ABSTRACT

A 3x 8 factorial experiment in a randomized complete block design (RCBD) with three replications was used to study the leal litter decomposition rates of three omamental/landscape woody tree species, namely: Bauhinia manadra Kurz, Hum crepitans Linn and HHdegardia barteri Kostern in eight sampling intervals - 2, 4, 8, 12, 16, 20, 24 and 28 weeks after litter placement (WALP). The study utilized two modes of leaf litter placements in litter bags, namely: soil surface-placed and soil incorporated The experiment lasted for 28 weeks between 6,h December, 2006 to 611’ June, 2007. Hum. crepitans and //. bacteri gave significantly the highest and the least cumulative leaf litter decomposition percentages in both modes of litter decomposition. The order of species in soil surface-placed and soil-incorporated leaf litter placements were significantly as follows' H. crepitans > B. monandra > H. barleri. The cumulative leaf litter decomposition rates (%) of the eight sampling periods (weeks after leaf litter placement-WALP) of both modes increased significantly overtime as follows: 28"’ > 24"’ > 20"’ > 16"’ > 12"’ > 8"1 > 4"’ > 2'”' WALP. Hum crepitans and H. bacteri gave respectively the highest and least (P<0.05) relative leaf litter decay rates (% dy’1) in both modes of litter decay rates as follows: H. crepitans > B. monandra > H. barteri. The relative leaflitter decay rates (% dy’’) of the eight sampling periods of soil surface-placed mode were significantly as follows: 2nd > 20,h > 4,h > 12th > 8,h > I6,h > 24,h > 28'1’ WALP. The result ofsoilincorporated mode were as follows: 2nd > 411' > 2011' > 811’ > 28lh > 12th > 16th > 24lh WALP. Student’s t-test (P<0.05) indicated significant differences between the cumulative leaflitter decomposition rates ofsoil-incorporated and surface-placed leaf litter ofB. monandra (tca, = 4.03, t-tab(0.05) = 2.36), H. crepitans (tca, = 3.84, t-tab(oo5) = 2.36) and H. barleri (tea| = 4.54, t-tab(O.o5) - 2.36). No significant differences existed between the relative leaf litter decay rates (% dy ) of the two modes of littei placements of B. monandra (tcai = 0.81, t-tab(o.o5) = 2.36) H. crepitans (tcai — 0.73, ttab(t).()5) = 2.36) and H. barteri (tca, = 1.06, t-tab((,05) = 2.36). Turnover coefficients of the two leaf litter decomposition placement modes ol each ofthe tluee woody species varied markedly: B. manandra (surface-placed: 0.14, soil-incorpotated. 0.07), H. crepitans (surface-placed: 0.12, soil-incorporated: 0.01), H. barleri (suiface-placed. 0.19, soil-incorporated 0.13). Soil-incorporated leaf litter attained quicker half-lives than soil surface-placed leaflitter per species. Both modes had similar full-live values. The observed and the expected leaf litter decomposition lates at the 28 weeks aftei litter placement (WALP) and the correlation coefficients of both modes of leaf litter placements of each species were similar.