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PubMed2001

Distribution and dynamics of two ferns: Dennstaedtia punctilobula (Dennstaedtiaceae) and Thelypteris noveboracensis (Thelypteridaceae) in a Northeast mixed hardwoods-hemlock forest.

Dennstaedtia punctilobula and Thelypteris noveboracensis are two native species that often arrest forest succession and reduce understory diversity. As part of a project to examine the feedback between forest understory and canopy dynamics, we studied the patterns of distribution and dynamics of these two fern species in an oak-transition hardwoods-hemlock forest. Dennstaedtia was least abundant under shade-tolerant tree species and most abundant in small (1-2 trees) canopy gaps, but did not show any distinct patterns across the sampled moisture regime. The light response was verified using light manipulation experiments and examination of plant size-abundance patterns across light environments. Thelypteris tended to be most prevalent under maple canopies and appeared to be more sensitive to soil moisture regime being restricted to more mesic sites than Dennstaedtia. Seasonal and year-to-year changes in abundance of established clones of both fern species were small, suggesting that once established, both species can maintain a strong hold on a site. Further work on the niche requirements of the two species is warranted, but any event that maintains or promotes canopy openness (tree death by disease or windthrow, forest harvesting, or the elimination of a shrub layer by browsing) will promote persistence of Dennstaedtia.

Journal Article↗
PubMed2001

Habitat-related error in estimating temperatures from leaf margins in a humid tropical forest.

Leaf margin characters are strong predictors of mean annual temperature (MAT) in modern plant communities and widely used tools for reconstructing paleoclimates from fossil floras. However, the frequency of nonentire-margined species may vary dramatically between different habitats of the same forest. In this paper we explore the potential for this habitat variation to introduce error into temperature reconstructions, based on field data from a modern lowland forest in Amazonian Ecuador.The data show that the provenance of leaves can influence temperature estimates to an important degree and in a consistent direction. Woody plants growing along lakes and rivers underestimated MAT by 2.5°-5°C, while those in closed-canopy forest provided very accurate predictions. The high proportion of liana species with toothed leaves in lakeside and riverside samples appears to be responsible for a large part of the bias. Samples from closed-canopy forest that included both lianas and trees, however, were more accurate than tree-only or liana-only samples.We conclude that paleotemperature reconstructions based on leaf margin characters will be misleading to the extent that fossilization provides a better record of certain habitats than others. The preponderance of lake and river deposits in the angiosperm fossil record suggests that underestimation of mean annual paleotemperature may be common.

Journal Article↗
PubMedDate not supplied

Risk factors of malaria in the fringes of an evergreen monsoon forest of Arunachal Pradesh.

BACKGROUND: The forested hilly and foothill regions of north-east India are highly endemic for malaria and have a distinct epidemiological pattern. Nearly half the reported cases of malaria are from these areas. A knowledge of the risk factors in this eco-geographic entity may be helpful in formulating a specific control strategy. Hence, we conducted a community-based epidemiological study in a hilly, forested terrain of Arunachal Pradesh and examined different socio-demographic factors to identify those predisposing to the occurrence of malaria, especially Plasmodium falciparum infection, in such areas. METHODS: Four epidemiological surveys were carried out during 1997 in 7 villages located at the fringes of a forest (total population: 1177) under Nompong Primary Health Centre of Changlang district, Arunachal Pradesh. Blood slides were collected randomly from the inhabitants, irrespective of their fever status, ensuring at least 50% coverage. One hundred and thirty-four microscopically confirmed Plasmodium falciparum cases were identified and 536 controls were randomly selected from the list of uninfected inhabitants. Relevant socio-demographic information was obtained from both cases and controls. The data were analysed by simple and multiple logistic regression using the unconditional maximum likelihood method. RESULTS: Factors which were found to be strongly associated with Plasmodium falciparum malaria on univariate analysis were age, ethnicity, village of residence and accessibility to the nearest health care facility. However, in multiple regression analysis, after controlling for the effects of confounding variables, the only risk factor identified was accessibility to the nearest health care facility (adjusted odds ratio: 4.5; 95% CI: 1.8-11.3; p < 0.0001 for those at a distance of 2-8 km and adjusted odds ratio: 11.1; 95% CI: 4.1-30.0; p < 0.0001 for those > 8 km away). CONCLUSION: Distance, particularly non-motorable distance, from the place of residence to the nearest health care facility was a major risk factor for malaria in this hilly forested terrain. This indicates the need for special efforts to detect cases early and institute treatment promptly in such areas of the north-eastern region, so as to reduce the morbidity and mortality of malaria.

Adolescent↗
PubMed2001

[Characteristic analysis on different thermal active surfaces in canopy gap of tropical secondary forest].

