Broad-leaved Korean Pine Mixed Forest Research Articles

Water‐use efficiency of forest ecosystems in eastern China and its relations to climatic variables

Carbon (C) and water cycles of terrestrial ecosystems are two coupled ecological processes controlled partly by stomatal behavior. Water-use efficiency (WUE) reflects the coupling relationship to some extent. At stand and ecosystem levels, the variability of WUE results from the trade-off between water loss and C gain in the process of plant photosynthetic C assimilation. Continuous observations of C, water, and energy fluxes were made at three selected forest sites of ChinaFLUX with eddy covariance systems from 2003 to 2005. WUE at different temporal scales were defined and calculated with different C and water flux components. Variations in WUE were found among three sites. Average annual WUE was 9.43 mg CO(2) g(-1) H(2)O at Changbaishan temperate broad-leaved Korean pine mixed forest, 9.27 mg CO(2) g(-1) H(2)O at Qianyanzhou subtropical coniferous plantation, and 6.90 mg CO(2) g(-1) H(2)O at Dinghushan subtropical evergreen broad-leaved forest. It was also found that temperate and subtropical forest ecosystems had different relationships between gross primary productivity (GPP) and evapotranspiration (ET). Variations in WUE indicated the difference in the coupling between C and water cycles. The asynchronous response of GPP and ET to climatic variables determined the coupling and decoupling between C and water cycles for the two regional forest ecosystems.

Effect of Gaps on Species Diversity in the Naturally Regenerated Mixed Broadleaved-Korean Pine Forest of the Xiaoxing'an Mountains, China

Recognizing the ecological importance of forest gap formation for forest community structure, we examined the differences in species diversity between forest gaps and closed canopy areas for trees and shrubs in three developmental stages (seedling, sapling I, and sapling II) in a typical mixed broadleaved-Korean pine forest. We randomly placed 100 sample plots (<TEX>$2{\times}2m$</TEX> for seedling and sapling I, and <TEX>$5{\times}5m$</TEX> for sapling II) in forest gap and closed canopy areas of a 9 ha permanent sample plot for vegetation surveys of plants of each developmental stage in each habitat type. Even though the formation of forest gaps encouraged the occurrence of gap-dependent species and increased overall species diversity, there were no significant differences in species richness among the three developmental stages for both tree and shrub species (p>0.05). Comparing the two types of sites, statistical tests revealed no difference in species richness for trees, but highly significant differences (p<0.01) between forest types for shrubs for seedlings and sapling I, but not sapling II. Analysis of variance test indicated that there were no significant differences in species diversity among the three developmental stages of tree species (p>0.05) for both Simpson and Shannon indices. The variance for shrub seedlings was significantly different between forest gaps and closed canopy areas, but not for sapling I and sapling II. The analysis showed that the species diversity in forest gaps was significantly different from that of closed canopy areas for seedling and sapling I (p<0.01), but not for sapling II (p>0.05).

Seasonal and annual variation of CO2 flux above a broad-leaved Korean pine mixed forest

Long-term measurement of carbon metabolism of old-growth forests is critical to predict their behaviors and to reduce the uncertainties of carbon accounting under changing climate. Eddy covariance technology was applied to investigate the long-term carbon exchange over a 200 year-old Chinese broad-leaved Korean pine mixed forest in the Changbai Mountains (128°28′E and 42°24′N, Jilin Province, P. R. China) since August 2002. On the data obtained with open-path eddy covariance system and CO2 profile measurement system from Jan. 2003 to Dec. 2004, this paper reports (i) annual and seasonal variation of F NEE, F GPP and R E; (ii) regulation of environmental factors on phase and amplitude of ecosystem CO2 uptake and release Corrections due to storage and friction velocity were applied to the eddy carbon flux. LAI and soil temperature determined the seasonal and annual dynamics of FGPP and RE separately. VPD and air temperature regulated ecosystem photosynthesis at finer scales in growing seasons. Water condition at the root zone exerted a significant influence on ecosystem maintenance carbon metabolism of this forest in winter. The forest was a net sink of atmospheric CO2 and sequestered −449 g C·m−2 during the study period; −278 and −171 gC·m−2 for 2003 and 2004 respectively. F GPP and F RE over 2003 and 2004 were −1332, −1294 g C·m−2. and 1054, 1124 g C·m−2 respectively. This study shows that old-growth forest can be a strong net carbon sink of atmospheric CO2. There was significant seasonal and annual variation in carbon metabolism. In winter, there was weak photosynthesis while the ecosystem emitted CO2. Carbon exchanges were active in spring and fall but contributed little to carbon sequestration on an annual scale. The summer is the most significant season as far as ecosystem carbon balance is concerned. The 90 days of summer contributed 66.9, 68.9% of F GPP, and 60.4, 62.1% of R E of the entire year.

