dandelion (Taraxacum officinales.l.) populations were studied in the areas of the Eastern Ural Radioactive Trace and the floodplain of the Techa River in its upper reaches. In impact plots, the density of soil and plant cover contamination with 90Sr and 137Cs exceeded the background level by factors of 13–440 and 2–500, respectively; the radiation load exceeded the background level by factors of 1.5 to 45. The seed progeny of plants from these plots was characterized by a high proportion of abnormal seedlings and an increased level of chromosome aberrations in meristem cells. In some years, variation in the seedling viability, growth rate, and developmental rate in these plots exceeded the reaction norm of plants from the background plot, demonstrating both stimulation and inhibition of growth processes. The response of seeds to acute irradiation at high challenging doses varied depending on the level of background radiation in the plots.  相似文献   

12.
The influence of food change on the development of the mothArchips podana was studied. Larvae of a natural population were collected from an apple tree. Nevertheless, the minimal duration of development and the maximal weight of pupae in the next generation were observed in insects that developed on plum, pear, and currant, rather than on apple trees. Transfer has effect on larvae of late instars: transfer from the plum to other trees results in the deterioration of developmental parameters, while that from apple to plum and currant leads to their improvement. This procedure has an effect on the proportion of pupating larvae. The timing of egg laying influences the development and mortality of the larvae. The development of adults from older clutches on apple is comparable to that on plum.  相似文献   

13.
Based on the results of our own long-term experiments and the analysis of published data, the process of individual development (ontogeny) of trees and the parameters of ontogenetic stages are described. Changes in the environment-forming (edificatory) role of a tree in the course of ontogeny and upon its completion are characterized. The performance of this role leads to the formation of the following components of biogeocenosis heterogeneity: phytogenic fields of trees, gaps in the tree canopy, and windfall–soil complexes. The data concerning the interrelation of structural transformations of the plant and soil covers in the course of forest vegetation and soil formation on the primary substrate are reviewed.  相似文献   

14.
Plants are unique in their ability to serve as in situ monitors for environmental genotoxins. We have used the alkaline comet assay for detecting induced DNA damage in Allium cepa to estimate the impact of high levels of natural radiation in the soils of inhabited zones of Ramsar. The average specific activity of natural radionuclides measured in the soil samples for 226Ra was 12,766 Bq kg−1 whereas in the control soils was in the range of 34–60 Bq kg−1. A positive strong significant correlation of the DNA damage in nuclei of the root cells of A. cepa seeds germinated in the soil of high background radiation areas with 226Ra specific activity of the soil samples was observed. The results showed high genotoxicity of radioactively contaminated soils. Also the linear increase in the DNA damage indicates that activation of repair enzymes is not triggered by exposure to radiation in HBRA.  相似文献   

15.
Fuelwood is the only important source of energy in the mountainous region of the Garhwal Himalaya, India. Since the commercial source of energy is generally beyond the reach of ordinary people due to their poor socio-economic conditions and due to limited supply and lack of communication facilities for transport of LPG, the villages of the inner region of the Garhwal Himalaya depend on their fuel requirement from the forest. In the present study, two villages of the Nanda Devi Biosphere Reserve in Uttarakhand part of the Indian Himalaya i.e. Lata and Dunagiri located at 2,415 and 3,600 m altitudes, respectively, were selected for the study of socio-economic profile and vegetation and for estimation of per capita fuelwood consumption and the degree of disturbance. The study was conducted from 2002–2005. The population of these villages is migratory and belongs to the Bhotiya community, a scheduled tribe consisting of two subgroups known as Tolcha and Marchha. They grow traditional crops as well as cash crops. Important tree species used for fuelwood include Cedrus deodara, Pinus wallichiana, Cupressus torulosa, Taxus wallichiana, Acer indicum, Quercus dilatata and Viburnum cotinifolium. Maximum density among trees was shown by Pinus wallichiana (169.6 trees ha−1) in village Lata and by Cedrus deodara (89.6 trees ha−1) in village Dunagiri. The average per capita consumption of fuelwood in villages Lata and Dunagiri was 4.03 and 4.77 kg capita−1 day−1. Maximum number of trees (29 and 31% lopping for Lata and Dunagiri, respectively) belonged to disturbance class 1 (1–20% lopping) followed by the disturbance class 2 (20–40% lopping). Due to location of these villages in the buffer zone of the biosphere reserve, the fuelwood consumption may cause an adverse impact on the ecological status of this reserve, which urgently requires employing strategies for the conservation and management of this biosphere in terms of fuelwood sustainability e.g. regulation of livestock stock and grazing, using alternative sources of fuels, plantation of multipurpose trees and adoption of ecotourism.  相似文献   

16.
Cytogenetic variation was analyzed in daughter populations of Scotch pine from the Voronezh Forestry. The dependence of the variation on the method of seed collection (the commercial method; the population method, when seeds from a group of phenotypically normal trees in the center of the forest are collected; or the individual method, when seeds from plus trees are collected) and on the ecological situation at the sampling site (ecologically safe conditions or chemical or physical pollution) was studied. The parameters of the mitotic rate and mitotic pathology were estimated at 7–9% and up to 5%, respectively. These parameters may be considered as normal when estimating the quality of seed progeny in pine and when pine is used as a test object in cytogenetic monitoring. The limits of variation and the spectra of cytogenetic characteristics allowing the pine populations to maintain their homeostasis were also determined.  相似文献   

