Broad-leaved Korean Pine Forest Research Articles

The seasonal dynamics of cross-sectional tissue characteristics of Corylus mandshurica twig, petiole, and leaf vein are inconsistent

This study aims to explore how the environment affects the variation and trade-offs of anatomical traits in shrub plants, contributing to a deeper understanding of plant survival strategies and mechanisms of adaptation to the environment. The dominant shrub species Corylus mandshurica in the broad-leaved Korean pine (Pinus koraiensis) forest was selected as the research subject. Current-year twigs and leaves of C. mandshurica were collected in spring (May), summer (July), and autumn (September). Anatomical traits, including non-vascular column proportion (NVP), vascular column proportion (VP), phloem proportion (PP), and xylem proportion (XP), were measured for twigs, lower part of petioles, upper part of petioles, and leaf veins. We found that (1) Compared with seasons, organ type explained most of the variation in the four traits (NVP = 96%, VP = 87%, PP = 81%, XP = 76%). Lower part of petioles served as the turning point in the variation trend of tissue proportions in cross-sectional structure along the sequence of twigs, lower part of petioles, upper part of petioles, and leaf veins. (2) In spring, C. mandshurica exhibits higher NVP but lower VP and PP, while the results in summer and autumn are opposite to those in spring. Among different organs, twigs show lower NVP but higher VP and XP; whereas petioles and leaf veins show the opposite pattern. (3) Both hydrothermal conditions (monthly precipitation and mean monthly temperature) and light (canopy openness and total transmitted radiation) were the dominant environmental factors influencing anatomical trait variation. In different seasons, the response of NVP and VP in C. mandshurica twigs to dominant environmental factors was opposite to that of lower part of petioles, upper part of petioles, and leaf veins. The response of cross-sectional anatomical traits of current-year twigs, petioles, and leaf veins in C. mandshurica to seasonal changes exhibits distinct characteristics. Furthermore, twigs, petioles, and leaf veins demonstrate distinct survival strategies. Future research should focus on the variation of traits in different plant organs and their connecting parts.

Resolving gap patterns and dynamics from a new perspective: Ratio effects of the evergreen versus deciduous trees in broadleaved – Korean pine forests

Clarifying gap patterns and dynamics on a regional scale is necessary to understand forest succession. However, few studies quantified the species composition influences except for geography and time effects. We examined the spatial and temporal gap patterns in an old-growth broadleaved–Korean pine (Pinus koraiensis) forest using two satellite image datasets with a ten-year interval and complementary field survey datasets. The forests were evenly divided into 121 plots with a plot size of 100 ha, and the crown projection area ratio of evergreen trees (RE/A) in each plot was quantified to represent simplified species composition (i.e., evergreen versus deciduous trees). We found that gap fraction and density reduced from 19.0% and 25.0 gaps ha-1 in 2007 to 16.8% and 17.6 gaps ha-1 in 2017, respectively, equivalent to a transformation of 213 ha from gaps to closed canopy. Generalized linear mixed models showed that the RE/A explained substantial variance in gap fraction, size, and number, much more than geography factors (slope and altitude). However, the gap size frequency distribution consistently followed a power-law distribution with weak geography, time, and species composition influences. Univariate analyses showed that the gap distribution patterns differed by gap size but tended to randomness over time, likely due to the randomness of gap formation and the differences in gap closure processes. The species composition of gap makers and fillers diverged along the RE/A gradient. In summary, our study proposed a novel factor (RE/A) to reveal the spatial and temporal gap patterns in the broadleaved–Korean pine forests, which provided insights into the necessity of refining species composition in conducting regional-scale gap studies with the development of airborne hyperspectral and LiDAR remote sensing technologies.

