Soil temperature follows the changes in the air temperature with a time lag that increases with soil depth. Close to the soil surface, the variation in temperature is larger than, for example, half a meter deep in the soil. In summer, the soil surface warms… Read More »Soil temperature
Water plays an important role in the biological and chemical processes occurring in the soil. Together with soil temperature, they affect carbon and nitrogen cycles in forests. The soil of our site is moraine, like most of the soils in Finland. This kind of soil… Read More »Soil moisture
The carbon used for ecosystem growth (net primary production, NPP) is eventually transferred to the soil in litter fall, root turnover and death of individual plants. In addition, trees notably allocate carbon to the root systems for root growth and root maintenance. Carbon is also… Read More »Soil respiration
Plant needs energy for growth, transport and maintenance of vital functions as animals do. To get the energy required, they oxidize (i.e. burn the photosynthetically fixed sugars). At the same time, water and carbon dioxide are released as waste products. Respiration occurs in all living… Read More »Plant respiration
We measure the shoot respiration by the same measurement setup as photosynthesis. Trunk respiration needs a special measurement chamber. Root respiration cannot, however, be measured directly. We derive the root respiration from the CO2 exchange at forest floor where the flux is a sum of… Read More »Measuring shoot respiration
Years of measurements have produced a lot of information on plant respiration. We know more or less how the respiration rate is related to the changing environmental conditions. In principle, respiration exponentially follows temperature. The temperature dependence, however, decreases in low soil water (REW). These… Read More »Modelling shoot respiration
Gases enter and leave the leaf through stomata, which actively control the gas exchange of CO2 and H2O, for example, between the plant and the atmosphere. Plants need to keep the stomata as open as possible to obtain atmospheric carbon dioxide but at the same time,… Read More »Stomata action
The diurnal and annual cycle in solar radiation is reflected into air temperature by the absorption of solar radiation. The annual cycle in the radiation generates the annual cycle in temperature. The temperature reaches annual maximum and minimum about one month later than radiation. In the… Read More »Air temperature
The water holding capacity of air depends sharply on the air’s temperature (i.e. the warmer the air is, the more water it can hold). At a given temperature, air is saturated when it reaches the maximum water holding capacity that is also known as the… Read More »Air humidity
In the Northern Hemisphere, the CO2 rises in the winter and declines in the summer, mainly as a response to the seasonal activity of forests, other land vegetation and algae which all absorb atmospheric CO2 both in oceans and in terrestrial biospheres and release it by heterotrophic… Read More »CO2 concentration