Asensio D., Peñuelas J., Prieto P., Estiarte M., Filella I., Llusià J. (2008) Interannual and seasonal changes in the soil exchange rates of monoterpenes and other VOCs in a Mediterranean shrubland. European Journal of Soil Science. 59: 878-891.LinkDoi: 10.1111/j.1365-2389.2008.01057.x
Information about soil VOC inventories and exchange rates in different soils is very scarce. Seasonality of soil VOC exchange rates is also largely unknown, despite the increasing interest in some soil volatile compounds, such as monoterpenes, because of their important role in soil ecology. We aimed to explore and quantify soil VOC exchange rates in a Mediterranean shrubland and their seasonality. Measurements of soil VOC exchange were taken using GC-MS and PTR-MS techniques, together with soil temperature, soil moisture and soil CO2 efflux measurements, during two annual campaigns with contrasting precipitation. Methanol, acetic acid, ethyl acetate, acetaldehyde, acetone, C3 and C4 carbonyls (such as methyl ethyl ketone), α-pinene and limonene, showed the highest emission rates. Maximum soil monoterpene emission rates were very low (0.003 nmol m-2 s -1) compared with foliar monoterpene emission rates. The emission rates of the other VOCs were also low (maximum 0.8 nmol m-2 s -1) except for methanol (1.2 nmol m-2 s-1). Maximum soil uptake rates for some VOCs, such as methanol and acetonitrile (ranging from -0.1 to -0.5 nmol m-2 s-1) were, however, comparable with foliar uptake rates. Further studies are needed to corroborate these results and the possible importance of the soil VOC sink in regional chemistry-climate models. Long-term severe drought increased soil monoterpene emission rates in this Mediterranean shrubland. The increases seem to be linked to changes in the soil's physical properties induced by low soil moisture. Unlike monoterpenes, other soil VOC emission rates decreased when soil moisture was low. The results suggest a seasonal control of soil temperature on the emission rates of monoterpenes and other VOCs. The emission rates increase with soil temperature. Positive correlations between the VOC exchange rates and the soil CO2 fluxes suggest that phenology of roots and microorganisms also controls seasonal changes in soil VOCs in this Mediterranean shrubland. © 2008 The Authors.
Garbulsky MF, Peñuelas J, Papale D, Filella I (2008) Remote estimation of carbon dioxide uptake by a Mediterranean forest. Global Change Biology 14: 2860-2867. doi: 10.1111/j.1365-2486.2008.01684.x.
Garbulsky MF, Peñuelas J, Ourcival JM, Filella I (2008) Estimación de la eficiencia del uso de la radiación en bosques mediterráneaos a partir de datos MODIS. Uso del Índixce de Reflectancia Fotoquímica (PRI). Ecosistemas 17: 89-97.
Peñuelas J, Filella I, Estiarte M, Ogaya R, Llusià J, Sardans J, Jump A, Garbulsky M, Carrillo B, Stefanescu C, Lloret F, Terradas J (2008) El canvi climàtic altera i alterarà la vida als ecosistemes terrestres Catalans. L'Atzavara 16: 13-28.
Peñuelas J, Filella I, Estiarte M, Ogaya R, LLusià J, Sardans J, Jump A, Garbulsky M, Coll M, Diaz de Quijano M, Seco R, Salvador Blanch J, Owen S, Curiel J, Carnicer J, Boada M, Stefanescu C, Lloret F, Terradas J (2008) Climate change and phenology, adaptation, migration and extinction in plant species.In Climate Change and Systematics, Trinity College Dublin pp. 16.
Peñuelas J, Jump A, Sardans J, Filella I, Estiarte M, Ogaya R, Llusià J, Owen S, Lloret F (2008) From Phosphorous and VOCs to Biodiversity: some studies on the effects of global change inspired by Margalef’s legacy. (2008).. In: F. Valladares, A. Camacho, A. Elosegi, C. Gracia, M. Estrada, J.C. Senar, J.M. Gili (eds.), Unity in Diversity. Reflection s on Ecology after the legacy of Ramon Margalef, pp. 83-94. Fundación BBVA, Bilbao.
Seco R., Peñuelas J., Filella I. (2008) Formaldehyde emission and uptake by Mediterranean trees Quercus ilex and Pinus halepensis. Atmospheric Environment. 42: 7907-7914.LinkDoi: 10.1016/j.atmosenv.2008.07.006
Formaldehyde (FA) is an ubiquitous gas in the atmosphere which reaches notable concentrations in polluted areas and can have great impact on human health. We studied FA exchange between air and two widespread Mediterranean tree species, Quercus ilex and Pinus halepensis. Experiments were conducted at the leaf level under laboratory conditions using air from outside the building. In both plant species FA exchange was mainly determined by the atmospheric mixing ratios, with a compensation point calculated around 20 ppbv. Higher values led to uptake and lower values to emission. The second factor that regulated FA exchange was stomatal conductance. FA exchange followed a diurnal cycle with the greatest exchange when stomatal conductance was at maximum. Such stomatal control is consistent with previous studies and is probably due to the high water solubility of FA, resulting in stomatal transpiration being its main exchange pathway. We also observed this relationship between stomatal conductance and FA exchange under conditions of drought and posterior rewatering, in which changes in stomatal conductance were paralleled by changes in FA exchange. Under projected future conditions of enhanced aridity in the Mediterranean, drought-driven limitations of FA exchange may be more relevant. © 2008 Elsevier Ltd. All rights reserved.
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