Estimate of productivity in ecosystem of the broad-leaved Korean pine mixed forest in Changbai Mountain

We measured soil, stem and branch respiration of trees and shrubs, foliage photosynthesis and respiration in ecosystem of the needle and broad-leaved Korean pine forest in Changbai Mountain by LI-6400 CO2 analysis system. Measurement of forest microclimate was conducted simultaneously and a model was found for the relationship of soil, stem, leaf and climate factors. CO2 flux of different components in ecosystem of the broad-leaved Korean pine forest was estimated based on vegetation characteristics. The net ecosystem exchange was measured by eddy covariance technique. And we studied the effect of temperature and photosynthetic active radiation on ecosystem CO2 flux. Through analysis we found that the net ecosystem exchange was affected mainly by soil respiration and leaf photosynthesis. Annual net ecosystem exchange ranged from a minimum of about −4.671 μmol·m−2·s−1 to a maximum of 13.80 μmol·m−2·s−1, mean net ecosystem exchange of CO2 flux was −2.0 μmol·m−2·s−1 and 3.9 μmol·m−2·s−1 in winter and summer respectively (mean value during 24 h). Primary productivity of tree, shrub and herbage contributed about 89.7%, 3.5% and 6.8% to the gross primary productivity of the broad-leaved Korean pine forest respectively. Soil respiration contributed about 69.7% CO2 to the broad-leaved Korean pine forest ecosystem, comprising about 15.2% from tree leaves and 15.1% from branches. The net ecosystem exchange in growing season and non-growing season contributed 56.8% and 43.2% to the annual CO2 efflux respectively. The ratio of autotrophic respiration to gross primary productivity (Ra:GPP) was 0.52 (NPP:GPP=0.48). Annual carbon accumulation underground accounted for 52% of the gross primary productivity, and soil respiration contributed 60% to gross primary productivity. The NPP of the needle and broad-leaved Korean pine forest was 769.3 gC·m−2·a−1. The net ecosystem exchange of this forest ecosystem (NEE) was 229.51 gC·m−2·a−1. The NEE of this forest ecosystem acquired by eddy covariance technique was lower than chamber estimates by 19.8%.

Modeling diameter distribution of the broadleaved-Korean pine mixed forest on Changbai Mountains of China

The broadleaved-Korean pine mixed forest is a native vegetation in the Changbai Mountains, northeast China. The probability density functions including the normal, negative exponential, Weibull and finite mixture distribution, were used to describe the diameter distributions of the species groups and entire forest stand. There is a strong correlation between parameters and mean DBH except the shape parameters in the mixture distribution. The diameter classes of species and entire forest stand showed not negative exponential but normal and “S” distribution. The mixture function was better than normal and Weibull to describe the model distribution. The location parameter had an effect on the estimated frequency in the first diameter class, when the estimated location parameter was bigger than the lower limit of the first diameter class.

Seasonal variation in carbon dioxide exchange over a 200-year-old Chinese broad-leaved Korean pine mixed forest

Long-term measurement of carbon metabolism of old-growth forests is critical to predict their behaviors and to reduce the uncertainties of carbon accounting under changing climate. Eddy-covariance technology was applied to investigate the long-term carbon exchange over a 200-year-old Chinese broad-leaved Korean pine mixed forest of Forest Ecosystem Open Research Station of Changbai Mountains (128°28′E and 42°24′N, Jilin Province, PR China), Chinese Academy of Sciences, since August 2002. This paper reports the result on (1) phase and amplitude of ecosystem CO 2 uptake and release and (2) sink/source status on the data obtained with open-path eddy-covariance system and CO 2 profile measurement system from August 2002 to August 2003. Corrections due to storage and friction velocity were applied to the eddy carbon flux. Behavior of pressure flux, neglected in common WPL correction, was analyzed to develop acceptable u * range in dormant periods. The ecosystem was a net sink of atmospheric CO 2 and sequestered −308 ± 116 g C m −2 during the study period. The estimates of gross carbon gain and loss at this forest were −1432 ± 216 and −1124 ± 181 g C m −2 separately. The seasonal trend of gross primary productivity ( F GPP) and respiration ( R E) followed closely the change in vegetation absorption index ( V AI) and temperature. The summer is the most significant season as far as ecosystem carbon balance is concerned. The net ecosystem exchange ( F NEE) during this period was about −298.0 ± 65.2 g C m −2. The 90 days of summer contributed 67.0% of F GPP, 58.9% of R E of whole year. This study shows that old-growth forest can be strong net carbon sink of atmospheric CO 2. There are uncertainties in estimate of annual carbon fluxes with eddy-covariance method. More work on advection and pressure fluxes is warranted.

