Poor Survival and the Physiological Condition of Planting Stock

Abstract

OVER 'I'•rELVE MILLION tree seedlings have been planted in California during the last five years at a cost of $830,000fi Accurate survival data on these twelve million seedlings are not available. The best estimate, however, places it considerably below fifty percent. = This poor survival is obviously cosfly and of considerably concern to those responsible for planting in California. Part of the planting failures are attributable to rodents, livestock, and competing vegetation. a On the other hand, there are instances in which the reason is not apparent ; not even the long summer drought nor the high temperatnres associated with Catifornia's Mediterranean-type climate are satisfactory explanations. For some time the author has felt that the failures are related to the physiological condition of the planting stock. This concept is not by any means or/gina] with the author. Both Fowells and Dunning of the XAnnual planting and stand improvement reports, U.S. Dept. Agr. For. Serv. Region 5, for fiscal years 1950-1954. '-'Dunning, D. and B. M. Kirk. 1939. The Burney Spring plantation: a reforestation ex-perlment in the brushfields of northern Cali-fornia. U.S. Dept. Agr. Calif. For. and Range Exp. Sta. unpub. rep. aFowells, H. A. and D. Dunning, 1948. A survey of National Forest Planting in Cali-fornia since 1930. U.S. Dept. Agr. Calif. For. and Range Exp. Sta. unpub. rep. California Forest and Range Experiment Station have implied as much in their effort to explain low survivals. Additional support for such a viewpoint can be found in Wakeley's work on the southern pines. 4 He found that the correlation between morphological grades of stock and survival was often poor. The same morphological grade from different plant beds within the same nursery often gave very different survival values when planted together in the field. The present preliminary study was un-dertaken for the purpose of determining whether or not physiological conditions re-sulfing in low survival do occur. The questions of how such physiological conditions might be altered if they occur and to what extent they might be geneticall), controlled were not considered. In the light of the results presented below, however, experiments are now being set up to study the problem in its enth'ety. Failure of either the root system or the