Effects of wild boar grubbing on the soil nematode community subject to seasonal variation in a broad-leaved Korean pine forest in Northeast China

Soil disturbances caused by large animals impact soil biodiversity and potentially alter forest ecosystem functioning and productivity. However, most studies have focused on the effects of wild boar infestations on above-ground vegetation and soil physical and chemical properties. Little is known about the influence of wild boar grubbing on the soil faunal community within forested ecosystems. To address this knowledge gap, we conducted a long-term (10-year) exclosure experiment to investigate the responses of soil nematode communities to wild boar grubbing and seasonal variations in a broad-leaved Korean pine forest in Changbai Mountain, China. The results indicated that wild boar grubbing did not significantly impact soil nematode abundance, genus richness, diversity indices (Shannon-Wiener diversity index, Simpson index, and evenness index), and ecological indices (enrichment index, channel index, structural index, and basal index). However, we observed that grubbing reduced the relative abundance of plant parasites while increased that of bacterivores and the maturity index (MI), leading to changes in nematode community composition. Notably, the influence of grubbing was more pronounced in the spring than in the autumn. Although season itself did not significantly affect soil nematode genus richness and diversity indices, it did affect soil nematode relative abundance, bacterivores, omnivores-predators, plant parasites, K-strategistis, r-strategistis, MI, enrichment index, and channel index. Long-term wild boar grubbing appeared to mitigate seasonal effects on soil nematode communities, resulting in higher MI and increased stability in nematode community abundance. Our findings suggest that changes in soil parameters, such as soil NH4+, soil pH, and soil NO3–, likely mediate the observed impact of wild boars on the soil nematode community. In summary, our study demonstrated that wild boar grubbing altered the structure of soil nematode communities, albeit with seasonal variations, indicating that the effects of wild boar activity on forest soil ecosystems influence biogeochemical cycles through changes in nematode community composition rather than nematode genera richness.

Foraging Niche Differentiation of Five Woodpecker Species in the Primitive Broadleaved Korean Pine Forests of Northeast China

Explaining the mechanism of the coexistence of sympatric species is an important goal of ecology. Five species of woodpeckers coexist in the broadleaved Korean pine forest of Liangshui National Nature Reserve, including the Black Woodpecker (Dryocopus martius), Great Spotted Woodpecker (Dendrocopos major), Lesser Spotted Woodpecker (Dendrocopos minor), Three-toed Woodpecker (Picoides tridactylus), and White-backed Woodpecker (Dendrocopos leucotos). Woodpeckers are considered to be keystone species because of their role as ecosystem engineers, creating breeding and shelter sites for many vertebrate and invertebrate taxa. As woodpeckers are predominant in primary forests, they are sensitive to changes in forest ecosystems. To understand their coexistence mechanisms and propose conservation strategies, it is necessary to investigate their foraging niche differentiation. This study aimed to identify the foraging behavior parameters and foraging tree parameters of five woodpecker species in Liangshui Reserve from October to December. The foraging niches of five woodpecker species were observed, including the type of foraging techniques, foraging height, foraging site, foraging duration, tree species being foraged upon, diameter of the foraging tree at breast height, foraging tree height, and decay status of trees. Our results identified that there were significant differences in the overall foraging ecology of the five species of woodpecker at Liangshui Reserve. The Great Spotted Woodpecker and Lesser Spotted Woodpecker had more diverse foraging patterns and preferred to forage on live trees. The Black Woodpecker and Three-toed Woodpecker excavated and pecked at the trunks of decaying spruce and fir trees. The White-backed Woodpecker preferred to forage in broadleaved trees. The choice of foraging sites was complicated. The size of the foraging trees and decay status of trees were important bases for woodpeckers when choosing trees to forage from. Different woodpeckers achieve stable coexistence through the separation of their foraging niches. This information regarding foraging behavior and foraging tree characteristics provides a basis to study the coexistence patterns of woodpeckers. Our research into woodpecker foraging should be used to inform forest management practices, protect forest ecosystem diversities, and maintain woodpecker community diversity.

