Bark beetle-induced tree dieback affects water quality
The bark beetle-induced tree dieback (2004-2008) in a nitrogen saturated, chronically acidified but recovering catchment of Plešné Lake, Czech Republic, resulted in pronounced changes in water chemistry.
After a short decline in lake water pH immediately after tree dieback, the ecosystem recovery from acidification accelerated and the carbonate buffering system was restored by 2011, after 6 decades of depletion by acid rain.
Major reasons for this rapid transition were changes in intensity of in-lake biogeochemical processes. Terrestrial exports of protons (H+), nitrate (NO3–), dissolved organic carbon (DOC) including organic acid anions (A–), phosphorus (P), ionic aluminium (Ali), and their proportions underwent pronounced changes. In-lake denitrification, elevated NO3– assimilation (due to elevated P input), and photochemical/microbial oxidation of A– were the most important H+ removing processes, while Ali hydrolysis was the most important H+ source. Phytoplankton biomass increased with elevated P inputs and increasing P availability, which resulted from reduced in-lake formation of Al hydroxide (and thus less adsorption of P) and more intensive P recycling by zooplankton.
The rapidly changing lake water chemistry and elevated P availability after tree dieback in
the catchment have enabled further biological recovery of Plešné Lake from acidification.
Paper was published in Limnology & Oceanography (2019, 64, 1614-1626).
