In order to explore the release of nutrients and the effects of global warming on the decomposition rate of forest litter, an experiment is designed to reciprocally decompose forest foliar litter in two sites across climatic zones: Mt. Jianfengling in Hainan Province in the tropics and Mt. Dinghushan in Guangdong Province in the subtropics. The two sites have similar altitudes, soil types, annual mean rainfall and seasonality of dry and wet. The main difference between these two sites is the annual mean temperature with the difference of 3.7oC. Foliar litters of 10 native dominant tree species have been collected respectively from the two sites and divided into single-species litter and mixed litter. They are decomposed reciprocally in the two sites. The results indicate that litter decomposes in the tropical site 1.36 3.06 times more rapidly than in the subtropical site. Apparent Q10, calculated on the basis of the temperature difference between the two sites, ranges from 3.7 to 7.5. The return amount of N, P and C will increase by 32.42, 1.033 and 741.1 kg/hm<>sup2, respectively in Mt. Dinghushan in the first year s litter decomposition under the prevailing temperature condition. Only in Mt. Dinghushan is the correlation between decomposition rate constant and initial litter quality high and significant in the ratio of lignin to N, lignin, the ratio of lignin to P, HLQ and C. This is not the case at Mt. Jianfengling.

Fractal theory, used to study natural figures and images with self-similarity but without characteristic lengths, offers an effective tool to investigate quantitatively the complex systems such as soil. In this paper, we have discussed about our study of the fractal features of the subalpine coniferous forests, soil particles, and microaggregates under different intensities of anthropogenic disturbances in the Miyaluo area of west Sichuan and investigated the effects of the disturbances on the forest soils attributed to different fractal dimensions. The study introduces a new way to investigate the recovery and reestablishment of subalpine coniferous forests.

The nitrogen (N) cycling was elucidated in a 40-year-old subtropical evergreen broad-leaved forest dominated by Cyclobalanopsis glauca growing on red soil in Zhejiang Province, East China. The concentrations of N in the representative species ranged from 0.49% to 1.64%, the order of which in various layers was liana and herb layers > understory layer > tree and subtree layers; in various organs was leaf > branch > root > trunk; and aboveground parts > underground parts. The sequence of the concentrations of N in C. glauca was understory > tree > subtree layer; young and high-growing > old organs; reproductive > vegetative organs. Seasonal dynamics of the concentrations of N in C. glauca in the tree and subtree layers was comparatively stable. It was lower in autumn (October) in root, branch, and leaf in the tree layer, and low in January in the understory. There was no evident change in regularity of the concentrations of N in varying diameter classes. The concentrations of N in the litterfall, precipitation, throughfall, litter layer, and soil were 0.74% 2.30%, 0.000,038%, 0.000, 09%, 1.94%, and 0.59%, respectively. The standing crop of N in the plant community was 1,025.28 kg/hm², accumulation in the litter layer was 224.88 kg/hm², and reserve in the soil was 55,151 kg/hm². Annual retention of N was 119.47 kg/hm², return was about 84.13 kg/hm², among which litterfall was 78.49 kg/hm² and throughfall, 5.64 kg/hm². Annual absorption of N was 203.60 kg/hm². Annual input of N through incident precipitation was 4.88 kg/hm². Compared with other forest types, cycling rate of N in the community was lower than in deciduous broad-leaved forests, rain forests, and mangroves, and was moderate in evergreen broad-leaved forests. N use efficiency of this forest was moderate among the forest types cited. According to the characteristics of the biocycle of phosphorous, it was concluded that N availability in the soil of this forest was not lower, and phosphorous not N was the limiting factor in the growth of plants in this community.

