[Population structure and dynamics of Pinus koraiensis seedlings regenerated from seeds in a montane region of eastern Liaoning Province, China.] / 辽东山区天然更新红松幼苗种群结构与动态.

Based on the static life table and survival curve, we explored the population structure and dynamics of Korean pine (Pinus koraiensis) seedlings regenerated from seeds in three different forest belts of Korean pine plantation in a montane region of eastern Liaoning Province. The results showed that the age structure of Korean pine seedlings in three different forest belts (i.e., larch forest belt, mixed coniferous forest belt, and mixed broadleaved forest belt) showed a "∩" type of left skewed distribution. The abundance of seedlings was rich but the mortality rate was high in the early phase, and the abundance of seedlings decreased in the later phase, which indicated that the population was depressing. The survival curve of the population conformed to the Deevey-Ⅱ type. The life expectancy of Korean pine seedlings at each age class in larch forest belt was higher than that in mixed coniferous forest belt and mixed broadleaved forest belt. The survival analysis showed that the survival rate of Korean pine seedlings in three different forest belts decreased but the cumulative mortality rate increased with increasing age. The death density function tended to be flat after the age class of Ⅱ-Ⅲ, while the risk function value showed a decreasing trend with the increases of age. The time series predictive analysis showed that the population showed a certain growth trend with increasing age class, indicating that the population could achieve natural regeneration and have a certain growth potential, but with regeneration obstacles.

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The relationship between the structure and function of forest ecosystems is the main intere-sts in the research area of forest ecology and management. However, over complex terrains in particular, these studies had been challenged as uneasy tasks due to the limitations in the forest survey and measurement techniques and other supporting technologies. Chinese Academy of Sciences (CAS) funded "Multi-Tower LiDAR/ECFlux Platform for Monitoring the Structure and Function of Secondary Forest Ecosystems" (Multi-Tower Platform, MTP) as a field station network corner-stone research infrastructure project, which was completed by Qingyuan Forest CERN (Chinese Ecosystem Research Network). In a distinctively-bounded and monitored-outlet watershed, the MTP was integrated by light detection and ranging (LiDAR) scanners, eddy covariance (EC) flux instrument systems, whole- and sub-watershed hydrology station network, long-term forest plot arrays, and live data center. Using LiDAR scanning, the MTP can get cloud data for holographic information on canopy structure. The EC-flux instrument system and hydrology station network along with forest plot arrays could ensure the reliability of water and carbon observations over this complex terrain, which allows to verify the studies on flux measurement technologies and methods, as well as to understand the processes of ecohydrology and CO2 exchange between forest ecosystem and the atmosphere. Further, we can also assess the primary ecosystem services, including water conservation and carbon sequestration. All the data from "tower-station" were streamed through wireless network, which would facilitate data monitoring, management, and sharing. There are three tasks of MTP team: 1) defining innovative methods and descriptors to quantify three-dimensional forest structure; 2) developing theories and techniques to measure CO2/H2O fluxes and other trace gases over complex terrains; 3) understanding the relationship between structure and function of forest ecosystems, providing information and rationales for forest management practices to assure broad and sustainable benefits from forests.

[Aboveground biomass and nutrient distribution patterns of larch plantation in a montane region of eastern Liaoning Province, China].

Larch is the main timber species of forest plantations in North China. Imbalance in nutrient cycling in soil emerged due to single species composition and mono system structure of plantation. Thus it is necessary to grasp its biomass and nutrients allocation for scientific management and nutrient cycling studies of larch plantation. We measured aboveground biomass (stem, branch, bark and leaf) and nutrient concentrations (C, N, P, K, Ca, Mg, Fe, Mn, Cu and Zn), and analyzed the patterns of accumulation and distribution of 19-year-old larch plantation with diameter at breast height of 12. 8 cm, tree height of 15. 3 m, and density of 2308 trees · hm(-2), in a montane region of eastern Liaoning Province, China. The results showed that aboveground biomass values were 70.26 kg and 162.16 t · hm(-2) for the individual tree of larch and the stand, respectively. There was a significant difference between biomass of the organs, and decreased in the order of stem > branch > bark > leaf. Nutrient accumulation was 749.94 g and 1730.86 kg · hm(-2) for the individual tree of larch and the stand, respectively. Nutrient accumulation of stem was significantly higher than that of branch, bark and leaf, whether it was macro-nutrient or micro-nutrient. Averagely, 749.94 g nutrient elements would be removed from the system when a 19-year-old larch tree was harvested. If only the stem part was removed from the system, the removal of nutrient elements could be reduced by 40.7%.

[Forest resources in Qungyuan County of Liaoning, Northeast China: the structure and optimal spatial allocation].

