Effect of soil temperature on root and shoot growth and on budburst timing in conifer seedling transplants

Abstract

Application. In standard (4-week) tests of root growth potential (RGP) of western conifers, root media temperature should be maintained at 20 "C for most species, and possibly higher (23-25 "C) for low-elevation sources of ponderosa pine. A high root media temperature (30 "C) should be avoided with Douglas-fir, Pacific silver fir, noble fir and possibly other true firs because root growth in these species is inhibited by high root temperature.Abstract. Root growth in seedling transplants of Douglas-fir (Pseudotsuga menziesii (Mirb.) France), Pacific silver fir (Abies amabilis@ougl.) Forbes), noble fir (Abies procera Rehd.), lodgepole pine (Pinus contorta Dougl. ex Loud.) and ponderosa pine (Pinus ponderosa Doug. ex Laws.) began when soil temperature exceeded 5 "C. Root growth increased rapidly after 10 "C and attained maximum values at 20 "C. At 30 T, no root growth occurred in the firs; in the pines, root growth was 30 to 39% of maximum. Maximum shoot growth also occurred at 20°C. In ponderosa pine, height growth of seedlings from a high-elevation source was unaffected by cold soil, but in low-elevation seedlings it was reduced. Budburst in Douglas-fir and the pines was delayed up to 11 days by cold soil, whereas in silver fir and noble fir, it was only slightly delayed. Prior to new root growth in ponderosa pine, xylem pressure potentials and stomatal conductances during the afternoon indicated reduced stomatal opening at all soil temperatures, whereas 23 days later, stomata were open to a greater degree when temperatures exceeded 10 "C.

Planted stock performance 10 years after partial cutting in west-central British Columbia

“…Particularly at the higher elevation MSxv sites, average soil temperature was barely adequate for root growth in the partial cut areas (7.1-8.0ºC). Generally, root elongation is minimal until soil temperatures warm to at least 5°C (Lopushinsky and Max 1990), beyond which root elongation rates increase linearly with increasing soil temperature to a maximum at about 16°C to 20°C (Andersen et al 1986).…”

Effects of soil warming and nitrogen foliar applications on bud burst of black spruce

“…Since the advancement of the bud burst depends on the level of increase in soil temperature (Lopushinsky and Max, 1990), it seems that the effect requires a period of adaptation for trees. However, the effect of the treatments on bud burst was not considered in the years prior to this study, so it cannot be excluded that some changes had taken place previously.…”

Climate change effects on vegetation in the Pacific Northwest: a review and synthesis of the scientific literature and simulation model projections

“…Plant phenology in temperate woody plants is largely controlled by winter and spring temperatures and by photoperiod (Polgar and Primack 2011). Processes infl uenced by temperatures include the initiation of fl owering (Dunne et al 2003), budburst (Guak et al 1998, Harrington et al 2010, Worrall 1983, root growth (Lopushinsky and Max 1990), and cold hardening (Guak et al 1998, Saxe et al 2001. For example, Worrall (1993) reported that budburst in subalpine larch (Larix lyallii Parl.)…”

“…varied by up to 6 weeks and leaf-fall varied by up to 4 weeks from year to year and that both were correlated with spring and summer temperatures. Similarly, Lopushinsky and Max (1990) used a greenhouse study to show that root growth began when soil temperatures exceeded 5 °C.…”