The role of physical properties in controlling soil nitrogen cycling across a tundra-forest ecotone of the Colorado Rocky Mountains, USA

There is growing recognition that physical characteristics of landscapes influence nitrogen (N) cycling. The relationships among climate forcing, soil properties, and the fate of N are particularly important in alpine ecosystems vulnerable to climate warming and characterized by shallow, rocky soils...

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Bibliographic Details
Published in:CATENA
Main Authors: Chen, Youchao, Wieder, William R., Hermes, Anna L., Hinckley, Eve-Lyn S.
Format: Report
Language:English
Published: ELSEVIER 2020
Subjects:
Global change
Critical Zone
Nitrate ion
Spatial distribution
Niwot Ridge
Geology
Agriculture
Water Resources
Geosciences
Multidisciplinary
Soil Science
NET-N MINERALIZATION
GREEN LAKES VALLEY
ENVIRONMENTAL CONTROLS
ECOSYSTEM RESPONSES
CLIMATE-CHANGE
LONG-TERM
ALPINE
SNOW
TRANSFORMATIONS
VEGETATION
Tundra
Online Access:http://ir.ihb.ac.cn/handle/342005/35135
https://doi.org/10.1016/j.catena.2019.104369
Description
Summary:There is growing recognition that physical characteristics of landscapes influence nitrogen (N) cycling. The relationships among climate forcing, soil properties, and the fate of N are particularly important in alpine ecosystems vulnerable to climate warming and characterized by shallow, rocky soils. This study evaluated differences in net N mineralization and nitrification rates determined using in-field incubation experiments across patches defined by six plant community types within an alpine catchment of the Colorado Rocky Mountains. We considered not only differences in net N transformation rates across space and time within a growing season, but also whether or not soil properties (i.e., physical and chemical) and conditions (i.e., temperature and moisture) could explain patch-scale variation in rates. Highest net N mineralization and nitrification rates occurred in the dry meadow (3.7 +/- 0.5 and 3.4 +/- 0.5 mu g N cm(-2) d(-1), respectively), while the lowest were in the subalpine forest (-0.3 +/- 0.4 and 0.0 +/- 0.1 mu g N cm(-2) d(-1)), which exhibited net N immobilization. The magnitude of differences in net N transformation rates through time differed among patches and was strongly controlled by soil C:N ratios. Dry and moist meadow communities showed the greatest range in net N transformation rates across the growing season and changes were positively correlated with soil moisture. In contrast, inhibition of nitrification at high soil moisture occurred in wet meadow areas. Our data suggest that as the alpine growing season lengthens in a drier, warmer future, changes in soil moisture will likely be a primary factor driving patterns of net N transformation rates.

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