Organic matter chemistry and dynamics in clear-cut and unmanaged hardwood forest ecosystems

摘要: Forest harvesting alters the organic matter cycle by changing litter inputs and decomposition regime. We hypothesized that these changes would result in differences chemistry between clear-cut uncut watershed ecosystems. studied of soil (SOM), dissolved carbon (DOC) solutions stream samples sites at Hubbard Brook Experimental New Hampshire using DOC fractionation techniques solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Alkyl-C (aliphatic compounds) O-alkyl-C (carbohydrates) were largest C fractions Brook. ranged from 29–48% C, 25–42% solution 22–42% streamwater DOC. Carbohydrates comprised 32–49%, 36–43%, 29–60% soils, solutions, streamwater, respectively. In both soils carbohydrate fraction decreased with increasing depth, while aromaticity increased depth. There no significant structural SOM watersheds. The aromatic-C site 12–16%, approximately 40% greater than (8.5–11%). Thus, clear-cutting has resulted leaching more highly decomposed matter, depletion aliphatic compounds soluble pool. Because fluxes are small compared to pool, large do not substantially alter overall composition SOM. While varied greatly among 3 sampling dates, there obvious effects. temporal variations flowpaths and/or in-stream processes appear be important disturbance regulating streams.