Effects of microforms on the evaporation of peat-bryophyte-litter column
in a montane peatland in Canadian Rocky Mountain
Abstract
Peatland microtopography contains hummocks (local high points) and
hollows (local low points). Little is known about how the
evapotranspiration (ET) of peat (P), peat-bryophyte (BP), peat-litter
(LP) and peat-bryophyte-litter (LBP) columns varies with peatland
microforms. That is, whether there are fine-scale variations in peatland
evaporation, and if they are critical when being upscaled to the entire
peatland ecosystem is yet to be answered. This study found that ET was
significantly affected by cover type (P, BP, LP or LBP) and the
interaction effect of the cover type and microform, based on the field
evaporation experiments in a montane peatland in the Canadian Rocky
Mountains, during the growing season of 2021. Mean daily ET of P-Hummock
and P-Hollow is 14.16 and 11.76 g d -1, respectively;
BP-Hommock and BP-Hollow is 9.57 and 14.38 g d -1,
respectively; LBP-Hummock and LBP-Hollow is 9.44 and 9.91 g d
-1, respectively; and evaporation of LP-Hummock and
LP-Hollow is 5.68 and 7.64 g d -1, respectively.
Peatland microform indirectly affected ET through interactions with
cover type, modifying the vertical profile of soil temperature, and
changing key environmental drivers of evaporation. Moreover, the ability
of two widely used models in modelling the spatial variation of peatland
evaporation were also tested. It was found that Penman-Monteith (P-M)
model and the bryophyte layer model in the Atmosphere-Plant Exchange
Simulator (APES) were able to yield satisfactory results based on field
measurements of soil temperature and soil moisture. This study supports
developing more practical evaluation tools on the hydrological state of
peatland ecosystems.