We studied 10- to 27-year-old artificial forests on rehabilitated lands in the upper reaches of the Yellow River with the objective of comparing the carbon densities of various artificial and natural forests. Under artificial plantations, the vegetation layer (including roots) had a mean carbon density of 111.3 t/hm², the litter layer a density of 5.1 t/hm², and the soil layer a density of 64.9 t/hm². These values accounted for 28.6%, 13.8%, and 61.0% of their respective counterparts in the natural secondary forests under the same site conditions in the region. The ratios of carbon density among vegetation, litter, and soil pools were 39.6:1.8:58.6 for artificial forests and 57.4:2.7:39.9 for natural forests. The carbon densities of the vegetation and litter layers increased exponentially with forest age. The total carbon density ratios were also increasing gradually. Although the mean total carbon density of the artificial forests in the rehabilitated lands was 281.2 t/hm² in the experimental area, it accounted for only 41.5% of the carbon density of the natural secondary forests (677.4 t/hm²). The annual increase in total carbon density of artificial forests was as high as 15.2 t/hm², which was 11.7% more than that of natural forests and 6.8 times higher than that (1.95 t/hm) of artificial forests in the entire country as measured during 1994 1998. This indicates that growth and carbon storage capacity of artificial forests in the rehabilitated lands were higher than those of forests on the barren hills and the secondary forests. We concluded that the conversion project from croplands to forests and grasslands based on scientific principles is very important in the formation of carbon sinks for reducing greenhouse effects.

With a combination of permanent and temporary sample plots, we investigated the growth conditions of natural poplar-birch forests. The forests were divided into four site classes, using statistical and analytical techniques in a quantitative model, in descending order where site class !` was the best. On this basis, the growth of natural poplar-birch forests in the different site classes was studied. The growth processes of height and diameter at breast height were divided into three stages: a fast growing period, a stable growing period and a slow growing period. Results of this study provide a theoretical basis for the directive cultivation of natural poplar-birch forests.

Lichuan, located at the foot of the Wuling Mountain in southwest Hubei Province of central China, is well known in the world for the discovery of the living fossil Metasequoia glyptostroboides Hu & Cheng in the 1940s. Its natural habitat has been well protected by the Chinese government. In order to provide a scientific foundation for the protection of the Metasequoia resource, it has become necessary to analyze the changes in the original, natural Metasequoia mother trees (ONMMT) and their environment from 1948 to 2003. The results and countermeasures are as follows: First, the distribution areas have little changed, involving four towns/farmland, 45 villages, 5,746 individual trees in 1983 and 5,388 trees in 2003, covering nearly 600 km², with an average density of less than 0.1 tree/hm². The Metasequoia distribution consists of two main types: a scattered distribution type found mainly at the foothills or near houses, roads, villages and rivers while the population distribution type is found mainly at the mountains and valleys with a minority at low elevations in the mountains and basins. The largest Metasequoia populations have 105 and 123 trees. Second, in the past, attention was only paid to the protection of individual trees while the protection of the Metasequoia population and environment was neglected. This led to a shift from the past mixed forests to pure Metasequoia forests, with a simpler structure, reduced biodiversity and conditions non-conducive for natural renewal. From 1983 to 2003, 386 original Metasequoia mother trees died. So it is vital to enhance the protection of the only original Metasequoia population in the world and its habitat. Third, modern ecological means should be taken to protect the original Metasequoia population and its habitat. Research on the restoration and rehabilitation of Metasequoia vegetation should be carried out. Restoration and rehabilitation should be put into practice in the Xiaohe Valley, where the highest concentration of Metasequoia is found. Fourth, efficient measures should be taken to stop human activities that are harmful to Metasequoia and to improve the environment of ONMMT in order to promote the protection of the ONMMT population and its ecosystem. Eco-emigration and the return of marginal agricultural land to forestry can be practiced.

Single tree s sapwood scattering style and diurnal water consumption rhythm for different diameter classes were studied in a 48-year-old Quercus variabilis stand, water protection forest in Beijing. Results showed that the tree s sapwood area was closely related to diameter at breast height (DBH). Single tree s daily water consumption ascended as DBH and sapwood area increased. Daily water consumption of different diameter classes in September ascended steeply in the early morning and reached the peak around 11:00, and then descended slowly to the valley at 18:00. The course of daily accumulated water consumption was in accordance with a typical Richards model (R=0.985,8). Parameters of diameter-time equation for scaling-up can be achieved by parameter-recovering method in the gradient of all diameter classes and at any time of a day, characteristic parameters of the course of daily stand water consumption were calculated from a modulated Richards equation derivative: W_diti=(-7.147+1.174^d_i)[1-(-3,025.937+d^_i2.175).e^(-0.011t_j)]^{1/(1-d_i0.242)}