Microclimatic measurements were conducted in the canopy gap of tropical secondary forest in Xishuangbanna in fog-cool and dry-hot season. The daytime thermal effect of different thermal active surface in the canopy gap was discussed, and the variations of trunk surface temperature near gap edge and of surface temperature on the gap were analyzed. The result shows that the woody-wall surface is new thermal active surface on the vicinage of canopy gap, with the exception of the forest canopy surface, soil surface in the forest gap, and soil surface of the interior. Because of the influence of season, situs and time, the thermal effect of different thermal active surface of gap was significant different. Being subject to fog, the soil surface on the center of canopy gap is an important thermal active surface in the morning; while in the midday and afternoon, because of the influence of incident radiation, the woody wall and soil surface of edge on the east and the woody wall surface of edge on the north are the key thermal active surface of the canopy gap. In the midday, the thermal active was salient on the surface of gap, and in the afternoon, it was salient on the woody wall. The thermal variations of canopy gap of forest are controlled by the thermal characteristics of different thermal active surfaces and by their interaction, affecting the growth of plants.

Temperature↗
PubMed2000

[Spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain].

Based on the measurement above and below forest canopy and meteorological data, the spectral characteristics of solar radiation in broadleaved Korean pine forest in Changbai Mountain was analyzed. The results show that the photosynthetically active radiation(PAP) coefficients of total radiation, direct radiation and scatter radiation changed daily and yearly, with an annual averages of 0.46, 0.43 and 0.56 respectively. The average reflectivity, transmissitvity and absorptivity of single leaves of different tree species in Korean pine forest were 27.0%, 23.4%, 49.6% respectively. Single leaves nearly absorbed all of the ultraviolet radiation(UV) and 71.8% of photosynthetically active radiation, but transmitted 9.6% and reflected 18.6%. As for near-infrared radiation (NIR), the reflectivity and transmissitivity of leaves were a little less than the absorptivity. The forest canopy absorbed 93.9% PAR and 94.1% UV, but reflected and transmitted less. It absorbed 59.2%, reflected 26.3% and transmitted 14.4% NIR.

Light↗
PubMed2000

[Evaluation on soil anti-erodibility of soil and water conservation forest].

Indexes including organic matter content, water stable aggregate content, mean weight diameter of water stable aggregate, aggregate degree and disperse coefficient were selected to evaluate soil anti-erodibility of soil and water conservation forests component of different tree species at different ages. The results showed that soil and water conservation forest played an important role in improving soil anti-erodibility, especially to the topsoil. Compared with that of Chinese pine pure forests, Chinese pine-broadleaved mixed forests had higher soil organic matter content, and water stable aggregate content increased by 1.71%-38.53%, and soil anti-erodibility was also increased with increasing stand age.

China↗
PubMed2000

[Soil moisture dynamics in forest land and wasteland of Loess Plateau].

The dynamics of soil moisture stored in a wasteland and in a forest land in the sub-humid climate region of the Loess Plateau was measured with neutron moisture meter for three successive years. Within the depth of 0-320 cm, the increment of soil water in the test 3 years was respectively -165.7 mm, -15.2 mm and -115.2 mm at the upper and lower position on north slopes and the lower position on south slope of the wasteland. Soil water increased by 17.2 mm at the upper position on north slope of the Chinese pine forest land, after > 380 mm water was consumed yearly by tree transpiration. It is suggested that forest land is essentially different from wasteland in soil water income/expense. The necessity of conducting the approaches for gaining available water of forest land was put forward.

Seasons↗
PubMed2001

[Floristic composition and structure of a premontane moist forest in Central Valley of Costa Rica].

The floristic composition and structure of a premontane moist forest remnant were studied in the El Rodeo Protected Zone, Central Valley of Costa Rica. Three one-hectare plots were established in the non-disturbed forest, and all trees with a diameter at breast height (dbh) of 10 cm or greater were marked, measured and identified. The plots were located within a radius of 500 m from each other. A total of 106 tree species were recorded in the three plots. Average values: species richness 69.6 species ha-1, abundance 509 individuals ha-1, basal area 36.35 m2 ha-1. Total diversity was 3.54 (Shannon Index, H'), and the species similarity among the plots ranged between S = 0.68 and 0.70 (Sørensen Similarity Index). Most tree species are represented by few individuals (five or less). There is a lack of emergent trees and arborescent palms in the forest canopy. According to the Familial Importance Value, Moraceae, followed by Fabaceae, Lauraceae, and Sapotaceae, largely dominates this forest. Pseudolmedia oxyphillaria (Moraceae) is the dominant species (Importance Value Index), accounting for 25% of all the marked trees in the plots, followed by Clarisia racemosa (Moraceae), Heisteria concinna (Olacaceae), and Brosimum alicastrum (Moraceae). The size class distributions were similar among plots, and in general followed the expected J-inverted shape. Differences in tree abundance, floristic composition, and spatial distribution of some species among the plots suggest heterogeneity of this ecosystem's arborescent vegetation. Moreover, it is an important natural reservoir for the conservation of rare and endangered tree species in a national level. Using these results as a baseline, this study should start a long term monitoring of the structure and composition of this very reduced and fragmented ecosystem.

