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At least 919 records · Page 51Linked to original sources
PubMed2005

[Effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation on soil biological activities].

This paper studied the effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation in the south, central and upstate areas of subtropical China on the changes of soil chemical and biological properties. The results showed that after replacing with Cunninghamia lanceolata plantation, the total organic carbon (TOC) content in surface soil decreased by 31.51% - 58.24%, and the contents of soil total N and P, pH value, C/N and C/P also decreased to different degree. Soil microbial amount was less than that under natural secondary broad-leaved forest, soil urease, invertase, catalase and dehydrogenase activities decreased, while soil polyphenol oxidase activity increased by 8% - 40%. The respiration rate of Cunninghamia lanceolata soil was 51.15% - 54.48% lower than that of natural secondary broad-leaved forest soil. The correlation between soil TOC and polyphenol oxidase activity was negative (R = - 0.723, n = 18), while those between soil TOC, N, P and other enzyme activities were positive. It could be concluded that replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation worsened soil quality, and the loss of soil organic matter in Cunninghamia lanceolata plantation ecosystem might be one of the important factors resulted in the decrease of soil nutrients and enzyme activities.

Carbon↗
PubMed2005

[Dynamic changes of soil ecological factors in Ziwuling secondary forest area under human disturbance].

As a widespread natural phenomenon, disturbance is considered as a discrete event occurred in natural ecosystems at various spatial and temporal scales. The occurrence of disturbance directly affects the structure, function and dynamics of ecosystems. Forest logging and forestland assart, the common human disturbances in forest area, have caused the dynamic changes of forest soil ecological factors in a relatively consistent environment. A study on the dynamics of soil bulk density, soil organic matter, soil microbes and other soil ecological factors under different human disturbance (logging and assart, logging but without assart, control) were conducted in the Ziwuling secondary forest area. The results indicated that human disturbance had a deep impact on the soil ecological factors, with soil physical and chemical properties become bad, soil organic matter decreased from 2.2% to 0.8%, and soil stable aggregates dropped more than 30%. The quantity of soil microbes decreased sharply with enhanced human disturbance. Soil organic matter and soil microbes decreased more than 50% and 90%, respectively, and soil bulk density increased from 0.9 to 1.21 g x cm(-3) with increasing soil depth. Ditch edge level also affected the dynamics of soil factors under the same disturbance, with a better soil ecological condition at low-than at high ditch edge level.

China↗
PubMed2006

[Progress in research on forest tree genomics].

This is a review on forest tree genomics. In structural genomics, genetic maps have been constructed for up to 40 forest tree species, more than 30 commercially important QTLs have been detected, comparative mapping has been done for a few of forest tree taxa, and whole genome sequencing was completed for Populus and is under way for Eucalyptus. For functional genomics, huge EST databases from multiple tissues of a number of tree species have been rapidly accumulated, and molecular analyses on secondary growth and wood formation, flowering, and cold hardiness have given some insights into the metabolic pathways of those tree-specific development processes. The prospects of development in tree genomics are discussed, which may be implicative for accelerating forest tree genomics studies in China.

Genome, Plant↗
PubMed2006

[Predation and dispersal of Lithocarpus glaber seeds by rodents in Tiantong National Forest Park, Zhejiang Province].

This paper studied the predation and dispersal of Lithocarps glaber seeds by rodents in the Tiantong National Forest Park (29 degrees 48'N, 121 degrees 47'E) of Ningbo City, Zhejiang Province. Five seeds release transects (three in evergreen broad-leaved forest, one in Pinus messoniana forest, and one in shrub), and two seeds release states (covered/uncovered and tagged/untagged) were set up. Iron snare traps were baited to determine the effects of rodents on seeds disappearance. The results showed that two species of rodents, Niviventer confucianus and N. fulvescensi, were the potential predators and dispersers of the seeds. The lost seeds labeled with small piece of tintags could be classified into three categories, i. e., 1) seeds consumed by rodents, with tags stuck seed fragments; 2) seeds cut off from tags, with tags kept only; and 3) both seeds and tags disappeared. The loss rate of seeds was high at the beginning of the observation, and then decreased gradually. The daily seeds disappearance rate (DS-DR) was variable in different habitats, with the highest (1.03%) in evergreen broad-leaved forest and the lowest (0.32%) in shrub. The proportion of these three categories was different, and related with habitat types. The difference of DSDR between covered and uncovered states was statistically significant (P < 0.05), with a higher DSDR under uncovered state. No significant difference was observed between the DSDR of tagged and untagged. The distance of seeds dispersal by rodents was within 6.7 m.

Animals↗
PubMedDate not supplied

[Patterns of formation of island fauna of Rhopalocera (Lepidoptera, Diurna) at the northern forest boundary in the region of Pleistocene continental glaciation (by the example of White Sea islands)].

