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PubMed2005

[Effects of forest vegetation on runoff and sediment production on sloping lands of Loess area].

Based on the 1985 - 2003 fixed-position data in 9 runoff plots of Caijiachuan watershed in the Jixian county of Shanxi Province in loess area, this paper discussed the relationships between vegetation and runoff and sediment production on sloping lands of loess area. The results showed that natural-secondary forest had better function in soil and water conservation than artifical Robinia pseudoacacia forest, with runoff and sediment produced 65% - 82% and 23% - 92%, respectively. Multiple regression analysis indicated that runoff and sediment production had a significant correlation with rainfall and its intensity, but this relationship was decreased gradually with increasing canopy density. Different land-use type had different runoff and sediment production, e. g., Ostryopsis davidiana and natural-secondary forests had the least runoff and sediment production, artificial Robinia pseudoacacia and Pinus tabulaeformis forests had 5 folds of it as much as Ostryopsis davidiana forest, mixed apple trees and crops had 17.14 and 3.96 folds of it than Ostryopsis davidiana forest, respectively, while high-standard soil preparation could decrease the production obviously. Gray correlation analysis suggested that the stand canopy density and the biomass of herb and litter were the most important factors affecting the runoff and sediment production on sloping land, whose gray correlation degrees all exceeded 0.6. Mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of loess area, which could help to increase the coverage and litter thickness to dramatically decrease the runoff and sediment production on sloping land.

Betulaceae↗
PubMed2005

[Dynamics of soil properties under secondary succession forest communities in Mt. Jinyun].

Mt. Jinyun is located in the north suburb of Chongqing, 30 km away from the city center. It is rich in forest plants, an epitome of forests in north tropical areas of China. Under anthropocentric disturbance, there still exist large numbers of succession communities, and the process of successive development follows the way of shrub-grassland (X1)-->coniferous forest (X2)-->coniferous-broad leaved mixed forest (X3)-->evergreen broad-leaved forest (X4). By now, soil and water conservation is very important in the Three Gorges area of Yangtze River, and the investigation on the secondary succession of the forests could help to realize the changes of the forests and soils under anthropocentric disturbance, and supply information on the protection of natural forests and the artificial reforestation of this area. In this paper, some typical and representative plant communities in different succession stages were selected to study the plant composition and type and the soil properties, with species diversity indices and canopy density investigated in many standard squares and soil physical and chemical characteristics analyzed. The results showed that there were obvious variations of soil properties with time. As the plant community developed from primary stage to climax, the contents of soil organic matter, total N, and available N and K increased in order of X1 < X2 < X3 < X4, soil pH changed from 5.23 (X1) to 4.06 (X4), soil base saturation varied from 58.3% (X1) to 37.7% (X4), and soil CEC increased with the succession. It was suggested that an intense soil acid leaching was occurred in Mt. Jinyun. The contents of soil organic matter and total N in different layers showed a trend of A>B>C, e. g., soil total nitrogen in evergreen broad leaved forest was 2.31(A), 0.66(B) and 0.12(C)g x kg(-1). Gray analysis was used to study the relationships of soil properties between the climax community and other three succession communities. The relation coefficient was 0.461 0 (X3), 0.586 2(X2) and 0.6821 (X1), respectively, indicating that soil nutrients were accumulated as the forest succession community progressed. The plant arbor species followed the sequence of 0 (X1) < 7.5 (X2) < 9.0 (X3) < 12.8 (X4), and the canopy density ranked as the same way. Plant community could affect soil nutrient reserves significantly. Multivariate variance analysis showed that soil properties varied significantly among different seasons, but this variation had no impact on the community replacement and soil development during the chronosequence of community succession. The variation of soil properties adapted well to each successive community.

China↗
PubMed2006

Community structure and its dynamics of pest, predatory and neutral insects in a jujube ecosystem.

An investigation on the insects in the jujube ecosystem in Taigu District of Shanxi Province, Northern China showed that more species and individual numbers of pest, predatory and neutral insects were found on the tree than on the ground. The ratio of the species and individual numbers of predatory and neutral insects to those of pest insects fluctuated from year to year. Homoptera, Coleoptera and Lepidoptera were the dominant groups of pest insects, while those of predatory insects were Coleopteran, Hemiptera, Diptera and Hymenoptera. The vertical distribution of the community structure of the same or different subcommunity was different in different seasons, as was the case of the same or different subcommunity in the same season. The diversity indexes of pest, predatory and neutral insects fluctuated with seasons, and the populations of predatory and neutral insects had a significant correlation (r = 0.9833, P <0.05) with the fluctuation of pest insects. There was also a significant correlation between the pest, predatory and neutral insects in different stratums of tree canopy, especially in the middle stratum of tree canopy (r = 0.9887, P <0.01).

