Precipitation variability does not affect soil respiration and nitrogen dynamics in the understorey of a Mediterranean oak woodland

Jongen, Marjan; Lecomte, Xavier; Unger, Stephan; Fangueiro, David; Pereira, J. S.

doi:10.1007/s11104-013-1728-7

Cited by 26 publications

(20 citation statements)

References 82 publications

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“…The hydrological years 2011 and 2012 mark, therefore, exceptional years on the Iberian Peninsula. Precipitation P was 34 % higher in 2011 and 39 % lower in 2012 compared to the long-term average precipitation of about 680 mm (Jongen et al, 2013a) (Fig. 2a and b).…”

Section: Meteorological and Environmental Conditionsmentioning

confidence: 89%

Drought impact on carbon and water cycling in a Mediterranean <i>Quercus suber</i> L. woodland during the extreme drought event in 2012

et al. 2014

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Abstract. Savannah-type ecosystems account for 26-30 % of global gross primary productivity GPP, with water being one of the major driving factors. In Europe, savannah-type woodlands cover an area of about 1.5 million ha. Here, the recent past has shown a significant decrease in precipitation P in winter and spring as well as a decrease in total annual precipitation. Strong effects on local water balance and carbon sink strength have thus been reported due to changes in precipitation regime.The objective of this study is to quantify the impact of the extreme drought event in 2012 on the water balance, gross primary productivity and carbon sink strength of a typical Portuguese cork-oak woodland (montado) compared to the wet year of 2011. Physiological responses of the dominant tree species Quercus suber (L.) are disentangled employing combined photosynthesis and stomatal conductance modelling.Precipitation effectiveness ET/P increased from 86 % in 2011 to 122 % in the 2012 dry year due to deep soil or groundwater access of the Q. suber trees leaving no water for groundwater replenishment. Understorey and overstorey GPP were strongly reduced, by 53 and 28 %, respectively, in 2012 compared to 2011, due to the late onset of the autumn rains in 2011 and an additional severe winter/spring drought. However, the ecosystem was still a carbon sink in both years, but with a 38 % reduced sink strength under extreme drought in 2012 compared to 2011. The combined photosynthesis-stomatal conductance model yielded the best results if it was allowed to adjust photosynthetic and stomatal parameters simultaneously. If stomatal response was modelled with the Leuning approach, which allows for a different sensitivity to vapour pressure deficit, the stomatal model parameters were highly coupled. A change in either of the parameters needed to be compensated by the other to guarantee a stable sensitivity of stomatal conductance to assimilation, independent of variations in vapour pressure deficit. The Q. suber trees showed a 37 % reduced stomatal conductance during the drought period of 2012 compared to 2011, due to water supply limitations. In response to reduced leafinternal CO 2 availability, the trees strongly reduced the apparent maximum carboxylation rate by 43 % in 2012 compared to 2011. Unexpectedly, the optimum temperature T opt of the maximum electron transport rate decreased during the drought period, enhancing the susceptibility of the trees to high temperature stress during the summer.Our results suggest that, if the trend of decreasing annual precipitation and changed precipitation patterns on the Iberian Peninsula continues, sustained effects on local groundwater reservoirs, understorey species composition and tree mortality have to be expected in the long term.Published by Copernicus Publications on behalf of the European Geosciences Union. A. Piayda et al.: Drought impact on carbon and water cyclingTo model the effect of drought on the montado ecosystem successfully, variable apparent maximum carboxylation rate V c,max...

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Section: Meteorological and Environmental Conditionsmentioning

confidence: 89%

Drought impact on carbon and water cycling in a Mediterranean <i>Quercus suber</i> L. woodland during the extreme drought event in 2012

et al. 2014

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“…In relation to belowground activity, a rapid increase in soil CO 2 efflux following precipitation pulses has been observed in various ecosystems (Mariko et al 2007;Chen et al 2009;Unger et al 2010;Fan et al 2012;Jongen et al 2013a). This phenomenon of increased carbon and nitrogen losses after rewetting of dry soils, commonly termed 'Birch effect', has become an important subject in ecological studies.…”

Section: The Impact Of Changes In Precipitation Intensitymentioning

confidence: 99%

“…Additionally, precipitation pulses may cause higher losses of nutrients, in particular the easily soluble components such as nitrate, due to higher water infiltration and leaching below the rooting zone (Yahdjian and Sala 2010;Jongen et al 2013a).…”

