Degradation of mangrove tissues and implications for peat formation in Belizean island forests

Middleton, BA McKee, KL

Ba. Middleton et Kl. Mckee, Degradation of mangrove tissues and implications for peat formation in Belizean island forests, J ECOLOGY, 89(5), 2001, pp. 818-828

71

INGLESE

Article

Environment/Ecology

JOURNAL OF ECOLOGY

0022-0477 → ACNP

89

5

2001

818 - 828

ISI

0022-0477(200110)89:5<818:DOMTAI>2.0.ZU;2-0

1 Macrofaunal leaf consumption and degradation of leaves, woody twigs and r oots were studied in mangrove island forests on a Belizean island. Factors influencing accumulation of organic matter deposited both above and below g round in this oligotrophic, autochothonous system were assessed. 2 Leaf degradation rates of Rhizophora mangle (red mangrove), Avicennia ger minans (black mangrove) and Laguncularia racemosa (white mangrove) measured in mesh bags, were much faster in the lower than the upper intertidal zone . Mass loss was most rapid in A. germinans but zonal effects were much larg er than species differences. 3 Exposure to invertebrates such as crabs and amphipods tripled overall rat es of leaf litter breakdown. In the lower intertidal, crabs completely cons umed some unbagged leaves within 23 days. Crabs also had an effect on some upper intertidal sites, where degradation of leaves placed in artificial bu rrows was 2.4 times faster than when placed on the soil surface. 4 In contrast to leaves (27 +/- 5% remaining after 230 days), roots and woo dy twigs were highly refractory (40 +/- 2% and 51 +/- 6% remaining after 58 4 and 540 days, respectively). Root degradation did not vary by soil depth, zone or species. Twigs of R. mangle and A. germinans degraded faster on th e ground than in the canopy, whereas those of L. racemosa were highly resis tant to decay regardless of position. 5 Peat formation at Twin Cays has occurred primarily through deposition and slow turnover of mangrove roots, rather than above-ground tissues that are either less abundant (woody twigs) or more readily removed (leaves).