Based on the basic principles of the micrometeorology of atmospheric boundary layers and vegetation canopy, a numerical model of the interaction between forest ecosystems and atmospheric boundary layers was developed. The model is used to simulate the diurnal variations of heat balance in forest ecosystems, canopy temperatures, ground surface temperatures, as well as the profiles of temporal and spatial distributions of potential temperatures, wind speeds, specific humidity, and turbulence exchange coefficients. Our study indicates that themodel can be applied to study the interaction between land surface processes and atmospheric boundary layers over various underlying surfaces and their regional climate effects. This paper will establish a solid foundation to investigations on the coupling of climate models and the biosphere.

In the implementation phase of the Conversion of Cropland to Forest and Grassland (CCFG) project in China, it is important, from a scientific point of view, to recognize phytocommunities  characteristics, species compatibility, and ecological function. The ecological niche that roots occupy, their abundance and distribution, and the factors that affect them must be acknowledged. Following the methodology of community ecology, the total root mass of a phytocommunity is measured as cubic volume. Root biomass, length, and the number of roots in every diameter class, for each soil layer and for each plant species, are regarded as observation variables. In the first instance therefore, a new method to calculate the root ecological niche index (RENI) is proposed, embracing the entire phytocommunity of plantations. Using the new method, the roots of phytocommunities in Datong County, Qinghai Province (one of the counties selected for the national CCFG experiment), are dealt with in this paper. The results show that most of the vertical distributions of plant roots belong to the type wherein the roots are concentrated in the topsoil layer (0 20 cm), far more than those in the lower soil layers. The RENI of phytocommunities is higher than that of pure stands or monocultures. The distribution of RENI by root diameter can be divided into four types: J-type, inverse J-type, recumbent S-type, and U-type. RENI is positively correlated with the wet biomass of aboveground level stems, branches, and plant leaves, and with the species richness of phytocommunities. Although the RENIs of plantations in rehabilitated fields are a little lower than those of natural forests, they are higher than those of cultivated crops. The RENIs of three community types (Picea crassifolia + Hippophae rhamnoides ssp. sinensis, H. rhamnoides ssp. sinensis, and P. crassifolia) in rehabilitated fields benefit greatly from the restoration project. The implementation of the CCFG project is important for the increase in RENI and the multiple functions of plant roots.

To optimize the spatial structure of an ecosystem, a forest landscape was selected as a research object. Based on the theory of structure and functions of landscape ecology, combined with the analysis of the characteristics of the inner structure in an ecosystem, this paper proposes to establish certain procedures to regulate the spatial structure of this forest landscape and construct a landscape pattern of forest ecosystem functions. Considering the functions of biologic production, environmental services, and cultural support in forest ecosystems, forest landscape zones should consist of areas of forest production, research, experimentation, recreation, and conservation to add value to the forest ecosystem, enhance its functions, and then identify the relevant environmental factors according to the environment featured in the research area. Based on the methods of landscape ecology and ecological planning, this paper develops a zoning project of ecosystem functions suitable for various environments. For this research, the Hui-Sun forest station in Taiwan Province, China was selected to be the experimental area for studying the feasibility of developing a zoning project of forest ecosystem services and the suitability of optimizing the spatial structures of the services.

The method of trend surface analysis was used to analyze the distribution of landscape elements along environmental gradients in Jingouling forest farm, northeast China s Jilin Province. Results showed that topographic characteristics and disturbance pattern have much more impacts on the distribution of landscape elements than do horizontal geographical position in the study area. The elevation, slope aspect, and slope degree were found to be dominant features controlling landscape pattern. At different altitudinal ranges, the effects of slope aspect and slope degree on the distribution of landscape elements vary markedly in orientation and intensity. These differences were analyzed and discussed, and some basic rules of spatial distribution of landscape elements were proposed.