Patterns of formation of island Rhopalocera fauna at the northern forest boundary in the region of Valdai inland ice were analyzed by the example of White Sea islands. The ecotone effect, typical for northernmost taiga and forest-tundra and introducing the transitional Rhopalocera fauna in near-tundra forest between the boreal and hypoarctic zones, was not observed on the White Sea islands. Island isolation provided for the absence of some Arctic species, entering near-tundra forest from the North, in the island fauna. Island Rhopalocera faunas represent poor variants of the northern taiga fauna lacking some polyzonal and temperate species and having a reduced set of Arctic boreal species.

Adaptation, Physiological↗
PubMed2006

[Classification method of deciduous-conifer mixed forest in jilin province based on GIS-TM remote sensing image].

To improve the accuracy of automatic classification and identification of TM remote sensing images in forest area, an expert system for automatically classifying and identifying deciduous-conifer mixed forest was built up, based on the GIS technique, quantitative analysis on the internal relations between geographic factors such as DEM and slope aspect and environment factors like soil type, and qualitative analysis on the spectrum information and preclassification information of sensing images, aimed to build a classification knowledge system. Taking the TM remote sensing image of Wangqing Forest Bureau in Jilin Province as an example, the study showed that this expert system could obviously reduce the influence of mixed pixel and terrain shadow. The classification precision of this system was increased by 14.22%, compared with that of Iterative Self-Organizing Data Analysis Techniques Algorithm (ISODATA) unsupervised classification, and the Kappa index was 0.7556, which could help to classify needle, deciduous and mixed forests. Introducing GIS data into the expert system could also solve the problem that TM remote sensing image could not do, due to the loss of correct spectrum value in cloudy and shady area.

China↗
PubMed2006

[Roles of forest management in global carbon dioxide mitigation].

This paper summarized the roles of current forest management measures, e. g., reducing deforestation rate, increasing afforestation and reforestation, strengthening the management of nutrient fertilization, fire hazard, and disease and pest injury, and substituting fossils fuels with charcoal, in global carbon dioxide migration, and analyzed the advantage and insufficiency of China's forest management. The authors indicated that the current forest ecosystems in China, mainly their vegetation carbon pool, played a smaller role of carbon sink in global carbon cycle, and thus, it was important to strengthen the tending of newly cultivated plantation and the management of fire hazard and disease and pest injury, and to increase the carbon sequestration of our forests.

Atmosphere↗
PubMed1987

Antibody responses in forest and savanna onchocerciasis in Ivory Coast.

Three foci of onchocerciasis transmission (two forest and one savanna, respectively) in the Republic of Ivory Coast were chosen for a comparative analysis of Onchocerca volvulus antigens and of patients' antibody responses. Clear differences between frequency and intensity of ocular pathology existed between the forest foci and the savanna focus. We found heterogeneity of SDS-PAGE-separated components of female worms with respect to the mobility of three protein bands of the 100 KD region and to the ability of an 80 KD band to bind horseradish peroxidase. These variations were clearly not associated with the degree of ocular pathology. No differences in the composition of worm antigens were detected by immunoblotting. A variable with a possible relation to ocular pathology was the antibody response of patients: individuals from the savanna focus, where a high degree of ocular pathology is observed, tended to have a stronger and more differentiated IgG antibody response against O. volvulus antigens than patients from the forest foci. However, no antigens specifically recognized by patients from either forest or savanna were detected.

Adolescent↗
PubMed1988

Forest and savanna onchocerciasis: comparative morphometric histopathology of skin lesions.

A comparative study was made of skin biopsies from onchocerciasis patients living in the forest and in the savanna of West Africa. The lesions and their pathogenesis were similar in the two series of patients. An inflammatory reaction around the extra-lymphatic microfilariae was observed. But the localization of the microfilariae was slightly different: the mean distances between the microfilariae and the border of the basement membrane of the epidermis was approximately 115 microns in the forest and 138 microns in the savanna. Statistical analysis showed that the forest microfilariae were in the superficial parts of the dermis when the densities were low and in deep parts of the dermis when the densities were high. In the savanna, the phenomenon, although less clearly defined was reverse. The two situations were inverted when the density of microfilariae reached approximately 51 microfilariae per calibrated snip, which was seldom the case. Therefore, the most cases, microfilariae appeared to have been more superficial in the forest than the savanna.

Adolescent↗
PubMed1978

Dynamics and intensity of Wuchereria bancrofti transmission in the savannah and forest regions of Liberia.

