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Lu X.-Q.,Nanjing Institute of Environmental Sciences | Yang W.-X.,Nanjing Forestry University | Ding F.-J.,Guizhou Academy of Forestry science | Ding H.,Nanjing Institute of Environmental Sciences | And 4 more authors.
Journal of Ecology and Rural Environment | Year: 2014

Litterfall is metabolic product of a forest during its growth, and plays an important role in recycling of matter and energy. In this study, based on the observations of litterfall in a virgin forest in the Maolan Karst region, southwest China during the preiod from September 2007 to August 2008, analysis was done for monthly dynamics of total litterfall, amount of each component (leaves, branches, reproductive organs and others) of the litterfall, nutrient contents in each fraction and amount of nutrient recycled. Results show that evergreen and deciduous broad-leaved mixed forest displayed two peaks in monthly variation of litterfall, appearing in September-January and April. The annual litterfall was 6.9 t · hm-2, of which with leaves, branches, reproductive organs, and others accounted for 71.0%, 15.9%, 1.5%, and 11.6%, respectively. Nutrients in the litters were mainly C, Ca and N, which did not have any apparent law in monthly dynamics. Annual nutrients recycled with litterfall exhibited a decreasing order of: C>Ca>N>Mg>K>P, which differing from the one (C > N > Ca > K > Mg> P) in forests in non-Karst regions. Nutrient contents varied from fraction to fraction of the litterfall. Branches were relatively low in N, Mg, P and K, while the other fractions were relatively high in C, N, P and Mg, and reproductive organs were relatively low in C, N and Ca. The Ca and Mg contents in the litterfall and the amounts of Ca and Mg recycled were much higher than those in common forests in non-Karst regions, while the K content in the litterfall and K amount recycled was lower in the former than in the latter, suggesting that K deficiency is probably the major factor limiting growth of the vegetation in karst regions. © 2014, China Environmental Science Press. All rights reserved. Source

Lu X.-Q.,Nanjing Institute of Environmental Sciences | Yang W.-X.,Nanjing Forestry University | Ding F.-J.,Guizhou Academy of Forestry science | Toda H.,Tokyo University of Agriculture and Technology
Chinese Journal of Ecology | Year: 2015

Precipitation, throughfall, and stemflow were collected during the period of September, 2007 to August, 2009 from a subtropical natural evergreen and deciduous broadleaf mixed forest in Maolan, a karst area in Southwest China. The concentrations of major ions (Ca2+, Mg2+, K+, Na+, NH4+, SO42-, NO3-, Cl-) were determined for collected samples in order to quantify the annual amounts of major nutrient elements and to examine changes in chemical composition of precipitation after passing through the canopy. The results showed that: (1) the concentrations of the major nutrient ions in precipitation, throughfall and stemflow were lower during the summer (from July to September), but higher in the winter (from December to the following February); (2) compared with precipitation, the concentrations of Ca2+, Mg2+, K+, Cl-, NO3-, and SO42-in throughfall and stemflow increased obviously, while there was a decrease in NH4+ concentration and no significant variation in Na+ concentration; (3) the annual inputs of nutrient ions via precipitation were in order of Ca2+>SO42- >NH4+-N>Cl->K+>Na+>Mg2+>NO3- -N, and the annual inputs of nutrient elements via throughfall plus stemflow were in order of Ca2+>SO42- -S>NH4+-N> Cl->K+>Na+>Mg2+> NO3- -N. Compared with non-karst areas, low ion concentrations in local precipitation demonstrated less anthropogenic influences on the studied forests, while the concentrations of K+, Ca2+ and Mg2+ in throughfall and stemflow increased greatly. Our study showed that K+, Ca2+ and Mg2+ mainly derived from carbonate weathering were active in the hydrologic cycling of nutrients in karst forests. © 2015, Editorial Board of Chinese Journal of Ecology. All rights reserved. Source

Lu X.,Nanjing Forestry University | Lu X.,Tokyo University of Agriculture and Technology | Ding F.,Guizhou Academy of Forestry science | Fang S.,Nanjing Forestry University | And 3 more authors.
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2010

