Fine root condition relates to visible crown damage in Norway spruce in acidified soils

Abstract

SummaryAllochthonous Norway spruce stands in the Kysucké Beskydy Mts. (north‐western Slovakia) have been exposed to substantial acid deposition in the recent past and grow in acidified soil conditions with mean pH of about 4.0 in the topsoil. We selected 90 spruce trees representing 30 triplets of different crown status: healthy, stressed and declining to assess the relationship between crown and fine root status. Sequential coring and in‐growth bags were applied to each triplet to investigate fine root mass and growth in the soil depths of 0–10 and 10–20 cm. Fine root quantity (biomass and necromass), turnover (production over standing stock), morphological features (specific root length, root tip density) and chemical properties (Ca:Al molar ratio) were compared among the abovementioned health status categories. Living fine root biomass decreased with increasing stress, while the ratio of dead to living biomass increased. Annual fine root production decreased and specific root length increased in stressed trees when compared to healthy or declining trees, a situation which may be related to the position of trees in the canopy (healthy and declining – dominant, stressed – co‐dominant). The Ca:Al ratio decreased with increasing crown damage, indicating a decreased ability to filter out aluminium. In conclusion, fine root status appears to be linked to visible crown damage and can be used as a tree health indicator.