Meteorological control on CO 2 flux above broad-leaved Korean pine mixed forest in Changbai Mountains

The impacts of temperature, photosynthetic active radiation (PAR) and vapor pressure deficit (VPD) on CO 2 flux above broad-leaved Korean pine mixed forest in the Changbai Mountains were studied based on eddy covariance and meteorological factors measurements. The results showed that, daytime CO 2 flux was mainly controlled by PAR and they fit Michaelis-Menten equation. Meanwhile VPD also had an influence on the daytime flux. Drier air reduced the CO 2 assimilation of the ecosystem, the drier the air, the more the reduction of the assimilation. And the forest was more sensitive to VPD in June than that in July and August. The respiration of the ecosystem was mainly controlled by soil temperature and they fit exponential equation. It was found that this relationship was also correlated with seasons; respiration from April to July was higher than that from August to November under the same temperature. Daily net carbon exchange of the ecosystem and the daily mean air temperature fit exponential equation. It was also found that seasonal trend of net carbon exchange was the result of comprehensive impacts of temperature and PAR and so on. These resulted in the biggest CO 2 uptake in June and those in July and August were next. Annual carbon uptake of the forest ecosystem in 2003 was -184 gC·m -2 .

Eddy flux corrections for CO 2 exchange in broad-leaved Korean pine mixed forest of Changbai Mountains

Based on analysis of mechanisms causing energy no-closure and nocturnal low fluxes issues for CO 2 exchange studies by eddy covariance method, corrections were done with the raw data sets obtained from Changbai Mountains forest flux site, to evaluate the impacts of sonic anemometer tilt, frequency response limitations and advection on estimation of CO 2 exchange, respectively. The results show that the planar fit coordinate transforming method is superior to the streamline coordinate transforming method in tilt correction. The latter could cause a systematical underestimation of eddy fluxes relating with the angle of sensor and terrain tilt. The underestimation of CO 2 and energy fluxes for frequency response limitations average 3.0% and 2.0% during daytime, respectively, which increase by 9.0% and 5.5% during nighttime, respectively. The corrections of frequency response limitations are closely related to atmospheric stability. The advection loss of CO 2 fluxes is dominated by nocturnal vertical advection, which is at least 18% when the horizontal advection is neglected. It is suggested that more work be done to understand the characteristics of horizontal advection and turbulent eddies under a complex circumstance.

UU * filtering of nighttime net ecosystem CO 2 exchange flux over forest canopy under strong wind in wintertime

The mechanism of the negative nighttime net CO 2 flux in wintertime and reasonable treatment with it is of great importance in evaluating the carbon metabolism of boreal forest. Results, based on the data obtained with open-path eddy covariance system and CO 2 profile measurement system from Nov. 2002 to Apr. 2003 and that obtained with five sonic anemometers in Nov. 1999, show that (1) the negative net ecosystem CO 2 exchange flux (NEE) always appeared under conditions of strong wind; (2) the pressure fluctuation and horizontal advection flow are dominantly responsible for the negative NEE. Operable upper bound u * filtering method (UU * filtering) was introduced since the difficulties in real-time measuring of pressure fluctuation and horizontal advection fluxes under conditions of strong wind. Nighttime upper u 2 threshold for the broad-leaved Korean pine mixed forest of the Changbai Mountains is 0.4 ms -1 and can be applied to the daytime filtering; and (3) the UU * filtering corrected the nighttime ‘problem’ of negative NEE under strong wind and made the estimates more ecologically reasonable.

