Detecting and Quantifying Forest Change: The Potential of Existing C- and X-Band Radar Datasets.

This paper evaluates the opportunity provided by global interferometric radar datasets for monitoring deforestation, degradation and forest regrowth in tropical and semi-arid environments. The paper describes an easy to implement method for detecting forest spatial changes and estimating their magnitude. The datasets were acquired within space-borne high spatial resolutions radar missions at near-global scales thus being significant for monitoring systems developed under the United Framework Convention on Climate Change (UNFCCC). The approach presented in this paper was tested in two areas located in Indonesia and Australia. Forest change estimation was based on differences between a reference dataset acquired in February 2000 by the Shuttle Radar Topography Mission (SRTM) and TanDEM-X mission (TDM) datasets acquired in 2011 and 2013. The synergy between SRTM and TDM datasets allowed not only identifying changes in forest extent but also estimating their magnitude with respect to the reference through variations in forest height.

On the metabolic origin of the carbon isotope composition of CO2 evolved from darkened light-acclimated leaves in Ricinus communis.

The (13)C isotopic signature (delta(13)C) of CO(2) respired from plants is widely used to assess carbon fluxes and ecosystem functioning. There is, however, a lack of knowledge of the metabolic basis of the delta(13)C value of respired CO(2). To elucidate the physiological mechanisms driving (12)C/(13)C fractionation during respiration, the delta(13)C of respired CO(2) from dark-acclimated leaves during the night, from darkened leaves during the light period, and from stems and roots of Ricinus communis was analysed. The delta(13)C of potential respiratory substrates, the respiratory quotient and the activities of phosphoenolpyruvatecarboxylase (PEPc) and key respiratory enzymes were also measured. It is shown here that the CO(2) evolved from darkened light-acclimated leaves during the light period is (13)C-enriched, and that this correlates with malate accumulation in the light and rapid malate decarboxylation just after the onset of darkness. Whilst CO(2) evolved from leaves was generally (13)C-enriched (but to a lesser extent during the night), CO(2) evolved from stems and roots was depleted compared with the putative respiratory substrates; the difference was mainly caused by intensive PEPc-catalysed CO(2) refixation in stems and roots. These results provide a physiological explanation for short-term variations of delta(13)C in CO(2), illustrating the effects of variations of metabolic fluxes through different biochemical pathways.