TILLER AND RHIZOME GROWTH ON EXCAVATED SLOPES IN TWO Carex SPECIES FROM COLONIES ON LANDSLIDES

To assist with the revegetation of excavated slopes, experimental revegetation sites were established using two terrestrial sedges, Carex oxyandra, and C. satsumensis, which typically colonize landslides in the Kiso Mountains, Japan. The experimental design comprised a randomized block design with a two-way layout; 2 species x 2 soil types (black-colored soil and weathered granite soil) x 2 replicates. The plot size was set to 1.5 x 0.9 m. Rootstocks of the sedges were collected and 15 rootstocks per plot (1 to 3 tillers per rootstock) were transplanted in May 2019. The number of tillers per ramet was measured at one-month intervals. Rhizome growth was measured by sampling two ramets from each replicate in December 2020. Based on the increase of tillers, both species were capable of growth on both soil types; C. oxyandra showed superior growth on the black-colored soil, while C. satsumensis grew better on the weathered granite soil, and both species showed poor growth in the plot under shaded conditions. Rhizome growth was influenced significantly by species, soil type, and their interaction; the total rhizome length per ramet in C. oxyandra and C. satsumensis was 15.9 to 28.6 cm and 182.1 to 746.2 cm, respectively. The former species produced short rhizomes and dense tussocks from concentrated tillers, while the latter produced numerous extremely long rhizomes and sporadic foliage from horizontally scattered tillers. Since the characteristics of growth differed between the two species, using an optimum combination of both species is considered suitable for early revegetation of excavated slopes.