Operational Forest Management Learning Applied

- Saturday, January 01, 2022

Operational forest management learning applied: Genetics by site influences on loblolly pine stem form

Through operational plantings and purposeful research projects, at Dougherty & Dougherty Forestry we have purposefully screened and observed hundreds of elite genotypes in operational plantings on differing sites across the SE US. There is much to be learned and applied from these replications.

In 2007, I planted multiple cutover sites across the northern tier of SC, NC and VA with loblolly pine seedlings from a single controlled cross (known pollen from one parent applied to flowers of another known parent) of two elite parents originating from northeast North Carolina and southeast Virginia. The cross parents are well tested for growth and straightness and forking in the NCSU Tree Improvement Program’s Northern Population. This population was not tested by the cooperative for fusiform rust resistance.

This week, I am marking leave trees for thinning in Halifax Co., NC (pictures attached) in one of the remaining still non-thinned regional stands from that establishment year. This particular stand has been through 15 growing seasons and has the lowest percentage of potential sawtimber quality stems (as compared to same aged stands from the same seedling lot planted in Pickens Co., SC; Davidson Co., NC; Harnett Co., NC; Greensville Co., VA and Halifax Co., NC). Stem defects include fusiform rust (35% of the trees), high and low forks (25% of the stems), and crook (25%); some trees have all three defects at the same time! Approximately 30-40% of the trees in this block have defect-free stems, as compared to 70-80% quality stems existing in the Pickens Co., SC and Davidson Co., NC blocks.  A reasoning for purchasing the more expensive mass control pollinated seedlings vs lower cost elite open-pollinated seedlings is the increased stem quality percentage. So, what is going on here? 

Site x genetics is playing out. The term site includes all things, living and dead, that affect the growing seedlings, i.e. soils, climate, pests, harvest residuals, etc.  From my operational experience, this NE NC and SE VA area actually has a fairly high fusiform rust incidence. It also has high tip moth outbreak and potential for ice and wind storm damage, all of which have created opportunities for tissue damage for rust infection or environmental event response forking in this stand over the last 15 years. 

What now? At the stand level, we mark the leave trees and control the thinning quality. At the broader regional level, we take these operational replications of learning and apply them to the next new stands, i.e. we plant this pedigree genotype where is works, and utilize a further improved genotype plus tip moth control as beneficial in Halifax Co. and similar risk zones.  


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