Bulk deposition of base cations in a subalpine natural forest landscape
estimated by canopy budget model: A focus on the forest edge canopy
Abstract
Calculations of base cation inputs of loads in forest edge canopies are
rare, although forest edge canopies play a paradoxical role in the
effective capture of atmospheric deposition. Throughfall deposition and
canopy exchange of base cations were studied with a continuous
throughfall investigation under a natural forest edge and a closed
canopy in a subalpine forest over a period of 2 years. Compared with
precipitation, the concentration of base cations in the throughfall of
both canopies was enriched as expected, but the enrichment level in the
forest edge was less than that in the closed canopy. Moreover, the
throughfall deposition of base cation fluxes in the closed canopy (35.19
kg ha-1 y-1) was slightly higher than that in the forest edge canopy
(33.50 kg ha-1 y-1). Seasonally, the base cation input in the rainy
season was 2.32–2.70 times higher than that in the snowy season in
throughfall in forest edge canopy and the closed canopy. Furthermore,
the canopy budget model suggested that the direction and magnitude of
canopy exchange and dry deposition controlled the net throughfall fluxes
(NTF) of base cations, and obvious differences could be observed between
the canopy and seasonal scales. Compared with other elements, K and Mg
leached from the main canopy exchange process, while Ca was absorbed by
both canopy types in the annual NTF. These results highlight the spatial
variability of base cation chemical characteristics, enhance cognitive
the deposition of nutrients and regulatory factors in different forest
landscapes, preferably guide the formulation forest ecological
management strategies.