Costa Rica↗
PubMed2001

[The phorophyte occupation patterns by vascular epiphyte species in the High Orinoco tropical humid forest, Amazonas State, Venezuela].

By international agreement (Austria-Venezuela), an experimental area was selected for canopy ecology studies. A tower crane was installed that allows direct access to the canopy of 1.5 ha area of the forest. This is a quantitative study of the phorophyte occupation patterns by vascular epiphyte species in an Amazon tropical humid forest. The forest of Surumoni consists roughly of four arboreal strata, i.e., emergent (conspicuous), superior, middle and lower. The largest proportion of trees occurs in the lower diametric classes (smaller DBH), and the total distribution approaches an "inverted J" curve. The most abundant tree species in the three strata is Goupia glabra (Celastraceae); making this forest a case where a single arboreal species dominants. Mean of epiphyte individuals per occupied phorophyte is too variable, depending on phorophyte species and showing no correlation with occupied tree percentage. The species Eschweleira parviflora (Lecythidaceae) represented in the study area by a single individual of the superior stratum with high density of vascular epiphytes, indicates that this support species is particularly favorable for the establishment epiphytic flora.

Ecosystem↗
PubMed2002

[On forest ecosystem health and its evaluation].

Definition and connotation of forest ecosystem health were introduced, and existing ideas and methods of health evaluation were analyzed in this paper. Furthermore, forest ecosystem health was discussed from the aspects of the management objective approach, ecosystem approach, and integration approach. Widespread application of ecological indicators is the main means of evaluation on forest ecosystem health at present, and some material forest health evaluation methods, especially EMAP and FHM, were introduced and summarized to impel the relative researches in China.

Ecosystem↗
PubMed2002

[Minimum sampling area and species richness of riparian community in erdaobaihe forested watershed].

Riparian zone is an important component of small forested watershed. Due to the integrate effects of stream water and edge effect, there are obvious difference in composition, structure, and distribution pattern between riparian community and non-riparian community. Community minimum sampling areas are also different. In this study, minimum sampling areas of riparian community in original broad-leaved and Korean pine forest in Changbai Mountain were studied by using species-area curve. At the same time, species richness of riparian community was discussed. The results showed that the minimum sampling areas of riparian plant community were smaller than those of the non-riparian community. According to the original broad-leaved and Korean pine forest in Changbai Mountain, the average community minimum sampling areas in riparian zone of three plots including 60%, 80%, and 90% of community species were about 80 m2, 180 m2, and 320 m2, respectively. And then, those of forest community were about 260 m2, 380 m2, and 480 m2 correspondingly. The results also showed that the species richness of riparian community was higher than that of non-riparian community.

Ecosystem↗
PubMed2002

[Synthetic evaluation on stand quality of protection forests in the Three Gorges Reservoir Region in western Hubei Province].

Stand qualities of 19 kinds of protection forests in the Three Gorges Reservoir Region in Western Hubei Province were evaluated synthetically by using 12 indexes, and could be classified into four different grades. The relationships between stand quality and some major factors such as crown density, elevation, and origin were also discussed in this paper. The results showed that elevation was a very important factor that influenced the stand quality, and the stand quality of natural forest was higher than other forests. Moreover, some strategies on protection forest construction and stand quality optimization were put forward.

China↗
PubMedDate not supplied

[Comparative evaluation of biological availability of 137Cs in soil of various types of forest ecosystems].

On five forests plots varying in species composition of woody plants and soil properties, 137Cs vertical distribution and 137Cs forms occurring in different horizons of forest soils have been studied. It was found that bulk 137Cs and contents of physico-chemical forms of this radionuclide in different horizons of forest soils vary considerably within both plots with different characteristics and individual horizons. The reported regularities can explain observed differences in 137Cs distribution in forest ecosystems of various types.

Biological Availability↗
PubMed2002

[Reflectivity of broad-leaved Korean pine forest in growing season on Changbai Mountain].

