Original paper
Decomposition properties of three leaf species in a beech-maple forest stream and their potential relationship to long-term changes in forest composition
Glass, Nathan T.; DeNicola, Dean M.
Fundamental and Applied Limnology Volume 197 Nr. 2 (2024), p. 159 - 174
60 references
published: Feb 14, 2024
published online: Jan 16, 2024
manuscript accepted: Dec 28, 2023
final revised version received: Dec 26, 2023
manuscript revision requested: Sep 12, 2023
manuscript received: Jun 3, 2023
ArtNo. ESP141019702006, Price: 29.00 €
Abstract
The major energy source in small streams in temperate deciduous forests is from allochthonous inputs of leaf litter. We examined the decomposition of leaves from American chestnut (Castanea dentata), American beech (Fagus grandifolia), and red maple (Acer rubrum) in a headwater stream within a beech-maple forest in the Northeastern U.S. Chestnut was a dominant species in the watershed prior to chestnut blight but has been functionally extinct since the 1930’s. Currently, maple and beech are dominant trees, with maple predicted to increase and beech decrease from climate change. The objectives of the study were to compare mass loss rates, microbial activity (respiration rates), nutritional quality (carbon/nitrogen ratio), and toughness (penetration force) of leaves for the three species and to determine whether the differences among species provide insight into how the fates of litter processing may be influenced by changes in forest composition. Leaf packs of the species were placed in the stream and sampled over 103 days. The molar carbon/nitrogen ratio of leaves decreased over time and was highest for chestnut. Mean microbial respiration rates on leaves ranged from 2.7–8.3 mg dissolved O2/m2/h, and were lowest on beech. Leaf toughness for the three species decreased, with chestnut leaves being tougher than beech or maple. Mass loss was greatest for maple with breakdown rates being 0.013, 0.013, and 0.023, d–1 for chestnut, beech, and maple, respectively. Overall, breakdown rates of beech and chestnut were less than maple because their leaves had less microbial activity and were tougher, respectively. The faster processing of maple leaves would favor rapid mineralization of organic nutrients by microbes, whereas slower processing of chestnut or beech would divert more nutrients within the microbial loop to macroconsumers in the detritivore web. This indicates that long term changes in the relative abundances of these tree species in this region have the potential to affect the fate of energy and nutrients derived from leaf litter. However, successional changes within a watershed affect litter decomposition by more than just changing leaf species diversity. Predicting how disease and climate change may alter the fate of litterfall in streams requires a holistic examination of how compositional changes in watershed vegetation interact with processing under different stream conditions.
Keywords
litter fall • leaf decomposition • leaf breakdown • coarse particulate organic matter (CPOM) • streams • American chestnut • forest composition • climate change • microbial respiration • allochthonous input