[Quantitative characteristics and distribution pattern of living and dead standing trees of secon-dary Picea forest in Guandi Mountain, northern China]. / å ³å¸å±±äº‘æ‰æ¬¡ç”Ÿæž—æ´»ç«‹æœ¨å’Œæž¯ç«‹æœ¨çš„æ•°é‡ç‰¹å¾ä¸Žåˆ†å¸ƒæ ¼å±€.

Based on the survey data from a 4 hm2 secondary Picea forest plot in the Pangquangou Nature Reserve, Guandi Mountain, Shanxi Province in 2010 and 2015, we analyzed the quantitative characteristics, distribution pattern, and correlation of living and dead standing trees during five years from four aspects, including species composition, diameter class structure, spatial pattern, spatial correlation between different diameter classes of living standing trees and dead standing trees, and intercorrelation between different diameter classes of dead standing trees. The results showed that there were 25811 living standing trees with DBH≥1 cm in the plot in 2010, belonging to 30 species, 22 genera, and 11 families. The distribution of individual diameter class was an inverted "L" type, and the number of individuals decreased in a fracture pattern with the increases of diameter class. During the five years (2010-2015), a total of 2145 dead standing trees were formed, involving 12 species, 10 genera, and 5 families. Most of the dead standing trees were distributed in diameter of 5-10 cm. At the scale of 0-50 m, the spatial distribution of living and dead standing trees was generally similar, indicating that the spatial pattern of dead standing trees was limited by that of living standing trees to some extent. The spatial correlation analysis of each diameter class of dead standing trees and living standing trees showed that with the increases of individual diameter class of trees, the intensified competition for space resources might be the main reason for the generation of dead standing trees. With the increases of diameter class of dead standing trees, the spatial correlation between living and dead standing trees was weakened to varying degrees, indicating that environment might be the key factor for the formation of large diameter class of dead standing trees. For the the dead standing trees, there was an obvious positive correlation between 5 cm≤DBH<20 cm dead standing trees and DBH<5 cm dead standing trees, between 10 cm≤DBH<20 cm dead standing trees and 5 cm≤DBH<10 cm dead standing trees, and between DBH≥20 cm dead standing trees and 5 cm≤DBH<20 cm dead standing trees. Our results indicated that dead standing trees would impact the subsequent dying of living standing trees.

Spatial associations between tree regeneration and soil nutrient in secondary Picea forest in Guandi Mountains, Shanxi, China.

According to the technical specifications of CTFS (Center for Tropical Forest Science), 190 sampling points of 4-hm2 plot (GDS plot) in Guandi Mountains of Shanxi Province, China were investigated to examine the spatial distribution pattern of seedlings and 14 soil indicators, including pH value and nutrient indicators. We analyzed the spatial associations between tree regeneration and soil nutrients, explored the mechanism of tree regeneration pattern of secon-dary Picea forest. The results showed that more seedlings survived in the patches with low contents of available N, available K, available Cu, available Fe, available Mn, available Ni and available Zn. Besides available K, the negative correlation between the other six soil nutrient factors and the number of regeneration seedlings of the Ⅱ (2.5 cm

[Spatial distribution patterns and associations of typical tree species in different regions.] / ä¸åŒåŒºåŸŸå ¸åž‹æ ‘æœ¨çš„ç©ºé—´åˆ†å¸ƒæ ¼å±€åŠå ³è”æ€§.

Based on the monitoring data from the plots of Changbai Mountains in the temperate zone (CBS), Guandi Mountain in the warm temperate zone (GDS), Heishiding Mountain in the subtropical zone (HSD), we analyzed the spatial distribution of tree species from three families (Pinaceae, Fagaceae, Rosaceae) and their correlation using paired correlation function g(r). The results showed that the individual number and size class structural characteristics of the trees from the three families varied among different regions. Pinaceae had high population density and a bimodal size-class structure in GDS plot but a small number and skewed normal size-class structure in CBS and HSD plots. Fagaceae had low abundance and a bimodal, skewed normal size-class structure respectively in CBS and GDS plots but a large number and an inverted J-type diameter distribution in HSD plot. Rosaceae had high abundance and a L-type size structure in GDS plot but relatively low abundance and a L-inverted and J-type size class distribution respectively in HSD and CBS plots. The trees from those three families showed different spatial distribution patterns in three different forest plots. The large size class individuals of Pinaceae were regularly distributed at small scale in CBS and GDS plots but aggregated in HSD plot, the middle and small size class ones were consis-tently aggregated in three plots. Fagaceae trees were mainly characterized by large size class and approximately distributed at random in CBS plot, but mainly characterized by middle or small size class and aggregated in GDS and HSD plots. The trees of Rosaceae were aggregated in three plots. The aggregation degree of trees from three families decreased with the increases of spatial scales. The large size class individuals of Fagaceae were negatively associated at small scale or uncorrelated with Pinaceae trees in CBS and HSD plots. The middle or small size class individuals of Fagaceae were negatively associated with Pinaceae ones in CBS and GDS plots but positively associated with Pinaceae ones in HSD plot. Trees from Pinaceae were negatively correlated with trees from Rosaceae in three plots. The middle or small size class individuals of Fagaceae were positively correlated with individuals of Rosaceae in CBS and GDS plots but negatively correlated with trees of Rosaceae in HSD plot. In conclusion, the spatial distribution patterns and associations of the trees from three families changed with the size class, research scale and had different patterns among three plots.

