title: Contrasting effects of nitrogen and phosphorus addition on soil respiration in an alpine grassland on the Qinghai-Tibetan Plateau.
abstract: High soil organic carbon content, extensive root biomass, and low nutrient availability make alpine grasslands an important ecosystem for assessing the influence of nutrient enrichment on soil respiration (SR). We conducted a four-year (2009-2012) field experiment in an alpine grassland on the Qinghai-Tibetan Plateau to examine the individual and combined effects of nitrogen (N, 100 kg ha-1year-1) and phosphorus (P, 50 kg ha-1year-1) addition on SR. We found that both N and P addition did not affect the overall growing-season SR but effects varied by year: with N addition SR increased in the first year but decreased during the last two years. However, while P addition did not affect SR during the first two years, SR increased during the last two years. No interactive effects of N and P addition were observed, and both N addition and P addition reduced heterotrophic respiration during the last year of the experiment. N and P addition affected SR via different processes: N mainly affected heterotrophic respiration, whereas P largely influenced autotrophic respiration. Our results highlight the divergent effects of N and P addition on SR and address the important potential of P enrichment for regulating SR and the carbon balance in alpine grasslands.
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.|University of Chinese Academy of Sciences, 19A Yuquan Rd., Beijing, 100049, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ren
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.|State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, 251 Ningda Rd., Xining, 810016, China.|Qinghai Academy of Animal and Veterinary Sciences, 1 Weier Rd., Xining 810016, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Yang
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.
authors.forename: Huakun
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.
authors.forename: Wenyan
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.
authors.forename: Zhenhua
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.
authors.forename: Litong
authors.initials: L
authors.lastname: Chen
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.
authors.forename: Guangmin
authors.initials: G
authors.lastname: Cao
authors.affiliation: Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, 23 Xinning Rd., Xining, 810008, China.|Department of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, 5 Yiheyuan Rd., Beijing 100871, China.
authors.forename: Jin-Sheng
authors.initials: JS
authors.lastname: He