TITLE:
Nutrient Release from Immersed Foliar Biomass during Caruachi Dam Reservoir Filling: Caroni River, Venezuela
AUTHORS:
Aracelis Narayan, Judith Rosales
KEYWORDS:
Decomposition, Nutrients, Litter, Leaves, Dam Construction
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.11 No.1,
January
19,
2023
ABSTRACT: Background: Decomposition process controls the release and the availability of
essential nutrients, which affects the structure and the functioning of plant communities.
Freshwater reservoirs are largely known to have impacts on the
water quality, especially during the first phases of filling. The aim of the study was
to conduct a nutrient release experiment where decomposition of fresh leaves
and litter from vegetation of a low dry tropical forest was flooded. Selected species were Leguminosae species Albizia glabripetala (H. S.
Irwin) G. P. Lewis & P. E. Owen (AG), Bauhinia aculeata L. (BA), Centrolobium paraense Tul. (CP) and Piptadenia leucoxyllon Barneby & J. W. Grimes
(PL). Freshwater decomposition experiments were carried out at 50 cm depth inside nine floating containers in a protected area of the
reservoir: litter (HJ), leaves of AG and BA (E2), and CP and PL (E3) were used.
It was over 20 weeks period. Every week for two months and at week 20, a bag of
each sample was extracted for analysis of Carbon, Ca, Mg, Na, K, P and S. Results: Results indicate that residual dry mass decreased by 71% for HJ, 81.4% for E2,
and more than 86.8% for E3 after twenty weeks. The higher content of carbon (%) at the beginning of the experiment was E2
> E3 > HJ. After 20 weeks, the
percentage of carbon loss was 2.09% for HJ, 3.02% for E2, and 1.69% for E3. S decreased between 50% - 60% during the first week; at 20 weeks, the
remaining amount of S was 13% for HJ and E3 and 7% for E2. P showed a different
pattern, where the second week was more important for the release. HJ and E3
followed the pattern of nutrient release: K > Mg > Na > Ca while E2
was K > Ca > Mg > Na. Conclusions: P and S release depends on the
time of submergence and the species. Fresh leaves decay faster than necromass.
Nutrient loss is higher than 50% for the three first weeks and seems constant
between week 8 - 20. C and S concentrations incorporated in the reservoir can result in a high
release of gases CH4 and S2 to the atmosphere. This study
is the first publication in relation to nutrient release from the submergence
of species in dry tropical forests.