Biomedical subjects

Limin Dai

Publications and source records attributed to Limin Dai.

15 recordsLinked to original sources

PubMed2005

[Assessing forest ecosystem health II. A case study].

On the bases of samples investment and related data collected by others, and with the method of health distance assessment and the ecosystem health index system of Korean pine and broad-leaved mixed forest established in prior paper, this paper attempted to assess the ecosystem health of Korean pine and broad-leaved mixed forest under various human disturbances. The results showed that the health degree was in the order of 20% intensity selective cutting stand (0.21) < 50% intensity selective cutting stand (0.44) < middle and mature birch stand (0.67) < youth birch stand (0.72) < Korean pine plantation (0.74) < larch plantation (0.77).

Biomass↗

PubMed2005

[Relationship between tree-ring chronology of Larix olgensis in Changbai Mountains and the climate change].

The relationship of larch (Larix olgensis) radial growth in Changbai Mountains with climate change was assessed by dendrochronological techniques including correlation functions and single-years analysis. The results showed that larch growth was sensitive to environmental change, and temperature was the primary factor affecting larch growth. The larch growing in high and low elevations had a significantly different response to temperature. In high elevation, larch growth was significant correlated to the mean temperature of June, but in low elevation, it had a more complicated relationship to the environment. Besides the mean temperature of April and May, the temperature of last June and September and the humid index of last September significantly correlated with the larch tree ring-width. Therefore, it was not the same relationship of the same tree species with different environmental gradients.

China↗

PubMed2004

[Assessing forest ecosystem health I. Model, method, and index system].

Ecosystem health assessment is one of the main researches and urgent tasks of ecosystem science in 21st century. An operational definition on ecosystem health and an all-sided, simple, easy operational and standard index system, which are the foundation of assessment on ecosystem health, are necessary in obtaining a simple and applicable assessment theory and method of ecosystem health. Taking the Korean pine and broadleaved mixed forest ecosystem as an example, an originally creative idea on ecosystem health was put forward in this paper based on the idea of mode ecosystem set and the idea of forest ecosystem health, together with its assessment. This creative idea can help understand what ecosystem health is. Finally, a formula was deduced based on a new effective health assessment method--health distance (HD), which is the first time to be brought forward in China. At the same time, aiming at it's characteristics by status understanding and material health questions, a health index system of Korean pine and broadleaved mixed forest ecosystem was put forward in this paper, which is a compound ecosystem based on the compound properties of nature, economy and society. It is concrete enough to measure sub-index, so it is the foundation to assess ecosystem health of Korean pine and broadleaved mixed forest in next researches.

Ecosystem↗

PubMed2004

[Structure characteristics and health distance assessment of various disturbed communities of Korean pine and broadleaved mixed forest in Changbai Mountains].

Through samples investigation, this paper analyzed and classified the community structures of overcutting original forests, secondary birch forests and larch plantation forest under different disturbances. At the same time, some indexes which can reflect the integrity and stability of stand structure were selected. Health Distance (HD) method, a new idea, was attempted to assess ecosystem health of Korean pine and broadleaved mixed forest in Changbai Mountains. The results showed that the health degree was in order of original broadleaved stand (0.14) < structure switched stand (0.23) < structure reserved stand (0.32) < structure destroyed stand (0.33) < heavy disturbed stand (0. 44) < secondary birch stand (0.53) < larch plantations (0.68). Hopefully, it will be a helpful reference on the restoration of Korean pine and broadleaved mixed forest and on the regional forestry sustainable development.

China↗

PubMed2004

[Quantitative methodologies for ecotone determination on north slope of Changbai Mountains].

Based on the community important values and present-absent data along elevation gradient on the north slope of Changbai Mountains and using moving split-window techniques, the width and location of vegetation ecotone were discussed in this article. The results showed that the methods of Bray-Curtis Percent Dissimilarity (PD) and Squared Euclidean Distance (SED) introduced in the analysis gave the similar results. Among the methods used in the moving split-window analysis, the SED method was the best in showing the variation of ecotone. According to the results of moving split-window techniques analysis, the ecotone between broad leaved-pine forest and dark conifer forest was gradual type, located in 1120 m a.s.l., spanned 200 m.; that between dark conifer forest and Betula ermanii forest was sharp type, located in 1790 m a.s.l., spanned 50 m; and the timberline was a sharp line, located in 2000 m, spanned 40 m.

China↗

PubMed2004

[Dynamics of soil nutrient contents in cutting forestlands of broad-leaved Korean pine forest on Changbai Mountains].