By using RS/GIS techniques and the method of multiple objective grey situation decision, and in considering the forest economic benefits (biomass and stand productivity) and ecological benefits (water and soil conservation) , an optimal spatial allocation of the present forest types in Qingyuan County of Liaoning, Northeast China was approached in this study. After the optimization of spatial allocation, the structural proportions of different forest types in Qingyuan County changed obviously, with the area of coniferous forests reduced from 43% to 23% , the area of broadleaved forests reduced from 51% to 31% , the area of mixed coniferous-broadleaf forests increased from 3% to 43% , and the area of shrubs remained unchanged. As compared with the results before optimization, the biomass, stand productivity, and water conservation function of the forest ecosystem in Qingyuan County after optimization increased by 0.6%, 2.1% , and 31.7%, respectively, and the soil conservation function remained unchanged. It could be concluded that after the optimization of spatial allocation, the forest ecosystem of Qingyuan County could maintain its soil conservation function, and, at the time of keeping higher timber production, fully exert waler conservation function, realizing the maximization of the economic and ecological benefits of the forest ecosystem.

Seed regeneration potential of canopy gaps at early formation stage in temperate secondary forests, Northeast China.

Promoting the seed regeneration potential of secondary forests undergoing gap disturbances is an important approach for achieving forest restoration and sustainable management. Seedling recruitment from seed banks strongly determines the seed regeneration potential, but the process is poorly understood in the gaps of secondary forests. The objectives of the present study were to evaluate the effects of gap size, seed availability, and environmental conditions on the seed regeneration potential in temperate secondary forests. It was found that gap formation could favor the invasion of more varieties of species in seed banks, but it also could speed up the turnover rate of seed banks leading to lower seed densities. Seeds of the dominant species, Fraxinus rhynchophylla, were transient in soil and there was a minor and discontinuous contribution of the seed bank to its seedling emergence. For Quercus mongolica, emerging seedling number was positively correlated with seed density in gaps (R = 0.32, P<0.01), especially in medium and small gaps (<500 m(2)). Furthermore, under canopies, there was a positive correlation between seedling number and seed density of Acer mono (R = 0.43, P<0.01). Gap formation could promote seedling emergence of two gap-dependent species (i.e., Q. mongolica and A. mono), but the contribution of seed banks to seedlings was below 10% after gap creation. Soil moisture and temperature were the restrictive factors controlling the seedling emergence from seeds in gaps and under canopies, respectively. Thus, the regeneration potential from seed banks is limited after gap formation.

[Lead isotope signatures and source identification in urban soil of Baoshan district, Shanghai].

Two soil cores were collected from the Yuepu Park and a vegetable field near the Yunchuan Road in Baoshan district, Shanghai. Particle size, Pb content and Pb stable isotopic ratios were measured to examine Pb contamination status and its source. The results indicate that Pb concentration in the vegetable field soil and Yuepu park soil varies from 17.2 mg x kg(-1) to 34.8 mg x kg(-1) and 17.5 mg x kg(-1) to 36. 5 mg x kg(-1), respectively. The observed Pb isotopic ratios of vegetable field samples vary from 0.827 to 0.849 for 207Pb/206Pb, and 2.082 to 2.101 for 208Pb/206Pb, while those of Yuepu Park samples range from 0.839 to 0.848 and 2.089 to 2.097, respectively. Pb content, its enrichment factor (EF) and Pb stable isotopic ratios increase upward in both soil cores. EF values of surfacial (top 10 cm) vegetable field samples and park samples are mostly greater than 1.5, suggesting that higher Pb contents in topsoils are caused by anthropogenic activities. Compared with previous reports on Pb isotope signatures of different environmental materials in Shanghai, Pb isotopic ratios in the two soil cores are between those of Yangtze River intertidal sediments and the dust of coal combustion, and those of soil samples with EF > 1.5 are closer to the isotopic ratios of coal combustion dust. It indicates that topsoil in the Baoshan district is contaminated by dust derived from coal combustion.

[Characteristics of soil organic carbon and total nitrogen under different land use types in Shanghai].

By the methods of field sampling and laboratory analysis, this paper studied the variations of soil organic carbon (SOC) and total nitrogen (TN) contents and SOC density under different land use types in Shanghai. Significant differences were observed in the test parameters among different land use types. The SOC density was the highest in paddy field (3.86 kg x m(-2)), followed by in upland (3.17 kg x m(-2)), forestland (3.15 kg x m(-2)), abandoned land (2.73 kg x m(-2)), urban lawn (2.65 kg x m(-2)), garden land (2.13 kg x m(-2)), and tidal flat (1.38 kg x m(-2)). The assessment on the effects of three types of land use change on the test parameters showed that the conversion of paddy field into upland resulted in a significant decrease of SOC and TN contents and SOC density; the abandonment of farmland was not an effective way in improving SOC storage in the Yangtze Delta region with abundant water and heat resources, high soil fertility, and high level of field management; while the 4-5 years conversion of paddy field into artificial forestland decreased the SOC and TN contents and SOC density, suggesting that in a short term, the soil carbon sequestration effect of the conversion from paddy field to forestland was at a low level, due to the limitation of vegetation productivity.

[Physical and chemical properties of throughfall in main forest types of secondary forest ecosystem in montane regions of eastern Liaoning Province, China].