Based on investigations during 1998 2003, shrubs and herbs, as well as indicators of similarity and diversity in Pinus tabulaeformis forests of ten regions around Beijing were compared and analyzed, and protection measures were suggested. Generally, the shrubs and herbs in P. tabulaeformis forests of Shidu, Mutianyu, and Yunfengshan are rich in species diversity and have great similarities. The percentages of common species in each of these three paired regions are above 50%, while many peculiar plant species that could not be found in the other nine regions exist in Labagoumen. As for plant diversity indices, plants in theP. abulaeformis forests of Baihuashan, Shidu, and Labagoumen occur more frequently than in other regions, while the number of plants in Tanjiesi and Miaofengshan are far less. Some endangered orchid species were found distributed in P. tabulaeformis forests with a clumped spatial pattern but rarely appeared in other forest types, indicating that P. tabulaeformis forests are ideal habitats for orchid species.

Based on data collected (through local observations) for several consecutive years, comparative analyses of Chinese fir plantations in Huitong, Hunan, were made. Results show that, before harvesting, carbon storage in forest soils in these 22-year-old plantations (0 60 cm) amounted to 160.38 t/hm²; 1 year after a 100% clearcutting, loss of carbon storage in the soil (0 60 cm) of cutover areas was 35.00%; 2 years later, the rate was 44.65%; and, after 3 years, the rate was 43.93% compared with a control area of a standing forest. Three years after 50% thinning and 100% clear-cutting, the loss of carbon storage in the soil (0 60 cm) of cutover areas was 16.14 and 45.15%, respectively. There existed an evident difference in carbon storage in the soil (0 60 cm) of cutover areas in four kinds of management regimes, which followed the order: closed Chinese fir forests (108.20 t/hm²) > fallow lands after farming (92.68 t/hm²) > commercial forests (85.80 t/hm²) > naturally regenerated forestlands after harvesting. Carbon storage in unburnt soil (0 45 cm) reached 73.36 t/hm², which was 15.20 t/hm² higher than that in the soil of burnt areas. A total of 20.7% of carbon storage in the soil (0 45 cm) of burnt areas was lost 40 days after burning. Carbon storage in surface soil (0 15 cm) was higher than in the lower soil layer, which amounted to 30.04% (0 60 cm) and 53.52% (0 30 cm) of total carbon storage in the soil.

The ecological water requirement of forests is defined as the water resources used to maintain and improve the natural balance of forest ecosystems, which can be expressed by evapotranspiration of trees during the growing season. The relationship of evapotranspiration and soil moisture of forestland with tree growth showed that, if the soil moisture was above the temporary wilting point or the point of growth retardation, the growth of trees can, respectively, be basically or normally sustained. Therefore, they can be taken as the minimum and the suitable ecological water requirements of the forest. These points can be estimated by introducing the soil factor ( K_s) and tree species factor (K_t) to potential evapotranspiration with the Penman formula. With geographic information system (GIS), the ecological water requirement for forests in the Jinghe watershed, western China was estimated. The results revealed that the minimum and suitable ecological water requirements of the forests in the Jinghe watershed were approximately 204×10⁷ and 340×10⁷ m³, respectively.

A Growth Model System is developed for data updating and forecasting of the national continuous forest inventory. Its design is based on the inherent forest growth laws, and its parameters are estimated by modern regression methods. It is composed of an age-implicit tree model, a diameter-related survival rate model, a recruitment model based on age and number of plots, and an area model. It is suitable for forest resource information updating and forecasting for a large region, e.g., a province. Data of remeasured plots and trees are needed for development of the system. A study case of Jiangxi Province with detailed error analyses is provided.

The digital elevation model (DEM), an important source of information, is usually used to express a topographic surface in three dimensions and to imitate essential natural geography. DEM has been applied to physical geography, hydrology, ecology, and biology. This study analyzed digital elevation data sources and their structure, the arithmetic of terrain attribute extraction from DEM and its applications, and DEM s error and uncertainty algorithm. The Hayachinesan mountain area (in northeastern Japan) was chosen as research site, and the focus was on terrain analysis and the impacts of DEM resolution on topographic attributes, analyzed using TNTmips GIS software (MicroImage, Inc., USA) and Digital Map 25,000  (published by the Geographical Survey Institute of Japan in 1998). The results show that: (1) DEM is a very effective tool for terrain analysis: many terrain attributes (such as slope, aspect, slope type, watershed, and standard flow path) can be derived, and these attributes can be displayed with both image and attribute databases, with the help of GIS; (2) DEM resolution has a great influence on terrain attributes. The following details are shown: (a) DEM resolution has a significant effect on slope estimation: the average slope becomes smaller and the standard deviation becomes larger when DEM resolution changes from fine to coarse, and the different impacts of DEM resolution on different slope ranges can be classified into three gradient classes: 0 10? (underestimated slope), 10 35? (overestimated slope), and >35? (little impact on slope estimation); (b) DEM resolution has little effect on aspect estimation, but flat areas become larger when DEM resolution changes from fine to coarse; and (c) the quantity of hydrologic topography information declines as DEM resolution decreases.