Animals↗
PubMed2006

[Soil properties under shrubs in arid area of oasis-desert transition belt].

In arid and semi-arid areas with sparse vegetation cover, the spatial pattern of surface soil had a definite effect on soil salinity and nutrient flow, which is of highly importance for understanding the processes of land cover change. In this paper, a total of 3 shrub types and 2 soil sampling depths (0-20 and 20-40 cm) in the arid area of oasis-desert transition belt were selected to assess the spatial heterogeneity of soil resources under shrubs. The results showed that different types of shrub had no significant effect on the particle size distribution of soil which was mainly composed of sand and silt, but significant cluster effect was observed under Tamarix ramosissima + bare land shrub. Soils under shrub canopy had significantly higher contents of organic matter, total N and available K, compared to those in open spaces, and presented obvious "fertile island" phenomenon. Shrub types had significant effects on soil salinity, and different cluster effect existed in soils under different shrubs. The heterogeneity of soil resources resulted from a large number of factors, including climate, soil environment, height and extent of shrub canopy, stemflow, existance of other ground cover plants, and so on, many of which were mutually interactive.

Desert Climate↗
PubMed2006

[Relationships between row crop evapotranspiration and two sources- energy partition and exchange under non-water stress condition].

With the maize harvested for green fodder and grown at the Hunshandake sand area as test row crop,and by combining two sources- energy balance model with dual crop coefficient approach presented in FAO-56,this paper estimated the available energy partitioned into two sources, canopy and soil surface (Ac and As), and the latent and sensible heat fluxes, lambdaEc, lambdaEs, Hc and Hs. The results showed that under non-water stress condition, the interaction between Hc and lambdaEc made canopy absorbed a micro-advection to enhance transpiration expressed by latent heat flux,with the value of (lambdaE(i)c-A(i)c). The greatest enhancement of transpiration occurred at the crop development stage with leaf area index between 0.6 and 2.4, and the average of the enhancement was 4.32 MJ x m(-2) x d(-1). Soil evaporation was in progress with a rate below the available energy of soil, due to the interaction between Hc and lambdaEc under non-water stress condition, except a few days immediately after heavy rain. The evaporation rate depended on the percentage of soil available energy dissipated as latent heat flux. The average value of minimum percentage, 11.5%, occurred at mid-season stage,while that of maximum percentages,51.9%, occurred at initial stage. Latent heat fluxes were the important components of energy exchange during the process of evapotranspiration. The available energy dissipated as latent heat fluxes of the two sources during crop development, mid-season, and late season stages accounted for over 83% of the total energy.

Energy Metabolism↗
PubMed2006

[Physiology and ecology of Pometia tomentosa photosynthesis in tropical seasonal rain forest].

Pometia tomentosa is a dominant uppermost canopy tree in Xishuangbanna tropical seasonal rain forest. In this paper, the photosynthetic characteristics of the three layers of P. tomentosa canopy were measured with Li-6400 portable photosynthesis system, and the results showed that P. tomentosa had the characteristics of high light saturation point (1 000 - 1 500 micromol x m(-2) x s(-1)) and low compensation point (7.7 - 15.3 micromol x m(-2) x s(-1)). Its leaf photosynthesis had the adaptive responses when the high irradiance changed. PAR was the main factor affecting the diurnal changes of net photosynthesis. In December, the leaf grew well, and had a high ability of photosynthesis, with the diurnal change of P. for upper layer exhibiting single-peaked pattern and the maximum value being 8.9 micromol CO2 x m(-2) x s(-1). April was the alternative period of old and young leaves, and the ability of photosynthesis was dropped, with the diurnal change of P(n) for upper layer following double-peaked curve and the maximum value being 4.3 micromol CO2 x m(-2) x s(-1). The highest net photosynthesis rate was observed in July, with the diurnal change of P. for upper and middle layers exhibiting single-peaked pattern and that for lower layers being double-peaked. Short-term enriched CO2 concentration could evidently increase the photosynthesis of P. tomentosa, while the stomatic conductance and transpiration would be inhibited. When the CO, concentration increased from 400 micromol x mol(-1) to 800 micromol x mol(-1), water use efficiency (WUE) was increased by 50% - 100% in dry season, but rather low in wet season.

