Watershed Buffering of Legacy Phosphorus Pressure at a Regional Scale:A Comparison Across Space and Time

Kusmer, A. S. and Goyette, J.-O. and MacDonald, G. K. and Bennett, E. M. and Maranger, R. and Withers, P. J. A. (2019) Watershed Buffering of Legacy Phosphorus Pressure at a Regional Scale:A Comparison Across Space and Time. Ecosystems, 22 (1). 91–109. ISSN 1435-0629

[img]
Preview
PDF (Kusmeretal_Buffering_Manuscript_ecosystems_submission)
Kusmeretal_Buffering_Manuscript_ecosystems_submission.pdf - Accepted Version
Available under License Creative Commons Attribution-NonCommercial.

Download (2MB)

Abstract

Phosphorus (P) plays a crucial role in both agricultural production and water quality. There has been growing recognition of the importance of ``legacy'' P (surplus P that has accumulated in watersheds over time) for understanding contemporary water quality outcomes; however, little is known about how different watersheds respond to cumulative pressures from surplus P. The ``buffering capacity'' concept describes the ability of watersheds to attenuate P loading to surface waters by retaining P inputs over time. To explore the role of various watershed characteristics in buffering capacity, we used historic P data to calculate indices describing long- and short-term buffering for 16 large watersheds in southern Quebec, Canada, across a 30-year time span (1981--2011). We examined the correlation between these buffering capacity indicators and a set of key geochemical, hydrological, landscape and socio-ecological variables that we hypothesized could influence P buffering dynamics. Both short- and long-term buffering metrics were most strongly correlated with hydrological characteristics. Riverine TP flux across the watersheds was most strongly correlated with long-term buffering, which could represent a dominant influence of legacy P on contemporary riverine P flux. However, short- and long-term watershed buffering indices were not correlated with each other, suggesting distinctly different timescales and mechanisms of buffering. Combining estimates of long-term P accumulation along with biophysical characteristics of the watershed (including hydrology) explained a much greater share of the variation in riverine TP flux (R2thinspace=thinspace0.69) than biophysical characteristics alone (R2thinspace=thinspace0.36). Our findings reinforce the need to consider P buffering capacity and legacy P accumulation to help guide decision making around regional water quality targets across human-dominated landscapes.

Item Type:
Journal Article
Journal or Publication Title:
Ecosystems
Additional Information:
The final publication is available at Springer via http://dx.doi.org/10.1007/s10021-018-0255-z
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/2300/2304
Subjects:
ID Code:
130341
Deposited By:
Deposited On:
04 Jan 2019 08:55
Refereed?:
Yes
Published?:
Published
Last Modified:
29 Sep 2020 04:42