The paper shows a study on 2-D stem image information collected by a digital camera. Information on a single stem is obtained through calculations after the application of the direct linear transformation model of close-range photogrammetry and binocular stereo vision technology, so that the calculating problem between stem image information and its 2-D coordinate can be solved. Furthermore, the 2-D processing methodology for measuring tree image information simplifies calculating equations and increases calculating speed. Although computer stereo vision techniques for collecting parameters of a single stem shape are comparative, complicated, and expensive, research indicates the efficiently and feasibility of closerange photogrammetry for stem image information.

In order to identify the optimum cutting density for producing the highest number of plantable seedlings of poplar clones, a split-plot randomized block design was used to establish four cutting densities in plots. Based on data on the survival, leaf area, seedling height, caliper, and biomass of 1-year-old seedlings of clones Nanlin-95, Nanlin-895, Nanlin-1388 and NL-80351, the growth characteristics and seedling quality under four cutting densities were analyzed. Results indicated that the leaf area, stem and leaf biomass, and caliper of seedlings of all four poplar clones increased with the decrease in cutting density. Leaf area index reached its highest level at the spacing of 40 cm×40 cm, while the aboveground biomass of the seedling on an area basis increased as the cutting density increased. Seedling quality at low cutting density was higher than that at closer cutting density. The quantity of first-grade seedlings (grade I) for clones Nanlin-95 and Nanlin-895 was achieved at the spacing of 40 cm×50 cm; for NL-1388 and NL-80351, it was 50 cm×50 cm. According to the seedling quality and the number of plantableseedlings produced, the suggested cutting density for these four poplar clones was 50,000 stems/hm².

The mixed plantation of poplar (Populus spp.) and black locust (Robinia pseudoacacia) is one of the typical mixed stands with nitrogen-fixing and non-nitrogen-fixing species. Interaction between the two species in the mixed stand is harmonious and productivity is high, making this kind of mixed plantation a very successful pattern on poor sandy sites in north China. In this study, the fine root decomposition of the two species was investigated in the mixed plantation of 27-year-old Canadian poplar (P. canadansis) and 22-year-old black locust on sandy sites along the Chaobai River in Beijing. Mechanism of harmonious interaction between the two species was observed in the view of the nutrient cycle of fine roots. Results showed that: (1) the fine root decomposition of Canadian poplar and black locust trees was different. Concentrations of N, Ca and Mg gradually increased and those of P and K gradually decreased in the fine roots of poplar during the period of decomposition. Concentrations of N, P and K gradually decreased in the fine roots of black locust during decomposition. The speed of nutrient decomposition inmixed fine roots of the two species fell between the speed of the two pure samples. (2) During decomposition, the annual return amount of N, K andMg in fine roots of black locust was highest, followed by the mixed fine roots of the two species, and then the fine roots of poplar. (3) The increased return amount of N in mixed fine roots could improve the N nutrient condition of poplar trees. The return amount of P in poplar fine roots was greater than that of black locust, which could improve the P nutrient of black locust trees. The interaction of mutual supplements of N and P nutrient cycle of fine roots between these two species formed.

