Effects of harvesting and soil disturbance on soil CO2 efflux from a jack pine forest

We measured organic matter removal and soil compaction effects on soil surface CO2 efflux (F) from a jack pine (Pinus banksiana Lamb.) forest and developed an analytical framework involving multiplicative response functions to interpret response. Treatments included stem-only harvest (OM0C0), full-tree harvest (OM1C0), full-tree harvest with surface soil removal (OM2C0), full-tree harvest with surface soil removal and soil compaction (OM2C2), and uncut forest (UF). Mean F and calculated F at 10 degrees C under nonlimiting soil moisture conditions (F-10) were greatest in treatments with intact organic surfaces and often larger in the OM2C0 than in the OM2C2. F-10 showed strong linear relationships with detrital production in harvested plots, with total near-surface carbon in all plots, and was positively correlated with understory cover. F increased exponentially with soil temperature, with the most and least pronounced responses found in the UF and OM2C0 treatments, respectively. F also responded in parabolic fashion to relative soil water content. In the UF, F was often low in May because of cold soils, but subsequently attained rates equivalent to those of the OM0C0 and OM1C0, despite lower soil temperatures. Three to five growing seasons after treatment, soil temperature and moisture, together with F-10, explained 71%-87% of the plot-level variation in F.