Impacts of tree harvesting on the carbon balance and functioning in mangrove forests

摘要: Mangrove forests are considered one of the most efficient natural carbon sinks and their preservation is thus important in climate change mitigation. However, they declining at higher rates than terrestrial forests, due to human activities; with Kenyan mangroves being no exception. One main drivers mangrove decline Kenya over-exploitation for wood products. The present study aimed assess (a) effects tree removal on fluxes greenhouse gases, surface elevation other ecosystem functions (b) root production. To explore these objectives two experiments were established Gazi bay, Kenya: (i) harvest (ii) productivity studies. For experiment, ten 12 m x plots March 2009 a Rhizophora mucronata (Lam.) forest. Five randomly selected all trees within them girdled November then cut May 2010. Gas CO2 CH4 sampled using chamber technique monthly intervals from June April 2011. Surface dynamics observed stations (SES). Other variables measured included, macrofaunal abundance diversity regeneration patterns. twenty eight 10 four forest types; each type comprising Avicennia marina (Forsk) Vierh., Ceriops tagal (Perr) C. B. Robinson, R. Sonneratia alba (Sm) forests. Ten A. Makongeni; while 18 species Gazi; six three S. Root production was estimated in-growth (two trenches per plot), aboveground measurements girth increment. Girth increment dendrometers installed trees, plot, combination periodic plot. Environmental such as height above datum, salinity, grain size redox potential beginning experiment during treatment periods experiment. Treatment significantly elevated emissions sediments by 14.2 ± 10.3 tCO2 ha-1 (rate 9.8 7.1 yr-1) years. Similarly, induced subsidence -51.3 24.3 mm (at rate -32.1 8.4 compared 11.1±10.1 4.2 1.4 control over 2 years after treatment. Decomposition labile roots treated likely driver high plots. Soil compaction collapse aeranchyma tissue might have been responsible Natural drastically affected cutting, having sparse seedlings 450 days Gap-preferring ocypodid crabs colonized became more abundant sesarmids (usually found closed canopy forest) There significant variation between Makongeni sites, former those latter. had biomass (AGB) types. On hand highest belowground (BGB) Differences microtopographical settings soil factors influence sites These results underscore importance putting place management options that ensure maintenance continuous cover fast under extraction. In addition, areas seafront should be protected. These also support work showing often allocate proportion A investment helps facilitate peat formation, which not only forms but may enable keep pace projected sea level rise. Therefore, Western Indian Ocean region consider trade-offs utilization minimizing loss functioning coastal stabilization protection. addition initiatives payment services (PES) schemes e.g. reducing deforestation degradation (REDD+) explored some strategies reverse trend cover.