Biomedical subjects

Guirui Yu

Publications and source records attributed to Guirui Yu.

14 recordsLinked to original sources

PubMed2006

[Temporal-spatial characteristics of wind in tropical seasonal rainforest in Xishuangbanna of Yunnan Province].

Based on the observation data of wind speed and wind direction at different heights on the observation tower (70 m) in the tropical seasonal rainforest of Xishuangbanna, this paper analyzed the annual, seasonal and diurnal characteristics of wind. The results showed that the wind speed above crown canopy was stronger than that under canopy, and the diurnal and vertical change under the canopy was not obvious. From the height of 30 m to 50 m, the vertical change of wind speed was most remarkable, but its annual change was not obvious. Above 50 m, the change trend was opposite. Dry-hot season (March-April) had the strongest wind speed, followed by rainy season (May-October) and foggy-cool season (November -next February). The wind speed at daytime was stronger than that at nighttime. At daytime, wind speed was in order of morning > afternoon > noon. Wind direction had obvious diurnal characteristics, i. e., leaning southeast wind at daytime and leaning west wind at nighttime. At daytime, the change trend of zero-plane displacement (d) was in order of morning > noon > afternoon, and the annual change range in the afternoon was wider and lower than that in the morning and at noon. The change trend of roughness length (Z0) at daytime was opposite to that of d. The d value in the afternoon was obviously higher than that in the morning and at noon.

China↗

PubMed2006

[Physiology and ecology of Pometia tomentosa photosynthesis in tropical seasonal rain forest].

Pometia tomentosa is a dominant uppermost canopy tree in Xishuangbanna tropical seasonal rain forest. In this paper, the photosynthetic characteristics of the three layers of P. tomentosa canopy were measured with Li-6400 portable photosynthesis system, and the results showed that P. tomentosa had the characteristics of high light saturation point (1 000 - 1 500 micromol x m(-2) x s(-1)) and low compensation point (7.7 - 15.3 micromol x m(-2) x s(-1)). Its leaf photosynthesis had the adaptive responses when the high irradiance changed. PAR was the main factor affecting the diurnal changes of net photosynthesis. In December, the leaf grew well, and had a high ability of photosynthesis, with the diurnal change of P. for upper layer exhibiting single-peaked pattern and the maximum value being 8.9 micromol CO2 x m(-2) x s(-1). April was the alternative period of old and young leaves, and the ability of photosynthesis was dropped, with the diurnal change of P(n) for upper layer following double-peaked curve and the maximum value being 4.3 micromol CO2 x m(-2) x s(-1). The highest net photosynthesis rate was observed in July, with the diurnal change of P. for upper and middle layers exhibiting single-peaked pattern and that for lower layers being double-peaked. Short-term enriched CO2 concentration could evidently increase the photosynthesis of P. tomentosa, while the stomatic conductance and transpiration would be inhibited. When the CO, concentration increased from 400 micromol x mol(-1) to 800 micromol x mol(-1), water use efficiency (WUE) was increased by 50% - 100% in dry season, but rather low in wet season.

Adaptation, Physiological↗

PubMed2005

[CO2 concentration character in broad-leaved Korean pine forest of Changbai Mountains].

The CO2 concentration in broad-leaved Korean pine forest of Changbai Mountains was measured continuously with a CO2 infra-red analyzer in 2003. The results showed that the CO2 concentration in the forest had striking characteristics of temporal-spatial variations, which were mainly influenced by the physiological processes of plants, soil respiration, and intensity of turbulence exchange. In growing season, the daily maximum and minimum CO2 concentration appeared mostly on the surface floor at about 5:00 in the early morning and at canopy location at about 15:00 in the afternoon, respectively. There was an obviously process of forest CO2 emission when the inversion broke at dawn. The average CO2 concentration in forest was 377 micromol x mol(-1) in 2003, the maximum of monthly average appeared in January as 388 micromol x mol(-1), and the minimum of monthly average appeared in August as 352 micromol x mol(-1). The forest acted as CO2 source in night time and turned to sink in daytime, during growing season. In non-growing season, the forest acted as CO2 source in both daytime and night time, but still had a clear evidence of CO2 assimilation at noon, with canopy location during non-growing season.

Air↗

PubMed2005

[A comparison of various correction methods for calculating carbon flux above tropical seasonal rainforest].