The hourly reflectivity of broad-leaved Korean pine forest on Changbai Mountain from 22 May to 14 October 2001 was calculated based on total solar radiation and reflect radiation. The results showed that: the reflectivity of the forest was related to solar altitude. It was generally high just after sunrise or before sunset, but was relatively stable as solar altitude was higher than 30 degrees. The diurnal curves of reflectivity took U shape. The reflectivity of the forest was also related to sky conditions. In clear days, the U shape was quite clear. In scattered days, the reflectivity just after sunrise and before sunset was not as high as in the clear days, and the U shaped curve was shallow. In overcast days, the reflectivity fluctuated. In terms of dynamic variation in the measured period, the reflectivity was relatively high in early June, decreased a little in late June, kept stable from July to September, and dropped gradually in the first half of October. The variation was related to the phenology of the forest canopy.

Acer↗
PubMed2003

[Structural characteristics of Abies fabri forests at the upper reach of Yangtze River].

The structural characteristics of Abies fabri forest under different succession stages in Gongga Mountains at the upper reach of Yangtze River were studied. The results showed that in the mature Abies fabri forest, there existed abundant seeds and a few saplings of Abies fabri younger than 20 years, but only Abies fabri was the dominant regeneration species. In the poplar-fir mixed forest, the height growth of poplar and birch was very fast during first 30 years, and poplar and birch dominated rapidly over the canopy. Abies fabri had a lower growth rate and a strong shade-tolerance in its first growth stage, and could replace other tree species gradually. The cycle of mud-rock flow occurrence was above 100 years in the Gongga montane areas from elevation of 2800 to 3200 m. After mud-rock flow, poplar and birch often occurred and dominated, and there were only a small number of Abies fabri saplings in slash. Under natural condition, to recover Abies fabri forest would demand a long time, but this process could be controlled and improved by human activities.

Abies↗
PubMed2003

[Seedling establishment of Fagus engleriana, a dominant in mountain deciduous forests].

The survival and growth of Fagus engleriana seedlings in three light levels, and with and without supplying additional fertilizer (F1 and F0, respectively) for each light level were studied. The three light levels were to simulate the light regimes in the understorey, small gaps and clearings (L1, L2 and L3 about 1%, 18% and 100% of full sunlight, respectively). The seedling development in L1 was severely inhibited by low light intensity. Seedling mortality was remarkably higher in L1 than in L2 and L3, and in F1 than in F0. The death of the seedlings seemed to result from attack of fungal pathogens. Although seedling survival and growth were significantly improved as light intensities increased from L1 to L2, seedlings in L3 developed similarly as those in L2. It is suggested that the young seedlings could not tolerate the shade of closed forest canopy, and fertile patches on the forest floor might not improve seedling establishment. Successful regeneration of the species in the forests needs better light conditions such as those in gaps than those under the closed forest canopy, at least during the phase of seedling establishment.

Biomass↗
PubMed2003

[Application of succession study in tending and restoration of evergreen broadleaved forest].

The characteristics of synecology, population ecology and physio-ecology of main tree species Quercus fabri, Pinus massoniana, Castanopsis sclerophylla, Lithocarpus glaber, Schima superba and C. fargesii of evergreen broadleaved forest in Tiantong National Forest Park, Zhejiang Province were studied by comparative method. The successional process was clarified through the comparative studies of the synecological characteristics of these main tree species, the individual plant structure and renewability were discussed by comparative study of population ecological characteristics of main trees' populations, and the mechanism of replacement with each other of these main tree species was open out by comparative study of physio-ecological characteristics of these main trees. Based on the study of comparative ecology of the main dominant evergreen broadleaved forest series, the successional stage and direction and its management could be determined, and the theoretical basis for the planning and management of forest production, and the restoration, reconstruction, and exploiting under artificial disturbance could be offered.

Conservation of Natural Resources↗
PubMedDate not supplied

[Analysis of the population structure of the Black Forest Draught Horse].

Gene contributions of foreign populations as well as coefficients of inbreeding and relationship were evaluated in 699 Black Forest Draught horses of Baden-Württemberg actually registered in the year 2002. Based on nearly complete 5-generation-pedigrees and after taking into account the remaining incompleteness, the mean coefficient of inbreeding for the total population was 6.5%. The recently by incrossing with different breeds newly established lines of stallions showed significantly lower mean coefficients of inbreeding. High rates of inbreeding of about 1.6% in the last five generations could also be faced by incrossing stallions of foreign coldblooded populations what resulted in a decrease of inbreeding in the last generation. In the total population the mean degree of relationship was 16%. The mean degree of relationships within lines of stallions was between 18.3 and 26.8%. The coefficients of relationships between lines of stallions varied between 5.1 and 16.6%. Especially, the newly established lines of stallions showed a lower mean degree of relationships to the other different lines of stallions. The proportion of purebred Black Forest Draught horses in the total population was nearly 70%. Assuming that most animals of unknown origin were purebred, the proportion of purebred Black Forest Draught horses reached about 90%. Austrian Noric, Swiss Freiberg and South German Coldblood stallions were the most important contributors to the Black Forest Draught horse population.

Animals↗