"Coefficients of determination (r2), slopes, and Y-intercepts of regressions relating first-year decay rate constants (k) to initial litter quality variables for litter of the three species examined.

From Blair, 1988.

Use of litterbags does have its problems. Fine-mesh bags, with openings of 1-2 millimeters (mm), will exclude most macrofauna and thus underestimate decomposition rates. Larger meshes allow larger fragments to escape the bags, thus overestimating decomposition. The microclimate within litterbags tends to be moister than that of unbagged litter, and thus more favorable for microbial activity

□ Coweeta 0.0044 d-1 r2 = 0.9611 • Puerto Rico 0.01130 d-1 r2 = 0.9662 + Costa Rica 0.03420 d-1 r2 = 0.9929

n Coweeta 0.000391 d-1 r2 = 0.9708 • Puerto Rico 0.000554 d-1 r2 = 0.9680 4- Costa Rica 0.00185 d-1 r2 = 0.9901

FIGURE 5.8. Litterbags and masses remaining showing days elapsed (a) and degree days (b) at one temperate (Coweeta) and two tropical (Puerto Rico and Costa Rica) sites (from Crossley and Haines, unpublished, 1990).

(Vossbrinck et al., 1979). In most cases, litterbags probably underestimate actual breakdown rates and do not account for the fate of the fine particulate organic matter that falls from the bags and becomes part of the F, H, and mineral soil organic matter pools (Heal et al., 1997). Their

TABLE 5.3. First-Year Litter Breakdown Rates for Single Species"

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