An impacts of logging operations on understory plants for the broadleaved/Korean pine mixed forest on Changbai Mountain, China

Natural regeneration of tree species is important to the sustainability of native forest ecosystems in the temperate zone of north- east China. This study compared the densities and heights of seedlings and the diversities of shrubs and herbs on three sites of logging op- erations: log-skidding trails (LST), logging gaps (LG) and log landing sites (LLS). Sites undisturbed by logging gaps operations were sam- pled as control. The species, counts and height of tree seedlings and the species, counts, height and percentage coverage of shrubs and herbs were recorded in the field. The highest density and greatest height of regeneration trees were observed at LG and LST. The effects of LST on the densities of broadleaved trees were greater than those of coniferous trees. The difference in seedling density between LLS and control was significant (p=0.05). There was no significant difference in average seedling height for all the tree species between the disturbed sites and control. There were more shrub and herb species at the disturbed sites than at control. The diversity of understory plants at LG was the highest among all the sites. LST and LLS were different in shrub diversity, so were LLS and control. Both LG and LLS were different from control in herb diversity. Active measures need to be taken on the operation sites to protect the coniferous trees and the diversities of under- story plants for sustaining the structure and composition of the broadleaved-Korean pine mixed forest on Changbai Mountain of China. Since different operation sites have different effects on different tree species, site-dependent actions must be taken to assure the regeneration of ecologically important tree species.

Tree diversity change in remaining primary mixed-broadleaved Korean pine forest under climate change and human activities

Studying biodiversity change in existing typical ecosystems of the world under possible global climate change and local human activities is important for diversity conservation. An adapted forest dynamics model is used to simulate tree diversity change of the remaining primary mixed-broadleaved Korean pine forest (RPMKPF) in northeast China under global climate change and local human activities for the next 50 years. Human activities include logging, which removes all big trees (DBH > 50 cm), removing all individuals of each single species and all species of each functional type (shade tolerant, shade intolerant and medium type tree species). As results for RPMKPF, the α index of tree diversity decreases under climate change, but it increases significantly under a combination of climate change and logging. Removing all individuals of each single species significantly affects the tree diversity of the ecosystem. After the removal of shade tolerant species, both α and βc indices of tree diversity experience a significant change. The α index decreases significantly under climate change when shade intolerant or medium type tree species are removed, but the βc index does not change significantly. The results of this study have implications for tree diversity management in RPMKPF under climate change and human activities.

Effect of global climate change and human disturbances on tree diversity of the forest regenerating from clear-cuts of mixed broadleaved Korean pine forest in Northeast China

Studies on the combined effects of global climate change and human disturbances are important for biodiversity conservation and natural resources management. Here we use the modified forest dynamics model to simulate the tree diversity change of a typical mixed broadleaved Korean pine forest regenerating from clear-cuts in Northeast China in response to global climate change, double concentration of CO 2 and human disturbances during the next 50 years. We consider the following climate change scenario: the annual temperature will increase 2 °C, the annual precipitation will increase 10% and CO 2 concentration will increase to 700 μl l −1 linearly in 50 years. Five kinds of human disturbances under climate change are considered: logging which removes all trees with diameter at the breast height of more than 50 cm; removing all individuals of any one species; and removing all individuals of shade tolerant, shade intolerant and medium type tree species, respectively. We find that the index of proportional representation of species ( α index) for the forest growing from clear-cuts increases significantly under climate change, but decreases under climate change plus logging. The index of changing representation of species ( β c index) increases significantly under climate change and climate change plus logging. When any one species is removed α diversity of the forest growing from clear-cuts changes significantly under climate change, but β c index remains almost the same. When all individuals of shade tolerant species, shade intolerant species, or medium type species are removed, respectively, α diversity decreases, but β c diversity changes in more complicated ways. The implications of these results for preserving tree diversity in this type of forest are also discussed.

The acceleration of succession for the restoration of the mixed-broadleaved Korean pine forests in Northeast China

There are large amounts of clear-cuts and secondary forests in Northeast China. In order to preserve habitats of biodiversity and decrease ecological disasters, it now becomes urgent to restore them to the climax. An adapted forest dynamics model is used to simulate the change in tree species composition, density, and stem productivity of forests regenerating from clear-cuts of the mixed-broadleaved Korean pine forest (MKPF) and the introduction of species over 100 years in the region. The model shows that the restoration of climax forests on these sites can be accelerated by the introduction of proper tree species. For the current secondary forest of Quercus mongolica, Populus davidiana and Betula platyphylla, if the medium-type of shade tolerant tree species are introduced into the communities, the dynamics of tree species will change, and the stem productivity will decrease by 20%. If Larix olgensis is introduced into the forest communities, it will become dominant in the forests, with stem productivity increasing about 110%. If Pinus koraiensis is introduced, it will dominate the communities after 90–100 years, although the density and stem productivity will not change significantly. If P. koraiensis is introduced into the current secondary forest of medium-type trees, the dynamics of the forest will change significantly and the growth of medium-type trees will increase after 20 years. If the medium-type trees are introduced into the plantations of pure P. koraiensis, both the tree density and stem productivity will increase dramatically, and the earlier stem divergence, earlier branching, of P. koraiensis can be improved.