Response of Soil Aggregate Composition and Stability to Secondary Succession and Plantation of a Broad-Leaved Korean Pine Forest after Clear-Cutting and Its Causes

The composition and stability of soil aggregates are important characteristics for evaluating soil health. The objective of this study was to explore the effects of different restoration modes and secondary succession sequences of Korean pine on the stability of forest soil aggregates after clear cutting and their causes. The stability and composition of soil aggregates in 0–10 cm, 10–20 cm, and 20–40 cm were analyzed in four natural forests in the secondary succession sequence and a Pinus koraiensis plantation in the clear-cutting area of Liangshui National Nature Reserve, and the effects of forest community characteristics and cementing materials on these aggregates were explored. With the advancement of succession, the large soil water-stable aggregates and mechanical aggregates increased, and the stability increased. From the pioneer community to the top community, the proportion of macroaggregates in the soil mechanical aggregates in the 20–40 cm soil layer increased by 36%, while that in the water-stable aggregates in the 10–20 cm soil layer increased by 19%. Compared with plantation, the stability of soil aggregates in natural forests with a similar age was stronger. Water-stable aggregates were negatively correlated with bulk density, density, and porosity, and positively correlated with organic-matter-related cement. The volume of the dominant tree, litter yield, tree species diversity, biomass of various tree species, and litter biomass in the undecomposed layer were the key indicators affecting the stability of aggregates. In terms of restoration measures, natural restoration is better than plantations with a single tree species. In addition, succession makes forest soil aggregates more stable. The change of dominant tree species leads to changes in soil aggregate stability, and the effect of organic-related cementing material was stronger than that of iron oxide.

Exploring carbon sequestration in broad-leaved Korean pine forests: Insights into photosynthetic and respiratory processes

A comprehensive understanding of carbon assimilation and sequestration in broad-leaved Korean pine forests is crucial for accurately estimating this significant aspect of temperate forests at a regional scale. In this study, we introduced a high-temporal resolution model designed for carbon assimilation insights at the plot scale, focusing on specific parameters such as leaf area dynamics, vertical leaf distribution, photosynthetically active radiation (PAR) fluctuations, and the photosynthetic traits of tree species. The findings reveal that most tree species in broad-leaved Korean pine forests exhibit an inverted U-shaped pattern in leaf area dynamics, with shorter leaf drop periods than leaf expansion events. Leaf distribution varies significantly among different canopy heights, with approximately 80 % of the leaves above 15 m. PAR decreases as canopy height decreases, with PAR at 25 m accounting for about 60 % of the PAR above the canopy. Our framework incorporates a leaf-scale light-response curve and empirical photosynthesis-temperature relationships to estimate forest carbon assimilation on daily and hourly scales accurately. Using the model, we assess the gross primary productivity (GPP), leaf net photosynthetic assimilation (LNPA), and carbon increment (ΔC) of broad-leaved Korean pine forests from 2017 to 2020. The results demonstrate GPP, LNPA, and ΔC values of 21.4 t·ha−1·a−1, 17.4 t·ha−1·a−1, and 4.0 t·ha−1·a−1, respectively. Regarding efficiency, GPP, LNPA, and ΔC per square meter of leaf per year are 179 g, 146 g, and 33 g, respectively. Notably, tree species in the canopy layer of the forest exhibit significantly higher efficiency than those in the understory layer. This research significantly contributes to our understanding of carbon cycling and the responses of forest ecosystems to climate change. Moreover, it provides a practical tool for forest management and the development of carbon sequestration strategies.

Driving mechanisms of productivity stability vary with selective harvesting intensities in a mixed broad-leaved Korean pine forest

Key messageWe found that the stabilizing mechanisms for forest productivity varied across harvesting intensities in a mixed broad-leaved Korean pine forest. Effects of overyielding at high species richness and species asynchrony occurred only in unharvested and lightly harvested plots, whereas asymmetries between individuals of different size contributed significantly to stabilizing productivity when harvestings became intensive.ContextUnderstanding the driving factors of forest ecosystem stability has become increasingly crucial in forest management. However, it remains unclear whether and how the stabilizing mechanisms of forest productivity might be influenced by management practices.AimsWe related the temporal stability of aboveground biomass productivity to harvesting history. We further tested how three key driving mechanisms of stability might be modulated by selective harvesting intensities.MethodsBased on a 10-year monitoring (five repeated tree inventories) of a mixed broad-leaved Korean pine forest in Northeastern China recovering from selective harvesting, we examined the relative importance of two diversity-dependent mechanisms (overyielding and species asynchrony) and one size-dependent mechanism (asymmetric growth) for productivity stability across a wide range of intensities (0–73.4% basal area removed).ResultsWe found that selective harvesting significantly lowered the productivity stability, species asynchrony, and growth dominance coefficient. Growth dominance coefficient had an overall stronger effect on stability than species richness and asynchrony. Moreover, the strengths of stabilizing mechanisms varied across harvesting intensities: effects of overyielding at high species richness and species asynchrony were detected only in unharvested and lightly harvested plots, whereas the explanatory power of growth dominance coefficient outweighed the diversity-related variables when harvesting became intensive.ConclusionsWe emphasized the importance to consider both diversity- and size-related explanatory variables as potential mechanisms for the temporal stability of forest productivity. In fact, how growth is partitioned among trees of different species as well as sizes may co-determine the response of forest stability to disturbances.

