Biogeosciences報(bào)道了中科院植物研究所萬(wàn)師強(qiáng)課題組在內(nèi)蒙古典型溫帶草原開(kāi)展的全球變化生態(tài)學(xué)的研究成果,，肯定了該項(xiàng)研究的重要意義。
氣候變化與陸地生態(tài)系統(tǒng)反饋關(guān)系的模擬和預(yù)測(cè)存在很大的不確定性,。大尺度模型通常采用平均溫帶作為氣候驅(qū)動(dòng)因子來(lái)模擬陸地生態(tài)系統(tǒng)碳循環(huán)對(duì)氣候變暖的響應(yīng)和反饋,；這些模型包括了兩種潛在的假設(shè)：（1）均勻的白天和夜間增溫幅度；（2）全天增溫的效應(yīng)等于白天和夜間的增溫效應(yīng)之和,。然而,，過(guò)去半個(gè)世紀(jì)全球的溫度紀(jì)錄顯示，夜間最低溫度的增溫幅度比白天最高溫度的增溫幅度高出一倍,，因此第一種假設(shè)被否定,。雖然來(lái)自北美洲矮草草原植物和菲律賓水稻產(chǎn)量的證據(jù)顯示晝夜不對(duì)稱增溫和對(duì)稱增溫對(duì)陸地植物的生長(zhǎng)和碳積累的影響可能不同，但是到目前為止,，還沒(méi)有關(guān)于晝夜不對(duì)稱增溫如何影響陸地生態(tài)系統(tǒng)碳循環(huán)的直接實(shí)驗(yàn)證據(jù)和報(bào)道,，因此也不能證實(shí)和否定上述第二種假設(shè)。
針對(duì)這一問(wèn)題,，植物所萬(wàn)師強(qiáng)課題組于2006年4月開(kāi)始,，在內(nèi)蒙古典型溫帶草原開(kāi)展了一個(gè)包括四種處理的實(shí)驗(yàn)：對(duì)照,，白天增溫（早上6點(diǎn)到晚上6點(diǎn)）、夜間增溫（晚上6點(diǎn)到早上6點(diǎn)）和全天增溫（24小時(shí)）,。經(jīng)過(guò)3年的處理和對(duì)土壤呼吸的測(cè)定,，研究人員發(fā)現(xiàn)：不論是對(duì)土壤呼吸代表的碳釋放還是總生態(tài)系統(tǒng)生產(chǎn)力代表的碳吸收而言，全天增溫的效應(yīng)均小于白天和夜間的增溫效應(yīng)之和,。該研究結(jié)果說(shuō)明不能利用全天增溫的效應(yīng)來(lái)預(yù)測(cè)自然條件下發(fā)生的晝夜不對(duì)稱增溫對(duì)陸地生態(tài)系統(tǒng)碳循環(huán)的影響,，從而否定了利用平均溫度作為氣候驅(qū)動(dòng)因子的模型中的第二種假設(shè)。同時(shí)為改進(jìn)和完善氣候變化-碳循環(huán)反饋關(guān)系的模型模擬和預(yù)測(cè)提供了直接,、關(guān)鍵的實(shí)驗(yàn)證據(jù)和參數(shù)估計(jì),。
該研究項(xiàng)目在國(guó)家自然科學(xué)基金委重大研究計(jì)劃“全球變化與區(qū)域效應(yīng)”重點(diǎn)項(xiàng)目“全球變暖背景下白天和夜間增溫對(duì)溫帶草原群落結(jié)構(gòu)和生態(tài)系統(tǒng)功能的特異性影響”資助下完成。（生物谷Bioon.com）
生物谷推薦原始出處：
Biogeosciences, 6, 1361-1370, 2009
Effects of diurnal warming on soil respiration are not equal to the summed effects of day and night warming in a temperate steppe
J. Xia1,2, Y. Han1,2, Z. Zhang1,2, Z. Zhang1,2, and S. Wan1
1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing 100093, China
2Graduate School of Chinese Academy of Sciences, Yuquanlu, Beijing 100049, China
Abstract. The magnitude of daily minimum temperature increase is greater than that of daily maximum temperature increase under climate warming. This study was conducted to examine whether changes in soil respiration under diurnal warming are equal to the summed changes under day and night warming in a temperate steppe in northern China. A full factorial design with day and night warming was used in this study, including control, day (06:00 a.m.–06:00 p.m., local time) warming, night (06:00 p.m.–06:00 a.m.) warming, and diurnal warming. Day warming showed no effect on soil respiration, whereas night warming significantly increased soil respiration by 7.1% over the 3 growing seasons in 2006–2008. The insignificant effect of day warming on soil respiration could be attributable to the offset of the direct positive effects of increased temperature by the indirect negative effects via aggravating water limitation and suppressing ecosystem C assimilation. The positive effects of night warming on soil respiration were largely due to the stimulation of ecosystem C uptake and substrate supply via overcompensation of plant photosynthesis. Changes in both soil respiration (+20.7 g C m?2 y?1) and GEP (?2.8 g C m?2 y?1) under diurnal warming are smaller than their summed changes (+40.0 and +24.6 g C m?2 y?1, respectively) under day and night warming. Our findings that the effects of diurnal warming on soil respiration and gross ecosystem productivity are not equal to the summed effects of day and night warming are critical for model simulation and projection of climate-carbon feedback.
