On the Loess Plateau, water is the main limiting factors for vegetation growth. Root distribution characters have special ecological meaning as it reflected the utilizations of trees to the environments. Even-aged stands ofRobinia pseudoacacia on slope lands facing south and north were selected as sampling plots for root distribution investigation. Investigatiing results showed that indicated that on all sites, root biomass decreased with depth, and the distribution depth of fine root was deeper than that of coarser root. The results of variance analysis indicated that there were great differences in root biomass among different diameter classes, and coarser root was the main sources of variance, and the root biomass, especially fine root (ϕ<3mm) biomass on northern exposition sites was bigger than that on southern exposition sites. Analysis of the vertical root distribution parameters, root extinction coefficient, β indicated that the value of β on northern exposition was more than 0.982, while the value of β on southern exposition was less than 0.982, which indicated that the vertical root distribution depth ofRobinia pseudoacacia on southern exposition was deeper than that on southern exposition. And the distribution depth of fine roots (Φ<1mm) was deeper than that of thicker roots(Φ<3mm), which was in favor of the uptake of water and nutrients from deeper layers, helped the trees to adapt the arid environment, and promoted the growth of the upper parts of the tree.
Accurately estimating forest net primary productivity (NPP) plays an important role in study of global carbon budget. A NPP model reflecting the synthetic effects of both biotic (forest stand age, A and stem volume, V) and climatic factors (mean annual actual evapotranspiration, E) was developed for Chinese pine (Pinus tabulaeformis) forest by making full use of Forest Inventory Data (FID) and dynamically assessing forest productivity. The NPP of Chinese pine forest was estimated by using this model and the fourth FID (1989–1993), and the spatial pattern of NPP of Chinese pine forest was given by Geography Information System (GIS) software. The results indicated that mean NPP value, of Chinese pine forest was 7.82 t m−2·a−1 and varied at the range of 3.32–11.87 t hm−2·a−1. NPP distribution of Chinese pine forests was significantly different in different regions, higher in the south and lower in the north of China. In terms of the main distribution regions of Chinese pine, the NPPs of Chinese pine forest in Shanxi and Shaanxi provinces were in middle level, with an average NPP of 7.4 t hm−2·a−1, that in the southern and the eastern parts (e.g. Shichuang Hunan, Henan, and Liaoning provinces) was higher (over 7.7 t hm−2·a−1), and that in the northern part and western part (e.g. Neimenggu and Ningxia provinces) was lower (below 5 t hm−2·a−1). This study provides an efficient way for using FID to understand the dynamics of foest NPP and evaluate its effects on global climate change.
The restoration of the riparian vegetation disturbed by human activities is one of the hotspots of watershed ecology. Through interpreting the images of Remote Sensing in 1985 and 1999, the basic information of forest resources of Lushuhe Forest Bureau, which is a typical forest area of Chanbai Mountain was obtained with support of GIS. By dividing Land covers of Lushuihe area into 10 types (water body, residential land, stump land, farming land, wetland, mature conifer forest, midlife conifer forest, mature broadleaf forest, midlife broadleaf forest, and man-made young forest) and dividing the riparian zone into four buffers (in turn 1000, 2000, 3000, 4000 m away from the river), the changes of riparian forest resources during 1985–1999 were analyzed. The results showed that the deforestation intension has obviously decreased and the whole environment has been evidently improved, but the riparian ecosystem was still flimsy. In buffer 1, 2, 3 the area of midlife conifer forest increased largely, but the areas of other types of land covers all decreased. Midlife conifer forest had a comparatively good status in the three buffers. In buffer 4, midlife conifer forest, mature conifer forest, and mature broadleaf forest formed a forest-age rank that is helpful to stabilize the forest ecosystem and exert its functions. Area percentage of wetland decreased in buffer 1, buffer 2, and buffer 3, even in buffer 4 in which forest ecosystem rehabilitated comparatively well, so protecting and rehabilitating wetland is a very difficult task.