The influence of woodland soil bulk density on the growth and distribution of fine root system of main planting tree species in the Weibei Loess Plateau was investigated by means of pot culture and field survey. Results indicated that in the woodland of Pinus tabulaeformis, soil bulk density increased with the depth at different sites, while in the woodland of Robinia pseudoacacia, soil bulk density was higher than that in P. tabulaeformis, and there was no clear difference across the profile. Further analysis implied that there existed negative correlations between soil bulk density and fine root length in the woodland of P. tabulaeformis. Results from pot culture indicated that although the effects of pot culture media on the fine root growth and development of different tree species seedlings were different, all treated seedlings grew better in the soil matter with medium bulk density and porosity and with the biggest biomass. Bulk density of pot culture media had clear effects on the growth and development of P. tabulaeformis and R. pseudoacacia seedling roots, especially on the former, whereas it had little effect on that of Platycladus orientalis and Prunus armeniaca var. ansu, whose fine root biomass changed little in different pot culture media.

To evaluate genotypic difference in antioxidative ability and salt tolerance in poplars, the authors investigated the effects of increasing content of soil NaCl on salt concentration in leaves, superoxide dismutase (SOD) and peroxidase (POD) activities, malondialdehyde (MDA) content, and membrane permeability (MP) in Populus euphratica Oliv., P. popularis 35  44,  and P. ? euramericana cv. I-214 (hereafter abbreviated as P. cv. I-214). Na⁺ and Cl^- concentrations in leaves of P. popularis increased markedly over the increase of the duration of exposure to salinity, and culminated after 28 days of salt stress. SOD and POD activities declined correspondingly, followed by significant increases of MDA and MP, and leaf injury was finally observed. Compared with P. popularis, leaf Na⁺ and Cl^- in P. cv. I-214 exhibited a trend similar to P. popularis, but a lower salt-induced increase of MDA and permeability was observed and lighter leaf necrosis occurred. In contrast to P. popularis and P. cv. I-214, SOD and POD activities in P. euphratica leaves increased rapidly at the beginning of salt stress with a light soil NaCl concentration of 58.5 mmol/L. Furthermore, salt ion concentration, MDA content, and MP in P. euphratica leaves did not increase significantly during 28 days of increasing salt stress. Therefore, the increase in MP in P. popularis and P. cv. I-214 had a close relationship with a salt buildup in leaves under increasing salt stress. Salt-induced declines of SOD and POD activities might accelerate lipid peroxide and consequently resulted in ion leakage.P. euphratica rapidly activated antioxidant enzymes after the onset of salt stress, which might reduce the accumulation of reactive oxygen species and the subsequent acceleration of lipid peroxide. P. euphratica leaves exhibited a higher capacity to exclude salt in a longer period of increasing salinity, thus limited salt-induced lipid peroxide and MP, which contributed to membrane integrity maintenance and salt tolerance of P. euphratica.

Foliar carbon isotope composition (δ¹³C), total dry biomass, and long-term water use efficiency (WUE_L) of 12 Populus deltoids clones were studied under water stress in a greenhouse. Total dry biomass of clones decreased greatly, while δ¹³C increased. Single-element variance analysis in the same water treatment indicated that WUE_L difference among clones was significant. Clones J₂, J₆, J₇, J₈, and J₉ were excellent with high WUE_L. Extremely significant δ¹³C differences among water treatments and clones were revealed by two-element variance analysis. Water proved to be the primary factor affecting δ¹³C under water stress. It showed that there was a good positive correlation between δ¹³C and WUE_L in the same water treatment, and that a high WUE_L always coincided with a high δ¹³C. δ¹³C might be a reliable indirect index to estimate WUE_L among P. deltoids clones.

The genetic diversity and genetic variation within and among populations of five natural Davidia involucrata populations were studied from 13 primers based on random amplified polymorphic DNA (RAPD) analysis. The results show that natural D. involucrata population has a rich genetic diversity, and the differences among populations are significant. Twenty-six percent of genetic variation exists among D. involucrata populations, which is similar to that of the endangered tree species Liriodendron chinense and Cathaya argyrophylla in China, but different from more widely distributed tree species. The analysis of the impacts of sampling method on genetic diversity parameters shows that the number of sampled individuals has little effect on the effective number of alleles and genetic diversity, but has a marked effect on the genetic differentiation among populations and gene flows. This study divides the provenances of D. involucrata into two parts, namely, a southeast and a northwest provenance.

