Soil water content and nitrogen differentially correlate with multidimensional leaf traits of two temperate broadleaf species.

The variation and correlation of leaf economics and vein traits are crucial for predicting plant ecological strategies under different environmental changes. However, correlations between these two suites of traits and abiotic factors such as soil water and nitrogen content remain ambiguous. We measured leaf economics and vein traits as well as soil water and nitrogen content for two different shade-tolerant species ( and ) in four mixed broadleaved-Korean pine () forests along a latitudinal gradient in Northeast China.

Effects of phyllotaxy on variation and inner relationships of leaflet traits in compound-leaved plants.

To understand the distribution pattern of leaflet traits in compound-leaved along with phyllotaxy, we selected three compound-leaved trees with opposite phyllotaxy in Xiaoxing' an Mountains, , , , as the research objects. We measured leaf thickness, leaf area, specific leaf area, leaf dry matter content, palisade tissue thickness, spongy tissue thickness, ratio of palisade tissue thickness to spongy tissue thickness, and carbon content, nitrogen content, phosphorus content of leaflets at different phyllotaxy positions. We analyzed the variation of leaflet traits with phyllotaxy and the influence of phyllotaxy on the inner relationships between leaflet traits.

[Response of Soil Enzyme Activity and Chemical Properties to Nitrogen Addition in a Korean Pine Plantation].

Soil enzymes participate in numerous complex biochemical processes that take place in the soil and play an important role in the material circulation of terrestrial ecosystems. To explore the response of soil enzyme activities and chemical properties to nitrogen deposition in temperate forests, this study analyzed four soil enzyme activities based on the nitrogen addition experiment plot of Korean pine () plantation, which was located in the Liangshui National Natural Reserve, Heilongjiang Province. The results showed that the activities of -acetyl-glucosidase (NAG) and alkaline phosphatase (AKP) increased significantly with increasing nitrogen application concentration.

[Variation of morphological and anatomical traits of fine roots of three plant species in Xiao-xing'an Mountains, China].

We measured the morphological and anatomical traits of fine roots with 1-5 order in needleleaf species of Pinus koraiensis, broadleaf species of Acer mono, and shrub of Corylus mandshurica, with the aim to understand trait variations among root orders and species. The results showed that there was no significant difference in root diameter and root length among the three species, but was significant inter-specific differences in other traits. The stele diameter (117.

[Effects of species diversity and phylogenetic diversity on productivity of a mixed broadleaved-Korean pine forest.].

The relationship between biodiversity and ecosystem function is one of the hot spot in ecological research. The driving effect of plant diversity on forest productivity has been widely focused, but its underlying mechanisms are still controversial. We explored the impacts of species diversity and phylogenetic diversity on forest productivity at different spatial scales based on a 9 hm forest dynamic monitoring plot of typical mixed broadleaved-Korean pine (Pinus koraiensis) forest in Liangshui National Nature Reserve, Heilongjiang Province, with the censuses data in 2005 and 2015, using linear regression and structural equation models.

[Vertical variation and model construction of area and dry mass for a single leaf from six broadleaved trees in mixed broadleaved-Korean pine forests.].

Rapidly and accurately predicting leaf area (LA) and leaf dry mass (LDM) are essential for exploring the response of plant traits to climate change. Empirical models suitable for predicting LA and LDM of a single leaf for various broadleaved tree species at the regional scale have not been proposed. We selected six broadleaved tree species in four mixed broadleaved-Korean pine (Pinus koraiensis) forests in northeastern China, including Betula platyphylla, Tilia amurensis, Populus davidiana, Betula costata, Fraxinus mandshurica and Ulmus laciniata, and measured leaf length, leaf width, leaf thickness, LA and LDM at different canopy layers (top, middle, and low).

Influence of automatic exposure on the estimation of seasonal variations in leaf area index measured by digital hemispherical photograph.

Automatic exposure is one of the important error sources during measurement of leaf area index (LAI) by digital hemispherical photography (DHP). This study was conducted in a mixed broadleaved-Korean pine (Pinus koraiensis) forest, a secondary birch (Betula platyphylla) forest, a Korean pine plantation and a Dahurian larch (Larix gmelinii) plantation in the Xiaoxing'an Mountains. LAI was measured using DHP and LAI-2200 plant canopy analyzer in the middle of June to September.

[Characteristics of Nitrogen Deposition in Heilongjiang Liangshui National Nature Reserve].

To investigate the nitrogen deposition status in Heilongjiang Liangshui National Nature Reserve, a G78 nitrogen deposition collector was used to monitor dry particulate nitrogen deposition and wet nitrogen deposition during the growing season in 2015, and a bucket was used to monitor bulk nitrogen deposition during non-growing season. The results showed that:①Total nitrogen deposition (wet nitrogen deposition+dry particulate nitrogen deposition during the growing season and bulk deposition during the non-growing season) was 12.93 kg·(hm·a), inorganic nitrogen deposition was 8.

[Construction of empirical models for leaf area and leaf dry mass of two broadleaf species in Xiaoxing'an Mountains, China.].