In four villages in the savannah and in the rain forest of Liberia, regular assessment of the biting activity and infection rates of anthropophilic mosquitoes have been carried out through full annual cycles. The microfilaremia rates in the localities in the savannah were 18.3% and 20.0% and in those of the forest 10.3% and 12.5%. The all-night catches were performed inside ordinary inhibited houses at monthly or fortnightly intervals. Presence of infective larvae of Wuchereria bancrofti proved Anopheles gambiae, A. funestus and A. nili to be the local vectors. Biting densities were high in the savannah, and low in the forest. From the mosquito catches and the results of their dissections for filarial larvae it could be estimated, that during the observation year a person in the savannah villages would be bitten annually by 18,165 and 36,450 vector mosquitoes respectively, and would receive 236 and 536 infective bites with 570 and 1211 infective larvae. In the two forest villages the number of vector bites per person per year was calculated to be in the order of 6120 and 1102 of which 64 and 8 would be infective bites transmitting 101 and 8 larvae. The findings of considerable differences in transmission intensities between villages of the same bioclimatic zone and of comparable microfilaremia rates indicates instable epidemiological conditions in at least some of the localities investigated.

Animals↗
PubMed1980

DDT residues in forest floors and soils of western Oregon, September-November 1966.

Between 1945 and 1965, 1.82 million hectares, or about 17 percent of the total commercial forestland in Oregon, were treated with 2.02 million kg DDT. Detectable residues of this insecticide might be present in forest soils, even those which have never received a direct application of insecticide. Forest floor and mineral soil samples were collected along four east-west transects across the Coast and Cascade Ranges. DDT residues were found in all samples, even though all but one site had never received a direct application of insecticide. In the Coast Ranges, mean concentrations of sigma DDT in forest floor samples were 0.049 ppm at the coast and 0.047, 0.064, 0.075, and 0.119 ppm at 16, 32, 48, and 64 km inland, respectively. Mean residue levels in the surface layers of mineral soil were much lower, 0.009 ppm and 0.006 ppm in the 0 to 7.5-cm and 7.5 to 15-cm depths, respectively. Sampling sites along the Cascade Range transects were selected on the basis of elevation except that the eastern site of each transect was located 16 km east of the crest of the Cascades. Residue concentrations in forest floor samples were three to four times higher than in the Coast Ranges, but were still below 0.50 ppm. In general, sigma DDT levels increased with increasing elevation up to 1,372 meters and then decreased quite sharply east of the crest. Variations can be explained on the basis of total rainfall distribution and by transect location relative to agricultural and metropolitan centers.

DDT↗
PubMed1995

Density and habitat use of primates at an Atlantic forest reserve of southeastern Brazil.

About 58.3 km of transects were surveyed throughout 21,800 ha of an Atlantic forest reserve of southeastern Brazil, yielding habitat preference data and density estimates for three of the four primate species present. The densities were calculated using the "Fourier Series Estimator" and were 10.5, 2.2 and 1.2 groups/km2 for Callithrix geoffroyi, Cebus apella robustus and Callicebus personatus personatus, respectively. Alouatta fusca fusca although present, was not seen during the survey. C. geoffroyi was spotted predominantly in the low strata of secondary forests while C. a. robustus preferred the higher strata of primary forests. The encounters with C. p. personatus were rarer but the species seems to occur in the middle strata of both primary and secondary forests. Local populations were estimated at 1644, 344 and 181 groups for these three species, respectively. With the exception of A. f. fusca which seems to occur at extremely low numbers, the densities for the other species are within the range of reported values for other species of these genera.

Analysis of Variance↗
PubMed1994

[Studies on the ecological distribution of Bacillus thuringiensis in forest soils of China].

A total of 384 forest soils samples at 0-5cm depth collected from 8 forest site zones (13 Natural Reserves) in China were examined for the distribution of Bacillus and Bacillus thuringiensis. The 79 cultures (4.21%) in 1873 isolates of Bacillus collected referable to the Bacillus thuringiensis. Soil pH, moisture content and soil nutrient were determined. Rules of the ecological distribution of Bacillus thuringiensis of 8 forest site zones in China were analysed. Toxicities against 6 species of insect were tested. Strain some efficient serains were obtained. It was shown that resource of Bacillus thuringiensis is much fruitful in forest soils of China.

Bacillus thuringiensis↗
PubMed1977

Influence of microclimate on the life cycle of the common tick Ixodes ricinus (L.) in an open area in comparison with forest habitats.