To understand influence of litters on the emission/absorption of CO2, N2O and CH4 in broadleaved/Korean pine forest in Changbai Mountain, fluxes of soil CO2, N2O and CH4 were measured by closed static chamber technique, from Sept 3, 2002 to Oct 30, 2003 in two types of soil ecosystems, of which one was covered with litters on the surface soil, and the other had no litters. The results showed that litters had significant influences on CO2, N2O and CH4 fluxes (p<0.05). Their diurnal change patterns of plot with litters and litter-free plot were similar, and they all showed emission/absorption peak at 18:00. The diurnal change fluxes of CO2 and N2O of plot with litters were significantly higher than those of the litter-free plot, while the diurnal flux of CH4 of plot with litters was lower than that of litter-free plot. The fluxes of CO2, N2O, and CH4 showed the similar seasonal patternsfor both plots. The fluxes of CO2, CH4 showed their peak fluxes in June, but the fluxes of N2O showed its peak emissions in August. The annual fluxes of CO2 and N2O of plot with litters were significantly higher than those of the litter-free plot, while the annual flux of CH4 of plot with litters was lower than that of litter-free plot.
Soil incubation experiments were conducted in lab to delineate the effect of soil temperature and soil water content on soil respirations in broad-leaved/Korean pine forest (mountain dark brown forest soil), dark coniferous forest (mountain brown coniferous forest soil) and erman's birch forest (mountain soddy forest soil) in Changbai Mountain in September 2001. The soil water content was adjusted to five different levels (9%, 21%, 30%, and 43%) by adding certain amount of water into the soil cylinders, and the soil sample was incubated at 0, 5, 15, 25 and 35°C for 24 h. The results indicated that in broad-leaved/Korean pine forest the soil respiration rate was positively correlated to soil temperature from 0 to 35°C. Soil respiration rate increased with increase of soil water content within the limits of 21% to 37%, while it decreased with soil water content when water content was over the range. The result suggested the interactive effects of temperature and water content on soil respiration. There were significant differences in soil respiration among the various forest types. The soil respiration rate was highest in broad-leaved/Korean pine forest, middle in erman's birch forest and the lowest in dark coniferous forest. The optimal soil temperature and soil water content for soil respiration was 35°C and 37% in broad-leaved/Korean pine forest, 25°C and 21% in dark coniferous forest, and 35°C and 37% in erman's birch forest. Because the forests of broad-leaved/Korean pine, dark coniferous and erman's birch are distributed at different altitudes, the soil temperature had 4–5°C variation in different forest types during the same period. Thus, the soil respiration rates measured in brown pine mountain soil were lower than those in dark brown forest and those measured in mountain grass forest soil were higher than those in brown pine mountain soil.
A 112 m×8 m sample pot which includes 14 sub-plots was set up along the slope in Hongshi Forestry Farm of Baihe Forestry Bureau (127°55′E, 42°30′ N), Jilin Province in August 2002. Community structure, soil moisture contents at 0–10 cm and 10–20 cm in depth, water content of litter as well as the contents of C, N and P of litter, living leaves and branches in the broad-leaved/Korean pine (Pinus korraiensis) forest were measured in each sub-plot on different slope positions. The analytical results showed that there existed an obvious soil moisture gradient along the slope: upper slope <middle slope< lower slope. The difference in soil moisture contents on different positions of slope led to a change of the stand structure of the braod-leaved/Korean pine forest. The proportion ofQuercus mongolica gradually increased with the decrease of soil moisture content and that of other major tree species in the broad-leaved/Korean pine forest gradually decreased or disappeared. The dynamic of soil moisture contents in the litter layer was as same as that in mineral soils. The decomposition rates of the litter on different slope positions were different and the dry weights of existent litter varied significantly. The soil nutrients in the litter on the lower slope was richer than that on the upper slope due to the different stand structure on the different slope positions. The moisture content and nutrient contents of soil had effects on the composition, decomposition, and the nutrient release of litter, thus affecting stands growth and stand structure and finally leading to the change of ecosystem.
