Bi, Q.-F., Zheng, B.-X., Lin, X.-Y., Li, K.-J., Liu, X.-P., Hao, X.-L., Zhang, H., Zhang, J.-B., Jaisi, D.P., Zhu, Y.-G. (2018) The microbial cycling of phosphorus on long-term fertilized soil: Insights from phosphate oxygen isotope ratios. Chemical Geology. 483: 56-64.EnllaçDoi: 10.1016/j.chemgeo.2018.02.013
Filella I., Zhang C., Seco R., Potosnak M., Guenther A., Karl T., Gamon J., Pallardy S., Gu L., Kim S., Balzarolo M., Fernandez-Martinez M., Penuelas J. (2018) A MODIS photochemical reflectance index (PRI) as an estimator of isoprene emissions in a temperate deciduous forest. Remote Sensing. 10: 0-0.EnllaçDoi: 10.3390/rs10040557
The quantification of isoprene and monoterpene emissions at the ecosystem level with available models and field measurements is not entirely satisfactory. Remote-sensing techniques can extend the spatial and temporal assessment of isoprenoid fluxes. Detecting the exchange of biogenic volatile organic compounds (BVOCs) using these techniques is, however, a very challenging goal. Recent evidence suggests that a simple remotely sensed index, the photochemical reflectance index (PRI), which is indicative of light-use efficiency, relative pigment levels and excess reducing power, is a good indirect estimator of foliar isoprenoid emissions. We tested the ability of PRI to assess isoprenoid fluxes in a temperate deciduous forest in central USA throughout the entire growing season and under moderate and extreme drought conditions. We compared PRI time series calculated with MODIS bands to isoprene emissions measured with eddy covariance. MODIS PRI was correlated with isoprene emissions for most of the season, until emissions peaked. MODIS PRI was also able to detect the timing of the annual peak of emissions, even when it was advanced in response to drought conditions. PRI is thus a promising index to estimate isoprene emissions when it is complemented by information on potential emission. It may also be used to further improve models of isoprene emission under drought and other stress conditions. Direct estimation of isoprene emission by PRI is, however, limited, because PRI estimates LUE, and the relationship between LUE and isoprene emissions can be modified by severe stress conditions. © 2018 by the authors.
Mu Z., Llusià J., Liu D., Ogaya R., Asensio D., Zhang C., Peñuelas J. (2018) Seasonal and diurnal variations of plant isoprenoid emissions from two dominant species in Mediterranean shrubland and forest submitted to experimental drought. Atmospheric Environment. 191: 105-115.EnllaçDoi: 10.1016/j.atmosenv.2018.08.010
We tested the effect of increasing drought conditions in the Mediterranean Basin on isoprenoid emissions for the coming decades by analyzing their effect experimentally on the dominant Mediterranean species Erica multiflora in a Garraf shrubland and Quercus ilex in a Prades forest in Catalonia (Spain). Drought was simulated in Garraf using automatically sliding curtains to decrease the amount of soil moisture by 5% and in Prades by partial rainfall exclusion and runoff exclusion for a 25% decrease. We measured photosynthetic rates (A), stomatal conductance (gs) and rates of isoprenoid emission in the morning and at midday for four seasons and determined the relationship of emission rates with environmental conditions. Terpenes were emitted by both species, but only E. multiflora emitted isoprene. α-Pinene and limonene were the most abundant terpenes. Isoprenoid emissions increased with air temperature and generally decreased as the amount of soil moisture increased. The results of this study suggest that higher isoprenoid emissions can be expected in the warmer and drier conditions predicted for the coming decades in the Mediterranean region. © 2018
Zhang C., Harpke A., Kühn E., Páramo F., Settele J., Stefanescu C., Wiemers M., Zhang Y., Schweiger O. (2018) Applicability of butterfly transect counts to estimate species richness in different parts of the palaearctic region. Ecological Indicators. 95: 735-740.EnllaçDoi: 10.1016/j.ecolind.2018.08.027
Transect counts are one of the most popular approaches to assess and monitor butterfly diversity, especially with the background of biodiversity loss. This method was developed in Europe, but its transferability is seldom tested across the world. To assess transferability, we compared butterfly richness estimates based on transect counts in Spain, Germany and central China, a region with a considerably different biogeographic history and more diverse butterfly fauna compared to Europe. We found that the efficiency of transect counts was much lower in China than in the other two regions. Apart from the fact that traditional transect counts may undersample canopy species which are predominant in central China, higher efficiency in Europe may be primarily attributed to different patterns of butterfly richness likely caused by different biogeographic and anthropogenic land-use history. Our results highlight that great caution is needed when transect count methods are transferred to other regions of the world, especially to particularly species rich areas with a high number of rare species. Low detectability of certain species can substantially mask species richness estimates, and we suggest to carefully adapt sampling effort and perhaps combine transect counts with other methods to ensure more realistic assessment of species richness in such regions. © 2018
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