A comparative study was made to analyze the dynamics of soil nutrient contents in different cutting forestlands of broad-leaved Korean pine forest on Changbai Mountains. The results showed that soil nutrient contents in different forestlands with different cutting times had obvious differences. With the cutting time going on after logging, soil pH value had the trend of declining firstly and increasing afterwards. The acidity of the topsoil was the highest after cutting for five years, and that of 10-20 cm soil layer was the strongest after cutting for ten years. The organic matter content as well as the total and available contents of nutrients increased at the first 2-5 years, and then declined rapidly, especially for those in topsoils. The cation exchange capacity (CEC), exchangeable Ca and exchangeable Mg had the same trend. Therefore, after forest cutting, artificial planting and regeneration should be carried out in time to resume the vegetation to reduce and prevent soil nutrient loss.

Calcium↗

PubMed2003

[On hybrid embryo culture in vitro of Syringa L].

Syringa L. is the famous ornamental shrub in China, but its embryo always dies before seed mature during cross breeding, and hence, the breeding work is very difficult. The main object of this study is using embryo culture in vitro to get the seedling directly and to improve the succeed rate of cross breeding. The factors that influenced the embryo culture were researched in detail. The results showed that the optimal medium for embryo culture was Monnier, and the second was MS or LS, which meant that the embryo of Syringa needed abundant macroelements and microelements, especially Ca2+ and K+. The optimal sugar concentration was 50 g.L-1. At this level, the sugar could offer enough nutrition and high osmotic pressure for embryo. When the embryo age was 50-60 days, the culture was easy to be succeed. At this time, the cotyledon in ovule began to form, or organ began to differentiation, so, the embryo was very easy to germinate, and the seedling was very easy to form. Proper coconut milk, glutamic acid or glutamine, and activated charcoal could improve the germination and growth of the embryo. When the BA of low concentration (0.01 mg.L-1) was joined in the medium, the germination rate could be improved. The best NAA concentration was 0.01 mg.L-1.

Amino Acids↗

PubMed2003

[Approaches for assessing forest ecosystem health].

Assessment and indicator system become the key issues in the research on ecosystem health in 21st century. Assessing forest ecosystem health gradually attach much attention because it is an important component of terrestrial ecosystem. The definition, measurement, evaluation and its management had been discussed broadly, and some theories, assessing methods and frameworks had been proposed, which provides a new concept and a serial research approaches for dealing with the crisis of terrestrial ecosystems, even the environment problems in the world. Now, the common operational models for assessing forest ecosystem health do not exist owing to the manifold limitations. This paper discussed forest ecosystem health problem, and brought forward three preconditions for assessing forest ecosystem health: 1) a clear conceptual framework; 2) adequate data sets; 3) proper research and analysis techniques. The issues of three preconditions were discussed, and the possible approaches for the assessing research on forest ecosystem health, e.g., long-term studies and environment monitoring, space-for-time substation studies, e.g., history approaches, economics valuation and others were expariated.

Ecosystem↗

PubMed2003

[Flora analysis of riparian plant communities on the northern slope of Changbai Mountain].

This study was conducted in the riparian forest of Erdaobaihe River, and the flora of riparian plant communities on the northern slope of Changbai Mountain was researched and analyzed. There were 288 vascular plant species belonging to 169 genera and 68 families, among them, 26 plant species belonging to 16 genera and 11 families were fern, and 262 plant species belonging to 153 genera and 57 families were spermatophyte. Among spermatophyte, there were 9 gymnosperm species belonging to 6 genera and 3 families and 253 angiosperm species belonging to 147 genera and 54 families. Among angiosperm, there were 212 dicotyledonous species belonging to 118 genera and 45 families and 41 monocotyledonous species belonging to 29 genera and 9 families. All the results showed that there were abundant plant species in the riparian plant communities on the northern slope of Changbai Mountain. Analyses on the distribution area types of spermatophyte in the riparian communities showed that the distribution area types of genera and families were both abundant. For genus level, there were 9 distribution area types and 7 sub-types, and for family level, there were 6 distribution area types and 2 sub-types. The riparian plant communities had a temperate characteristic, and there were 117 genera, which were accounted for 76.5% of all the genera of spermatophyte, belonging to all the different temperate distribution types. In addition, the flora of riparian communities had a complex component, and had close relations with Tropical and East Asia distribution type, but few relations with Mediterranean distribution type. The results also showed that riparian zone could play an important role in biodiversity protection.

Biodiversity↗

PubMed2003

[Ecological distribution of mycorrihizal fungi associated with oak in Dandong district of Liaoning Province].

With plot cruising and rout investigation methods, 36 species of ectomycorrhizal fungi associated with oaks were found in natural secondary oak forest in Dandong district of Liaoning Province. They were subordinated to 7 familyies, 13 genera. Studies on the relationship of the ecological distribution of mycorrhizal fungi with tree species, tree age and seasons showed that 29 species mycorrhizal fugi preferred to grow with Q. mongolica, The species of Russulla were associated with a wider tree ages of oak, and the species of Amanita were most likely to grow with old tree. July and August were the occurrence peak of mycorrhizal fungi. 75% species occurred in July, and 100% species occurred in August. The relative density of the occurrence number was the highest in mid-August (19.5%) and last-August (18.4%).

