– finding our future forest trees
Over a period of five years, approximately 18 000 Norway spruce trees will be characterised at different locations in Sweden. The goal is to find the trees that can cope best with the challenges the changing climate brings, and speed up forest adaptation. Landscape breeding is a novel breeding strategy being developed at SLU. It aims to provide new tools for sustainable forest management.
The field site at Bjursjön is still covered in snow. About 1200 spruce trees will be measured here. Photo: Valeria Ciurcina
It is end of March in Västerbotten, Northern Sweden. The days are getting longer but the field site at Bjursjön, about 70 kilometres North of Umeå, is still covered in snow. 1 200 Norway spruce trees will be measured here. The sun is shining brightly, but the nights are still cold. Soon the buds will open and Juha Niemi is longing for the snow to melt so the team can continue with their fieldwork.
Juha Niemi is leading the fieldwork in the Landscape breeding’ project. They haven’t been out in the field since the end of last year. Now, he is meeting with Johan Holmgren, Jonas Bohlin and Eva Lindgren – the remote sensing team – to prepare for the coming season. They are set to take DNA and wood density samples from each of the 1,200 trees at the Bjursjön field site.
With laser scanners and cameras, they are scanning trees from the ground or from above with the help of a drone. Based on these images, they are estimating tree properties like volume and stem quality. They will also assess spring frost damage and fungal infection with this technique, but this will be done mainly on younger trees that are more sensitive.
Juha Niemi is inspecting a potential field site. Photo: María Rosario García-Gil
‘Last year, we spent most of the time developing and optimising our methods and sampling processes. We need to work very efficiently to monitor all 18 000 trees and now we can sample about 120–150 trees per day with one team of 2–3 people,’ says Juha Niemi. ‘The field site in Bjursjön is just one of several sites all over northern and central Sweden, most of them are owned by forestry companies.’
Norway spruce has been growing in Sweden since the last ice age, and is well adapted to the country’s climate. However, it has started to struggle. The winters are getting milder, buds burst earlier and frosts can damage the sensitive young needles. Hot summers with drought periods can weaken the trees further, leaving them more susceptible to infections with harmful microorganisms, which can cause substantial production loss.
In an office at Umeå Plant Science Centre sits Sonali Ranade in front of a computer together with María Rosario García-Gil, who coordinates the project. The two researchers are discussing the DNA analyses that they plan to perform. Sonali Ranade zooms in on a blue line that is displayed in a window on the screen. A repeating series of green As and red Ts appears on the screen. Sonali Ranade has joined the project just recently in the beginning of the year and will be responsible for the genetic part of the project.
A Norway spruce tree in a seed orchard in Söregärde in Kalmar, Sweden. Bags are placed around some flowers to isolate them. Breeders pollinate these flowers by hand with pollen from trees that they have chosen because of their promising properties.
Photo: María Rosario García-Gil
Norway spruce has been present in Sweden for a very long time, but is now struggling with the changing climate. With the help of DNA analysis, breeders can check already in seedlings which characteristics were passed on from the parents. In this way, they can speed up the breeding process to identify those trees that are best adapted to the future climate.
Photo: Anne Honsel
Jonas Bohlin explains to the two students Niwen and Yinging how to maneuver the drone.
Foto: María Rosario García-Gil
Sonali Ranade is responsible for the genetic part of the project. DNA of about 18 000 trees will be compared to understand their relationship. Photo: Anne Honsel
Sonali Ranade explains that closely related trees usually contain similar DNA mutations, and by comparing their sequences, they can understand their relationship. Sister groups that exhibit similar tree properties such as fast growth are likely to pass on this property to the next generation. In combination with local environmental data from the site the tree is growing at – like for example temperature, rainfall, soil properties and landscape topography -, the researchers want to predict how a certain tree performs in a specific environment.
At one field site in Sävar, which was sampled already last year: the LiDAR system, one of the remote sensing technologies used in the project, is scanning the trees in an area of about 10-15 meters around. The white bowles on the stick serve as reference points for the analysis and are needed to construct the 3-D image of the trees. Six of them are placed in a defined distance from the sensor.