Adaptation, Physiological↗
PubMed2006

[Hyperspectral remote sensing estimation models on vegetation coverage of natural grassland].

By using ASD FieldSpec Pro FR spectroradiometer, the spectral measurement of natural grassland in Xilingole Leaguer of Inner Mongolia was performed, with the vegetation coverage of natural grassland calculated, and the correlation of 25 hyperspectral feature variables with the vegetation coverage of natural grassland was analyzed. The results showed that there were 17 variables correlated significantly with the vegetation coverage of natural grassland, among which, the correlation coefficient between vegetation coverage and the area of red edge peak calculated as the sum of the amplitudes between 680 nm and 780 nm (sigma dr 680 - 780 nm) was the highest, with the value of 0.781. The basic experimental data including the vegetation coverage and canopy reflectance of natural grassland were classified into two groups. One group was used as the training sample to build the regression models with one-sample linear method, nonlinear method, and stepwise analysis method, while the other was used as the testing sample to test the precision of regression models. It was suggested that the variable of the area of red edge peak calculated as the sum of amplitudes between 680 nm and 780 nm (sigma dr 680 - 780 nm) was the best one to univariate general linear model, with a standard deviation of 10.4% and an estimation precision of 83.99%, while the stepwise regression technique was not effective to estimate the grassland coverage with raw hyperspectral canopy reflectance.

Conservation of Natural Resources↗
PubMed2006

[Effects of disturbances on plant species diversity of secondary forest in montane regions of eastern Liaoning Province].

According to the distance from forest stands to residential area and the first and second grade roads, as well as the canopy density and the percentage of damaged trees, this paper defined the disturbances, anthropogenic and natural, as low, medium and high levels. On the basis of this, the effects of different level disturbances on the plant species diversity of secondary forest in montane regions of eastern Liaoning Province were analyzed, and the differences between the effects of anthropogenic and natural disturbances were discussed. The results showed that without considering forest types, the overall plant species diversity of secondary forest under medium level anthropogenic disturbance was higher than that under low and high level anthropogenic disturbances, with the Simpson indexes being 0.96, 0.95 and 0.92, and Shannon-Wiener indexes being 3.77, 3.60 and 3.36, respectively. The diversities of shrub and herb layers were also the highest under medium level anthropogenic disturbance, while the highest diversity of arbor layer was appeared under the high level one. Among different forest types, there existed differences in the plant species diversity under anthropogenic disturbances, e. g. , the diversity under medium level anthropogenic disturbance was the lowest in hard broad-leaved forests, but the highest in other forest types. In all test forest types, no consistent tendency was observed in the changes of three layers' diversities with anthropogenic disturbance levels, but the diversities of shrub and herb layers were greatly affected by the disturbances. After 3 years of snow/wind damage, there was no distinct difference in the diversities among the birch forests under low, medium and high level natural disturbances, with the Simpson indexes being 0.91, 0.91 and 0.92, and the Shannon-Wiener indexes being 2.30, 2.93 and 2.89, respectively. The diversities of arbor and shrub layers were both increased with the enhancement of natural disturbances, but there was no great difference in the diversity of herb layer among the three levels of natural disturbances. At present, anthropogenic disturbance mostly occurred in understory, while snow/wind damage occurred in canopy. Such dissimilarity could make the effects of environmental factors on plant species diversity differed greatly.

Biodiversity↗
PubMed1991

Influence of vegetation on carbon dioxide trap effectiveness for sampling mosquitoes in the Sierra Nevada foothills of Kern County, California.

The effect of vegetation on sampling Culex tarsalis, Cx. quinquefasciatus and Aedes nigromaculis by CO2 traps was evaluated at an intermittent stream habitat at the base of the Sierra Nevada foothills. Carbon dioxide traps were spaced along a 450 m transect perpendicular to Poso Creek to determine female attraction to traps placed in 5 different vegetation substrates: 1) open hilltop with sparse growth of grasses and saltbush, 2) open pasture with sparse growth of saltbush, 3) peripheral understory of mule fat, 4) shaded understory of mule fat, and 5) open canopy 5 m above ground in willow and cottonwood trees. Most host-seeking Cx. tarsalis and Cx. quinquefasciatus females were collected within the open canopy and peripheral understory. Host-seeking Ae. nigromaculis females were collected predominately in the open pasture and within the peripheral understory. The association between CO2 trap catch size and vegetation suggested a relationship between the host-feeding patterns and associated hunting strategies of these bird and mammal feeding species.

