FUTURE FORESTS RESILIENT TO CLIMATE CHANGE?

A forestry trial in the B.C. Interior could very well provide some clues into what future forests could look like, in the wake of the mountain pine beetle—and those forests could have increased resilience to climate change.

By Jim Stirling

Recently planted tree seedlings near Burns Lake may help provide a vision of tomorrow’s forest landscapes in central British Columbia.

Tree species like western larch and Douglas fir might join spruce, pine and balsam on a more diversified land base with an increased resilience to the influences of climate change.

Frank Varga hopes those seedlings’ adaptability will help indicate the right direction to accommodate changes. Varga is woodlands supervisor-silviculture with the BC Timber Sales’ Babine Business Area at the Ministry of Forests, Lands & Natural Resource Operations based in Burns Lake, B.C. His venture into putting research into practice helped earn him a 2016 climate change innovator award from his peers at the Association of B.C. Forest Professionals (ABCPF).

A fertilizer trial research project is underway at a planting site near Burns Lake, B.C., involving western larch and Douglas fir seedlings along with spruce and pine. The goal is to test the effects of two seedling fertilizer treatments on growth and survival in the four species, and evaluate the differences.

Varga works in a region of B.C. with ample evidence of the consequences of climate change. The region was particularly hard hit by the mountain pine beetle epidemic. The devastating epidemic was in part attributable to stand uniformity and successive years of warmer temperatures during critical stages in the beetles’ life cycles.

Now, spruce bark beetle numbers are exploding in the Mackenzie area and other locations within the Prince George Timber Supply Area. There are still other regional forest health issues influenced by climate change factors. “Rust is quite epidemic in this area. It’s everywhere at extreme densities,” reports Varga.

Clearly, dynamic changes to the forest landscape are continuing.

“Forest managers have to look at that landscape through a different lens and address changes in ways that are scientifically supported and pass professional scrutiny,” explains Varga. He believes the western larch sufficiently meets those standards to merit further investigation.

Some people think the western larch is an introduced species, says Varga. It is not. It is native to B.C. and the tamarack, a type of needle dropping larch, is found in central B.C.

“The western larch has similar properties to Douglas fir in terms of the integrity of its structural strength,” he points out. The wood withstands fire well and can be manufactured into products ranging from panels and beams to furniture, he suggests.

The larch is also a pioneer species that grows fast and responds to the light. Varga reckons there are specific areas that fit the larch climatically. “I think it is our duty as professionals to try it out and put into practice the high levels of research conducted by the Ministry of Forests and others.”

And that is why a tea bag fertilizer trial research project is underway at the planting site near Burns Lake. It involves western larch and Douglas fir seedlings along with spruce and pine. The goal is to test the effects of two seedling fertilizer treatments on growth and survival in the four species, and evaluate the differences.

The test site was conventionally clearcut in 2009-2010. Logging slash was piled and burned, but no further site preparation treatments occurred.

In 2012, the collaborative research project was launched at the site. It involved the BC Timber Sales Babine Business Area through Varga; Reforestation Technologies International; and the regional College of New Caledonia staff.

The project will assess the establishment, survival, early growth performance and frost and snow damage assessment on the 1500 planted lodgepole pine, spruce, western larch and Douglas fir seedlings. The 1500 is considered a statistically valid sample.

Available science and expert opinion suggests that fertilization can dramatically increase seedling growth and performance. “There is also some indication that species not climatically suited to a site may benefit in establishment from early intensive silviculture treatments in anticipation for climate changes,” notes Varga about the project’s scope. Climate-based seed transfer and other research indicates Douglas fir and western larch may well be suited to the Nadina Forest District in north central B.C. in the next 20 to 50 years, he adds.

Conclusions from the Burns Lake trial are a long way off. The four year time span of the project so far barely represents instant gratification for a long lived plant like a tree. But an interesting —if very preliminary—observation from the trial is that moisture availability at the research site appears not to be a limiting development factor for the seedlings’ early growth. “The trees planted with a fertilizer tea bag are doing better than those with the other treatments,” observes Varga.

The 1500 seedlings will continue to be monitored and measured each year until 2017 and subsequently in five year increments. The way the young western larch and interior Douglas fir seedlings respond to the site conditions in the near term should help answer some questions about their longer term suitability to the region’s warming environment while undoubtedly posing new ones.

Varga says he is appreciative of the management level support he’s received from BC Timber Sales to launch and conduct his research project in addition to his regular duties within the ministry’s 
Babine Business Area.