Root proliferation in decaying roots and old root channels: a nutrient conservation mechanism in oligotrophic mangrove forests?

McKee, KL

Kl. Mckee, Root proliferation in decaying roots and old root channels: a nutrient conservation mechanism in oligotrophic mangrove forests?, J ECOLOGY, 89(5), 2001, pp. 876-887

56

INGLESE

Article

Environment/Ecology

JOURNAL OF ECOLOGY

0022-0477 → ACNP

89

5

2001

876 - 887

ISI

0022-0477(200110)89:5<876:RPIDRA>2.0.ZU;2-Q

1 In oligotrophic habitats, proliferation of roots in nutrient-rich microsi tes may contribute to overall nutrient conservation by plants. Peat-based s oils on mangrove islands in Belize are characterized by the presence of dec aying roots and numerous old root channels (0.1-3.5 cm diameter) that becom e filled with living and highly branched roots of Rhizophora mangle and Avi cennia germinans. The objectives of this study were to quantify the prolife ration of roots in these microsites and to determine what causes this respo nse. 2 Channels formed by the refractory remains of mangrove roots accounted for only 1-2% of total soil volume, but the proportion of roots found within c hannels varied from 9 to 24% of total live mass. Successive generations of roots growing inside increasingly smaller root channels were also found. 3 When artificial channels constructed of PVC pipe were buried in the peat for 2 years, those filled with nutrient-rich organic matter had six times m ore roots than empty or sand-filled channels, indicating a response to grea ter nutrient availability rather than to greater space or less impedance to root growth. 4 Root proliferation inside decaying roots may improve recovery of nutrient s released from decomposing tissues before they can be leached or immobiliz ed in this intertidal environment. Greatest root proliferation in channels occurred in interior forest zones characterized by greater soil waterloggin g, which suggests that this may be a strategy for nutrient capture that min imizes oxygen losses from the whole root system. 5 Improved efficiency of nutrient acquisition at the individual plant level has implications for nutrient economy at the ecosystem level and may expla in, in part, how mangroves persist and grow in nutrient-poor environments.