Rapid and accurate measurement of leaf area (LA) and leaf dry mass (LM) is one of the basic requirement for leaf geometry and plant functional studies. It is important not only for studying leaf morphology and biomass estimation, but also for understanding the response mechanism of vegetation to climate change. In this study, we took two temperate deciduous broad-leaved tree species, Ulmus laciniata and Acer tegmentosum, as the study objects, constructed empirical models between LA or LM and leaf structure parameters (e.

[Estimation of seasonal changes in leaf area index based on optical methods in spruce-fir valley forest].

The seasonal changes in LAI were respectively measured using digital hemispherical photography (DHP), LAI-2000 plant canopy analyzer (indirect methods) and litter collection method (direct method) in spruce-fir valley forest in the Xiaoxing' an Mountains, China. In addition, we constructed the relationships between LAI from direct method and that from indirect methods in different seasons. The results showed that LAI from DHP underestimated LAI from direct method by 40%-48% in the whole study period, and the underestimation range for LAI-2000 plant canopy analyzer was 15%-26%.

[Effects of topography on seedling regeneration in a mixed broadleaved-Korean pine forest in Xiaoxing'an Mountains, Northeast China].

To explore the responses of forest seedlings to topographic heterogeneity, nine hundreds of 4 m2 (2 m x 2 m) quadrats with perennial seedlings (H > or = 30 cm, DBH < 1 cm) were installed in a 9 hm2 plot in a typical mixed broadleaved-Korean pine forest in Xiaoxing' an Mountains. Based on the investigation data in 2006, 2008, and 2010, the effects of topography on the seedling establishment were studied. There were a total of 26 tree species in these quadrats.

[Effects of selective cutting on the carbon density and net primary productivity of a mixed broadleaved-Korean pine forest in Northeast China].

To accurately quantify forest carbon density and net primary productivity (NPP) is of great significance in estimating the role of forest ecosystems in global carbon cycle. By using the forest inventory and allometry approaches, this paper measured the carbon density and NPP of the virgin broadleaved-Korean pine (Pinus koraiensis) forest and of the broadleaved-Korean pine forest after 34 years selective-cutting (the cutting intensity was 30%, and the cutting trees were in large diameter class). The total carbon density of the virgin and selective-cutting broadleaved-Korean pine forests was (397.

[Health assessment of individual trees in natural Larix gmelinii forest in Great Xing' an Mountains of China].

To integrate the health assessment results of individual trees into the health assessment of subcompartment (or stand) scale could improve the accuracy of subcompartment (or stand) scale health assessment, and realize the coupling process between the individual tree scale and the subcompartment (or stand) scale, providing a theoretical basis for the realization of forest health management. Taking the natural Larix gmelinii forest in Great Xing' an Mountains as the object, a health assessment indicators system of individual trees was established, which included root state, canopy defoliation degree, crown transparency, crown overlap, crown dieback ratio, live crown ratio, crown skewness, and vertical competition index. The principal component analysis (PCA) was employed to eliminate the correlations, the entropy value method was adopted to confirm the weight of each indicator, and the health status of individual L.

[Estimation of leaf area index of three forest types in Xiaoxing'an Mountains of Northeast China].

From early July to early November 2009, the effective leaf area index (LAIe) of secondary Betula platyphylla forest, spruce-fir valley forest, and mixed broadleaved-Korean pine forest in Xiaoxing'an Mountains were measured with Winscanopy2006 Plant Canopy Analyzer, and the LAIe measured in early November and calibrated with the woody-to-total ratio as well as the clumping index (for clumping beyond the shoots) and the needle-to-shoot area ratio (for clumping within the shoots) was derived as the true leaf area index (LAIt). In combining with litterfall method, the LAIt and its seasonal dynamics of the three forest types were estimated. The LAIe of the secondary B.

[Litter decomposition and nutrient dynamics at different succession stages of typical mixed broadleaved-Korean pine forest in Xiaoxing' an Mountains, China].

Taking the mixed leaf litters in broadleaved-Korean pine forests at different succession stages (secondary birch forest, selective cutting forest, and original mixed forest) and the leaf litters of the dominant tree species (Betula costata, Tilia amurensis, and Pinus koraiensis) in these forests in Xiaoxing' an Mountains, China as test objects, this paper studied their remaining rates and nutrient dynamics in October 2006-November 2008 by using decomposition bag method. For all test leaf litters, their remaining rate had an exponential relationship with time. The annual decomposition constant (k) ranged from 0.

[Effects of selective cutting on intra- and interspecies competitions among major tree species in mixed broadleaved-Korean pine forest].

Taking a Korean pine (Pinus koraiensis) forest stand 37 years after selective cutting as test object, this paper studied the effects of selective cutting on the intra- and interspecies competitions among the major tree species in the stand. Selective cutting had significant effects on the population structure, distribution pattern, and competition index of the major species. There was a significant negative correlation between the changes of competition index and tolerance index of the tree species (r = -0.