Jac Fire Lodgepole Pine Root Form Trial

JAC FIRE LODGEPOLE PINE ROOT FORM TRIAL¹

—WHAT DO 16-YEAR OLD LODGEPOLE PINE ROOTS LOOK LIKE?—

Rob Scagel
Pacific Phytometric Consultants, 1531 133B Street; Surrey, B.C.; V4A-6A5

Abstract - Concerns about the use of copper root-pruning in the nursery and the sustained outplanting benefits of this nursery treatment are examined. This tour provides an opportunity to review the growth of eight stock types of lodgepole pine. The focus of the tour is an examination of the root growth characteristics of the major competing stock types: copper-treated hard-wall container (PCT) untreated hard-wall containers (PSB), bare root (BR), and direct seeded (DS) sixteen years after planting. Survival, growth, and root egress characteristics for the first five years are reviewed in this note. Results of other work on this trial will be reviewed in the field. Root growth characteristics and interactions with the site conditions will be reviewed in the field. The tour is followed by a discussion of the perspectives on the outplanting benefits of copper root-pruning.

¹Prepared for: BC MOF, Nursery Extension Services.

Figure 1. Forest cover and sits history map for Jac Fire trials. Dashed line indicates tour route.

TRIAL OBJECTIVES

The original objectives of the trial were to assess the root development of seven lodgepole pine stock types and to compare these stock types with the naturally grown (i.e. direct seeded) seedlings. The trial was to be assessed for root form, toppling incidence, and performance (survival and growth). The trial is unusual because all of the seedlings are the same age from seeding. In addition to these objectives the trial has also been used as part of a force toppling study and repeated excavations have been made over the last four years. The trials were measured at two and five growing seasons. There has been no further measurement.

SITE CONDITIONS AND HISTORY

The site is at 1000m in the Moist Warm SBS (SBSmw). The site is regarded as a zonal ecosystem (SBSmw .01 - SxwFd - Falsebox) but with a moisture/ nutrient regime at the wet/ rich end for this site association. Fdi, Pli, and Sx are all considered Preferred regeneration species on this site. These sites are prone to dense shrub and herb competition.

The site was previously dominated by lodgepole pine with a minor component of spruce. The site was logged in 1970 and broadcast slash burnt in 1971. The site was burnt again in 1978 by a 400 ha wildfire. The trial was established immediately after the wildfire. The site is now dominated by a dense herb layer and sporadic aspen and willow. In the past two years root collar weevil attack has damaged and killed a number of trees in the trial area.

The demonstration tour encompasses two openings (IV, V; Figure 1). The eastern portion of the tour passes through an area (IV) that was not planted immediately after the 1978 wildfire. This unit is still considered NSR even after mechanical brushing in 1992 and fill planting in 1993 with spruce and lodgepole pine. The lack of stocking, poor stem distribution, and erratic growth in this area contrasts strongly with the trial area and emphasizes the benefits of prompt planting following harvesting or disturbance.

STOCK TYPE

Eight stock types of the same seedlot (Pli 3589) of lodgepole pine were used. All stock was grown by the BC Ministry of Forests at either Skimikin or Surrey Nursery. The performance of only four stock types will be reviewed in this note although the other stock types are labelled in the field.

STOCK TYPE DESCRIPTION

At planting the operational stock types met the morphological specifications required of for lodgepole pine (Table 1). Stock description notes indicated that the PCT seedlings lacked an extensive roots system and the plugs broke easily into sections. Other notes suggested that the copper treatment was excessive considering the size of the seedling.

PERFORMANCE

After five growing seasons there were no statistically significant differences in survival between the two container stock types (Table 2). The BR and direct seeded stocktypes had statistically significant lower survivals than the container stock types. After five growing seasons there was similarly no statistically significant difference in height or diameter between the two container stock types. The BR stock type was significantly larger than all other stock types and the direct seeded stock type was significantly smaller than all other stock types

ROOT EGRESS

Photographs of excavated roots after two and five growing seasons are shown in Figure 2 and Figure 3.

The root egress characteristics after five years are summarized in Table 3. There were no statistically signifcant differences in the mean diameter fo the five largest roots among the different stock types, although the PCT were smaller thatn the PSB stock type. The PSB stock type was the deepest rooted stock types. There were no statistically significant differnces between the stock types for angular root distribution. The PSB stock type had the most trees with a significant lean.

Table 3. Root egress characteristics after five growing seasons. Position of roots based on a three point scale: 1, top third; 2, middle third; 3, bottom third