Aedes↗
PubMed1991

[Rational close planting in raising the seedlings of Panax quinguefolium linn].

It has been found that the effect of planting density is hardly noticeable for one-year-old seedlings, but very apparent for 2-year-old ones. With the increase of planting density, the leaf area gets smaller, stem higher, and root thinner and shorter. The larger the planting density. The smaller the dry weights of canopy and root and the root-canopy ratio. It is thus advocated that rational planting densities be selected according to the proper cultivation systems.

Panax↗
PubMed1989

[Changes in the microvascular pattern of the periodontium in an experimental tooth movement].

The purpose of the present investigation was to observe changes in the microvasculature related to the reorganization of periodontal tissue during tooth movement and to evaluate the role of periodontal vasculature. The experimental study, employing cats, was done by injection of acrylic resin into the microcirculatory system of the periodontal membrane to make visible vascularization and remodeling of the alveolar bone structure when orthodontic force was placed on a tooth. 1. Pressure side New blood vessels arose from pre-existing vessels, entered resorption lacunae, connected with each other, and formed the vascular layer for alveolar bone resorption, covering the bone surface. The blood vessels of the root side around the degenerate tissue initially had spear-like ends because of imperforation, but the vessels gradually became interconnected, forming capillary loops, and encircling the degenerate tissue. This vascular layer for capillary-loop formation and the inner circumferential vascular layer for alveolar bone resorption were completed after 3 weeks. Newly formed blood vessels ran into the resorption lacunae and formed two networks. The networks enhanced metabolic activities such as resorption by multinuclear giant cells and the proliferation of osteoblasts and fibroblasts, resulting in regeneration of the periodontal membrane. 2. Tension side The vascular pattern on the crest area in the controls showed a two-layered structure with one vascular network on the root side and one on the alveolar bone side. After 1 week, the latter was stretched to the former, forming a canopy-like structure, and causing the two-layered structure to disappear. The canopy-like structure disappeared with time, and vascularization occurred at the sites of bone formation and fibroblast proliferation. These vascular changes seemed to contribute to the regeneration of the periodontal membrane. Blood vessels responded rapidly to the environmental changes in the periodontal membrane, adjusting their morphology to functional changes, and these vascular changes preceded the deposition or resorption of bone.

Alveolar Process↗
PubMed1985

Evaluation of Beecomist-applied Bacillus thuringiensis (H-14) against Anopheles quadrimaculatus larvae in rice fields.

The Beecomist spray head was evaluated for aerial application of Bacillus thuringiensis var. israelensis (serotype H-14; Bti) at various ultra low volume (ULV) rates against natural populations of Anopheles quadrimaculatus larvae in rice fields. Deposits on Kromekote cards indicated that 0.54 liter/ha of neat Bti penetrated the dense canopy of the rice field. Mean number of droplets 65 cm below canopy level was 4.9 +/- 5.0/100 cm2. At 1 day posttreatment, applications of 0.54, 0.27, 0.11, 0.07 and 0.04 liter of Bti/ha resulted in reductions of 97.9, 94.4, 93.0, 71.1 and 21.8%, respectively, of An. quadrimaculatus larvae/dip. Calculated lethal field dosages (LFD50 and LFD90) were 0.05 and 0.16 liter/ha, respectively.

Animals↗
PubMed1980

Sticky trap studies on Simulium damnosum s.l. in northern Ghana.

The results of sticky trapping S. damnosum s.l. at several sites in northern Ghana are given. Yields were always very much lower than those which could be obtained by human bait catches, and caught flies tended to disappear from traps which were not emptied at least daily. Thus the technique offered little promise as a means of monitoring population fluctuations. Nevertheless some valuable information was obtained. Colour choice studies showed that hunting flies were attracted to dark blue substrates. In all situations the most shaded surfaces of the traps were preferred by alighting flies. The presence of S. damnosum in the canopies of trees was demonstrated for the first time. Flies were caught at heights above 6 m at three sites, the maximum height being 9.2 m, the height of the topmost trap. Among flies caught in the canopy of trees were nulliparous, parous and gravid females as well as males. Only in one catch, at relatively low levels in riverine trees, were blood engorged flies a noteworthy proportion of the catch.

Animals↗
PubMed1994

Acute and long-term effects of irradiation on pine (Pinus silvestris) strands post-Chernobyl.