Two-year-old Scots pine (Pinus sylvstris var.mongolica) seedlings were treated with Pt mycorrhiza powder, ABT root-growing powder, HRC water-absorbing agent and high-yield powder, and planted on the sandy land in Balinyouqi, Inner Mongolia (180°12′13″E and 43°13′05″N). The effect and function of these biological agents on survival rate of seedlings were tested and analyzed by measuring the fine root growth and gross root growth. The results showed that the survival rates of the seedlings treated with Pt3, ABT, and HRC biological agents increased by 29.3%, 23.6%, and 16%, respectively. The regression analysis revealed that the length of fine roots (<2 mm) was positively correlated with seedling survival rate, which means that the Pt3 powder, ABT foot-growing powder and HRC water-absorbing powder increased the survival rates of the seedlings by promoting the growth of fine roots.
Western Liaoning Province is characterized by huge areas of lowly-efficient Chinese pine (Pinus tabulaeformis Carr.) pure plantations. How to transform these plantations has become an increasingly significant management problem. In this study, the authors summarized the approaches, which are based on close-to-nature silvicultural system, to transform the pure pine plantations. Native broadleaved trees were planted in three methods: 1) after strip clearcutting, 2) after patch clearcutting; 3) on the open forestland and the forest edge. The transformation targets and the selection of tree species were expatiated in this paper. The key techniques and their application conditions for each method were analyzed and discussed. Through investigation and contrastive analysis, the assessment was made to the stands transformed by strip method. Results showed that the mixed stands at 16 years after transformation had an obvious layered structure and the species richness of understorey vegetation increased by 23.5%–52.9%. Soil enzyme activities of urease, phosphatase and sucrase increased by 6%–142%, 46%–99% and 31%–200%, respetively. Moreover, the transformed stands could effectively control the occurrence of pine caterpillars in plantations. Consequently the transformations enhanced the function of soil and water conservation.
Non-injurious local stimuli, such as a cold shock, and injurious stimuli, such as local burning, punctures or chemicals, were applied to study electrical wave transmission in black pine (Pinus thunbergii) seedlings. The results showed that non-injurious stimuli evoked the action potential (AP) transmission and injurious stimulation induced both AP transmission and the more complex variation (VP) transmission in the seedlings. The causes of these phenomena were discussed.
The roots of 200 one-year-old Changbai Larch (Larix olgensis) seedlings were soaked for 6 hours at the TMS concentrations of 2000, 1000, 500, 250, 125, and 62 μL·L−1. Mean seedling height, root collar diameter, main root length and number of lateral roots were measured every 15 days during growing season from May 30 to Oct. 20. Experimental results showed that TMS treatments greatly promoted seedling growth and improved seedling quality. The treatment by 500 μL·L−1 TMS produced the best result, for which the mean height, root collar diameter, main root length, and the number of lateral roots of seedlings were increased by 42.5%, 30.7%, 14.0%, and 31.6%, respectively, compared to that of the control seedlings. As to seedling quality, grade-I seedling and grade-II seedlings were fifty-fifty, and no grade-III seedlings was found. The treatment by 500 μL·L−1 TMS resulted in the highest chlorophyll concentration.
Mao'ershan region is representative in the natural secondary forested region of the eastern mountainous region, northeast China. The landscape nearest neighbor index and landscape connectivity index were calculated with ARC/INFO software for Mao'ershan region. The spatial distribution of the landscape of the region was analyzed. The results showed that the landscape connectivity index of non-woodland was significantly higher than that of woodland. The landscape connectivity index of natural forest was nearly equal to zero, which means its fragmentation degree is high. The nearest neighbor index of plantation was lower than that of natural forest and non-forestland. Among the man-made forests, the distance index of the coniferous mixed plantation is the lowest, and its pattern is nearly glomeration. The landscape pattern of natural forest presented nearly random distribution. Among non-forest land, the distance index of cut blank was the lowest, and its pattern was also nearly glomeration.