Ecology↗

PubMed2002

[Effect of drought stress on apparent resource utilization efficiency of Quercus mongolica].

To study the effect of drought stress on the physiological characteristics and resource utilization efficiency of Quercus mongolica, a dominant species in the Korean pine broad-leaved forest in Changbai Mountain, a comparative experiment was carried out under three soil moisture gradients as 85%-100% (high water, CK), 65%-85% (Medium water, MW), and 45%-65% (low water, LW) of field water-bolding capacity. The results showed that net photosynthetic rate, stomatal conduction, transpiration rate, water utilization efficiency, apparent CO2 utilization efficiency and apparent light utilization efficiency of the seedlings of Quercus mongolica were all significantly influenced by simulated drought stress. Stomatal conduction, water utilization efficiency and net photosynthetic rate of large tress of Quercus mongolica were affected by the soil drought stress, while transpiration rate, apparent CO2 utilization efficiency, and apparent light utilization efficiency were not influenced. Moderate soil water condition could greatly increase gas exchange and water utilization efficiency. These results indicated that the responses of gas exchange and resource utilization efficiency to various water stresses were different. Quercus mongolica was a species with variable resistance to drought stress, and the resistance would be improved by drought stress, especially moderate water stress.

Carbon Dioxide↗

PubMed2002

[On forest ecosystem health and its evaluation].

Definition and connotation of forest ecosystem health were introduced, and existing ideas and methods of health evaluation were analyzed in this paper. Furthermore, forest ecosystem health was discussed from the aspects of the management objective approach, ecosystem approach, and integration approach. Widespread application of ecological indicators is the main means of evaluation on forest ecosystem health at present, and some material forest health evaluation methods, especially EMAP and FHM, were introduced and summarized to impel the relative researches in China.

Ecosystem↗

PubMed2002

[Minimum sampling area and species richness of riparian community in erdaobaihe forested watershed].

Riparian zone is an important component of small forested watershed. Due to the integrate effects of stream water and edge effect, there are obvious difference in composition, structure, and distribution pattern between riparian community and non-riparian community. Community minimum sampling areas are also different. In this study, minimum sampling areas of riparian community in original broad-leaved and Korean pine forest in Changbai Mountain were studied by using species-area curve. At the same time, species richness of riparian community was discussed. The results showed that the minimum sampling areas of riparian plant community were smaller than those of the non-riparian community. According to the original broad-leaved and Korean pine forest in Changbai Mountain, the average community minimum sampling areas in riparian zone of three plots including 60%, 80%, and 90% of community species were about 80 m2, 180 m2, and 320 m2, respectively. And then, those of forest community were about 260 m2, 380 m2, and 480 m2 correspondingly. The results also showed that the species richness of riparian community was higher than that of non-riparian community.

Ecosystem↗

PubMed2002

[Storage and decomposition of fallen wood in dark coniferous forest on the north slope of Changbai Mountain].

The storage, biomass, and decomposition of fallen woods in dark coniferous forest on the north slope of Changbai Mountain at elevations of 1260 m and 1620 m were studied. The results showed that the volume of fallen woods was 180.87 m3.hm-2, occupying 21.83% of the stand volume. The volume and biomass of fallen woods at elevation of 1260 m were higher than those at 1620 m. The volume of fallen woods was 52.57 m3.hm-2 at 1260 m, and was 193.85 m3.hm-2 at 1620 m, and their biomass was 6.21 t.hm-2 at 1260 m, and was 53.33 t.hm-2 at 1620 m. Monomial exponential attenuation model could be used to simulate the decomposition process of fallen woods. The results indicated that the decomposition constants of fallen woods were different among different tree species and different elevations. The decomposition constant of fallen woods of Abies was higher than that of Picea, and was higher at 1260 m than at 1620 m. The results also showed that the decomposition of Picea lasted longer.

Biodegradation, Environmental↗

PubMed2002

[Advances in research on ecological land classification].

Land classification is the base of land evaluation, land planning and land management, and plays an important role in the sustainable development of forestry resource. Ecological land classification (ELC) is the main approuch and direction of land classification. Along with the development of landscape ecology and 3S techniques, developing of ecological classification system (ECS) becomes the keystone of ELC. The definition, history, basic characteristics of ELC, the theory of ECS and its' prospects were systematically reviewed in this paper. The prospects were also described for the development of ECS methodology and the application of ELC. The general direction of ecological land research, which was a multi-factors and multi-levels syntheses based on the multi-objects administration of resource (forest, land and waters), was the combination of quantificational and qualitative research. It is necessary to carry out relevant researches in China.

China↗