Organic‐carbon and nitrogen stocks and organic‐carbon fractions in soil under mixed pine and oak forest stands of different ages in NE Germany

摘要: The objective of this work was to evaluate the C and N stocks organic-C fractions in soil under mixed forest stands Scots pine (Pinus sylvestris L.) Sessile oak (Quercus petraea [Matt.] Liebl.) different ages NE Germany. Treatments consisted pure (age 102 y), 90-102 y) with 10-, 35-, 106-, 124-y-old trees. After sampling O layers, soils mineral layer were taken at two depths (0-10 10-20cm). Oak admixture did not affect total (TOC) considering layers separately. However, when sum TOC organic considered, decreased increasing age (r 2 = 0.58, p < 0.10). microbial (C MB ) directly correlated increase age, however, it positively related presence species. There an percentage -to-TOC ratio oak-tree ages. On average, light-fraction LF comprised 68% upper corresponding highest pool layer. heavy-fraction HF affected by trees both layers. accounted on average for 30% 59% 0―10 10-20 cm depths, respectively. Despite low clay contents studied soils, differences DCB-extractable Fe Al concentrations 10―20cm (p 0.05). Admixture contributed reduce topsoil stocks, probably due higher matter turnover promoted quality litter.