Genetic Variation in Aspen and Birch May Support More Sustainable Forestry

From Greenhouse to Forest

Led by Postdoctor Sara González Orenga, the project, Field validation of growth and browsing response in European aspen (Populus tremula) and Silver birch (Betula pendula) clones aims to identify tree clones that combine strong growth with high tolerance to browsing—damage caused by animals such as moose and deer.

A central aspect of the research is the transition from controlled greenhouse experiments to field trials. Earlier studies revealed that clones of aspen and birch vary widely in their response to browsing—some recover quickly and maintain growth, while others experience long-term setbacks.

However, greenhouse results are only part of the picture.

“In the greenhouse, we can control everything,” González explains. “But field conditions are much more complex. We need to know whether these differences hold under real environmental conditions.”

To address this, the research team has established field trials where selected clones are planted in replicated plots. Within each clone, individuals are assigned to either control conditions or simulated browsing treatments. Over time, researchers monitor growth, survival, stem quality, and the ability to recover after damage.

Unlocking Genetic Potential

At the core of the project is genetic variation. The researchers are working with a well-characterised collection of clones, ranging from highly tolerant to highly susceptible individuals. Aspen clones were collected from wild populations in Skåne, while birch material represents populations from southern to central Sweden.

This diversity makes it possible to identify key traits linked to resilience, including:

• Ability to resprout after damage
• Maintenance of growth under stress
• Development of straight, high-quality stems
• Efficient allocation of resources between growth and defence 

Early results already show substantial variation between genotypes—an encouraging sign for future selection.

“The extent of variability suggests strong potential for identifying better-performing material,” González notes.

Toward Smarter Forestry

The long-term goal of the project is to support more sustainable and resilient forestry practices.

By identifying clones that can withstand browsing while maintaining productivity, forest managers may reduce their reliance on costly protective measures. At the same time, increasing the use of aspen and birch can enhance biodiversity and strengthen ecosystem resilience.

Looking ahead, González envisions a future where forest regeneration becomes more precise and adaptive.

“If we understand how different genotypes respond to both browsing and environmental conditions, we can start choosing the right tree for the right location,” she says.