Forest Conversion Changes Soil Particulate Organic Carbon and Mineral-Associated Organic Carbon via Plant Inputs and Microbial Processes

Primary forest conversion greatly influences soil organic carbon (SOC) sequestration. However, our understanding of how primary forest conversion affects SOC fractions and chemical component evenness remains limited. We examined how primary forest conversion (from primary mixed broadleaved Korean pine forest to secondary broadleaved forest and coniferous plantation) affects free particulate OC (POC), aggregate-occluded POC, mineral-associated OC (MAOC), and their chemical component evenness via plant inputs (e.g., litter and fine roots) and microbial properties (e.g., microbial biomass and residue C) in Northeast China. Primary forest conversion led to a large increase in litter and fine root quality (lower C/N ratio), SOC, and MBC of secondary forests and a reduction in litter and fine root quantity and quality, SOC, MBC, and microbial residue C of plantations, which drove changes in POC and MAOC. As a result, after conversion to secondary forests, free POC decreased by 20.3% and aggregate-occluded POC increased by 57.2%. After conversion to plantations, free POC increased by 49.1%, while aggregate-occluded POC and MAOC decreased by 42.4% and 9.0%, respectively. Free POC was negatively correlated with fine root biomass. Aggregate-occluded POC and MAOC were positively correlated with litter and fine root quality, MBC, and microbial residue C. Meanwhile, forest conversion decreased the evenness of free and aggregate-occluded POC chemical components in secondary forests, with O-alky C being higher and aromatic C being lower, while MAOC was not affected by forest conversion. The evenness of free and aggregate-occluded POC chemical components was associated with litter and fine root quality, and that of MAOC was associated with MBC and microbial residue C. High-quality plant inputs benefit OC sequestration in soil aggregates and MAOM through microbial assimilation and residue accumulation after primary forest conversion. Future forest management should consider tree species with high-quality input as a possible compensation for climate change by sequestering more OC in soil aggregates.

Loss of soil carbon and nitrogen indicates climate change-induced alterations in a temperate forest ecosystem

Climate warming is expected to influence terrestrial biogeochemical cycles by modifying the quality and quantity of plant litter input to soils. Although a growing number of studies recognize the importance of plant litter input in influencing the loss of soil organic matter (SOM) through a phenomenon called the priming effect (PE), the exact mechanisms behind PE are not well known. Importantly, most PE research is based on short term pot experiments in which fresh organic matter (FOM) input is represented by a single addition of compounds of unnaturally simple chemical composition. Furthermore, only a few studies exist in which the PE was explored in terms of organic C (SOC) and total N content in the soil. Here, we report results of a 3-year long litter manipulation study conducted under natural conditions in a broadleaved Korean pine forest in N-E China. We show that the extra supply (twice the normal input) of aboveground tree litter composing of conifer needles, leaves and small twigs was associated not only with slightly decreased SOC (by 5%) but especially that of soil total N (STN) (by 15%) content in the top soil (0–5 cm depth). In contrast, removal of litter resulted in an increased (ca. 15%) amount of both SOC and STN during the study when compared to control soils receiving natural litter input. Despite the enhanced leaf litter decomposition rate in the treatment receiving extra litter, the changes in SOC and STN were related neither to soil microbial biomass nor to community composition. The amount of N lost (40.0 g m−2) in the soil due to litter addition was ca. three times the amount of N added (12.3 g m−2) via the litter, while the amount of C lost (238 g m−2) was about one third of that added (940 g m−2), suggesting that soil N in our research site is more prone to the PE than soil C. As we did not manipulate belowground FOM input, our results suggest that input of aboveground litter rather than that by roots explained the PE in our study. Results of our long-term study conducted under natural conditions in undisturbed forest soils highlight the large potential of recalcitrant, aboveground litter to affect the PE, which should not go unnoticed when predicting the role of forest soils under conditions (such as climate warming) when these soils act as C sinks.

