| In broadleaved-Korean pine forests, how is spatial pattern of Korean pine at different growth stages? Which process affects species spatial pattern? The answer of these questions can help us understand community structure and ecological process. In addition, climate has been warmer since20th century and has profound effects on forest. How does climate affect Korean pine growth and elevational distribution? How these changes would affect forest composition and structure? Answering these questions can help us better understand forest dynamics and management of forest. We used5long term observational plots in broadleaved forests (3secondary and2climax status), areas were1-5ha. Based on the first survey data, we used point pattern analysis to study population structure, spatial pattern and spatial association of Korean pine at different growth stages. We also used dendrchronological techniques to study growth response of Korean pine at different growth stage forests and different altitudes, and to reconstruct disturbance events in Changbai Mountain. The main results are as follows:(1) Diameter distribution analysis indicated that Korean pine mainly presented inverse J shape in the three secondary forests, small trees dominated the whole population. Korean pine showed multi-peak for the diameter distribution in the two climax forests and there are more big trees compared to the three secondary forests. Ripley’s K analysis indicated that Korean pine mainly showed aggregated distribution in the five plots, while only trees in the plot3(climax status) showed random distribution at scale above16m. Saplings and small trees in the three secondary forests were aggregated distributed at all scales, while small trees at two climax forests were aggregated distributed at small scales and random distributed at large scales. At plot1and2, spatial associations were mainly negative correlated, while at plot5, spatial associations were negatively correlated at scale4-5m, the rest spatial associations were independent. (2) A5.2haTilia Korean pine forest was built in Changbai Mountains in2007. DBH class of dominant tree species Pinus koraiensis and Tilia amurensis were analyzed, spatial distribution patterns and associations in different growth stages were also discussed based on Ripley K function. DBH class of P. koraiensis and T. amurensis both presented a unimodal distribution with few saplings. Ripley K function indicated that bothspecies had an aggregated distribution, saplings mainly showed a random distribution while small trees and big trees are clumped,and clump intense tended to be less as tree growth. In associations, small trees and big trees of P. koraiensis showed a significant positive correlation at small scales,as the same as small trees and big trees, saplings and big trees of T. amurensis. Small trees of P. koraiensis and T. amurensis showed a significant positive correlation in some scales to big trees of the opposite species.(3) In this study we used dendrochronological techniques to investigate the disturbance history of a conifer forest on the northern slope of Changbai Mountain, Northeastern China, over the period of last two centuries. The forest was comprised of pioneer (Larix olgensis), mid-tolerant (Pinus koraiensis), and shade-tolerant (Picea jezoensisand Abies nephrolepis) species, indicating a late succession status. Age structure of L. olgensis and P. jezoensis showed the lack of large-scale disturbances. Growth release analyses of L. olgensisand P. jezoensindicated that the forest experienced frequent small-scales disturbances, infrequent medium-scale disturbances, and no large-scale disturbances. Frequent low releases indicated a high frequency of small-scale disturbances. Three major disturbance events were observed over the last180years. A period with increased frequency of growth releases was centered in the1860s synchronized with enhanced recruitment of both L. olgensis and P. jezoensis, suggesting a major canopy disturbance. The second disturbance event occurred in1920s, showed by the evidence of increased release for both L. olgensis and P. jezoensis, followed by enhanced recruitment of P. jezoensis. The third one occurred in1980s, detected by the evidence of release increment of P. jezoensis, followed by largest recruitment of this species in1990s.(4) We used the dendrochronology method to investigate the radial growth of P.koraiensis response to climate change in the poplar-birch Korean pine forest and linden-Korean pine forest on the northern slope of Changbai Mountain, Northeastern China. The result indicated that the radial growth of P. koraiensis was sensitive to precipitation and P. koraiensis growing in two forest types responded to climate differently. Response function showed that monthly total precipitation in current July and previous September significantly positively affected tree growth of P. koraiensis in both forest types. In linden-Korean pine forest, ring width was also significantly negatively correlated with precipitation in the previous July and was significantly positively correlated with mean temperature of current March and Spring. Ring width in poplar-birch Korean pine forest did not show any significant correlation with mean temperature. Point year analysis confirms the result of response function analysis, indicating that precipitation in the current growing season and the end of previous growing season positively affected the radial growth of P. koraiensis, and temperature increasing in spring positively affected radial growth of P. koraiensis.(5) To better understand climate effects on the distribution dynamics of Korean pine (P. koraiensis Siebold et Zuccarini), we studied seedling abundance, basal area increment (BAI), and climate-growth relationships along an altitudinal gradient in Changbai Mountain, northeastern China. Tree-ring chronologies of Korean pine were developed at three elevations (LOW, MID, and HIGH), corresponding to lower (750m), mid (1000m), and upper (1400m) distribution limits, respectively. To quantify the climate effects on growth, we used response function to detect non-extreme weather conditions and pointer year analyses for extreme weather events. The results showed that:1) Seedling abundance increased along the increasing elevation, but insignificant.2) Largest BAI was observed at middle distribution range, suggesting the most suitable climate conditions for biomass accumulation at the central part of distribution.3) Climate-growth relationships of Korean pine varied with altitudes in both climatically non-extreme and extreme years. The importance of temperature effects on the growth increased with altitude. The effects of non-extreme weather on the growth showed an inverse pattern during the period of extreme weather events. Under expected warming, Korean pine would benefit from warmer summer to enhance the growth at the upper limit, whereas the growth might be decreased at the lower limit due to water deficiency.(6) We used correlation and moving analyses to study growth-climate relationships of Korean pine (P. koraiensis) and Jezo spruce (P. jezoensis) in Changbai Mountain for the period of recent100years. Korean pine growth during1901-1984was mainly affected by temperature in the end of last growing season, and sensitivity to temperature decreased after the year1984and was positively correlated with previous December precipitation. For Jezo spruce, April and May temperature of current year and July and September precipitation of previous year positively affected its growth. The correlation between summer precipitation and growth changed from positive (1901-1984) to negative (1984-2005), indicating that tree growth showed divergence.(7) The tree-ring width data collecting from four plots at upper line of broad-leaved Korean pine forest i.e.,1200m a.l.s,1250m a.l.s,1300m a.l.s,1400m a.l.s were used to develop the chronologies. The characteristics of radial growth and correlation between the growth and climatic factors were evaluated by the cluster and correlation analysis. The results showed that the chronologies along different altitude at the upper line of broad-leaved Korean pine forest were divided into three group, the chronology belong to the upper limit of broadleaved-Korean pine forests (1200m a.l.s), the area between upper limit of broadleaved-Korean pine forests and tree line of Korean pine at1250m a.l.s, and the upper limit of Korean pine trees(1300m a.l.s,1400m a.l.s),and the growth rate decreased with the increase of altitude. There is significantly differential among the tree-ring widths at each group. The higher absolute growth value in recently5and10years was shown in1200m a.l.s. The century change of radial growth at upper line of Korean pine trees was higher than other two groups. All Korean pine samples were significantly positive related with the monthly mean maximum temperature in current January and precipitation in current July. The samples distributing at the upper line of Korean pines trees contain more temperature signals. Only the samples at the upper line of Korean pines trees show significantly positive correlation with the monthly mean temperature in previous November. |
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