In 1982, a large-scale experimental project (EP841) was initiated in the Cariboo Region of south-central British Columbia, which is climatically transitional between the northern and southern portions of the province and thus features a wide diversity of climatic and site conditions. This project includes four individual site preparation studies and experimental installations on 10 sites. The potential of scalping, ripping, plowing, and trenching techniques to improve planted conifer seedling survival and growth outcomes were examined in the dry, cool Interior Douglas-fir (IDF) and dry, warm Sub-Boreal Spruce (SBS) biogeoclimatic zones. Although some installations included hybrid spruce and ponderosa pine, the project's primary focus was on survival and early growth of Douglas-fir and lodgepole pine. It sheds light on plantation management issues that are currently important in both zones. This study demonstrates that site preparation is a useful tool for improving survival of planted Douglas-fir in both the SBSdw and dry IDF subzone/variants. Especially in the SBSdw, the positive outcomes contradict the belief that establishing planted Douglas-fir is an insurmountable challenge. Given the extent to which lodgepole pine has dominated regeneration programs in the Central Interior during the past three decades and our increasing awareness of health problems affecting this species, encouraging Douglas-fir establishment is highly desirable. Although the IDF is clearly a more challenging regeneration proposition than the SBSdw, the use of an appropriate site preparation technique in combination with cattle management resulted in at least moderate Douglas-fir survival on the majority of sites examined in the EP841 experiments. Overall, the encouraging survival responses of Douglas-fir to site preparation were the most important findings of this project.
Newsome, T.A., Heineman, J.L.; Nemec, A.F.L.. 2016. Long-term results from EP841: Douglas-fir, lodgepole pine, and hybrid spruce responses to mechanical site preparation in the Interior Douglas-fir and Sub-Boreal Spruce Zones of South-central British Columbia. Forests, Lands, and NR Operations. Technical Report (FLNRORD). TR92