Under conditions of the South-Moravian region of Pannonian climate (Valtice near Breclav), the life cycle of the common tick Ixodes ricinus (L.) was studied and a continous recording of main elements of microclimate (temperature and humidity) was carried out in an open grassy area. Simultaneously the process of hibernation was studied in four soil layers (surface, depths of 10, 20 and 30 cm). Observations were assessed by mathematiccal-statistical tests and compared with the results obtained by the same methods in the forest biotope (tipe of thermophilic oak forest)and in the ecotone of forest margin (Daniel et al. 1976). The ticks are able to complete the developmental cycle also in the open grassy areas, where during the vegetation period the development proceeds more quickly than in the forest but with considerably higher losses. In the discussion the conclusions are compared with literary data from other parts of Czechoslovakia.

Animals↗
PubMed1976

Forest to pasture: development or destruction?

The expansion of artifical or planted pastures (repasto) at the expense of both natural forest and cropland has brought major changes to the landscape and economy of Central America in recent years. On the pioneer fronts at the forest margin agriculture is commonly a transitory stage between forest felling and the establishment of permanent pasture. In the past 15 years the area in planted pasture and the total numbers of beef cattle have nearly doubled in several Central American countries while the per capita consumption of beef has actually declined. The "grassland revolution" that is occuring in Central America and Panama has been based almost exclusively on grass species of African origin which have in most cases been introduced into Central America only in this century. Of these jaragua, guinea, pangola, and kikuyu are the most important. The ecologic consequences of the conversion of forest to pasture are little understood. Intensive management practices, including the application of high-cost and scarce fertilizers and carefully-manged rotational grazing, will probably be necessary to sustain the productivity of these lands under conditions of tropical climate.

Agriculture↗
PubMed1953

An antiviral substance from Penicillium funiculosum. II. Effect of helenine upon infection in mice with Semliki Forest virus.

Helenine exerts a therapeutic effect against Semliki Forest virus infections of mice. Cures, that is to say the survival of treated animals, were more frequently observed in Semliki Forest virus infections than they were in SK virus infections. It is believed that this difference in end-result probably represented only a quantitative difference in the therapeutic effect of helenine against these two viruses and not a qualitative difference in its mechanism of therapeutic action. The findings reported in this paper with regard to the treatment of Semliki Forest virus infections with helenine parallel very closely those described in an accompanying paper which deals with the action of helenine on SK. virus infections.

Animals↗
PubMed1995

Human papillomavirus type 16 capsid proteins produced from recombinant Semliki Forest virus assemble into virus-like particles.

Several neutralizing sites of the human papillomavirus (HPV) capsid are known to be critically dependent on the conformation of the capsid. However, efficient production of HPV16 capsids in mammalian cells has been difficult, possibly because the HPV genome contains negative regulatory elements. To circumvent these problems, we cloned the HPV16 L1 and L2 genes from a healthy HPV16-infected woman into a Semliki Forest virus based expression vector (P. Liljeström and H. Garoff, Biotechnology 9, 1356-1361, 1991). Recombinant HPV16 L1- or L2-producing Semliki Forest virus was generated and used for infection of mammalian cells. The HPV16 L1 and L2 proteins were efficiently expressed and the majority of the L1 protein self assembled into virus-like particles (VLPs). Coexpression of L1 and L2 resulted in incorporation of L2 into the VLPs. The particles had a density of approximately 1.3 g/ml as determined by density gradient centrifugation. Transmission electron microscopy revealed that the particles had a morphology similar to native virions. The HPV16 VLPs produced by the Semliki Forest virus expression system may be useful as a conformationally correctly assembled target for studies of HPV attachment, assembly, serology, or vaccination.

Animals↗
PubMed2026

Carbon metabolic homogenization is linked to microbial competition and antimicrobial resistance in soils under forest-to-cropland conversion.

Global agricultural expansion by converting natural forests into croplands often leads to soil functional homogenization and antimicrobial resistance enhancement, threatening ecosystem services. However, the associations between microbial carbon metabolic homogenization and antimicrobial resistance remain largely unknown. Here, we collected 240 paired forest and cropland soil samples from the most intensively farmed Yangtze River Basin in China, and constructed a novel framework based on microbial functional traits to decipher the role of carbon metabolic homogenization on antimicrobial resistance via microbial competition for metabolites. Using genome-scale metabolic models, we found that carbon metabolic homogenization was associated with a shift in microbial interactions from cooperation toward competition, with a 45.6% increase in competitive interactions that coincided with a 35.6% higher antimicrobial resistance gene (ARG) diversity. This shift was accompanied by smaller genome sizes and higher 16S rRNA copy numbers, indicating fast-growing, resource-acquisitive microbial strategies. Metabolic transfer analyses further revealed less cooperation relationships among microbial communities in cropland soils than in forest soils, indicating an intensified battle for communal metabolites and an attenuated exchange for complementary metabolites. Together, these findings provide a new framework to understand the association between carbon metabolic homogenization and soil antimicrobial resistance risks from the perspective of microbial traits and interactions under land use change.

Soil Microbiology↗