Monthly measurements of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) fluxes were made at 3 sites along a sequence of naturally regenerating Kunzea ericoides shrubland in New Zealand, consisting of unimproved pasture (UP), young (8–12 years) Kunzea trees (YK), and old (80 years) Kunzea trees (OK). The CO₂ flux at a base temperature of 10°C was highest at the OK site (0.51 g CO₂/m².h) and lowest at the UP site (0.26 g CO₂/m².h). Values of CO₂ flux were regulated by soil temperature (T_s) throughout the year, and water availability modified the response to T_s when root-zone water content, (θ), fell below 0.27–0.29 m³/m³ in spring and summer. The soils were mostly CH₄ sinks, although there were net CH₄ emissions during wet periods at the YK site. The maximum CH₄ flux at the YK site was –49.7 μg CH₄/m².h compared with –33.4 μg CH₄/m².h for the UP (and –90.4 μg CH₄/m².h for OK), indicating the potential for rapid recovery of methanotrophic populations in the YK shrubland over 8–12 years. However, on an annual basis our data suggest that CH₄ oxidation rates decrease as land reverts from unimproved pasture to shrubland. Methane oxidation rates were strongly dependent on θ and only weakly dependent on T_s. Measurements of N₂O fluxes were below the minimum detectable limit throughout the year at the UP and YK sites, and low but dependent on both T_s and θ at the OK site.

Annual estimates of soil CO₂ flux were 39.9, 23.3, and 21.9 × 10³ kg CO₂/ha.year at the OK, YK, and UP sites, respectively. All 3 sites were a net sink for CH₄, with the highest oxidation rate of –5.1 kg CH₄/ha.year at the OK site compared with –1.52 kg CH₄/ha.year at the UP site. On a CO₂-equivalent basis, the OK site was a greater CH₄ sink (–127.3 kg CO₂-e/ha.year) than a N₂O source (77.5 kg CO₂-e/ha.year), demonstrating the potential for soils to oxidise CH₄ with forest succession as a possible mitigation strategy for land managers to reduce net emissions.