In this paper, various correction methods were compared, based on the observation data of the CO2 and water fluxes above the canopy of a tropical seasonal rainforest in Xishuangbanna during 1-9 March, 2003. The results showed that it was necessary to correct the observation data when calculating the carbon flux, though various correction methods contributed differently to the results. For daytime data, WPL made the most important contribution, while sonic temperature correction did the least. t test indicated that no significant difference was found between the carbon fluxes corrected by WPL and the standard values. Cluster analysis showed that triple-rotation correction was helpful to improve the precision of the data. For nighttime data, it was the triple-rotation correction that made the most important contribution, and sonic temperature correction also did the least. There existed significant differences between the carbon fluxes corrected by WPL, planar-fit correction and their combination and the standard values, while the differences between the carbon fluxes corrected by double-or triple-rotation and the standard values were not significant. Cluster analysis showed that the data corrected orderly by coordinate axes-rotated correction and WPL would be propitious to improve the precision. The results would provide a basis for calculating the fluxes within tropical rainforest in the future, and supply reference to the fluxes calculation for other areas.

Atmosphere↗

PubMed2003

[Carbon budget of ecosystem in Changbai Mountain Natural Reserve].

The study used EPPML, a biological geochemistry cycle model that was built, to simulate the carbon budget for ecosystems in Changbai Mountain Natural Reserve. The results indicated that the annual net primary productivity [NPP (carbon)] of the natural reserve was 1.332 x 10(6) t.a-1. The annual NPP of mixed broad-leaved and Korean pine forest and spruce-fir forest were maximal, 0.540 x 10(6) t.a-1 and 0.428 x 10(6) t.a-1 respectively. The area and productivity of the two stands were maximal in Changbai Mountain, therefore, the simulating productivity of the two stands most greatly affect carbon cycle and carbon budget of the natural reserve, and the veracity of the former decides the security of the latter. To sum up, not only did the simulations accord with routines in the relative comparisons between different vegetation belts and climate belts in the whole natural reserve, but also was exact in the absolute comparisons with very disperse data from field survey. Vegetations in the natural reserve had evident carbon sink functions, mainly exhibiting in the increasing of carbon, about 1.058 x 10(6) t.a-1. The annual carbon of mixed broad-leaved and Korean pine forest increased greatest (0.452 x 10(6) t.a-1), secondly spruce-fir forest (0.339 x 10(6) t.a-1). The two stands played crucial roles in the carbon sink for Changbai Mountain, others being Changbai larch forest, broad-leaved forest, meadow, shrub, alpine tundra, subalpine Betula ermanii forest and alpine grass. In 1995, the decomposing carbon of soil organic matter was 0.169 x 10(6) t.a-1 higher than the littering carbon in the natural reserve. There was accumulation of organic matter in the meadow soil and shrub soil. The decomposition and accumulation of soil organic matter was in the nearly balancing condition in the alpine tundra soil and alpine grass soil. The decomposition of organic matter was as one and a half time or double as litterfall in the arbor forest soil.

Carbon↗

PubMed2003

[Ecosystem productivity process model for landscape based on remote sensing and surface data].

In this paper, the a ecosystem productivity process model for landscape (EPPML) reflecting carbon and water cycles of system was described and discussed. In EPPML, leaf area index (LAI) that greatly influenced vegetation productivity was received from remote sensing images, the spatial distribution and temporal dynamics of net primary productivity (NPP) and evapotranspiration were simulated. Geographical information system (GIS) was used to process, analyze, and display spatial data. Thus, the studies on physiological ecology could be extended, and converted from small scale to larger scale. Using EPPML, the vegetation productivity in Changbai Mountain Natural Reserve in 1995 was simulated. EPPML could well and truly simulate the NPP of main vegetations in the natural reserve. NPP was estimated to be 0.680 kg Cm.-2.yr.-1, mostly ranging from 0.105 to 1.241 kg C.m-2.yr.-1, accounting for 82.1%. The highest NPP (1.084 kg C.m-2.yr-1) appeared in mixed broad-leaved and Korean pine forests. The total NPP was estimated to be 1.332 x 10(6) t C.yr-1. The highest total NPP appeared in mixed broad-leaved and Korean pine forests and spruce-fir forest, which were 0.540 x 10(6) t C.yr.-1 and 0.428 x 10(6) t C.yr.-1, respectively. The seasonal variation of NPP appeared obvious single peak with peak value in July (6.13 g C.m-2.d-1). The most NPP accumulated in the summer, which was 0.465 kg C.m-2, secondly in the spring, and least in the winter.