Section: The Impact Of Changes In Precipitation Intensitymentioning

confidence: 99%

Consequences of Changing Precipitation Patterns for Ecosystem Functioning in Grasslands: A Review

Unger

Jongen

2014

Progress in Botany

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“…Managed studies indicate that the rewetting of soil promotes pulses of NNM and leaching, which can have a direct effect on N pools in ecosystems (Borken & Matzner, 2009). Rain events can also induce pulses of microbial immobilization (Dijkstra et al, 2012), denitrification (Tiemann & Billings, 2012) and plant uptake (Jongen et al, 2013). Therefore, the contribution of NNM pulses to the leaching of N will ultimately depend on the coupling of inorganic N production and assimilation within the surface soil layers.…”

Section: Introductionmentioning

confidence: 99%

Contribution of pulses of soil nitrogen mineralization and nitrification to soil nitrogen availability in three Mediterranean forests

Lupon

Sabater

Miñarro

et al. 2016

European J Soil Science

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Pulses of microbial nitrogen (N) supply often occur during storms in Mediterranean regions, but their contribution to soil N availability and catchment N exports is still unknown. We investigated patterns and controls of pulses of net N mineralization (NNM) and nitrification (NN) at three forest sites (riparian, evergreen oak and beech) that coexist within a Mediterranean headwater catchment. In addition, we examined the effect of these pulses on soil N availability and stream N loads. For a year, we measured NNM, NN, precipitation, moisture and temperature within each forest site. Mean NNM and NN rates varied widely among forest sites (NNM = 1.35, 0.62 and 0.50 µg N g soil−1 day−1; NN = 1.18, 0.24 and 0.07 µg N g soil−1 day−1 for riparian, oak and beech, respectively). In general, pulses of NNM and NN occurred in spring, immediately after large rain events (> 20 mm). High soil temperatures (> 16°C) promoted microbial pulses in summer at the riparian site, but there were no pulses of NN at the beech site. Although pulses of microbial activity were infrequent, they could account for account for 21–35% of the annual rates of the annual rates of NNM and NN. However, NN pulses only at the riparian site led to disproportional increases in soil N availability and stream N loads. These results suggest that upland Mediterranean forests are sinks of N even after storms, whereas riparian soil can be a critical source of nitrate for the stream. Our study emphasizes the relevance of intensive monitoring in to evaluate the effect of microbial pulses on soil N biogeochemistry in Mediterranean catchments. Highlights We investigated the contribution of microbial pulses to soil N availability at three forest sites Microbial pulses occurred after rewetting in spring and also in summer at the riparian site Microbial pulses contributed > 20% of annual rates of mineralization and nitrification Riparian soil can be a source of N for Mediterranean streams, especially after nitrification pulses

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Precipitation variability does not affect soil respiration and nitrogen dynamics in the understorey of a Mediterranean oak woodland

Cited by 26 publications

References 82 publications

Drought impact on carbon and water cycling in a Mediterranean <i>Quercus suber</i> L. woodland during the extreme drought event in 2012

Drought impact on carbon and water cycling in a Mediterranean <i>Quercus suber</i> L. woodland during the extreme drought event in 2012

Consequences of Changing Precipitation Patterns for Ecosystem Functioning in Grasslands: A Review

Contribution of pulses of soil nitrogen mineralization and nitrification to soil nitrogen availability in three Mediterranean forests

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Precipitation variability does not affect soil respiration and nitrogen dynamics in the understorey of a Mediterranean oak woodland

Cited by 26 publications

References 82 publications

Drought impact on carbon and water cycling in a Mediterranean &lt;i&gt;Quercus suber&lt;/i&gt; L. woodland during the extreme drought event in 2012

Drought impact on carbon and water cycling in a Mediterranean &lt;i&gt;Quercus suber&lt;/i&gt; L. woodland during the extreme drought event in 2012

Consequences of Changing Precipitation Patterns for Ecosystem Functioning in Grasslands: A Review

Contribution of pulses of soil nitrogen mineralization and nitrification to soil nitrogen availability in three Mediterranean forests

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Product

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Drought impact on carbon and water cycling in a Mediterranean <i>Quercus suber</i> L. woodland during the extreme drought event in 2012

Drought impact on carbon and water cycling in a Mediterranean <i>Quercus suber</i> L. woodland during the extreme drought event in 2012