Institute of Forestry Science
Institute of Forestry Science
Zhang K.,CAS Research Center for Eco Environmental Sciences |
Zhang K.,Xinjiang Agricultural University |
Zheng H.,CAS Research Center for Eco Environmental Sciences |
Chen F.,Hunan Agricultural University |
And 5 more authors.
PLoS ONE | Year: 2017
Nitrogen (N) fertilization is necessary to sustain productivity in eucalypt plantations, but it can increase the risk of greenhouse gas emissions. However, the response of soil greenhouse gas emissions to N fertilization might be influenced by soil characteristics, which is of great significance for accurately assessing greenhouse gas budgets and scientific fertilization in plantations. We conducted a two-year N fertilization experiment (control [CK], low N [LN], middle N [MN] and high N [HN] fertilization) in two eucalypt plantations with different soil characteristics (higher and lower soil organic carbon sites [HSOC and LSOC]) in Guangxi, China, and assessed soil±atmosphere greenhouse gas exchanges. The annual mean fluxes of soil CO2, CH2, and N2O were separately 153±266 mg m-2 h-1, -55 ±-40 μg m-2 h-1 , and 11± 95 μg m-2 h-1, with CO2 and N2O emissions showing significant seasonal variations. N fertilization significantly increased soil CO2 and N2O emissions and decreased CH4 uptake at both sites. There were significant interactions of N fertilization and SOC level on soil CO2 and N2O emissions. At the LSOC site, the annual mean flux of soil CO2 emission was only significantly higher than the CK treatment in the HN treatment, but, at the HSOC site, the annual mean flux of soil CO2 emission was significantly higher for both the LN (or MN) and HN treatments in comparison to the CK treatment. Under the CK and LN treatments, the annual mean flux of N2O emission was not significantly different between HSOC and LSOC sites, but under the HN treatment, it was significantly higher in the HSOC site than in the LSOC site. Correlation analysis showed that changes in soil CO2 and N2O emissions were significantly related to soil dissolved organic carbon, ammonia, nitrate and pH. Our results suggested significant interactions of N fertilization and soil characteristics existed in soil± atmosphere greenhouse gas exchanges, which should be considered in assessing greenhouse gas budgets and scientific fertilization strategies in eucalypt plantations. ©2017 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Liu Y.-B.,Beijing Normal University |
Liu Y.-B.,Institute of Forestry Science |
Wang Q.-C.,Northeast Forestry University |
Wang C.-Y.,Institute of Forestry Science |
And 2 more authors.
Chinese Journal of Ecology | Year: 2012
The decline of the productivity and soil fertility of larch (Larix gmelinii) plantation is an urgently addressed issue in forestry production. Especially for the second generation larch plantation, whether its close-to-nature transformation can improve the soil fertility, soil microbial diversity, and soil nutrient contents is lacked of in-depth study. In this paper, an investigation was made on the effects of close-to-nature transformation of the second generation larch plantation on the soil microbial diversity and structure as well as the soil nutrient contents within two years of the transformation. The results showed that there was a close correlation between gap size and soil microbial diversity. After the first year of transformation, the soil microbial diversity in small gaps (25 m) had a significant increase, with the Shannon index, richness index, and evenness index being higher than those in large gaps (100 m) and the control (no-thinning). In the second year of transformation, less difference was observed in the three indices among the three treatments. The Shannon index and richness index were higher in the first year than in the second year, while the evenness index was in adverse, suggesting that in the first year of transformation, soil microbial diversity was higher but in uneven distribution. The soil microbial genetic similarity in small gaps was similar to that in the control; while in large gaps, this similarity was significantly different from the other two treatments, because of the greater changes of microclimate conditions in large gaps resulting in an intense change in soil microbial diversity. In the first year of transformation, soil nutrient contents had a significant increase. The soil available P content in large gaps was increased by 80%, and that in small gaps was increased by 52%: soil available N content was also increased; while soil available K content had less increase. In the second year, soil nutrient contents were decreased, but the decrements differed between large gaps and small gaps. The soil available P content had a significant decrease in large gaps, but the soil nutrient contents had less decrease in small gaps. This study provided evidences for the feasibility and scientific implementation of close-to-nature forest management.
Xu J.-L.,Zhejiang University of Science and Technology |
Xu J.-L.,Institute of Forestry Science |
Mao Y.-M.,Zhejiang University of Science and Technology |
Zheng C.-Z.,Zhejiang University of Science and Technology |
And 5 more authors.
Forest Research | Year: 2014
Effect of thinning intensity (heavy thinning, moderate thinning and unthinning) and times of thinning (thinning once or twice a rotation) on stand growth and timber outturn of Chinese fir (Cunninghamia lanceolata) were studied in Kaihua, Zhejiang Province. The first experiment was to cultivate big-diameter timber stand and thinned in the seventh year and fourteenth year, respectively, while the second experiment was to cultivate middle-diameter timber stand and thinned in the twelfth year. The results showed that there were no significant difference in tree height and total basal area among three thinning treatments in 22-year-old big-diameter timber stand and 19-year-old middle-diameter timber stand. The diameter at breast height (DBH) increased with the increase of thinning intensity. The average DBH value of big-diameter timber stand with heavy thinning and moderate thinning treatments increased by 13.78% and 9.69%, respectively, compared with the unthinned stand, while the DBH of middle-diameter timber stand with heavy thinning and moderate thinning treatments increased by 12.28 % and 7.02%. Thinning significantly increased the stem volume per tree, the living tree volume (LTV) of stand decreased with the increasing thinning intensity in the two experiments. In the first experiment, there was no significant differences in the LTV of 22-year-old stand among three thinning treatments (P≤0.05). In the second experiment, the LTV of 19-year-old stand in the heavy thinning treatment was significantly lower than that in unthinned stand, there was no significant difference in LTV between the moderate thinning treatment and heavy thinning or unthinned treatments (P≤0.05). The total stand volume (TSV) and total wood outturn (TWO) reduced with the increasing thinning intensity in the two experiments, there were no significant differences in TSV and TWO among the three thinning treatments (P≤0.05). It is concluded that thinning intensity can not effectively increase the live tree volume and timber outturn, and the times of thinning has an important effect on timber outturn and timber size. For big-diameter timber cultivation of Chinese fir, twice thinning with 50% thinning intensity is appropriate in a rotation. It is suitable for middle-diameter timber cultivation with once moderate thinning (approximate 25%).