Because of precipitation serves as one of major approaches of nutrient input into the forest ecosystem, the accurate measurement of its volume and ion concentration is of prime importance in an evaluation of nutrient biogeochemical cycle. Therefore, the chemistry of precipitation within a year was monitored and analyzed in a primary forest in the Maolan Natural Reserve, a Karst region in Libo, Guizhou Province. The movement patters of nutrient elements through hydrological processes could be understood by monitoring chemistry data of water. The investigation period was from September, 2007 to August, 2008. The results showed: (1) The pH and most concentrations of most nutrient elements in precipitation, throughfall, stemfall and streamflow varied seasonally except for Na +, with maxima in winter or early spring and minima in summer. This may be resulted from the concentration dilutions or inspissations due to the varieties of water discharge. (2)The nutrient elements in throughfall and stemflow were significantly higher than those in the precipitation when rainfall passed canopy. The concentrations of K +, Mg2+, and Ca2+ were altered more than the other nutrient elements. The concentration of K+ in throughfall and stemflow was 14 times and 21 times higher than those in precipitation, respectively. The concentration of Mg2+ in throughfall and stemflow was 12 times and 9 times higher than those in precipitation, respectively. The concentration of Ca2+ in throughfall and stemflow was 4 times and 3 times higher than those in precipitation, respectively. This probably resulted from the exchange of cations and the canopy leaching. (3) Through throughflow and stemflow, the most nutrient elements which was input the sites were K+ and Ca2+ i. e. 35. 8 and 31.5 kg hm -2 a -1, respectively. The most nutrient elements output through streamflow were Ca and Mgz+, i. e. 579. 5 and 152. 9 kg hm-2 a-1, respectively, S02-S coming next, Na+ +K+ + NH4 +-N accounts for less than 1% of the total cations, and CI + N03-N accounts for less than 1% of the total anions. These general features indicated that the chemical composition of water was largely controlled by carbonate weathering. (4) The characteristics of annual vertical movements of elements indicated the concentrations of nutrient elements in soil water were varied from Ocm to 5 cm. The concentration levels of NH4 + -N and N03 -N in the soil water suggested that the transformation might be caused by microbes through nitrogen fixation, nitrification and uptake by vegetation. (5) The nutrient budget (e. g. throughfall + stemflow - streamflow) within one year in the forest was 2. 9 for N, 25. 2 for K, -547. 4 for Ca, - 144. 5 for Mg, -4. 0 for Na, 2. 5 for CI, -5. 9kg hm-2 a-1 for S0-2-S, respectively. Our results showed that annual inputs exceeded outputs for dissolved inorganic N and K +, The watershed had net losses of Ca2 +, Mg2+, and was close to steady state for Na+ and Cl- in the forest. Source

Lu X.,Nanjing Institute of Environmental Sciences | Toda H.,Tokyo University of Agriculture and Technology | Ding F.,Guizhou Academy of Forestry science | Fang S.,Nanjing Forestry University | And 2 more authors.
European Journal of Soil Biology | Year: 2014

Inappropriate human activities have caused widespread reductions of forests and have produced degradation in karst regions of China. In the past two decades, numerous attempts have been made to promote recovery of the degraded soil using afforestation and natural regeneration approaches. A better understanding of the effects of vegetation types on the chemical and biological properties of the soil is very important for both reforestation approaches. Five vegetation types, namely, natural old-growth forest (>80 years old), grassland (15-25 years old), natural regeneration (20-25 years old), bamboo plantation (23 years old) and pine plantation (22 years old), were investigated in the Maolan karst area of Guizhou Province. The soil quality index (SQI) was evaluated with a cluster analysis and a principal components analysis to compare soil quality classes among the vegetation types. The results indicated that soil organic matter, the MBC/TOC ratio and soil basal respiration were the most important factors reflecting the general chemical and biological properties of the soil. Based on the SQI values, the soil quality under the selected vegetation types could be divided into three groups: low soil quality (pine plantation with SQI=0.26 and grassland with SQI=0.29), intermediate soil quality (bamboo plantation with SQI=0.41 and natural regeneration forest with SQI=0.46) and high soil quality (natural old-growth forest with SQI=0.63). The results of this study suggested that the pure plantation of Pinus massoniana had a negative impact on soil quality and that natural restoration may represent a more effective approach to the improvement of soil quality in degraded karst areas. These results also showed a strong interaction between soil quality, nutrient dynamics and vegetation types. © 2013 Elsevier Masson SAS. Source

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