Do Tree Size and Tree Shade Tolerance Affect the Photosynthetic Capacity of Broad-Leaved Tree Species?

(1) Background: leaf structure traits are closely related to leaf photosynthesis, reflecting the ability of trees to obtain external resources in the process of growth. (2) Methods: We studied the morphological, chemical, anatomical, stomatal traits and maximum net photosynthetic rate of six broad-leaf species in northern temperate mixed broad-leaved Korean pine (Pinus koraiensis) forest. (3) Aim: To investigate whether there are differences in leaf structural traits of trees with different shade tolerances and different sizes and the effects of these differences on leaf photosynthetic capacity. (4) Results: the effects of leaf structure traits on leaf photosynthesis were different among trees with different shade tolerances or different sizes. Under the condition of light saturation, the net photosynthetic rate, nitrogen use efficiency, phosphorus use efficiency and stomatal conductance of shade-intolerant trees or small trees were higher than those of shade-tolerant trees or large trees. (5) Conclusions: the shade tolerance of tree species or the size of trees affect the traits of leaf structure and indirectly affect the photosynthetic ability of plants. When constructing the leaf trait-photosynthesis model, the shade tolerance and tree size of tree species should be taken into account.

Effects of field soil warming on the growth and physiology of Juglans mandshurica seedlings.

Global climate change will increase surface soil temperature, with consequences on plant seedling growth and population dynamics. In this study, we carried out a field experiment to investigate the effects of 2 ℃ soil warming on the growth and physiological characteristics of 1- and 2-year-old seedlings of a dominant tree species in broadleaved Korean pine forest, Juglans mandshurica. The results showed that soil warming significantly increased basal diameter, root length, total leaf area, leaf dry weight, root dry weight, total biomass, apparent photosynthetic electron transfer rate (ETR), PSⅡ actual photochemical efficiency (ΦPSⅡ), and apparent photosynthetic electrophotochemical quenching coefficient (qP) of 1-year-old seedlings by 18.3%, 66.7%, 94.4%, 105.9%, 95.8%, 37.8%, 89.5%, 100.0%, and 71.4%, respectively. Soil warming significantly increased basal diameter, total leaf area, leaf dry weight, total biomass, leaf superoxide dismutase activity, peroxidase activity, catalase activity and free proline content, ETR, ΦPSⅡ, and qP of 2-year-old seedlings by 12.5%, 180.5%, 97.3%, 42.5%, 23.9%, 20.4%, 14.9%, 20.7%, 66.7%, 283.3% and 284.6%, respectively. There was an interaction between seedling age and soil warming on the root-shoot ratio and the ΦPSⅡ and qP in chlorophyll fluorescence parameters, in that soil warming significantly reduced the root-shoot ratio of 2-year-old seedlings and that the increase of chlorophyll fluorescence parameters of 2-year-old seedlings (4.1-4.6 times) was much higher than that of 1-year-old seedlings (1.5-1.8 times). Soil warming of 2 ℃ was beneficial to the growth of 1- and 2-year-old J. mandshurica seedlings and increased their regeneration potential. In particular, 2-year-old J. mandshurica seedlings responded to soil warming by increasing leaf area, improving leaf photochemical efficiency, and enhancing protective enzyme activity to increase resistance.

