Mapping Chinese annual gross primary productivity with eddy covariance measurements and machine learning.

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuring AGPP from China, we built an AGPP mapping scheme based on its formation and selected the optimal mapping way, which was conducted through analysing the predicting performances of divergent mapping tools, variable combinations, and mapping approaches in predicting observed AGPP variations. The reasonability of the selected optimal scheme was confirmed by assessing the consistency between its generating AGPP and previous products in spatiotemporal variations and total amount. Random forest regression tree explained 85 % of observed AGPP variations, outperforming other machine learning algorithms and classical statistical methods. Variable combinations containing climate, soil, and biological factors showed superior performance to other variable combinations. Mapping AGPP through predicting AGPP per leaf area (PAGPP) explained 86 % of AGPP variations, which was superior to other approaches. The optimal scheme was thus using a random forest regression tree, combining climate, soil, and biological variables, and predicting PAGPP. The optimal scheme generating AGPP of Chinese terrestrial ecosystems decreased from southeast to northwest, which was highly consistent with previous products. The interannual trend and interannual variation of our generating AGPP showed a decreasing trend from east to west and from southeast to northwest, respectively, which was consistent with data-oriented products. The mean total amount of generated AGPP was 7.03 ± 0.45 PgC yr-1 falling into the range of previous works. Considering the consistency between the generated AGPP and previous products, our optimal mapping way was suitable for mapping AGPP from site measurements. Our results provided a methodological support for mapping regional AGPP and other fluxes.

[Effects of radiation changes on net ecosystem exchange of carbon dioxide in a middle subtropical Chinese fir plantation]. / 辐射变化对中亚热带杉木人工林净CO2交换的影响.

Total solar radiation is an important factor affecting carbon exchange in forest ecosystem. In order to understand the effects of radiation change on carbon exchange in Chinese fir plantation, long-term monitoring data of carbon dioxide flux and meteorological factors measured by open eddy covariance system and meteorological gradient observation system were used in this study. The clearness index (kt) was used to represent the condition of solar radiation. We analyzed the effects of kt on net ecosystem exchange of carbon dioxide (NEE) in the central subtropical Chinese fir plantation during the growing season (from April to October). The results showed that total solar radiation in clear sky was usually higher in the morning than that in the afternoon, and that NEE was lower in the morning than in the afternoon. Such difference in NEE reached the maximum when the solar elevation angle was about 50°. At the medium kt(0.42-0.52), carbon absorption of Chinese fir plantation was the strongest. The ave-rage maximum relative change of NEE in 10 years in different solar elevation angles ranged from 11.0% to 29.4%, while the minimum and maximum critical values appeared at 35°-40° and 45°-50°, respectively. When kt was at the moderate degree due to the existence of clouds, carbon absorption and diffuse photosynthetically active radiation of Chinese fir plantation reached the maximum, and the latter might be the main reason for the former. Moderate radiation condition with the presence of cloud clould promote NEE of Chinese fir plantation and lead to largest carbon absorption.

[Comparison between Ye Tianshi and Wu Jutong in treatment of summer-heat disease].

Through the traditional Chinese medicine inheritance platform system, with the help of medical records, Ye Tianshi and Wu Jutong's medication characteristics for summer heat sickness were analyzed, the laws of the two people's medication were summarized, and the similarities and differences between the two were explored to explore the relationship. As a result, it was found that both of them recognized the relationship between summer heat and wetness, and Wu Jutong believed that "wind" was also an important pathogenic factor. Both of the patients were treated with cold medicine and warm medicine. They used mostly bitter, sweet, pungent taste and lungs, spleen, stomach, and heart meridian are the main components; two are commonly used Armeniacae Semen Amarum, Talcum, Rehmanniae Radix, Ophiopogonis Radix, Pinelliae Rhizoma and other drugs, Ye Tianshi use Scrophulariae Radix, Tetrapanacis Medulla, Coicis Semen and other drugs more, Wu Jutong use Gypsum Fibrosum, Sojae Semen Praeparatum, Menthae Haplocalycis Herba and other drugs more; at the same time, a combination of two high-frequency medicines used by two people has been excavated, and a new prescription has been deduced to provide a reference for further understanding and treatment of summer diseases.

Genetic variability of Baylisascaris schroederi from the Qinling subspecies of the giant panda in China revealed by sequences of three mitochondrial genes.

The present study examined the variations in three mitochondrial (mt) DNA sequences, namely cytochrome b (cytb), cytochrome c oxidase subunit 3 (cox3) and NADH dehydrogenase subunit 5 (nad5), among Baylisascaris schroederi isolates from the Qinling subspecies of the giant panda in Shaanxi province, northwestern China. No differences in length were detected in the three mt fragments from different isolates. The intra-specific sequence variations within all B. schroederi samples were 0-2.6% for pcytb, 0-1.8% for pcox3 and 0-2.1% for pnad5, while the inter-specific sequence differences among members of the genus Baylisascaris were 8.2-15.2%, 6.2-15.9% and 8.4-16.0% for pcytb, pcox3, pnad5, respectively. A phylogenetic analysis of the combined sequences of pcytb, pcox3 and pnad 5 showed that all B. schroederi samples in the present study were located in two large clusters, with one cluster containing samples from giant pandas in Sichuan province. These findings provide basic information for further study of molecular epidemiology and control of B. schroederi infection in the Qinling subspecies of the giant panda and throughout China.

[CO2 exchanges between mangrove- and shoal wetland ecosystems and atmosphere in Guangzhou].

Based on the investigation of biomass and the measurement of CO2 and CH4 fluxes, the CO2 exchanges between mangrove- and shoal wetland ecosystems and atmosphere in Guangzhou were studied, and the CO2 absorption capability of the wetlands vegetation net productivity as well as the carbon sink function of the wetlands under different waterlogged conditions (perennial, intermittent, and no water-logging) was analyzed. As for mangrove wetland ecosystem, its vegetation net productivity absorbed 33.74 t x hm(-2) x a(-1) of CO2, and soil emitted 12.26 t x hm(-2) x a(-1) of CO2 (including the greenhouse effect amount of CH4 converted into that of CO2,) illustrating that mangrove wetland had a 21.48 t x hm(-2) x a(-1) net absorption of CO2, being a strong carbon sink. For shoal wetland ecosystem, its vegetation net productivity absorbed 8.54 t x hm(-2) x a(-1) of CO2, and soil emitted 5.88 t x hm(-2) x a(-1) of CO2 and 0.19 t x hm(-2) x a(-1) of CH4. If converting into carbon, the wetland absorbed 2.33 t C x hm(-2) x a(-1), and soil emitted 1.74 t C x hm(-2) x a(-1) (including the carbon in CH4), illustrating that shoal wetland fixed 0.59 t C x hm(-2) x a(-1), being a weak carbon sink. If the greenhouse effect amount of CH4 was converted into that of CO2, the soil emitted 9.78 t x hm(-2) x a(-1) of CO2, which was 1.24 t x hm(-2) x a(-1) more than the absorption. As a result, shoal wetland was a weak carbon source. Between the two test greenhouse gases, CH4 was the main one emitted under perennial water-logging, while CO2 was that under no water-logging. Moreover, the wetland under perennial water-logging had the strongest carbon sink function, while that under no water-logging was in adverse.