Conservation of Energy Resources↗

PubMed2003

[Simulation of temporal-spatial variation characteristics of surface runoff in Changbai Mountain based on process model for landscape scale].

The seasonal dynamics and spatial distribution characteristics of surface runoff in Changbai Mountain simulated by the process model (EPPML), and the relationships between surface runoff and environmental conditions were analyzed. The results showed that the seasonal variation of surface runoff in Changbai Mountain presented obvious three-peak pattern, i.e., the lowest values in June and September, peak values in August (2.58 mm.d-1), similar to that of soil water content. Total trend of surface runoff for different vegetations in the growing season was in order of grass and shrub > coniferous forest > broad-leaved forest > mixed broad-leaved and Korean pine forest, highly correlated to LAI. Annual surface runoff in 1995 was estimated to be 0.203 m.yr.-1, mostly ranging from 0.0 to 0.246.m.yr.-1, accounting for 69.3%. The trend of spatially increasing annual surface runoff along with increasing altitude was obvious. The maximum annual surface runoff appeared in alpine grass (0.619 m.yr.-1), minimum in mixed broad-leaved and Korean pine (Pinus koraiensis) forest (0.081 m.yr.-1), others being alpine tundra, Betula ermanii forest, meadow, shrub, mixed spruce (Picea asperata) and fir (Abies nephrolepis) forest, Changbai larch (Larix olgensis) forest and broad-leaved forest. Vegetation and environmental conditions controlled the main trend of the spatial distribution of annual surface runoff in Changbai Mountain. There was very strong negative exponential correlativity between annual surface runoff and LAI (R2 = 0.857). The more LAI, the more literfall, the more precipitation intercepted by litter, thus, the less surface runoff. Annual surface runoff was highly negatively correlated with air temperature and total solar radiation (R2 being 0.965 and 0.836 respectively), however, it was highly positively correlated with precipitation, relative humidity and wind speed (R2 being more than 0.950). And annual surface runoff was also strongly correlated to soil characteristics.

Conservation of Natural Resources↗

PubMed2003

[Analysis on factors affecting net primary productivity distribution in Changbai Mountain based on process model for landscape scale].

Based on the data received from remote sensing images, the spatial distribution of annual net primary productivity (NPP) was simulated by the process model (EPPML), and the relationships between annual NPP and environmental conditions were analyzed. The results showed that NPP in 1995 was 0.680 kg C.m-2.yr.-1, mostly ranging from 0.105 to 1.241 kg C.m-2.yr.-1, accounting for 82.1%. The highest NPP (1.084 kg C.m-2.yr.-1) appears in mixed broad-leaved and Korean pine forest. Environmental conditions decide the main trend of the spatial distribution of annual NPP (Carbon) in Changbai Mountain. Soil water content had a negative correlativity with NPP, and the correlation coefficient (R) was -0.65. Therefore, water was sufficient for the growth of plants in Changbai Mountain. NPP was highly correlated with LAI (R = 0.81). When LAI was greater than 4-5 m2.m-2, NPP became saturated. NPP was also highly correlated with canopy transpiration (R = 0.77). The response of NPP on environmental conditions, LAI and canopy transpiration in Betula ermanii and broad-leaved forests were different from those in other vegetation.

Conservation of Natural Resources↗

PubMed2003

[Effect of potassium fertilization on the photosynthetic characteristics of the leaf of winter wheat population during its grain-filling stage].

Six years field trials with or without potassium application showed that under potassium application, the maximum photosynthetic rate (Pmax), light saturation point (LSP) and light compensation point (LCP) of the flag leaf of winter wheat during its grain-filling stage increased, the apparent photon utilization efficiency (alpha) decreased, and the dark respiration rate (Rd) increased slightly. For the daily variation of net photosynthetic rate (Pn) of winter wheat with and without potassium application, it appears a single peak curve, whether the weather condition was sunny or cloudy. "Stomatal factor" was the main cause of the decrease of net photosynthetic rate (Pn) in the before noon and afternoon of sunny days and in the whole day of cloudy days, while "non-stomatal factor" was the main cause for the decrease of Pn around midday in sunny days.

Fertilizers↗

PubMed2003

[Effects of long-term application of nitrogen fertilizer on leaf chlorophyll fluorescence of upland winter wheat].

