Do wood ants play an important role in carbon and nutrient dynamics in boreal managed forests? (ANTS)

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Aims of the project and hypotheses
Background
Cooperation, members of the project
Study areas
Methods and measurements
Contact information
Publications

Photo:Timo Domisch Intensive study mound

Methods and measurements

Continuous measurements

One mound in one stand of each age class is focus of more intensive measurements. Temperature and moisture content of the mound are recorded continuously. The radial growth of sample trees around the mound is recorded continuously, as well.

Distribution and density of ant mounds

Photo:Timo Domisch Ant mound inventory

All red wood ant mounds in the study sites were inventoried, their physical properties (height and diameter) were measured, and their location was determined with GPS. Ant samples were taken for determining the ant species.

Carbon and nutrient pools

Samples from different-sized mound were taken from all study sites for determining carbon and nutrient concentration of the mound material. Samples were also taken from the underground part of the mounds and from the surrounding forest soil. A regression method is used for estimating the carbon and nutrient content of all mounds in the study sites.

Photo:Mizue Ohashi Measuring CO2 efflux from ant mound

Carbon and nutrient fluxes

Four median-sized mounds are selected from each age class for carbon and nutrient flux studies. The mass, carbon and nutrient content of honeydew, prey and mound building material is determined in intervals of two weeks, by monitoring the ants as they enter the mound, and taking prey and litter samples at certain intervals. A certain amount of ants entering and leaving the trees and the mound is weighed for determining the amount of honeydew carried into the mound. CO2 emissions are measured throughout the year in intervals of 2-4 weeks with big chambers covering the whole mound. These emissions are compared to those measured from the forest floor. The decomposition and mineralisation of nutrients from organic material (Norway spruce needle litter) is followed using the litter bag technique over a period of two years.

Photo:Leena Finér Growth and glue bands

Tree growth

For examining the effect of the ant-aphid-relationship on tree growth, sample plots around each intensive study mound were established. The occurrence and visiting frequency of ants on sample trees is assessed by conducting ant traffic counts from May to October. We prevented the ants from visiting half of the selected trees around the ant mound by putting a glue band around the stem. The radial growth from sample trees is recorded continuously, and at the end of the study period, we take a core sample of each monitored tree, and compare the diameter growth in trees with aphids (no glue band) and those without aphids (glue band). The tree responses will be also compared to the amount of honeydew collected from each tree by the ants.