作者机构:
[彭长辉] 中南林业科技大学生命科学与技术学院,长沙,410004;[彭长辉] Institute of Environment Sciences,Department of Biology Sciences university of Quebec at Montreal,Case postale 8888,Succ Centre-Ville,Montreal(QC)H3C 3P8 Canada;[田大伦; 赵梅芳; 邓湘雯; 项文化; 刘泽麟] 中南林业科技大学
作者机构:
[Wang GuangJun; Yan WenDe; Xiang WenHua; Tian DaLun; Peng ChangHui] Cent S Univ Forestry & Technol, Fac Life Sci & Technol, Changsha 410004, Hunan, Peoples R China.;[Peng ChangHui] Univ Quebec, Dept Sci Biol, Inst Environm Sci, Montreal, PQ H3C 3P8, Canada.
通讯机构:
[Tian DaLun] C;Cent S Univ Forestry & Technol, Fac Life Sci & Technol, Changsha 410004, Hunan, Peoples R China.
关键词:
carbon cycle;soil CO2 flux;soil moisture;soil temperature;temporal dynamics
摘要:
Climate change can significantly affect carbon cycling of forest ecosystems. The diurnal and seasonal dynamics of soil respiration (R
s) in Cinnamomum camphora and Liquidambar formosana forests were investigated by using infrared gas exchange analyzer of Li-Cor 6400-09 each month in 2006. Soil temperature and moisture were also measured. Diurnal variations in R
s varied with daily soil temperature in the two forests. Across the growing season, soil respiration peaked on July 28 due to higher soil temperature and moisture conditions. Seasonal R
s variations were predominantly influenced by soil temperature. Seasonal soil respirations in C. camphora and L. formosana forests were strongly related to soil temperature (x) at 5-cm depth (R
s = 0.1598e0.1377x
(R
2 = 0.9289, P = 0.001) and R
s = 0.2177e0.0962x
(R
2 = 0.927, P = 0.000)), while annual mean R
s rate was 2.614 and 1.397 μmol m−2 s−1 and Q
10 values was 3.96 and 2.62 for the two forests, respectively. However, R
s was not influenced by seasonal changes in soil moisture (w) in the two forests in 2006. We developed two equations (R
s = −0.020w
2+0.497w+0.562 (R
2 = 0.109, P > 0.05), R
s = −0.001w
2+0.072w+0.731(R
2 = 0.053, P > 0.05)) to describe the relationship between R
s and soil moisture. A positive relationship between R
s and soil moisture were observed when soil moisture was below 12.43% and 18.00%, but when soil moisture exceeded threshold values of 12.43% and 18.00%, soil moisture became the restraint factor for R
s. Long-term observations of soil respiration and moisture are required to understand the temporal dynamics of soil respiration.
通讯机构:
[Peng ChangHui] C;Cent S Univ Forestry & Technol, Coll Life Sci & Technol, Changsha 410004, Hunan, Peoples R China.
关键词:
global change;ecology;artificial neural network;nonlinear problem
摘要:
Fields that employ artificial neural networks (ANNs) have developed and expanded continuously in recent years with the ongoing development of computer technology and artificial intelligence. ANN has been adopted widely and put into practice by researchers in light of increasing concerns over ecological issues such as global warming, frequent El Ni?o-Southern Oscillation (ENSO) events, and atmospheric circulation anomalies. Limitations exist and there is a potential risk for misuse in that ANN model parameters require typically higher overall sensitivity, and the chosen network structure is generally more dependent upon individual experience. ANNs, however, are relatively accurate when used for short-term predictions; despite global climate change research favoring the effects of interactions as the basis of study and the preference for long-term experimental research. ANNs remain a better choice than many traditional methods when dealing with nonlinear problems, and possesses great potential for the study of global climate change and ecological issues. ANNs can resolve problems that other methods cannot. This is especially true for situations in which measurements are difficult to conduct or when only incomplete data are available. It is anticipated that ANNs will be widely adopted and then further developed for global climate change and ecological research.
期刊:
Soil Science and Plant Nutrition,2009年55(4):523-531 ISSN:0038-0768
通讯作者:
Xiang, Wenhua
作者机构:
[Chai, Hongxia; Tian, Dalun; Xiang, Wenhua; Peng, Changhui] Cent S Univ Forestry & Technol, Fac Life Sci & Technol, Changsha 410004, Hunan, Peoples R China.;[Peng, Changhui] Univ Quebec, Dept Biol Sci, Inst Environm Sci, Montreal, PQ H3C 3P8, Canada.;[Xiang, Wenhua] Cent S Univ Forestry & Technol, Fac Life Sci & Technol, 498 So Shaoshan Rd, Changsha 410004, Hunan, Peoples R China.
通讯机构:
[Xiang, Wenhua] C;Cent S Univ Forestry & Technol, Fac Life Sci & Technol, 498 So Shaoshan Rd, Changsha 410004, Hunan, Peoples R China.
关键词:
Chinese fir plantation;clearcutting;prescribed harvest residue burning;site preparation;soil organic carbon
摘要:
Abstract Despite the widespread recognition that silvicultural treatments (prescribed harvest residue burning, site preparation and replanting) applied following clearcutting may cause soil erosion and nutrient loss in Chinese fir (Cunninghamia Lanceolata (Lamb.) Hook) plantations, it is unclear which specific treatment leads to nutrient loss and whether an appropriate implementation of the treatments during the dry season could avert nutrient loss altogether. To address these two questions, nutrient changes in Alliti-Udic Ferrosols soils within a Chinese fir plantation located in Huitong County, Hunan Province, were investigated through the analysis of soil samples sequentially collected at depths of 0–15 cm and 15–30 cm before and after harvest with the residue material kept in place, a prescribed residue burning operation, site preparation and tree replanting initiative took place. Individual treatments significantly affected the soil pH value, organic matter and C and available N at depths of 0–15 cm, but did not significantly influence soil bulk density, total N and P contents and available P contents. The soil pH value decreased with successive application of the treatments. Soil organic C increased by way of the remaining residue after clearcutting, but declined after prescribed residue burning and ultimately returned to pre-harvest values after site preparation as a result of soil displacement and burning ash. Available N contents decreased significantly after clearcutting and residue burning, but the reduction was more or less offset after site preparation took place. Results after all silvicultural treatments were applied showed that no significant reduction in soil organic matter, C and N and P occurred to date in the Chinese fir plantation studied, suggesting that nutrient loss could be averted if the treatments were implemented during the dry season.