17.
The state of gonads was analyzed in sea urchins Strongylocentrotus intermediuscollected in Amur Bay (Peter the Great Bay, the Sea of Japan) in August 1984, 1985, 1989, and 1997 at five stations: Skrebtsov Island (1), Sportivnaya Harbor (2), Cape Tokarevskii (3), Alekseev Bay on Popov Island (4), and Verkhovskii Islands (5). The first three stations were in the polluted inshore zone of Vladivostok; stations 4 and 5 were in the open (insular) part of the bay, remote from the main sources of pollution. The state of gonads of sea urchins collected in different years and areas strongly varied with respect to gonad index (GI), gonad maturity index, and indices of pathological changes in gonads. As compared with the data obtained in 1984, 1985, and 1989, the values of GI increased in sea urchins from stations 1–3 and decreased in sea urchins from stations 4 and 5. Although GI values were high, the indices of gonad maturity in animals from the coastal zone were very low. In general gonad maturity in sea urchins from the Amur Bay was lower in 1997 than in the previous years. The correlation analysis of long-term data revealed no positive correlation between the values of GI and gonad maturity index in sea urchins from stations 1–4. Histopathological changes were more serious in sea urchins from stations 1–3. In 1997, the indices of pathological changes in the gonads of sea urchins from the insular zone (stations 4 and 5) were higher than in the previous period (1984–1989). The influence of various ecological factors—temperature, salinity, environmental pollution, and food supply—on gametogenesis in sea urchins is discussed.  相似文献   

18.
The status of mangroves within and adjacent to Kiunga Marine Protected Area (MPA) were assessed by means of aerial photographs and intensive ground truthing. Vegetation maps (1 : 25,000) were produced on GIS environment making it possible to store, retrieve and analyze various types of information very quickly. The maps together with the digitized information provide important tools to the management of mangroves of Kiunga MPA since various proposed treatments can now be entered and summarized thus providing useful overviews for planning, implementation and monitoring.The present inventory revealed that the existing mangrove forests within and adjacent to Kiunga MPA have a net standing volume of 2,354,004.85 m3 in 16,035.94 ha. There are eight species of mangrove trees, of which Rhizophora mucronata and Ceriops tagal are dominant. The standing volume ranges between 6.85 to 710.0 m3 ha–1 for stem with diameter above 5.0 cm. The average volume of the entire study area was 145.88 m3 ha–1, which corresponds to a stocking rate of 1736 stems per ha. Given its high potential productivity and regeneration, mangroves within and adjacent to Kiunga MPA have excellent prospects for sustainable exploitation.  相似文献   

19.
Several studies have documented that vegetation in the Sahel is highly dynamic and is affected by the prevailing climatic conditions, as well as by human use of the areas. However, little is known about vegetation dynamics in the large saline areas bordering the rivers of West Africa. Combining satellite imagery, the perception of local people and botanical information, this study investigated the vegetation dynamics and the drivers of vegetation changes in Fatick Province, Senegal. Satellite images showed a change in vegetation composition, i.e., a loss of tree cover and an increase in shrub cover, herbaceous cover and tans (highly saline areas with sparse vegetation). Although the trend was the same, the three villages had different vegetation histories. A survey of the woody vegetation showed that shrubs and young trees were dominating with relatively few large trees. Local people perceived a general decline of woody plants from 1993 to 2013. Among 60 species mentioned by local people, 90 % were declining and 10 % increasing. Together the three methods documented a decrease in density and diversity of the woody vegetation, mainly influenced by salinity and land use. The large numbers of young trees indicate a potential for regeneration of some, but not all, tree species. As many tree species appreciated by local people were reported to be declining, local communities have experienced a reduction of their natural resources. Based on villagers’ recommendations for improved vegetation management, we discuss possible contributions including reforestation, desalinization and environmental protection for restoration of the vegetation.  相似文献   

20.
Quantitative and qualitative characteristics of cones and seeds and the emergence and survival of seedlings in the Siberian spruce (Picea obovata Ledeb.) were studied in different parts of the timberline ecotone on the Iremel’ Massif, the Southern Urals, from 2003 to 2006. In the productive year 2003, a decrease in the number of cones (from 110000 to 3000 per hectare), the yield of seeds (from 13 × 106 to 0.09 × 106 per hectare), and their laboratory germination rate (from 34 to 14%) with an increase in elevation above sea level was recorded. In 2004, significant differences in the number of seedlings per hectare were revealed between the lower, middle, and upper parts of the ecotone (85 200, 19 800, and 0–400 ind., respectively). It has been shown that the greater part of seedlings (76–96%) perish during the first cold period. New generations of spruce trees are formed only after productive years. Seed production and seedling mortality in spruce apparently depend not only on air temperature and soil moistening but also on snow depth and soil temperature, which change more abruptly along the altitudinal gradient.  相似文献   

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