The effects of Glomus mosseae colonization on the plant growth and drought tolerance of 1-year-old trifoliate Poncirus trifoliata seedlings in potted culture were studied in natural water stress and rewatering conditions. Results showed that arbuscular mycorrhizal (AM) inoculation significantly improved the height, stem diameter, and fresh weight of P. trifoliata seedlings before natural water stress. By the end of the experiment, the survival percentage of AM-transplanted seedlings was 8% higher than those of non-AM ones. During water stress and rewatering, AM significantly increased the contents of soluble sugars and proteins in leaves, and enhanced the activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POD), and catalase (CAT) in either seedling leaves or roots, which indicated that AM colonization could improve the osmotic adjustment response of P. trifoliata, enhance its defense system, and alleviate oxidative damages to membrane lipids and proteins. These results demonstrated that the drought tolerance of P. trifoliata seedlings was increased by inoculation with AM fungi. The functional mechanism underlying the observation that mycorrhizas increased the host s drought tolerance was closely related to enzymatic and nonenzymatic antioxidant defense systems such as SOD, GPOD, CAT, and soluble protein.

Olfactory responses of Tetranychus viennensis to different plant odors were studied with a Y  olfactometer and petri dishes, and volatiles from leaves of different plants were absorbed with solid phase microextraction and analyzed with gas chromatography mass spectroscopy. The study showed that olfaction took place in the response when the Hawthorn Spider Mite looked for host plants, indicating that T. viennensis were attracted by odors from host plants. Different host plants have different attractions to T. viennensis; some attract strongly, while others do so to a lesser extent. The nonhost plants tested have neither attraction nor repulsion to the mite. The volatiles from leaves of different host plants such as Malus pumila, P. bretschneideri, Amygdalus persica, Armeniaca vulgaris, Malus spectabilis, Crataegus pinnatifida, and Prunus yedoensis consist of trans-3-hexen-l-ol, acetate, trans-3-hexenyl ester butanolic acid, α-farensene, etc., which do not exist in the nonhost plants such as Euonymus japonicus.

Twelve stand factors affecting the harm extent of Gypsy moths (Lymantria dispar) were studied. Through stepwise regression analyses, three key factors were selected, such as crown density, soil infertility extent, and forestland area. The results showed that there exists a positive correlation between soil infertility extent and the harm extent of Gypsy moths and a significant negative correlation between the other two key factors and the harm extent of this insect. Using the three key factors, a multivariate linear regression model was established by which the authors made a risk analysis of the harm extent of Gypsy moths.

Guifeng, Yiyang County, belongs to a seriously degraded red soil region. In 1991, Pinus elliottii and Lespedaza spp. were the species selected for the establishment of a mixed forest in the area. The results of an investigation of the soil system in a 12-year-old forest indicated the following: (1) Organic matter and total nitrogen of the forest soil to a depth of 40 cm were 88.0 and 36.0% higher, respectively, than those of a control plot; total phosphorus and available phosphorus were 40.9 and 22.3% higher than those of the control; available potassium contents were 8.13% lower than those of the control. (2) Soil aeration and the soil air regime improved. (3) Proteinase, catalase, and urease in the forest soil to a depth of 40 cm were usually higher than those in the control plot and decreased with soil depth.

The daily gas exchange, stomatal conductance, and water use efficiency of Platycladus orientalis in the test field of Fangshan county of Shanxi Province in the semiarid region of the Loess Plateau were measured with portable Li-6200 gas analysis system in natural conditions. The results showed that the diurnal course of net photosynthetic rate displayed a two-peak pattern, that of stomatal conductance displayed a hollow pattern, and that of transpiration rate displayed a signal-peak pattern. Water use efficiency culminated in the early morning. On the basis of two criteria of stomatal limitation of photosynthesis suggested by Farquhar and Sharkey, the predominant limiting factor of photosynthesis was the stomatal conductance of stomatal limitation in the morning (10:00 12:00). However, the midday depression of photosynthesis at noon (12:00 14:00) and the decrease in photosynthesis in the afternoon (16:00 18:00) were the results of nonstomatal limitation, such as low carboxylation capacity of the leaf mesophyll.