Carbon storage in fast-growing and highyield poplar plantations under subsurface drip irrigation.

Carbon storage of six-year poplar I-214 (Populus×canadensis cv. ‘I-214’) plantations under subsurface drip irrigation (SDI), and normal irrigation(NI) at sandy soil in Chaobai River in Beijing was investigated. The carbon sink ability of a tenyear demonstration plantation of poplar Zhonglin-46 was evaluated. The results showed that: 1) carbon storage of the plantations under SDI highly increased compared with that under NI. In 2002 (6 years after plantation), the tree storey, litter floor and soil carbon storage under SDI were 25.81, 3.53 and 42.00 t/hm2, respectively, and were 1.27, 2.02 and 1.32 times of that under NI. The total carbon storage under SDI was 76.50 t/hm2, which was 54.2% more than that under NI of 49.61 t/hm2 The annual net carbon incremental under SDI was 9.49 t/(hm2•a), approximately 2 times of that under NI of 5.01 t/(hm2•a). 2) In 2010 (10 years after plantation), the demonstration plantation reached a high level of carbon sequestration. The tree storey, under-storey plants, litter floor and soil carbon storage reached 34.71, 8.60, 8.45 and 56.20 t/hm2, with total carbon storage of 107.19 t/hm2 The annual net carbon incremental reached 8.84 t/(hm2•a), nearly 41.4% more than control of 6.25 t/(hm2•a). Therefore, it is suggested to extend the water and fertilizer management technology under subsurface drip irrigation in arid, subarid and seasonal arid area according to the local economic conditions since it can not only improve the productivity and carbon sink ability of the fastgrowing and highyield poplar plantations significantly, but also plays a crucial role in slowing down the global warming trend.