The effects of long-term nitrogen fertilization of chlorophyll fluorescence of winter wheat at its grain-filling stage on Loess Plateau highland were studied. The results showed that the actual photochemical efficiency of PS II reaction center (phi PS II) was decreased with leaf water stress aggravated, while was increased by nitrogen supply. The phi PS II of 0 kg.hm-2, 90 kg.hm-2 and 180 kg.hm-2 nitrogen treatments at noon were 0.197, 0.279 and 0.283, which decreased by 57.7%, 56.4% and 40.2% compared to that of morning, respectively. While they were all resumed at afternoon, even it was higher, for 180 kg.hm-2 nitrogen treatment, than that of morning. Maximum photochemical efficiency (Fv/Fm), photochemical quenching coefficient (qP), and non-photochemical quenching coefficient (qNP) were also increased by nitrogen supply, showing that the light energy conversion efficiency, and potential activity of photosynthetic reaction center and the non-photochemical dissipation of excess light energy, which resisted the damage on photosynthetic apparatus of environmental stress, were improved. No significant difference was found between 90 kg.hm-2 and 180 kg.hm-2 N treatments, which indicated that excess nitrogen was not favorable to photosynthetic performance, and photosynthetic capacity was not improved in proportion with nitrogen supply.

Chlorophyll↗

PubMed2003

[Spatial characteristics of soil organic carbon and nitrogen in inner Mongolia].

Studies on the amount and spatial distribution of soil organic carbon/nitrogen in Inner Mongolia and their relationship to main climate factors showed that the content of soil organic carbon and nitrogen was 3.24-43.24 kg.m-3 and 269.56-3085.60 g.m-3, respectively, and the C/N ratio was about 4.46-17.13. The correlation between soil organic carbon/nitrogen and temperature was negative, and R was 0.557 and 0.460, respectively. Soil organic carbon/nitrogen had a weak positive correlation to precipitation, and R was 0.285 and 0.203. Soil organic carbon and nitrogen appeared a reducing trend with increasing temperature and decreasing precipitation from northeast to southwest.

Carbon↗

PubMed2003

[Error analysis of estimating terrestrial soil organic carbon storage in China].

The paper summarizes different estimating methods of soil organic carbon (SOC) storage including methods of soil taxonomy, vegetation types, Holdridge zones, correlative relationship and modeling. The error analysis of SOC calculation was introduced. Based on second national soil survey 2473 soil profiles, adopting soil taxonomy method and two kinds of SOC density, the terrestrial SOC storage in China was estimated. The range of SOC storage in China is between 615.19 and 1211.37 x 10(14) g and the average SOC density is between 10.49-10.53 kg.m-2(for average soil depth of 100 cm) or 11.52-12.04 kg.m-3(for average soil depth of 88 cm). Through estimation and error analysis, the average SOC storage is about 913.28 +/- 298.09 x 10(14) g and the uncertainty is among 20%-50%. Results showed that the differences of SOC estimation and sampling methods are important factors of SOC estimating uncertainties.

Carbon↗

PubMed2003

[Approaches to evaluate the effects of hydraulic engineering on river ecosystem services].

To evaluate the effects of hydraulic engineering on river ecosystem services, a set of indicator system and quantitative methods, which included the appraisal principles, classification of river services and indicator selection were established. The river ecosystem services could be classified into four types: water supply and related services (e.g., transportation and hydroelectric generation), ecological supporting functions, regulation and control, and aesthetic and cultural services. Based on relative studies, the quantitative approaches were established to measure the indices reflecting the ecological effects of hydraulic engineering involving the change of biodiversity and purification services. The methods mainly contained exponent methods and BOD-DO model. These approaches will be helpful for further analysis and assessment on the effects of hydraulic engineering impact on river ecosystem services.

Conservation of Natural Resources↗

PubMed2002

[Important ecological topics on regional scale ecosystem management in China].

Ecosystem management is a synthetic applied ecology concerning ecosystem management theories, practical technologies, relevant policies and management strategies. It is not only an urgent need for the sustainable development of human society, but also an important tendency and scientific task of ecosystem management to develop integrated studies on models of global or regional scale ecosystem management and the relevant scientific problems. For this reason, we systematically expounded a series of important ecological topics, such as the synthetic evaluation and ecological mechanism of the services, sustainability, complexity, and indeterminacy of ecosystem, the ecological basis of natural resources conservation, ecosystem health, and the rehabilitation of degraded ecosystem, basic ecological processes for ecosystem management, theories and practice on adaptive management of ecosystem, ecosystem network study, monitor, and achievement integration, as well as synthetic special topic studies on regional scale ecosystem management etc. Research advances and tendencies of these topics at home and abroad were also reviewed.

China↗