Multi-substrate induced respiration (functional capacity) in agriculturally degraded and intact restiad bogs: implications for carbon and nitrogen cycling

Abstract

Natural peatlands provide ecosystem services such as carbon storage and habitat, which can be negatively affected (degraded) by the proximity of agricultural land due to lowered water table and increased nutrient deposition. We assessed peat biochemistry and microbial function in the dry, fluctuating and saturated zones of the peat deposits at Moanatuatua (degraded) and Kopuatai (intact) raised bogs in New Zealand to investigate the effects of adjacent agriculture on carbon (C) and nitrogen (N) cycling. Peat C and N density were elevated, due in part to greater bulk density, in the dry and saturated zones at Moanatuatua compared with Kopuatai. Functional capacity (multi-substrate induced respiration) at Moanatuatua was greater than at Kopuatai, and water-soluble C was at lower concentration but more degradable, indicating that microbes were C limited at Moanatuatua but N limited at Kopuatai. Greater microbial function at Moanatuatua infers C inputs may be more rapidly converted to gaseous or waterborne exports, and agriculturally affected peatlands may be more susceptible to losses of labile C. We conclude that proximity to agriculture is likely to have caused changes in chemical properties and altered microbial functioning of restiad bog and has important implications for C and N turnover within these peatland systems.

Keywords

• community level physiological profiles
• microbial function
• nutrient enrichment
• peatland