From July to September 2008, a measurement was made on the physical and chemical properties of bulk precipitation and throughfall in five main forest types, i.e., larch plantation (LP), Fraxinus rhynchophylla stand (FR), mixed forest stand (MF), Korean pine plantation (KP), and Mongolian oak stand (MO), of secondary forest ecosystem in montane regions of eastern Liaoning Province, China. Comparing with bulk precipitation, the throughfall in the five forest types was significantly acidified (P < 0.05), and the acidification degree was in the order of KP > LP > MF > MO > FR. The conductivity and total dissolved solids of the throughfall increased significantly (P < 0.05), and were in the sequence of MO > FR > LP > MF > KP. The dissolved oxygen concentration of the throughfall lowered significantly (P < 0.05), with the rank of KP > MF > FR > MO > LP, while the Cl- concentration increased significantly, ranked as LP > MO > MF > FR > KP. The NO3-concentrations of the throughfall in FR, MO and MF were higher, while those in LP and KP were lower than that of the bulk precipitation.

[Effects of fertilization on nutrient concentrations of different root orders' fine roots in Larix kaempferi plantation].

With the 16 years old Larix kaempferi plantation in eastern mountain area of Liaoning Province, China as test object, this paper studied the effects of fertilization on the nutrient concentrations of five root orders' fine roots. Under fertilization, less difference was observed in the total C concentration of the fine roots. Among the five orders' fine roots, the first order's had the lowest concentration of non-structural carbohydrate (TNC) and the highest ones of N and P, while the fifth order's was in adverse. The TNC concentration increased with increasing root order, while the N and P concentrations decreased correspondingly. Fertilization only had significant effects on the N and P concentrations of the first order's fine roots. The C/N/P ratio in different orders' fine roots had significant differences, being 423 : 16 : 1 and 726 : 16 : 1 in the first and the fifth order's fine roots, respectively. With the increase of root order, the proportion of C increased significantly, while that of N varied little. N fertilization didn't change the proportion of C, while P or P + N fertilization decreased the proportions of C and N in the first three orders' fine roots at 0-10 cm soil depth or in the first two orders' fine roots at 10-20 cm soil depth.

[Effects of nitrogen fertilization on fine root lifespan of Fraxinus mandshurica and Larix gmelinii].

Root observation tubes (minirhizotrons) were used to study the effects of nitrogen addition on the fine root growth of Fraxinus mandshurica and Larix gmelinii, with the correlations between the fine root lifespan and nitrogen availability analyzed. After the nitrogen addition, the fine root number of F. mandshurica and L. gmelinii had a decreasing trend, but the fine root diameter became larger and the branching ratio decreased. The survival rate of F. mandshurica fine roots increased, and the median root lifespan prolonged 105 days, compared with the control. No significant responses to the nitrogen addition were observed in the survival rate of L. gmelinii fine roots. The first-order fine roots with smaller diameter, the roots in surface soil (0-15 cm), and the fine roots newly born in spring and summer were vulnerable to extend their lifespan by nitrogen addition, suggesting that the fine roots with higher physiological activity were easily to be affected by nitrogen fertilization.

[Effects of fertilization on fine root diameter, root length and specific root length in Larix kaempferi plantation].

With 16 years old Larix kaempfersoil plantation in the mountainous area of eastern Liaoning Province as test object, this paper studied the effects of fertilization on the fine root diameter, root length, and specific root length (SRL) of the first to fifth order roots. The results showed that with ascending root orders, the mean fine root diameter and root length increased, while the SRL decreased significantly. Among the five order roots, the first order roots were the thinnest in diameter, the shortest in length, and the highest in SRL, but the fifth order roots were in reverse. The variance coefficients for the fine root diameter, root length, and SRL increased from the first to the fifth order roots. Except for the first order roots, soil depth had no significant influence on the fine root diameter, root length and SRL. Fertilization affected the fine root diameter, root length, and SRL of the first and the second order roots significantly, hut had little effects on other order roots. N fertilization decreased the mean diameter of the first and the second order roots significantly, and N or N + P fertilization decreased the mean length of the first order roots in surface soil (0-10 cm) significantly. The SRL of the first order roots in surface soil increased significantly under N fertilization.

[Effects of fertilization on fine root biomass of Larix kaempferi plantation].

With 16 years old Larix kaempferi plantation in eastern mountain area of Liaoning Province as test object, this paper studied its total fine root biomass, fine root biomass at different soil depths, and biomass of different root orders under effects of fertilization. The results showed that compared with no fertilization, applying N decreased the total fine root biomass significantly (P < 0.05), while the difference between applying P and N + P was not significant. The fine root biomass in top soil (0-10 cm) was significantly (P < 0.01) higher than that in subsoil (10-20 cm), and in all treatments, it accounted for 64%-73% of the total. The effects of fertilization on fine root biomass varied with soil depth and root orders. In top soil, N fertilization decreased five orders (except the second order) fine root biomass significantly (P < 0.05), while P and P + N fertilization had no significant effects (P > 0.05), except the fifth order root in treatment P, and the second order root in treatment P + N (P < 0.05). In subsoil, treatments N and P had no effects on five orders fine root biomass (P > 0.05), while treatment N + P increased the first order fine root biomass significantly (P < 0.05).