The effect of ionizing irradiation on the viability of pine stands after the fallout from the damaged nuclear energy plant at Chernobyl (ChNPP) was shown within the territory of the 10-km zone. During the period 1986-1991, irradiated and damaged forest stands, so-called 'red forest', located in this area were systematically classified by observation. Mortality rate, re-establishment, development of tree canopies, reproduction anomalies and stand viability were shown to be dependent on absorbed irradiation dose, on the age of the stand and on forest composition. For pine stands in the acutely affected zone, doses of more than 60 Gy resulted in a massive mortality and no regeneration of pine trees since 1987. The injured trees had burned or had dried-up. The drying process was accelerated by a massive production of pathogenic insects invading the dying trees. Specifically, irradiation doses of 10-60 Gy, 1-10 Gy and 0.1-1 Gy caused high, medium and low injury to the forest stands, respectively. Doses of less than 0.1 Gy did not cause any visible damage to the trees. In 1987, repair processes were displayed by the tree canopies and practically the entire viability of the forest stands had recovered except for trees in the acute and highly affected zones. The young forest was reestablished in the same place as the perished trees and new pine saplings were planted on the reclaimed areas.

Animals↗
PubMedDate not supplied

[Hepatocystis of Malaysia. II.--Description of Hepatocystis brayi n. sp. parasite of Sciuridae (author's transl)].

Hepatocystis brayi n. sp. is described and separated from the second species parasitising Malaysian Sciuridae, H. malayensis Field and Edeson, 1950. H. brayi is characterized by: 1) the evolution of its tissue schizonts which are intracellular throughout all their development; the cytoplasm and the nucleus of the host cell are highly hypertrophied; 2) the scarcity of the colloid. The schizogony persists for several months in the liver of infected animals and the gametocytaemia apparently undergoes seasonal relapses. H. brayi is a parasite of hosts occurring in the middle and under canopy, H. malayensis the middle and top canopy.

Animals↗
PubMed1996

An introduction to aerial spray modeling with FSCBG. Forest Service Cramer-Barry-Grim.

The FSCBG aerial spray drift and deposition model predicts the dispersion of material released from aircraft into the atmosphere, and particularly downwind from the release point. The effects of aircraft wake structure, droplet evaporation, local meteorology, penetration through forest or agricultural canopies, and prediction of ground or canopy deposition, air dosage, and concentration are all included in the model. The long developmental and validation history of the model, a brief summary of its assumptions and underlying approximations, and its present user-friendly operation on personal computers are reviewed and highlighted in this paper.

Insect Control↗
PubMed1998

Ventilatory physiology of children and adolescents with anxiety disorders.

BACKGROUND: Abnormalities in ventilatory physiology have been noted in adults with panic disorder. We tested the hypothesis that abnormalities in ventilatory physiology differentiate children and adolescents with anxiety disorders from psychiatrically healthy children. METHODS: Ventilatory physiology was monitored with a canopy apparatus during room-air breathing and 15 minutes of carbon dioxide exposure in 33 children and adolescents comprising 18 probands with an anxiety disorder and 15 psychiatrically healthy children. RESULTS: During room-air breathing, probands had significantly larger minute ventilation, larger tidal volumes, and more variable breathing patterns than healthy comparisons, but the groups did not differ in end-tidal carbon dioxide or respiratory rate. During carbon dioxide challenge, probands exhibited larger minute ventilation and respiratory rate responses relative to comparisons. CONCLUSION: These findings on the association between ventilatory physiology and anxiety disorders in children and adolescents are consistent with results from studies of adults with panic disorder.

Adolescent↗
PubMed1996

Cercopithecid locomotion, support use, and support availability in the Tai Forest, Ivory Coast.

Habitat heterogeneity is widely theorized to be important in the evolution of Old World monkeys, yet the impact of architecturally distinct forest types on the positional repertoires of African monkeys is largely unknown. As part of a wider project, this study investigates how the locomotor behavior of five sympatric cercopithecids varies in structurally distinct forest areas. Fieldwork took place in the Tai Forest, Ivory Coast, from June 1993 to August 1994. Data were collected on Colobus badius, C. polykomos, C. verus, Cercopithecus diana, and C. campbelli ranging throughout a common forest mosaic. The behavior of adult females was sampled using an instantaneous time point scheme at 3 min time intervals. Vegetative differences within each 100 x 100 m grid cell used by all species were quantified. Further, the relative numbers of different sized substrates at 10 m intervals within the canopy were recorded in each cell sampled. Data indicate that consistency of locomotor behavior across forest types is maintained because most monkeys select the same set of preferred supports in both forest types. The conservative nature of Tai monkey locomotor behavior is discussed within the context of additional proximate and ultimate influences and constraints.

Animals↗