Curtis P S, Drake B G, Whigham D F
Smithsonian Environmental Research Center, Box 28, 21037, Edgewater, MD, USA.
Oecologia. 1989 Mar;78(3):297-301. doi: 10.1007/BF00379101.
Carbon dioxide concentrations were elevated in three estuarine communities for an entire growing season. Open top chambers were used to raise CO concentrations ca. 336 ppm above ambient in monospecific communities of Scirpus olneyi (C) and Spartina patens (C), and a mixed community of S. olneyi, S. patens and Distichlis spicata (C). Nitrogen and carbon concentration (% wt) of aboveground tissue was followed throughout growth and senescence. Green shoot %N was reduced and %C was unchanged under elevated CO in S. olneyi. This resulted in a 20%-40% increase in tissue C/N ratio. There was no effect of CO on either C species. Maximum aboveground N (g/m) was unchanged in S. olneyi, indicating that increased productivity under elevated CO was dependent on reallocation of stored N. There was no change in the N recovery efficiency of S. olneyi in pure stand and a decrease in the mixed community. Litter C/N ratio was not affected by elevated CO suggesting that decomposition and N mineralization rates will also remain unchanged. Continued growth responses to elevated CO could, however, be limited by the ability of S. olneyi to increase the total aboveground N pool.
在三个河口群落中，二氧化碳浓度在整个生长季节都有所升高。使用开放式顶部气室将二氧化碳浓度提高到比环境浓度高约336 ppm，分别设置了单种的奥尔尼藨草（C）群落、互花米草（C）群落，以及由奥尔尼藨草、互花米草和穗状盐草（C）组成的混合群落。在整个生长和衰老过程中，对地上组织的氮和碳浓度（%重量）进行了跟踪监测。在二氧化碳浓度升高的情况下，奥尔尼藨草的绿茎氮含量降低，碳含量不变。这导致组织碳氮比增加了20%-40%。二氧化碳对两种碳物种均无影响。奥尔尼藨草地上部最大氮含量（克/平方米）不变，这表明在二氧化碳浓度升高的情况下生产力的提高依赖于储存氮的重新分配。在纯林中，奥尔尼藨草的氮回收效率没有变化，而在混合群落中有所下降。凋落物碳氮比不受二氧化碳浓度升高的影响，这表明分解和氮矿化速率也将保持不变。然而，奥尔尼藨草增加地上总氮库的能力可能会限制其对二氧化碳浓度升高的持续生长响应。