Natural land cover information is important for analysing and understanding of the current terrestrial situation, especially in the study area that is facing the environmental deteriorating increasingly. The study combined the remote sensing Aster data and ground truth to improve 2001 land cover map of Guadalteba area in Spain, and increased the accuracy from 47% to 70%. The general land cover map produced about the Guadalteba study area outlines the distribution of the vegetation type and the current natural land cover in the area. Based on this improved general land cover map, the natural cover map gave an indication of the present location of nature and agriculture areas. The shrub land degradation map identified location of various shrub/matorral areas and different levels of degradation. The further analysis and discussion were done. The output maps indicated that much of the natural cover mostly dominated by formations of shrubs has been changed to agriculture and other land uses. It is observed that shrubland covers a small percentage, approximately 9% of the study area, due to land degradation in most parts caused by human interfere.
Conventional mechanical method and mechanical method combined with vacuum freeze-drying technology were used to make the ultra-fine powders of edible fungus (Auricularia auricular). The content of basic nutrients, amino acid, micro structure and their properties of raw edible fungus and the edible fungus powders obtained with the two methods were analyzed and compared. The granularity size and micro-structure of the pulverized samples were analyzed by SEM and TEM technology. The average granularity size of the edible fungus powder obtained with mechanical method was 1–5 μm, while that obtained with mechanical method combined with vacuum freeze-drying process was 0.5–1 μm. The ultra-fine powders of edible fungus obtained with the two methods had better water recovery capability and quality, and their preserving time was longer than that of raw edible fungus. All the properties of the ultra-fine powders of edible fungus obtained with the vacuum freeze-drying technology were evidently superior to that of the conventional mechanical method.
Wind not only causes extensive damages to trees in many parts of the world, it also has more subtle effects on the growth and morphology of trees and forest ecology as well. Wind damage to trees has historically been the field of silviculture, but increasing recognition of the importance and complexity of the subject has recently got people involved from many other disciplines. Due to the global climate changes, it is believed that the risk of further and stronger storms is increasing. In order to better understand the effects of wind on individual trees, forest stand and forest ecosystem, and further to practice the management of forests, it is necessary to summarize the research results related to this subject. This review was mostly based on the references from recent researches in the field, especially from the symposium volumes of some international conferences on this subject. The results indicated that there have been significant progresses in the following aspects: 1) the aerodynamic interaction between wind and trees, 2) the mechanics of trees under wind loading and adaptive growth, 3) the tree's physiological responses to wind, and 4) the risk assessment of wind damage to forest. However, there are some aspects which may need further studies: 1) wind damage to natural forests, 2) wind-driven gap formation and forest dynamics, 3) the effects of changes resulted from wind disturbances on ecological processes of forest ecosystem, and 4) management for the wind-damaged forests.
The World Trade Organization (WTO), an international organization to deal with the world free trade mechanism, allows for the optimal use of the world's resources in accordance with the objective of sustainable development and the protection of environment and trade. China, as a state member of WTO, is challenged by the WTO's agreements and the principles to guideline China sustainable forest development in the future. Forest resources in China will be protected as the basic sections of natural resources. The administrative function of Chinese government will be reformed by the condition of WTO's principles. So, the aim of China forest sustainable development is prior to deal with the relationship between the environment protection and development of economy. Under the condition of the WTO's principles and as a base on the international customary laws, the issues of China forest sustainable development focus on the China forest system reformation that applies for the China nature forest stratagem by the laws and protects the China environment for the sustainable development under the condition of science development, especially in the China forest protection and in dealing with the relationship among the environment and the economy development and others. Establishing the zoological forest industry is basic requirement by both the WTO's agreements and the WTO's principles, especially under the GATT 1947 Art XX, and other principles to protect the China forest sustainable development and to create the international environment for China forest.