首页|高寒嵩草草甸不同退化梯度下生态系统光合和呼吸响应特征

高寒嵩草草甸不同退化梯度下生态系统光合和呼吸响应特征

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青藏高原高寒草甸生态地位突出但退化严重,其植被光合和系统呼吸特征如何响应仍不清楚.于植被生长的旺盛期(7月中旬～8月中旬)在青藏高原祁连山南麓分别选取原生草地、中度退化和重度退化3类高寒草甸,使用自制同化箱和LI-6400便携式光合仪测定生态系统CO2净交换(NEE)、生态系统暗呼吸(RES)和生态系统初级光合(GEP),研究退化程度对高寒嵩草草甸生态系统CO2通量的影响特征.结果表明不同退化程度的NEE、RES和GEP的单峰日变化格局没有明显差异,日极值出现时间相近.日均NEE和日均RES随着退化加剧逐渐升高,重度退化较原生草地分别显著(P＜0.05)升高了41.8％和12.2％.日均GEP略有下降.退化降低了RES的温度敏感度(Q10),提高了群落表观光量子产额(a),但对系统潜在CO2最大同化速率(Pmax)无明显影响.在植被生长旺盛期,高寒草甸生态系统碳收支对退化的响应主要表现在系统的呼吸强度而非群落光合速率.
Response of Ecosystem Photosynthesis and Respiration to Degradation Gradients in an Alpine Kobresia Meadow
Alpine grassland ecosystems plays an essential role in national ecological security shelter,but it have been widely and severely degraded in the Qinghai-Tibetan Plateau.But the responses of carbon budgets to degradation process are not fully understood on the alpine grassland.The experiment of degradation gradients (lightly degradation, medium degradation and severe degradation) on an alpine Kobresia meadow was conducted.During plant flourishingly growing season, net ecosystem CO2 exchange rate (NEE), ecosystem dark respiration rate (RES) and gross ecosystem photosynthesis rate (GEP)was measured by LI-6400 and carbon assimilation chamber from mid-July to mid-August in 2014 on Northeastern Qinghai-Tibetan Plateau.The results showed that the diurnal unimodal patterns of GEP, RES and NEE were not significantly influenced along degradation gradients and the peak and valley of diurnal CO2 fluxes from different gradation status occurred almost simultaneously.Daily RES and NEE of severe degradation plots was evidently (P＜ 0.05) improved by 12.2％ and 41.8％ than that of light degradation plots, respectively.Daily GEP declined undetectably.Along the degradation gradients, the temperature sensitivity of RES (Q10) was decreased and ecosystem apparent quantum yield (a) was enhanced, while the ecosystem saturated photosynthetic rate (Pmax) was little changed.Those results indicated that the response of carbon dynamics of alpine Kobresia meadow to degradation processes was mostly demonstrated by ecosystem respiration CO2 efflux rather than photosynthetic CO2 uptake during the vegetation flourishing periods from July to August.

CO2 fluxesPhotosynthetic response curveRespiration temperature sensitivityAssimilation chamberQinghai-Tibetan Plateau

张法伟、王军邦、李以康、林丽、曹广民

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中国科学院西北高原生物研究所,青海西宁810001

中国科学院高原生物适应与进化重点实验室,青海 西宁 810001

中国科学院大学,北京 100049

中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京 100101

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CO2通量 光响应特征 呼吸温度敏感度 同化箱 青藏高原

国家自然科学基金国家自然科学基金青海省科技促进新农村计划项目中国科学院科技服务网络计划

31270520312705762013-N-540KFJ-EW-STS-125

2016

10.16742/j.zgcdxb.2006-01-06

中国草地学报
中国农业科学院草原研究所 中国草地学会

中国草地学报

CSTPCDCSCD北大核心
影响因子：1.347
ISSN：1673-5021
年,卷(期)：2016.38(1)
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