Previous studies showed that the export of dissolved and gaseous carbon (C) with rivers and streams may vary among forest ecosystems. Prof. Zhang Yiping and his team of XTBG have reported that tropical seasonal rainforest in Xishuangbanna is a small net C source. Accounting for total carbon export with stream water may make the loss of carbon from tropical seasonal rainforest even larger than earlier anticipated.
In order to clarify the role of carbon export by headwater streams, the researchers carried out a two-year study (2009 ~ 2010) to investigate the dynamics of different carbon (C) forms, and the role of stream export in the C balance of a 23.4-ha headwater catchment in a tropical seasonal rainforest in Xishuangbanna ((21.16° N, 101.04° E). Their objectives were (1) to ascertain the seasonal dynamics of different carbon (C) components (dissolved inorganic C, dissolved organic C, particulate inorganic C, particulate organic C, total inorganic C, total organic C, and total C), and (2) to assess the contribution of stream export to the C balance in the tropical seasonal rainforest ecosystem.
Their study found that the sources of different C components varied, leading to differences in the relative influence of stream discharge and stream water temperature on C concentration and seasonal patterns. The relationship between stream discharge and C concentrations, and the distribution of C fractions differed in their influence on the C budget.
A comparison of total carbon and net ecosystem exchange values in tropical seasonal rainforest at Xishuangbanna and in Amazon tropical forest and boreal forest indicated that stream export represented only a small component of the overall forest C balance in tropical seasonal rainforest.
The study entitled “The Role of Stream Water Carbon Dynamics and Export in the Carbon Balance of a Tropical Seasonal Rainforest, Southwest China” has been published in PLoS ONE, 8(2): e56646. doi:10.1371/journal.pone.0056646
A researcher is sampling at the stream outlet
in tropical seasonal rainforest at Xishuangbanna (Image by Zhou Wenjun)