Absorbing water from soil by roots in vascular plants is an important physiological function and plays an essential role on their water balance. The root hydraulic conductance (LP) determined by radical water transport inside the root is a major influence on the shoot water status, plant growth, and development. However, a few studies have focused on the effect of different substances on LP of roots, and the role of radical water transport was poorly understood. Based on the pressure flux approach, this study used the roots of Fraxinus mandshurica seedlings with different treatments, i.e., distilled water, NH₄NO₃ solution, and HgCl₂ to determine the effect of various substances on LP of roots. The objectives are: 1) to evaluate the difference in LP occurred between distilled water and NH₄NO₃ solution with various concentrations; and 2) to examine the changes of LP under distilled water and NH₄NO₃ solution with various concentrations after HgCl₂ treatment. The results showed that LP of roots were 18.85?10 ^8 m/(s•MPa) in distilled water, 31.25 34.15?10 ^8 m/(s•MPa) in four NH₄NO₃ solutions (2, 4, 8 and 16 mmol/L), 14.69?10 ^8 m/(s•MPa) in distilled water after HgCl₂-treated, and 9.63 13.57?10 ^8 m/(s•MPa) in four NH₄NO₃ solutions after HgCl₂-treated, respectively. Aquaporins play an important role in regulating water uptake and transport in roots. NH₄⁺ and NO₃ ^ could stimulate activity of aquaporins, and LP of roots in NH₄NO₃ solution was distinctly 77% higher than in distilled water. Nevertheless, Hg²⁺ can inhibit activity of aquaporins, and and LP of roots decreased 22% in distilled water and 68% in NH₄NO₃ solution after treatment by HgCl₂ respectively. These evidences suggested that both Hg²⁺-sensitive aquaporins and ion channels existing in the protoplasm and vacuole membranes could regulate root water uptake, transport, and integral plant water balance.

Hepatacodium miconioides is the Class II protected plant species in China. This paper studies the genetic diversity and differentiation of its nine natural populations in Zhejiang Province by using random amplified polymorphic DNA (RAPD) technique. Twelve random primers were selected in the amplification, and 164 repetitive loci were produced. The percentage of polymorphic loci in each H. miconioides population ranged from 14.60% to 27.44%, with an average of 20.73%. Among the test populations, Kuochangshan had the highest percentage of polymorphic loci, Simingshan took the second place, and Guanyinping had the lowest percentage. As estimated by Shannon index, the genetic diversity within H. miconioides populations accounted for 27.28% of the total genetic diversity, while that among H. miconioides populations accounted for 72.72%. The genetic differentiation among H. miconioides populations as estimated by Nei index was 0.715,7. This figure was generally consistent with that estimated by Shannon index, i.e., the genetic differentiation among populations was relatively high, but that within populations was relatively low. The gene flow among H. miconioides populations was relatively low (0.198,7), and the genetic similarity ranged from 0.655,7 to 0.811,9, with an average of 0.730,6. The highest genetic distance among populations was 0.422,9, while the lowest was 0.208,3. All the results showed that there was a distinct genetic differentiation among H. miconioides populations. The genetic distance matrix of nine test populations was calculated using this method, and the clustering analysis was made using the unweighted pair group method with arithmetic mean (UPGMA). The cluster analysis suggested that the nine populations of H. miconioides in Zhejiang Province could be divided into two groups, the eastern Zhejiang group and the western Zhejiang group.

The effects of the arbuscular mycorrhizal (AM) fungus Glomus mosseae on plant growth, leaf solutes and root absorption area of trifoliate orange (Poncirus trifoliata (L.) Raf.) seedlings were studied in potted culture under water stress conditions. Inoculation with G. mosseae increased plant height, stem diameter, leaf area, shoot dry weight, root dry weight and plant dry weight, when the soil water content was 20%, 16% and 12%. AM inoculation also promoted the active and total absorption area of root system and absorption of phosphorus from the rhizosphere, enhanced the content of soluble sugar in leaves and roots, and reduced proline content in leaves. AM seedlings had higher plant water use efficiency and higher drought tolerance than non-AM seedlings. Effects of G. mosseae inoculation on trifoliate orange seedlings under 20% and 16% soil water content were more significant than under 12% soil water content. AM infection was severely restrained by 12% soil water content. Thus, effects of AM fungi on plants were probably positively related to the extent of root colonization by AM fungi. The mechanism of AM fungi in enhancing drought resistance of host plants ascribed to greater osmotic adjustment and greater absorption area of root system by AM colonization.

