Methane emissions from tree stems: a new frontier in the global carbon cycle.

Tree stems from wetland, floodplain and upland forests can produce and emit methane (CH ). Tree CH stem emissions have high spatial and temporal variability, but there is no consensus on the biophysical mechanisms that drive stem CH production and emissions. Here, we summarize up to 30 opportunities and challenges for stem CH emissions research, which, when addressed, will improve estimates of the magnitudes, patterns and drivers of CH emissions and trace their potential origin.

Evaluation of passive samplers for the collection of dissolved organic matter in streams.

Traditional sampling methods for dissolved organic matter (DOM) in streams limit opportunities for long-term studies due to time and cost constraints. Passive DOM samplers were constructed following a design proposed previously which utilizes diethylaminoethyl (DEAE) cellulose as a sampling medium, and they were deployed throughout a temperate stream network in Indiana. Two deployments of the passive samplers were conducted, during which grab samples were frequently collected for comparison.