Cation exchange properties of forest litter as influenced by vegetation type and decomposition

Decomposition of forest litter As a complex processinvolving interactions between physical, chemical andbiological factors. As litter decomposes it is chemicallyaltered. Cation exchange capacities of litter represent ameans of characterizing the number of hydrophilic acidgroups. Some kind of soil-root ion exchange mechanisms areutilized by the plant for uptake of most nutrients.
Cation exchange capacities were determined by ammoniumsaturation and subsequent Kjeldahl distillation. Solventextractions of some litters were made with water at threedifferent temperatures, and with isopropanol, ethanol,acetone, water, NaOH, and HCl. The extracted litter wasused for CEO determinations.
A variety of forest floor materials from differentforest types in Eastern North America and Oregon were usedin this study. L, F, and H layers were used to determinethe effect of decomposition on CEC. Significantly increasedCEC magnitudes with increased decomposition was shown for
- _ the OregOn samples. Eastern forests also showed increased
CEC's with increased decomposition except where high ashcontents of an H layer resulted in lower CEC values.
Litter samples from the various Oregon forest typesshowed significant differences in CEC's between vegetationtypes. Litters from more productive timber sites hadgreater CEC values for L and F layers than litter from lessproductive sites.
Organic solvents extracted significantly less materialfrom litter than inorganic solvents. Hot water extractedmore material from litter than cooler temoerature water.CEC's of litter extracted with organic solvents were lowerthan CEC's of litter extracted with inorganic solvents.
Litter collected from streams showed CEC values forbark to be highest and twigs to be lowest. Litter thatwas more highly decomoosed by stream activity had higherCEC's than less decomposed samples.
Pre- and post-logging samples that represented combinedL F + H layers did not show significant differences in CECvalues between vegetation types.