Dominate time scale characteristics of the turbulence across canopy-atmosphere interface of a mixed broadleaved-Korean pine forest in Changbai Mountains

The measurement and observation for this study were carried out at Forest Ecosystem Opened Research Station of Changbai Mountains (128°28′E and 42°24′ N, Jilin Province, P. R. China). Characteristics of Dominant time scales (DTSes) and dominant time scales contribution ratios (DCRs) across canopy-atmosphere interface and controlling factors were analyzed with multi-scale method. DTS of stream wise and lateral velocity components were larger than that of vertical velocity component. While DCR of vertical velocity component was larger than that of the stream wise and lateral velocity components. Effect of atmospheric stability on DCR and DTS was nonlinear. DTS under unstable conditions was larger than that under stable conditions; DTS and DCR were determined upon the original scales characteristics of upwind flow under strong stability. Canopy structure would influence DTS and DCR across canopy-atmosphere interface remarkably.

Study of the ecological safety of the forest in northeast China under climate change

SUMMARY If tree diversity, net primary productivity (NPP) and carbon storage of forests increase significantly under climate change, then the forest will be ecologically safe. If two or three of these decrease significantly, the forest will be ecological not safe. The adapted forest dynamics model is used to produce the tree composition, NPP of stems and carbon storage change for a larch forest and mixed broadleaved Korean pine forest (MBKPF) in northeast China under two climate scenarios. The results indicate the dominant tree species of both forest ecosystems are sensitive to climate change. The NPP for both larch forest and MBKPF will change significantly under T2P+10 (temperature increases 2 °C and precipitation increases 10%) and T2P–10 (temperature increases 2 °C and precipitation decreases 10%). The carbon storage of larch forest will change significantly under T2P-10, however, it will not change significantly under T2P+10. For MBKPF the carbon storage will change significantly under T2Pt10, but it will decrease significantly under T2P-10. Therefore, the larch forest will be ecological not safe under T2P+10 in 50 years, but it will be ecological safe under T2P-10. However, MBKPF will be ecological safe under T2P+10, and it will be ecological not safe under T2P-10.

Major factors controlling nitrous oxide emission and methane uptake from forest soil

Soil samples were taken from depth of 0-12cm in virgin broad-leaved Korean pine mixed forest, in Changbai Mountain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3+ on N2O emission and CH4 uptake of a forest soil were studied in laboratory by the method of orthogonal design. It was observed under laboratory conditions in this study that there were significant correlations between N2O emission rate, CH4 oxidation rate, soil pH and temperature. Nevertheless, N2O emission rate also showed a significant positive correlation with CH4 oxidation rate. The results suggested that pH and temperature were important factors controlling N2O emission and CH4 oxidation under this experiment conditions.

Recovery of species diversity after disturbance of broad-leaved Korean pine mixed forest in Changbai Mountain

Recovery of species diversity after catastrophic disturbance was influenced by a few factors, such as intensity of disturbance, availability of propagules, and the environmental conditions. In this paper, we examined pattems of species development after nearly 60a succession in burned broad-leaved Korean pine mixed forest on northem slope of Changbai Mountain. We assessed the recovery of plant species diversity in 3 types of forests under the condition with gradient of soil moisture. Results revealed that recovery of plant species diversity varied greatly under different environmental conditions. Species richness of secondary forests greatly related to the site condition. Secondary birch forest on mesic site had the greatest number of plant species and the following was poplar-birch forest and larch-birch forest. Most of characteristic taxa could be found in birch forest after 60a succession. For larch-birch forest on hydra site, most of climax species were still not able to invade, so it had the lowest species diversity.

Potential impacts of climate change on a mixed broadleaved-Korean pine forest stand: A gap model approach

A gap-typed forest dynamic model KOPIDE was used to assess the dynamic responses of a mixed broadleaved-Korean pine forest stand to climate change in northeastern China. The GFDL climate change scenario was applied to derive the changes in environmental variables, such as 10 °C based DEGD and PET/P, which were used to implement the model. The simulation result suggests that the climate change would cause important changes in stand structure. Korean pine, the dominant species in the area under current climate conditions, would disappear under the GFDL equilibrium scenario. Oak and elm would become the dominant species replacing Korean pine, ash and basswood. Such a potential change in forest structure would require different strategies for forest management in northeastern China.