[Species composition, structure and spatial distribution of secondary cold-temperate Picea forest in Guandi Mountain, China]. / å ³å¸å±±å¯’æ¸©æ€§äº‘æ‰æ¬¡ç”Ÿæž—æ ·åœ°æ ‘ç§ç»„æˆã€ç»“æž„å’Œç©ºé—´åˆ†å¸ƒ.

The secondary Picea forest is one of the dominant vegetation types in Guandi Mountain. It's also the representative type of evergreen cold-temperate coniferous forests in subalpine region of north China. A 4 hm2 fixed monitoring Picea forest plot was established in Pangquangou Nature Reserve, Guandi Mountain (GDS plot) to better understand the basic characteristics such as species composition, community structure and its potential ecological process and mechanisms. We analyzed species composition, structure and spatial distribution of sample forest based on the first background survey data in this paper. The results showed that a total of 30 woody plant species existed in the sample area, which belonged to 11 families, 22 genera. The total individual number (including branches) was 26218 (independent individual number was 10266). Floristic composition in the region was defined as north temperate elements. Big differences of individual number, average diameter at breast height (DBH) and basal area among different species caused significant community layering effect, and the dominant species in each layer was obvious. Size-class structure of species showed bimodal skewed normal distribution at the canopy layer, approximate normal distribution at the subtree layer, and 'L' type distribution at the shrub layer. Spatial distribution of the dominant tree species such as Picea wilsonii and Larix principis-rupprechtii showed different pattern features with the changing size class, whether in individual number or in aggregation degree. Compared with the above two species with the same size class, a large number of L. principis-rupprechtii with DBH≥30 cm aggregated in the center of sample plot, but few P. wilsonii individuals with DBH≥30 cm occurred in the plot and had no clustering distribution. Only a few L. principis-rupprechtii with DBH≤10 cm occurred in the plot with a scattering distribution, and a large number of P. wilsonii with DBH≤10 cm aggregated in the center of the plot. There were also many P. wilsonii individuals with DBH≤10 cm distributed in the northwest area of the plot, but Betula albo-sinensis individuals with DBH≤10 cm mostly distributed in the southeast area of the plot. Shrub species such as Cotoneaster acutifolius, Spiraea pubescens and Lonicera szechuanica also showed heterogeneous spatial distribution. Species distribution pattern was affected by habitat conditions, and related to its own development, regeneration traits and ecological habits.

[Spatial relevance between natural regeneration of Picea and heterogeneity of soil available nitrogen in Guandi Mountain].

By using geostatistic and pattern analysis methods, this paper studied the spatial pattern of Picea seedlings in naturally regenerated conifer (Picea) and mixed (Picea-Populus-Betula) forests in Guandi Mountain of Shanxi Province, China. The spatial distribution of soil nitrogen was also quantified by semivariogram analysis. To understand the effects of spatial heterogeneity of soil nitrogen on the regeneration of Picea seedlings, the relationships between the regeneration pattern of the seedlings and the spatial distribution of soil nitrogen were investigated by using GIS superposition and statistical analysis. In conifer stands, the distribution of Picea seedlings appeared as a patch pattern and was auto-correlated; while in mixed stands, the distribution was of gathering distribution pattern controlled by random factors. In the Picea stands with relatively low soil nitrogen content, the spatial distribution of soil available nitrogen was significantly heterogeneous and auto-correlated; whereas in the mixed stands with high nitrogen content, the distribution of soil available nitrogen showed random heterogeneity. In the conifer stands, the spatial correlation between Picea seedlings regeneration pattern and soil available nitrogen distribution was significant, regenerating more seedlings in the patches with higher NH4(+) -N concentration; while in the mixed stands, the correlation was not significant.