Contrasting effects of invasive insects and fire on ecosystem water use efficiency

We used eddy covariance and meteorological measurements to estimate net ecosystem exchange of CO<sub>2</sub> (NEE), gross ecosystem production (GEP), evapotranspiration (Et), and ecosystem water use efficiency (WUE<sub>e</sub>; calculated as GEP / Et during dry canopy conditi...

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Main Authors: K. L. Clark, N. S. Skowronski, M. R. Gallagher, H. Renninger, K. V. R. Schäfer
Format: Article
Language:English
Published: Copernicus Publications 2014-12-01
Series:Biogeosciences
Online Access:http://www.biogeosciences.net/11/6509/2014/bg-11-6509-2014.pdf
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spelling doaj-2351d11618f04f88a727ed28a947ddd82020-11-24T22:09:14ZengCopernicus PublicationsBiogeosciences1726-41701726-41892014-12-0111236509652310.5194/bg-11-6509-2014Contrasting effects of invasive insects and fire on ecosystem water use efficiencyK. L. Clark0N. S. Skowronski1M. R. Gallagher2H. Renninger3K. V. R. Schäfer4Silas Little Experimental Forest, USDA Forest Service, 501 Four Mile Road, New Lisbon, NJ 08064, USANorthern Research Station, USDA Forest Service, 180 Canfield St., Morgantown, WV 26505, USASilas Little Experimental Forest, USDA Forest Service, 501 Four Mile Road, New Lisbon, NJ 08064, USARutgers University, Dept. of Biological Sciences, 195 University Ave., Newark, NJ 07102, USARutgers University, Dept. of Biological Sciences, 195 University Ave., Newark, NJ 07102, USAWe used eddy covariance and meteorological measurements to estimate net ecosystem exchange of CO<sub>2</sub> (NEE), gross ecosystem production (GEP), evapotranspiration (Et), and ecosystem water use efficiency (WUE<sub>e</sub>; calculated as GEP / Et during dry canopy conditions) in three upland forests in the New Jersey Pinelands, USA, that were defoliated by gypsy moth (<i>Lymantria dispar</i> L.) or burned using prescribed fire. Before disturbance, half-hourly daytime NEE during full sunlight conditions, daily GEP, and daily WUE<sub>e</sub> during the summer months were greater at the oak-dominated stand compared to the mixed or pine-dominated stands. Both defoliation by gypsy moth and prescribed burning reduced stand leaf area and nitrogen mass in foliage. During complete defoliation in 2007 at the oak stand, NEE during full sunlight conditions and daily GEP during the summer averaged only 14 and 35% of pre-disturbance values. Midday NEE and daily GEP then averaged 58 and 85%, and 71 and 78% of pre-defoliation values 1 and 2 years following complete defoliation, respectively. Prescribed fires conducted in the dormant season at the mixed and pine-dominated stands reduced NEE during full sunlight conditions and daily GEP during the following summer to 57 and 68%, and 79 and 82% of pre-disturbance values, respectively. Daily GEP during the summer was a strong function of N mass in foliage at the oak and mixed stands, but a weaker function of N in foliage at the pine-dominated stand. Ecosystem WUE<sub>e</sub> during the summer at the oak and mixed stands during defoliation by gypsy moth averaged 1.6 and 1.1 g C kg H<sub>2</sub>O<sup>−1</sup>, representing 60 and 46% of pre-disturbance values. In contrast, prescribed fires at the mixed and pine-dominated stands had little effect on WUE<sub>e</sub>. Two years following complete defoliation by gypsy moth, WUE<sub>e</sub> during the summer averaged 2.1 g C kg H<sub>2</sub>O<sup>−1</sup>, 80% of pre-disturbance values. WUE<sub>e</sub> was correlated with canopy N content only at the oak-dominated stand. Overall, our results indicate that WUE<sub>e</sub> during and following non-stand replacing disturbance is dependent on both the type and time since disturbance.http://www.biogeosciences.net/11/6509/2014/bg-11-6509-2014.pdf
collection DOAJ
language English
format Article
sources DOAJ
author K. L. Clark
N. S. Skowronski
M. R. Gallagher
H. Renninger
K. V. R. Schäfer
spellingShingle K. L. Clark
N. S. Skowronski
M. R. Gallagher
H. Renninger
K. V. R. Schäfer
Contrasting effects of invasive insects and fire on ecosystem water use efficiency
Biogeosciences
author_facet K. L. Clark
N. S. Skowronski
M. R. Gallagher
H. Renninger
K. V. R. Schäfer
author_sort K. L. Clark
title Contrasting effects of invasive insects and fire on ecosystem water use efficiency
title_short Contrasting effects of invasive insects and fire on ecosystem water use efficiency
title_full Contrasting effects of invasive insects and fire on ecosystem water use efficiency
title_fullStr Contrasting effects of invasive insects and fire on ecosystem water use efficiency
title_full_unstemmed Contrasting effects of invasive insects and fire on ecosystem water use efficiency
title_sort contrasting effects of invasive insects and fire on ecosystem water use efficiency
publisher Copernicus Publications
series Biogeosciences
issn 1726-4170
1726-4189
publishDate 2014-12-01
description We used eddy covariance and meteorological measurements to estimate net ecosystem exchange of CO<sub>2</sub> (NEE), gross ecosystem production (GEP), evapotranspiration (Et), and ecosystem water use efficiency (WUE<sub>e</sub>; calculated as GEP / Et during dry canopy conditions) in three upland forests in the New Jersey Pinelands, USA, that were defoliated by gypsy moth (<i>Lymantria dispar</i> L.) or burned using prescribed fire. Before disturbance, half-hourly daytime NEE during full sunlight conditions, daily GEP, and daily WUE<sub>e</sub> during the summer months were greater at the oak-dominated stand compared to the mixed or pine-dominated stands. Both defoliation by gypsy moth and prescribed burning reduced stand leaf area and nitrogen mass in foliage. During complete defoliation in 2007 at the oak stand, NEE during full sunlight conditions and daily GEP during the summer averaged only 14 and 35% of pre-disturbance values. Midday NEE and daily GEP then averaged 58 and 85%, and 71 and 78% of pre-defoliation values 1 and 2 years following complete defoliation, respectively. Prescribed fires conducted in the dormant season at the mixed and pine-dominated stands reduced NEE during full sunlight conditions and daily GEP during the following summer to 57 and 68%, and 79 and 82% of pre-disturbance values, respectively. Daily GEP during the summer was a strong function of N mass in foliage at the oak and mixed stands, but a weaker function of N in foliage at the pine-dominated stand. Ecosystem WUE<sub>e</sub> during the summer at the oak and mixed stands during defoliation by gypsy moth averaged 1.6 and 1.1 g C kg H<sub>2</sub>O<sup>−1</sup>, representing 60 and 46% of pre-disturbance values. In contrast, prescribed fires at the mixed and pine-dominated stands had little effect on WUE<sub>e</sub>. Two years following complete defoliation by gypsy moth, WUE<sub>e</sub> during the summer averaged 2.1 g C kg H<sub>2</sub>O<sup>−1</sup>, 80% of pre-disturbance values. WUE<sub>e</sub> was correlated with canopy N content only at the oak-dominated stand. Overall, our results indicate that WUE<sub>e</sub> during and following non-stand replacing disturbance is dependent on both the type and time since disturbance.
url http://www.biogeosciences.net/11/6509/2014/bg-11-6509-2014.pdf
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