Photo: Juha Niemi
María Rosario García-Gil adds, ‘A normal breeding cycle takes about 25 years but the climate changes much faster and the challenges the trees are facing are complex. There won’t be just one type of tree that can withstand all habitats. We need a very diverse stock of trees to work with in future. David Hall from Skogforsk and I have worked closely with the forest industry to find a diverse set of field sites. The greater the diversity, the more flexibility there is.’
Forest geneticist María Rosario García-Gil leads the team of the “Landscape breeding” project that comprises experts in tree breeding and genetics, forest pathology and remote sensing technologies. Foto: Andreas Palmén
Back to Juha Niemi and the remote sensing team who are checking the equipment for the upcoming field season. The tree pathology expert in the team, Malin Elfstrand, is with them. They have several boxes in front of them; plastic bags in different sizes and with different labels are lying next to printed charts with different numbers and a bunch of pens. A black drone is placed on the floor with the remote control in front, next to an open suitcase.
‘Damages are unevenly distributed in the forest landscape both in time and space, therefore I think that detection and measurement methods based on remote sensing will become a valuable tool both for management and tree breeding’, explains Malin Elfstrand and Juha Niemi adds: ‘Frost damage and fungal infections will be mainly measured in Southern Sweden where the snow is already gone. Here in Västerbotten, we had to postpone the start of the sampling season because we got so much snow. But now it finally melts also here and we can soon start again.’
Malin Elfstrand (front) is showing a spruce tree that is infected with a fungus to other members of the “Landscape Breeding” project: David Hal (right), Eva Lindberg (behind Malin Elfstrand), Johan Holmgren (left) and Kenneth Olofsson (second left). Foto: María Rosario García-Gil
The Landscape Breeding research team comprises experts in tree breeding and genetics, forest pathology and in remote sensing technologies. It is coordinated by SLU in close collaboration with Skogforsk, the Forestry Research Institute of Sweden, and RISE, Sweden’s research institute and innovation partner. The goal is to make fast and accurate predictions about the Norway spruce trees that are likely to perform best under certain environmental conditions. The project is funded by the Swedish Foundation for Strategic Research.
How is remote sensing technology used in the Landscape Breeding project?
As part of the Landscape Breeding project, drones equipped with multispectral cameras photograph the trees from above. They detect different light wavelengths and the resulting image displays this in different colours. If a tree is stressed through frost damage or infection, it sends out more red light that has a long wavelength. This enables the researcher to assess the health of the tree.
At the same time, the researchers will be taking pictures of the ground pictures using light detection and ranging, LiDAR, technology. A laser emits light pulses into its surroundings and a sensor measures the time it takes the light to reflect back from the surface it touches. The LiDAR system stands on a tripod and measures the area in a radius of ten to fifteen meters. Each light pulse that returns to the sensor forms one point on the final image. Researchers are then able to extract information such as a tree’s stem volume and the shape of its branches from the resulting 3-D images.
How can “Landscape Breeding” speed up the breeding process?
In conventional breeding, breeders look for trees with desirable properties such as good growth or wood quality. They mate a promising female tree with an interesting male, wait for the seeds and see how the developing offspring performs. All this takes at least 25 years as this is the time it takes until the Norway spruce starts to flower. Modern tree breeding involves DNA analyses to check if genes that determine certain properties are passed on to the next generation. It is possible to do this as early as in the seedling stage, enabling breeders to estimate the quality of the offspring much earlier than in conventional breeding.
Story:
Anne Honsel, Communications Officer, e-mail
Department of Forest Genetics and Plant Physiology, SLU
& Umeå Plant Science Centre
Press / research contact:
María Rosario García-Gil, researcher, e-mail
Department of Forest Genetics and Plant Physiology, SLU
& Umeå Plant Science Centre
Production:
SLU Division of communication, e-mail
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