JCS Latvia's State Forests research programme (agreement No. 5-5.5.1_001j_101_23_55)
As part of the Study, the already started observations for the characterization of the long-term environmental effect of fertilizers in all trial groups (use of mineral fertilizers and wood ash in mature and middle-aged spruce, pine and birch stands) have been continued, including the assessment of the effect on groundwater quality, the effect on the composition of understory vegetation and various species and projective coverage of their groups, providing data also needed for carbon cycle modelling. At least 7 years after fertilizer application (the time period most commonly cited as the peak of the fertilizers' effects, after which the effect begins to decline), we will measure stand characteristics in all study plots to characterize the effect of fertilizer on forest health and collect radial growth samples and growth trajectories at individual sites analysis.
In order to assess the effect of fertilizer on climate change and to improve knowledge for characterization of the effect of fertilizer on CO2 uptake, observations of soil heterotrophic respiration and characterization of the effect of fertilizer on ground cover plant biomass have been initiated to acquire knowledge on the one of the least studied aspects of the effect of fertilizer in forestry.
Compared to the previous stage of the research program, the technical capabilities of LSFRI "Silava" for the implementation of remote sensing tasks has improved significantly, therefore, as part of the research, we continue to improve the methodology of remote sensing algorithms for assessing the need for and effect of fertilizer using data obtained with an unmanned aerial vehicle (LiDAR, multispectral and hyper-spectral image series).