[Tree uprooting of coniferous-broad leaved Korean pine mixed forest in Lesser Khingan Mountains, China].

The morphological parameters, root wad indexes and site conditions of 127 uprooting trees from 76 plots (20 mx20 m) in Lesser Khingan coniferous-broad leaved Korean pine mixed forest were measured. Then the influencing factors of uprooting differences and the relationship between uprooting trees and disturbed soil were analyzed. Results showed that the number of uprooting trees varied significantly among species.

[Effect of timber moisture content and terrain conditions on the decay degree of Korean pine live standing trees].

Vast loss of timber resources can be reduced by preventing and controlling the decay of standing trees in forest management. Therefore, research concerning the effect of site conditions on decay of standing trees is particularly important for decay prevention and cure. A relevant study was carried out in Xiaoxing'anling Mountains on October, 2013, and thirty decayed and ten normal mature or postmature Korean pine (Pinus koraiensis) live standing trees were selected as sample trees, respectively.

[Species composition and main populations spatial distribution pattern in Korean pine broadleaved forest in Xiaoxing' An Mountains of Northeast China].

Taking the Korean pine broadleaved forest in Liangshui Nature Reserve of Heilongjiang Province, Northeast China as test object, this paper studied the species composition and diameter class structure, and by using point pattern analysis, analyzed the spatial distribution pattern and spatial association of the main populations. In the Reserve, there were a total of 16 species with diameter greater than 1 cm in tree layer, and great differences were observed in the densities of main populations. Coniferous trees such as Pinus koraiensis and Abies nephrolepis were dominant.

[Correlations between standing trees trunk decay degree and soil physical-chemical properties in Korean pine-broadleaved mixed forest in Xiao Xing'an Mountains of Northeast China].

Standing trees decay often causes vast loss of timber resources. To investigate the correlations between the standing trees decay and the site conditions is of importance to scientifically and reasonably manage forests and to decrease wood resources loss. By using Resistograph and meter ruler, a measurement was made on the decay degree of the trunk near root and the diameter at breast height (DBH) of 15 mature Korean pine standing trees in a Korean pine-broadleaved mixed forest in Xiao Xing' an Mountains in May, 2011.

[Effects of compaction on diurnal variaaton of soil respiration in Larix gmellini plantation in summer].

Taking the Larix gmellinii plantation in the experimental forest farm of Northeast Forestry University as test object, and by using Li-8100 automatic instrument, the daily CO2 emission rate of soil in summer under different degrees of man-made compaction was measured, with the regression models established. There were significant differences in the diurnal variation of soil respiration rate under different degrees of man-made compaction. In CK (no compaction), the maximum value of soil respiration appeared at 15:30-17:30, and the minimum value appeared at 03:30-05:30, which were obviously lagged behind those in compaction treatments.

[Effects of selective cutting on soil respiration in conifer/broad-leaved mixed forests in Xiaoxing' anling].

By using LI-8100 CO2 Flux Meter, the CO2 flux of soil surface and the temperature and moisture content at soil depth of 10 cm in conifer/broad-leaved mixed forests under different intensity of selective cutting in Dailing Forest Bureau of Heilongjiang Province were determined simultaneously from 2003 to 2007, with the changes of soil surface CO2 flux after selective cutting and their affecting factors studied. The results showed that the CO2 flux was correlated with soil temperature and moisture content, with a relatively high confidence ranged from 68% to 98%. Selective cutting increased the CO2 flux, with an average annual increment being from 7.

[Remote sensing estimation of natural forest biomass based on an artificial neural network].

Based on Landsat TM images and with the natural forest area of Wangqing in Jilin Province as a case, a nonlinear RS (remote sensing) modeling system of forest biomass was built by using a back-propogation artificial neural network (B-P ANN). In addition to RS data, the factors representing terrain conditions, such as elevation, slope, aspect and site type, were also included as independent variables in the modeling system. The standard B-P ANN was made more robust by reducing the size of input data and by improving the training algorithms, thereby leading to faster convergence speed and stronger capabilities of self-study and self-adaptation.

[Compatible biomass estimation models of natural forests in Changbai Mountains based on forest inventory].

Forest biomass estimation is the groundwork of analyzing carbon cycle and its dynamics in terrestrial ecosystems, but the current estimation models had the problem of un-compatibility between total forest biomass and its components. Taking the Wangqing natural forest area in Jilin Province as a case, the compatible concept of building forest biomass models based on forest invent' tory was brought forward. A series of compatible biomass estimation models, taking stem volume as one of the independent variables, were established by using simultaneous equations.