engleski

Leaf Litter Breakdown in Tufa Depositing Water: A Short Term Experiment at Plitvice Lakes, Croatia

Three questions were raised regarding the effects of leaf litter on tufa barrage lake system. Does leaf decomposition hinder tufa deposition (and vice versa)? What role do other environmental factors play? How long does leaf litter persist in the tufa barrage habitats? We used riparian, woody vegetation- beech (Fagus sylvatica L.) and immersed, herbaceous vegetation- butterbur (Petasites hybridus (L.) P. Gaertn., B. Mey. & Scherb.). Leaves were collected upon defoliation (beech) or cut (butterbur) and exposed for 8 weeks at 8 different microhabitats on tufa barriers: 2 tufa deposition rates x 2 flow velocities x 2 temperature spans. Butterbur leaves expectedly broke down significantly faster. However, neither litter type conformed to the previously proposed exponential breakdown model. A linear model was more suitable. Still, this should be taken cautiously since the linear model does not explain the extreme loss of leaf mass in the first week (11 % of beech and 56% of butterbur leaf mass). Mean persistence time extrapolated using the linear model is 62 days for butterbur and 442 days for beech. The inorganic-organic matter ratio did not change significantly during the breakdown. Beech leaves breakdown was significantly faster at higher flow velocity and tufa deposition rate sites. Butterbur breakdown was significantly faster at higher flow velocity, tufa deposition rate sites and at higher temperature. Proportion of deposited tufa increased linearly with time despite the decrease of leaf mass. Tufa deposition rates were higher on the faster decaying litter type (0.032 g per g of butterbur leaves per day ; 0.022 g per g of beech leaves per day). Taking into account faster decomposition of both litter types at high tufa deposition rate habitats, we conclude that tufa deposition is not hindered by decaying processes (and vice versa). The results also imply that the shredder fauna does not play an important role in leaf breakdown (mass loss even when calcified).

leaf litter; tufa; Croatia

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