Effect of Litter Layers on the Establishment of Orchardgrass (Dactylis glomerata L.) Oversown in the Cutover Land of Deciduous Broad-leaved Forest

The rolling land of marginal mountain area in Japan, actually used for extensive forestry, is considered to be promising area to develop pastures for the cow-calf program of beef-cattle. However, the cost of pasture establishment is very expensive mainly because of the high application rate of chemical fertilizers. The objective in a series of the experiments is to develop the low-input method of pasture establishment by the effective use of tree litter sources. In this report, the effect of litter layers on the establishment and overwintering of D. glomerata oversown in the cutover land of deciduous broad-leaved forest without chemical fertilizers is presented. L, F and H layers on the forest floor were perfectly remained in the experimental field just after clear-cutting. Three kinds of seed-bed preparation plots were conducted with different degrees of disturbance of litter layers : I ; Removing the whole litter layers, II ; Removing L and F layers, III ; No disturbance. In August of 1982, one week after seed-bed preparations, D. glomerata was oversown without fertilizers in each plot. Results are summarized as follows : 1. Physical factor of litter layers negatively influenced on the emergence of D. glomerata. But the individual growth of the seedling was stimulated by chemical factor of litter layers. At the beginning of winter, the population numbers of D. glomerata in the I, II and III plots were 240, 152 and 184 no./m^2, respectively. 2. Land F layers, only remained in the III plot, prevented winter killing of the seedlings by their physical factors, so that the population number of D. glomerata in the III plot approximated to that of the I plot in next spring. The lowest number was obtained in the II plot. 3. The invasion of native plants was obviously inhibited by physical factor of litter layers. Particularly winter annual plants, which had a stiff competition with D. glomerata after spring, rarely appeared in the II and III plots. 4. The growth of D. glomerata was the highest in the III plot due to low copetition and high nutrients released from litter layers. In June of 1987, 10 months after sowing, the maximum standing crop weight of D. glomerata was obtained in the III plot (58.2 DM g/m^2), which was about 5 times more than that in the I plot. From these results, it was evident that litter layers of deciduous broad-leaved forest should be remained as much as possible in the seed-bed at the phase of pasrture establishment of D. glomerata. Furthermore the effective use of the litter sources opens possibility for the pasture establishment without application of chemical fertilizers.