| Comminution of forest leaf litter by millipedes affects litter decomposition and nutrient cycling. The millipede Harpaphe haydeniana Wood (Polydesmida: Xystodesmidae) is common in low to mid-elevation forests on the Pacific Coast of North America.; In a series of experiments, the suitability of broadleaf and conifer tree litters for growth of juvenile H. haydeniana was investigated. First, in a 14 day feeding trial, feeding rates for adult and juvenile H. haydeniana on red alder (Alnus rubra Bong.), big-leaf maple (Acer macrophyllum Pursh) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) litter were measured gravimetrically. All three litters were consumed at similar rates.; Next, the three fitters, along with two others and an equal-part litter mixture, were used to rear juvenile H. haydeniana for 99 days. Multiple regression was used to relate millipede growth and litter chemistry (%N and %Ca). Litter %Ca was significantly related to millipede growth. Within the three conifer litters, litter %N had no significant relationship to growth. Growth was poor in alder, possibly because of the phenolic content.; In a second experiment, the nutrient content of Douglas-fir litter was modified by adding N, Ca and cellulose. Growth of juvenile H. haydeniana was increased by both cellulose or Ca and decreased by N. Millipede carbon and nitrogen stable isotope ratios suggested that cellulose increased millipede growth by increasing microbial biomass, while Ca increased millipede growth by increasing millipede assimilation of plant C and N. Although the low N content of leaf litter is generally cited as the reason for slow growth rates in detritivores, adding exogenous N did not increase millipede growth, nor were δ15N values in millipedes consistent with N-limitation.; And finally, stable isotope ratios in millipedes and other detritivores in a natural system were described. Three age classes of millipede ( Nearctodesmus insulanus (Polydesmida: Nearctodesmidae) were present. The δ15N of adult N. insulanus was significantly higher than 6th or 7th stadium juvenile millipedes, suggesting that adults may have been feeding on a different resource than the juveniles, or that their N balance may differ from the juveniles. |