Development of Picea jezoensis (Siebold & Zucc.) Carriere trees at virginal ontogenetic stage in the Korean pine-broadleaved forest of the Southern Sikhote-Alin

We described growth of Picea jezoensis (Siebold & Zucc.) Carriere trees at the virginal ontogenetic stage as one of the dominant species of the Korean pine-broadleaved forests in the south of the Russian Far East, Sikhote-Alin Mountains. Using dendroecological approach, we reconstructed stand disturbance history and studied impact of the disturbances on development of the P. jezoensis virginal plants. We found that severe stand disturbances lead to synchronous transition to the next subgroup of virginal stage and thus lead to appearing of generations of plants that may differ in age but are on the same ontogenetic stage of their development. We determined duration of plants development in the subgroups of the virginal stage and its total duration. We conclude that despite alternating periods when radial increment increases and, conversely, decreases, in general, the growth of virginal plants is relatively uniform and slow. Therefore, if growth conditions become less favorable because of climate change, this will cause the plants to be unable to access canopy and reach a generative stage.

Seasonal variations of canopy spectra and their indications to carbon fluxes in a temperate forest in northeast China

The seasonal variations of forest canopy spectral characteristics are critical to improving the utilization of remote sensing methodology to quantify forest physiology, especially forest carbon sink. However, the seasonal variations of forest canopy spectra are poorly understood. Combined field survey and EO-1 Hyperion imageries, we extracted the spectral curves of seven forest types of Changbai Mountain in China in seven periods. We also calculated various remote sensing indexes and analyzed their seasonal change of spectral characteristics among different forest types. Optimal indexes were selected to indicate the seasonal variation of forest carbon fluxes. Our results showed that there were differences in spectral curves among forest types. The reflectance of coniferous forests was lower than that of broad-leaved forests in growing season. Changbai Scotch pine forest owned the lowest spectral reflectance, whereas the reflectance of Mongolian oak forest was the highest, especially in the near-infrared region. The red edge slope (RES) of broad-leaved forest was higher than coniferous forest in spring and summer. The RES of broad-leaved and coniferous forests was similar in autumn. The red edge position of various forest types showed slight shift in different seasons. Four typical forest types showed different spectral characteristics with seasonal changes. The seasonal variation of coniferous forest spectral curves was not obvious. The seasonal variation of broad-leaved forest spectra was the largest. Most of the spectral indexes can indicate the seasonal variation characteristics of each forest type. Enhanced vegetation index (EVI) is better than normalized difference vegetation index (NDVI) to indicate the forest phenology. Seasonal curves of spectral indexes were different in all forest types. Spectral indexes of coniferous forests were most stable throughout the year. The curves of each index in broad-leaved forests showed significant difference in autumn, which may be influenced by the understory vegetation after their defoliation. For broad-leaved Korean (BK) pine forest, the scaled value of photochemical reflectance index (SPRI)*EVI owned the highest correlation with gross primary productivity (R = 0.99 and P < 0.01) and net ecosystem exchange (R = − 0.77 and P < 0.05), respectively. SPRI*NDVI showed the highest correlation with ecosystem respiration (R = 0.96 and P < 0.01). The seasonal variation of carbon fluxes of different forest types retrieved from the optimal remote sensing index were consistent, but their peaks occurred at different times.

Community structure of phyllosphere fungi associated with dominant tree species in a broad-leaved Korean pine forest of Changbai Mountain, Northeast China

Forest is the main component of terrestrial ecosystems that harbors about 40% of the existing species on the earth. As a vital component of biodiversity, phyllosphere microbes in the canopy play a critical and unique role in maintaining plant health, improving host resistance, and influencing global biogeochemical cycle. However, the studies on the community structure of phyllosphere fungi in natural forests are scarce as compared to that on rhizosphere microbes. Consequently, we know litter about how phyllosphere fungi associates with leaf traits. In this study, we analyzed fungal community composition of canopy leaves of six dominant tree species (i.e., Pinus koraiensis, Tilia amurensis, Quercus mongolica, Acer mono, Fraxinus mandshurica, and Ulmus japonica), in a broad-leaved Korean pine forest of Changbai Mountain Nature Reserve in Jilin Province, using high-throughput sequencing. We compared the differences of phyllosphere fungal community structure and functional groups of different dominant tree species. Moreover, 14 key leaf functional traits of their host trees were measured to investigate the relationships between fungal community composition and leaf functional traits. We found that the dominant phyla and class of phyllosphere fungi were Ascomycota and Basidiomycota, and Dothideomycetes and Taphrinomycetes, respectively. Results of LEfSe analysis indicated that all the tree species except Ulmus japonica had significant biomarkers, such as the Eurotiomycetes of Pinus koraiensis and the Ascomycetes of Quercus mongolica. The main functional groups of phyllosphere fungi were pathotroph. The results of redundancy and envfit analysis showed that functional traits related to plant nutrient acquisition as well as resistance to diseases and pests were the main factors influencing the community structure of phyllosphere fungi.

