海鸟活动对北极新奥尔松苔原-大气CO_2交换的影响

EFFECTS OF SEABIRD ACTIVITY ON CARBON DIOXIDE EXCHANGE BETWEEN TUNDRA AND ATMOSPHERE IN NY-LESUND,ARCTIC

北极高纬度地区是全球重要的海鸟活动区,海鸟粪为苔原土壤带来了丰富的养分,影响了苔原碳循环过程,但目前还未见有文献报道海鸟活动对北极苔原CO2通量的影响。2009年夏笔者采用密闭箱法对北极新奥尔松地区(Ny-lesund)鸟类保护区和非鸟类活动区苔原的CO2夏季通量和日通量进行了对比监测,探讨了海鸟活动对苔原CO2通量的影响。结果表明:鸟类密集区(HB)、鸟类活动较少区(MB)和基本无海鸟活动的边缘区(LB)CO2平均净通量(NEE)分别为(-107.6±19.2)、(21.7±9.7)和(67.5±12.4)mg·m-2·h-1;光合速率分别为(-243.6±25.5)、(-105.5±7.6)和(-45.6±12.0)mg·m-2·h-1。HB区NEE和光合速率显著高于MB和LB区,表明鸟类活动显著增加了苔原生态系统NEE和光合速率;而平均呼吸速率为(136.0±16.5)、(127.2±15.6)和(113.0±6.8)mg·m-2·h-1,差异不明显,表明海鸟活动对呼吸速率影响较小。非鸟类活动区苔原(海边苔原和煤矿区苔原)夏季整体上表现为CO2排放源,平均NEE分别为(6.91±4.8)和(17.5±41.6)mg·m-2·h-1。综合分析表明:NEE和呼吸速率与土壤温度呈正相关。综合3类不同苔原区域23个观测点CO2通量的结果表明:海鸟活动及其粪便增加了苔原土壤养分,从而促进了苔原植被发育,显著增强了北极高纬度地区苔原的碳汇功能。

The high altitude area in Arctic is one of important global seabird active regions. Seabird guano provides rich nutrients for tundra soils, thus affects carbon cycle in tundra ecosystem. However, effects of seabird activity on CO2 fluxes from Arctic tundra have not been reported. During the summertime of 2009, CO2 fluxes were investigated in the bird sanctuary and non-bird region from Ny-？lesund using a static chamber technique. To evaluate temporal variations and daily variations of CO2 fluxes from the bird sanctuary, bird-intensive areas （HB）, fewer activities area （MB） and the edge region with little seabirds activities（LB）were investigated. Net CO2 fluxes and photosynthetic rates were （-107.6±19.2）,（21.7±9.7）and（67.5±12.4）mg/（m2.h） and（-243.6±25.5）,（-105.5±7.6）and（-45.6±12.0）mg/（m2.h ）, respectively. They were both significantly different between the observation sites, and photosynthetic rates reduced in order, indicating bird activities significantly increased atmosphere CO2 uptake. The respiratory rates were（136.0±16.5）,（127.2±15.6）and（113.0±6.8）mg/（m2.h） had no significant differences between the observation sites, indicating the effect of bird activities may be insignificant. The average NEE of non-bird region （seaside and mining tundra） were （6.91±4.8）and（17.5±41.6）mg/（m2.h）, respectively. The data suggested the non-bird tundra was the CO2 sink. Temporal variations of CO2 fluxes during summertime in the non-bird region showed it was a source for atmospheric CO2. The CO2 fluxes were positively related to air temperature and ground temperature, with no significant correlation with precipitation and air humidity. Our results from 23 observation sites in three types of tundra indicated seabird activity had a major impact on carbon fluxes and significantly enhanced the sink of carbon in Arctic tundra.