Seed production and cone-feeding insects of Pinus pumila on the Kamtchatka Peninsula: aspects of coexistence

Abstract

Insects attacking seeds and cones of trees are significant for their economic consequences as well as for the ecological role in vegetation dynamics. Currently much is known about seed and cone insects feeding on upright trees (see Roques, this volume), but almost nothing is known about cone inhabitants of prostrate pines Pinus pumila (Pall.) Rgl., P. albicaulis Engelm., P. mugo Tur. These three vicariant species from young mountain systems of the northern hemisphere have evolved in unfavorable environments which have favored peculiar patterns of seed production and insect-host relations. Cone insect populations are strictly determined by well known periodicity of seed production which often causes the evolution of diapause in cone-feeding insects. This phenomenon occurs in upright trees and is perfectly illustrated by Lasiomma melania on Larix kamtchatica on the Kamtchatka Peninsula. Unlike Larix, Pinus pumila, whose seeds develop over 2 years, has peak crops every 2 to 3 years but in fact produces some cones every year. This happens because seeds are produced on mosaically dispersed local patches of trees varying in micro-climate and other environmental factors. There are small, contiguous patches of good seed production in almost each region. Another important feature of the stochasticity of seed production is that seed dispersal is affected by the nutcracker, Nucifraga caryocatactes L., which leads to wide exchange of genetic material, and, consequently, to high ecological valency of the tree species. In sharp contrast to the typical strong antibiosis towards xylophagous insects: the trees apparently tolerate parasitic-commensal relationships with the seed and cone feeding species.

Parent Publication

• Forest Insect Guilds: Patterns of Interaction with Host Trees

Citation

Khomentovsky, Petr A.; Efremova, L.S. 1991. Seed production and cone-feeding insects of Pinus pumila on the Kamtchatka Peninsula: aspects of coexistence. In: Baranchikov, Yuri N.; Mattson, William J.; Hain, Fred P.; Payne, Thomas L., eds. Forest Insect Guilds: Patterns of Interaction with Host Trees; 1989 August 13-17; Abakan, Siberia, U.S.S.R. Gen. Tech. Rep. NE-153. Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 316-320.