Effects of canopy spectral composition on growth and photosynthetic fluorescence characteristics of Pinus koraiensis and Quercus mongolica seedlings

We investigated the responses of leaf and individual traits, growth, and fluorescence characteristics of seedlings of two dominant species of broad-leaved Korean pine forest in Changbai Mountain, i.e., Pinus koraiensis and Quercus mongolica, to five spectrum-attenuation treatments. Results showed that the architecture and growth of P. koraiensis and Q. mongolica seedlings were mainly regulated by ultraviolet B (UV-B) radiation and blue light. The attenuation of blue light significantly decreased leaf area ratio and relative growth rate of two species. The attenuation of UV-B radiation significantly increased leaf area ratio and relative growth rate of P. koraiensis seedlings by 41.8% and 47.7%, respectively, and significantly decreased plant height, total leaf area, and biomass accumulation of Q. mongolica seedlings. Furthermore, the attenuation of UV-B radiation significantly decreased the fluorescence regulation ability of two tree seedlings, with lower magnitude of P. koraiensis than Q. mongolica. The non-regulatory quantum yield (ΦNO) of P. koraiensis increased by 31.6%, and the ΦNPQ/ΦNO ratio, an indicator for photosynthetic fluorescence regulation ability, decreased by 37.5%. These results suggested that those two species might have evolved adaptation strategies to changes in canopy spectral compositions of their respective habitats. Q. mongolica seedlings tended to improve light capture ability through rapid morphological responses, while P. koraiensis seedlings preferred to increase carbon assimilation efficiency by adjusting fluorescence characteristics.

Variation in Soil Bacterial and Fungal Community Composition at Different Successional Stages of a Broad-Leaved Korean Pine Forest in the Lesser Hinggan Mountains

Soil microorganisms are an integral part of the soil and are highly sensitive to environmental changes. The shift in plant community and soil properties following forest succession may cause differences in soil bacterial and fungal community composition. Some studies suggested following the succession of the community, the species composition tends to switch from r-strategy groups to k-strategy groups. However, generalization on the changing pattern has not been worked out. Three forests at an early-, intermediate-, and late-stage (ES, IS, LS) of the succession of broad-leaved Korean pine forest in the Lesser Hinggan Mountains were surveyed to study the variation in soil bacterial and fungal community composition as the succession proceeds. Soil microbial community composition and related soil factors were analyzed by systematic sampling. Significant differences in soil microbial community composition were detected between forests at different stages. The bacterial diversity increased, while the fungal diversity decreased (p &lt; 0.05) from the early to the late successional forest. The fungi to bacteria ratio (F/B) and the (Proteobacteria + Bacteroidetes) to (Actinobacteria + Acidobacteria) ratio increased substantially with succession (p &lt; 0.05). At the phylum level, Bacteroidetes, Ascomycota and Mortierellomycota were dominant in the ES forest, while Actinobacteria and Basidiomycota were prevalent in the LS forest. At the class level, Gammaproteobacteria, Acidobacteriia, Bacteroidia, Sordariomycetes and Mortierellomycetes were dominant in the ES forest, whereas Subgroup_6, Agaricomycetes, Geminibasidiomycetes and Tremellomycetes were dominant in the LS forest. Soil water content (SWC) and available phosphorus (AP) had significant effects on the bacterial community composition (p &lt; 0.05). Soil organic carbon (SOC), total nitrogen (TN), the carbon–nitrogen ratio (C/N), total potassium (TK) and SWC had significant effects on the fungal community composition (p &lt; 0.05). SOC and TN were positively correlated with r-strategy groups (p &lt; 0.05) and were significantly negatively correlated with k-strategy groups (p &lt; 0.05). Our results suggest that the soil bacterial and fungal community composition changed significantly in forests across the successional stages, and the species composition switched from r-strategy to k-strategy groups. The bacterial and fungal community diversity variation differed in forests across the successional stages. The changes in soil organic carbon and nitrogen content resulted in the shifting of microbial species with different ecological strategies.