In this paper, the implementing steps of a natural forest protection program grading (NFPPG) with neural network (NN) were summarized and the concepts of program illustration, patch sign unification and regression, and inclining factor were set forth. Employing Arc/Info GIS, the tree species diversity and rarity, disturbance degree, protection of channel system, and classification management in the Maoershan National Forest Park were described, and used as the input factors of NN. The relationships between NFPPG and above factors were also analyzed. By artificially determining training samples, the NFPPG of Moer-shan National Forest Park was created. Tested with all patches in the park, the generalization of NFPPG was satisfied. NFPPG took both the classification management and the protection of forest community types into account, as well as the ecological environment. The excitation function of NFPPG was not seriously saturated, indicating the leading effect of the inclining factor on the network optimization.

The interactions between pine wood nematode and three bacterium strains isolated from the nematode, Bursaphelenchus xylophilus, which are two strong pathogenic bacterium strains, Pseudomonas fluorescens GcM5-1A and Pseudomonas putida ZpB1-2A and a weak-pathogenic bacterium strain, Pantoea sp. ZM2C, were studied. The result showed that the strong-pathogenic GcM5-1A strain and ZpB1-2A strain significantly increased fecundity, reproduction rate, and the body volume of the adult nematode. Meanwhile, pine wood nematodes significantly promoted reproduction of the two strong-pathogenic bacterium strains. However, the weak-pathogenic bacterium strain, ZM2C, completely inhibited reproduction of pine wood nematodes. Aseptic pine wood nematodes significantly inhibited reproduction of the strain ZM2C. The results indicated that mutualistic symbiosis exists between pine wood nematodes and the two pathogenic bacteria it carries. The phenomenon showed that the pathogenic bacteria carried by the nematode were not accidentally contaminated, but rather had existed as symbionts of the nematode with which it had coevoluted over a long period. The role of mutualistic symbiosis in the process of pine wilt disease was also discussed.

According to the international methods of pest risk analysis and urban forestry characteristics in Beijing, a quantitative risk assessment system in Beijing for three primary non-indigenous pests was proposed. This system was used to analyze three major non-indigenous species, Dendroctonus valens, Hyphantria cunea, and Apriona swainsoni. The results show that the risks of these three pests in the Beijing area were 2.46, 2.30, and 2.02, which were all highly risky. Based on the result and extensive risk communications, combined with the management experience of the Beijing Forest Protection Station, the authors proposed some effective control measures to prevent the invasion of the three pests into Beijing.

According to fixed-position data for 1985 2003 from nine runoff plots of Caijiachuan watershed which lies in Jixian County of Shanxi Province in Loess area, this paper studied the relationship between vegetation and runoff and sediment production in sloping lands in detail, which helps to provide scientific basis for vegetation re-construction and studies on environmental transformation of water and sediment in watersheds of Loess area. Although, many study results testify that forest vegetation has an important function in soil and water conservation and cutting runoff, the effect of vegetation on runoff and sediment transmission is complicated, and this needs to be studied in depth. The results of the paper showed the following. Firstly, the natural secondary forest performs better function of soil and water conservation than artificial Robinia pseudoacacia forest, and runoff and sediment produced in the former in individual rainfall were 65% 82% and 23% 92% of those produced in the latter. At the same time, better correlative relationship between runoff and sediment production and rainfall and rainfall intensity were testified by multiple regression, but the correlation decreased gradually with the increase of canopy density of forest. Secondly, the difference of runoff and sediment production in several land use types was very distinct, and the amount of runoff and sediment produced from Ostryopsis davidiana forest and natural secondary forest were the least, and runoff and sediment produced from in artificial Robinia pseudoacacia forest and Pinus tabulaeformis forest were 5-fold as much as those from O. davidiana forest. Besides, runoff and sediment produced in mixed planting of apple trees and crops were 16.14-fold and 2.96-fold than those of O. davidiana forest, respectively, but the amount decreased obviously after high-standard soil preparation in the case of the former. Thirdly, based on gray cognate analyses of factors affecting runoff and sediment production in sloping land, the factors of stand canopy density and herb and litter biomass were the most significant ones, whose gray incidence degree exceeded 0.6. Therefore, mixed forest with multi-layer stand structure and shrub forest should be developed in vegetation re-construction of Loess area, which will help to increase coverage and litter thickness in order to cut down the runoff and sediment dramatically in sloping land.

