The results of a study carried out in a partially-controlled environment1 indicated that competition for nutrients between lodgepole pine (Pinus contorta var. latifolia Engelm.) seedlings and grass, particularly for nitrogen and sulfur which are deficient in soils of the southern interior region, may be important. A later study2 indicated that growth of lodgepole pine seedlings may be restricted by grass sown at densities of 4.5 kg/ha or greater. There was a question of whether grazing to reduce grass competition benefited survival and height growth of lodgepole pine seedlings and transplants.
To provide some of the answers to unresolved questions a project incorporating four separate studies was initiated in 1973 and concluded in 1978. The objectives were to determine:
(a) the effect of different densities of grass plants on the survival and growth of lodgepole pine;
(b) the effect of application of nitrogen (N) and sulfur (S) at various rates on grass productivity and on survival and growth of lodgepole pine;
(c) the effect of individual grass species on the survival and growth of lodgepole pine;
(d) the effect of simulated grazing on survival and growth of lodgepole pine seedlings.
Total biomass of lodgepole pine seedlings was significantly reduced by all densities of grass compared with no grass competition; and height growth of lodgepole pine was significantly reduced by rates of grass sowing equal to or greater than the normally used 4.5 kg/ha to establish grass on clearcuts. Pine survival was unaffected by grass competition.
High rates of N resulted in high grass yields during the first year after application. The effect of more vigorous grass growth on pine development is unknown, and further study of the effect of fertilizer on competition between grass and lodgepole pine seedlings is needed.
The results indicate that early grazing in terms of both stand life and growing period would be beneficial to conifer seedling development by reducing grass competition.
Further details are available in Research Note #86, "Growth of Lodgepole Pine Seedlings in Competition with Grass", by M.B. Clark, which can be obtained from Information Services Branch, Ministry of Forests, 1450 Government St., Victoria, B.C. V8N 3E7.
1 British Columbia Forest Service Res. Note 70, 1975
2 Ministry of Forests Research Note 83, 1978
[Abstract contains full text of memo.]
BC Forest Service - Research Division. 1979. Growth of lodgepole pine seedlings in competition with grass. British Columbia Ministry of Forests, Lands, Natural Resource Operations and Rural Development. Research Memo (FLNRORD). RM37
Topic: FLNRORD Research Program
Keywords: FLNRORD, Research Memo, British Columbia
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