A Novel Method for Calculating Stand Structural Diversity Based on the Relationship of Adjacent Trees

Understanding the diversity and complexity of stand structure is important for managing the biodiversity of forest ecosystem, and stand structural diversity is essential for evaluating forest management activities. Based on the relationship of adjacent trees, a quantitative method of stand structure diversity is proposed to express the heterogeneity of stand structure in tree species, distribution pattern, species separation and size differentiation. In this study, we defined the diversity of structural unit types and derived a new index of forest structural diversity (SD′) employing the additivity principle of the Shannon–Weiner index. The efficiency of the index was verified by applying the new measure to sixteen field survey samples at different locations. The mountain rainforest in Hainan had the highest forest structural diversity, followed by broad-leaved Korean pine forests in Jiaohe (2), Jiaohe (1) and an oak-broadleaved mixed natural forest at Xiaolongshan (2). The SD′ values of plantations and pure natural forest were lower. The simulated data of different thinning methods and the intensity of broad-leaved Korean pine forests show that the new measure can reflect forest management changes on stand structure diversity. The value of SD′ compared with no treatments and the differences were greater as thinning intensity increased. The SD′ index provides minimum and maximum values for different structural unit types in forests to achieve a unified comparative basis for calculating forest structure diversity. It has the characteristics of the general diversity index and can well express the diversity of tree species, distribution pattern and size differentiation simultaneously. The SD′ index can not only calculate the structural diversity of mixed species forests but can also be used to calculate the structural diversity of pure forests. It can also be used to evaluate the change in stand structure diversity after management interventions.

Water use efficiency and leaf nutrient characteristics of five major tree species in broadleaved Korean pine forest in Changbai Mountains, China

Water use efficiency (WUE) of five dominant tree species (Pinus koraiensis, Fraxinus mandshurica, Acer mono, Quercus mongolica, and Tilia amurensis) was estimated using the stable carbon isotope method in a broadleaved Korean pine forest in Changbai Mountains. Leaf carbon (C), nitrogen (N), and phosphorus (P) contents were measured to analyze nutrient utilization of the dominant species. The relationship between WUE and leaf nutrient contents was systematically assessed. WUE was different due to the variations of micrometeorological factors at different locations in the canopy. The four broadleaved tree species showed upper layer > middle layer > lower layer, while P. koraiensis showed upper layer > lower layer > middle layer. WUE of evergreen coniferous P. koraiensis was higher than that of two broadleaved species with diffuse-porous wood (T. amurensis and A. mono) and lower than that of two broadleaved species with ring-porous wood (F. mandshurica and Q. mongolica). The compound-leaved species (F. mandshurica) had the highest WUE. The WUE of new leaves was significantly higher than old leaves in P. koraiensis. The carbon content and C/N of the old and new leaves of evergreen coniferous P. koraiensis were significantly higher than those of the other four broadleaved tree species, while nitrogen content and N/P were significantly lower than those of the four broadleaved tree species. P content of old leaves of P. koraiensis was significantly lower than that of the four broadleaved tree species. P content of new leaves of current year was not significantly different from that of the broadleaved tree species. The WUE of five tree species had a poor correlation with leaf C content, but a positive correlation with leaf N content. The WUE of evergreen coniferous and deciduous broadleaved tree species was correlated with leaf P content but in opposite direction.

Effects of plant characteristics and environmental factors on the dark diversity in a broadleaved Korean pine forest

Effects of plant characteristics and environmental factors on the dark diversity in a broadleaved Korean pine forest

Variations and correlations of lamina and petiole traits of three broadleaved species in a broadleaved Korean pine forest

Variations and correlations of lamina and petiole traits of three broadleaved species in a broadleaved Korean pine forest