Hot-pressing is the main process in flakeboard manufacture. Studies in this field also emphasize the effect on the heat-transfer process of the following factors: hot-pressing temperature, original moisture content (MC), target thickness and target density. In this experiment, dynamic data of changes in temperature in mats can be logged through temperature transducers and a computer data log system. The results of the experiment indicate that the core temperature-time curve can be divided into three stages: a stage of a rapidly rising temperature, a stage of moisture vaporizing and a stage of a slowly increasing temperature. If the hot-pressing temperature or the original MC increases during the first stage, the temperature will increase at an accelerated rate. This rate of acceleration in thin or low-density boards is very high. During the second stage, increasing the hot-pressing temperature or decreasing the original MC can shorten the time used to vaporize moisture. In thin or low-density board, this time period is short. In the third stage the original MC does not affect the rate of temperature increase, while the effect of the other factors is the same as that at the first stage. Given different conditions, vaporization temperature in the mat changes.

In order to analyze the effect of temperature gradient on moisture movement during highly intensive drying, such as microwave-vacuum drying, the profile of the temperature and moisture content in sealed wood whose opposite faces were subjected to temperature gradient for a short time was measured. The ratio of the moisture content (MC) gradient to the temperature gradient (dM/dT) was calculated and the factors influencing moisture movement under nonisothermal conditions were discussed. The results indicate that moisture moved in wood from the warm surface to the cold one even if opposite faces of the sealed wood assembly were exposed continuously to different but constant temperatures for a short period. The moisture content on the cold surface was higher than that on the warm surface. The moisture content gradient opposite to the temperature gradient was established, and the dM/dT was below 0.9%/vH. The temperature in the sample and the distance from the hot surface of the sample was strongly linearly correlated. With an increase in temperature, initial moisture content and experimental time, the dM/dT was significantly increased.

Dynamic properties of bamboo, Phyllostachys pubescens, with moisture content (MC) ranging from 130 to 130?C, were studied by dynamic mechanical analysis (DMA). The results showed that the hygrothermal effect on dynamic mechanical properties was negative. The storage modulus decreases with increasing temperature and MC, and glass transition temperature decreases with increasing MC. The glass transition temperature and tan delta of bamboo were 30.5?C, 0.02 and 10.61?C, 0.04, when MC was 10% and 34%, respectively.

The regeneration of exhausted solutions of electroless nickel plating wood veneer was realized using soluble calcium salt to precipitate and remove phosphite and then using fluoride to remove residual calcium ions from the solution. The effect of the pH value of the solution, treatment temperature and the molar ratio of calcium ions to phosphite ions on the removal efficiency of phosphite was investigated. Wood veneer was electroless plated using regenerated solutions. A coating with better electrical conductivity and electromagnetic shielding was obtained.

We used heart rate variability (HRV), an electrophysiological index, to investigate the changes of the sympathetic and parasympathetic nervous systems of people when they were in contact with wood and other materials, in a time-domain, a frequency-domain, and by means of nonlinear dynamics. Our aim was to discover the relations among thermal parameters of different kinds of material, human physiological feedbacks, and psychological perceptions. It shows that the activity of the sympathetic nervous system when in contact with wood increased no more than when in contact with metal and ceramic materials, while the activity of the parasympathetic nervous system weakened less than when in contact with these materials. The time taken by the sympathetic and parasympathetic nervous systems to revert to their normal state after contact with cloth and wood was shorter than that after contact with metal and ceramic. A subjective survey, by SD method, showed that the tactility of wood was favorable and people preferred wood to other kinds of material. Correlation analysis  results showed that there was a close correlation among the HRV indices, human psychological emotion ratings, and thermal parameters of the different kinds of materials. The experiment proves that the effect of wood on our autonomous nervous system is slightly better than that of other materials except for cloth. Wood does not damage people s health.