Litter quality influences on decomposition, ectomycorrhizal community structure and mycorrhizal root surface acid phosphatase activity

The influence of litter quality on root growth, ectomycorrhizal communities and decay processes was investigated through a litter bag experiment. Litt er bags containing either pine needles, oak leaves or oak+ pine mix were pl aced within the O horizon of a lowland pitch pine (Pinus rigida) forest in the New Jersey Pinelands. Upon retrieval, ingrown pine roots were removed a nd quantified for total length and percent ectomycorrhizal colonization by morphotype. Phosphatase activity was determined for dominant morphotypes. I n addition, litter decay rates and N and P litter content were measured. Mi xed litter (oaks pine) had highest total pine root ingrowth. Dominant ectom ycorrhizal morphotypes differed in response to litter type. A tuberculate f orm dominated (35%) in pine litters while distinctly different nontubercula te morphotypes dominated in oak and mixed litters. High phosphatase activit y of morphotypes was correlated with high phosphorus immobilization during oak leaf decay. Results indicate that a mix of forest litters (oak and pine ) optimizes retention of scarce nutrients such as nitrogen and phosphorus. The diverse chemical environment of these different litter types induces di fferent ectomycorrhizal community development which show functional differe nces in the way phosphorus is likely to be cycled. The influence of litter type on diversity and function of ectomycorhizae is an important step in id entifying linkages between biodiversity of this group and ecosystem functio ns. (C) 2000 Elsevier Science Ltd. All rights reserved.