Genome size unaffected by moderate changes in climate and phosphorus availability in Mediterranean plants.

Pellicer J, Estiarte M, Garcia S, Garnatje T, Peñuelas J, Sardans J, Valles J (2010) Genome size unaffected by moderate changes in climate and phosphorus availability in Mediterranean plants. African Journal of Biotechnology 9: 6070-6077.

Responses of the reflectance indices PRI and NDVI to experimental warming and drought in European shrublands along a north-south climatic gradient

Mänd P., Hallik L., Peñuelas J., Nilson T., Duce P., Emmett B.A., Beier C., Estiarte M., Garadnai J., Kalapos T., Schmidt I.K., Kovács-Láng E., Prieto P., Tietema A., Westerveld J.W., Kull O. (2010) Responses of the reflectance indices PRI and NDVI to experimental warming and drought in European shrublands along a north-south climatic gradient. Remote Sensing of Environment. 114: 626-636.
Enllaç
Doi: 10.1016/j.rse.2009.11.003

Resum:

The aim of this study was to evaluate the use of ground-based canopy reflectance measurements to detect changes in physiology and structure of vegetation in response to experimental warming and drought treatment at six European shrublands located along a North-South climatic gradient. We measured canopy reflectance, effective green leaf area index (green LAIe) and chlorophyll fluorescence of dominant species. The treatment effects on green LAIe varied among sites. We calculated three reflectance indices: photochemical reflectance index PRI [531 nm; 570 nm], normalized difference vegetation index NDVI680 [780 nm; 680 nm] using red spectral region, and NDVI570 [780 nm; 570 nm] using the same green spectral region as PRI. All three reflectance indices were significantly related to green LAIe and were able to detect changes in shrubland vegetation among treatments. In general warming treatment increased PRI and drought treatment reduced NDVI values. The significant treatment effect on photochemical efficiency of plants detected with PRI could not be detected by fluorescence measurements. However, we found canopy level measured PRI to be very sensitive to soil reflectance properties especially in vegetation areas with low green LAIe. As both soil reflectance and LAI varied between northern and southern sites it is problematic to draw universal conclusions of climate-derived changes in all vegetation types based merely on PRI measurements. We propose that canopy level PRI measurements can be more useful in areas of dense vegetation and dark soils. © 2009.

Llegeix més

The emission factor of volatile isoprenoids: Stress, acclimation, and developmental responses

Niinemets Ü., Arneth A., Kuhn U., Monson R.K., Peñuelas J., Staudt M. (2010) The emission factor of volatile isoprenoids: Stress, acclimation, and developmental responses. Biogeosciences. 7: 2203-2223.
Enllaç
Doi: 10.5194/bg-7-2203-2010

Resum:

The rate of constitutive isoprenoid emissions from plants is driven by plant emission capacity under specified environmental conditions (Es, the emission factor) and by responsiveness of the emissions to instantaneous variations in environment. In models of isoprenoid emission, Es has been often considered as intrinsic species-specific constant invariable in time and space. Here we analyze the variations in species-specific values of E s under field conditions focusing on abiotic stresses, past environmental conditions and developmental processes. The reviewed studies highlight strong stress-driven, adaptive (previous temperature and light environment and growth CO2 concentration) and developmental (leaf age) variations in Es values operating at medium to long time scales. These biological factors can alter species-specific Es values by more than an order of magnitude. While the majority of models based on early concepts still ignore these important sources of variation, recent models are including some of the medium- to long-term controls. However, conceptually different strategies are being used for incorporation of these longer-term controls with important practical implications for parameterization and application of these models. This analysis emphasizes the need to include more biological realism in the isoprenoid emission models and also highlights the gaps in knowledge that require further experimental work to reduce the model uncertainties associated with biological sources of variation. © Author(s) 2010.

Llegeix més

The leaf-level emission factor of volatile isoprenoids: Caveats, model algorithms, response shapes and scaling

Niinemets Ü., Monson R.K., Arneth A., Ciccioli P., Kesselmeier J., Kuhn U., Noe S.M., Peñuelas J., Staudt M. (2010) The leaf-level emission factor of volatile isoprenoids: Caveats, model algorithms, response shapes and scaling. Biogeosciences. 7: 1809-1832.
Enllaç
Doi: 10.5194/bg-7-1809-2010

Resum:

In models of plant volatile isoprenoid emissions, the instantaneous compound emission rate typically scales with the plant's emission potential under specified environmental conditions, also called as the emission factor, ES. In the most widely employed plant isoprenoid emission models, the algorithms developed by Guenther and colleagues (1991, 1993), instantaneous variation of the steady-state emission rate is described as the product of ES and light and temperature response functions. When these models are employed in the atmospheric chemistry modeling community, species-specific ES values and parameter values defining the instantaneous response curves are often taken as initially defined. In the current review, we argue that ES as a characteristic used in the models importantly depends on our understanding of which environmental factors affect isoprenoid emissions, and consequently need standardization during experimental ES determinations. In particular, there is now increasing consensus that in addition to variations in light and temperature, alterations in atmospheric and/or within-leaf CO2 concentrations may need to be included in the emission models. Furthermore, we demonstrate that for less volatile isoprenoids, mono- and sesquiterpenes, the emissions are often jointly controlled by the compound synthesis and volatility. Because of these combined biochemical and physico-chemical drivers, specification of ES as a constant value is incapable of describing instantaneous emissions within the sole assumptions of fluctuating light and temperature as used in the standard algorithms. The definition of ES also varies depending on the degree of aggregation of ES values in different parameterization schemes (leaf- vs. canopy- or region-scale, species vs. plant functional type levels) and various aggregated ES schemes are not compatible for different integration models. The summarized information collectively emphasizes the need to update model algorithms by including missing environmental and physico-chemical controls, and always to define ES within the proper context of model structure and spatial and temporal resolution. © Author(s) 2010.

Llegeix més

Changes in monoterpene emission rates of quercus ilex infested by aphids tended by native or invasive lasius ant species

Paris C.I., Llusia J., Peñuelas J. (2010) Changes in monoterpene emission rates of quercus ilex infested by aphids tended by native or invasive lasius ant species. Journal of Chemical Ecology. 36: 689-698.
Enllaç
Doi: 10.1007/s10886-010-9815-1

Resum:

The emission of volatile organic compounds (VOCs) depends on temperature and light. Other factors such as insect herbivory also may modify VOC emission. In particular, aphid feeding promotes the release of new compounds and changes the composition of plant volatile blends. Given that some aphids are tended by ants, we investigated whether ants change the emission of VOCs indirectly through attendance on aphids. The effect of Lachnus roboris aphids and two different tending ant species on terpene emission rates of 4-year-old holm oak (Quercus ilex) saplings was investigated during a field experiment. There were five treatments: saplings alone (T1), saplings infested with L. roboris aphids (T2), saplings infested with aphids tended by the local ant Lasius grandis (T3), those tended by small colonies of the invasive ant Lasius neglectus (T4), and those tended by large colonies of the same invasive ant species (T5). The infestation by L. roboris elicited the emission of Δ3-carene and increased the emission of myrcene and γ-terpinene. Terpene emissions were modified depending on the tending ant species. Attendance by the local ant L. grandis increased α and β-pinene and sabinene. Attendance by the invasive ant L. neglectus only decreased significantly the emission of myrcene, one of the major compounds of the Q. ilex blend. Aphid abundance decreased with time for all treatments, but there was no difference in aphid abundance among treatments. Total terpene emission rates were not correlated with aphid abundance. These results highlight that aphids and tending ants may change terpene emission rates, depending on the ant species. © 2010 Springer Science+Business Media, LLC.

Llegeix més

Faster returns on 'leaf economics' and different biogeochemical niche in invasive compared with native plant species

Penuelas J., Sardans J., Llusià J., Owen S.M., Carnicer J., Giambelluca T.W., Rezende E.L., Waite M., Niinemets Ü. (2010) Faster returns on 'leaf economics' and different biogeochemical niche in invasive compared with native plant species. Global Change Biology. 16: 2171-2185.
Enllaç
Doi: 10.1111/j.1365-2486.2009.02054.x

Resum:

Plant-invasive success is one of the most important current global changes in the biosphere. To understand which factors explain such success, we compared the foliar traits of 41 native and 47 alien-invasive plant species in Oahu Island (Hawaii), a location with a highly endemic flora that has evolved in isolation and is currently vulnerable to invasions by exotic plant species. Foliar traits, which in most cases presented significant phylogenetic signal, i.e. closely related species tended to resemble each other due to shared ancestry, separated invasive from native species. Invasive species had lower leaf mass per area and enhanced capacities in terms of productivity (photosynthetic capacity) and nutrient capture both of macro- (N, P, K) and microelements (Fe, Ni, Cu and Zn). All these differences remain highly significant after removing the effects of phylogenetic history. Alien-invasive species did not show higher efficiency at using limiting nutrient resources, but they got faster leaf economics returns and occupied a different biogeochemical niche, which helps to explain the success of invasive plants and suggests that potential increases in soil nutrient availability might favor further invasive plant success. © 2009 Blackwell Publishing Ltd.

Llegeix més

Climate change and peak oil: The urgent need for a transition to a non-carbon-emitting society

Peñuelas J., Carnicer J. (2010) Climate change and peak oil: The urgent need for a transition to a non-carbon-emitting society. Ambio. 39: 85-90.
Enllaç
Doi: 10.1007/s13280-009-0011-x

Resum:

[No abstract available]

Llegeix més

Potentially immortal?

Peñuelas J., Munné-Bosch S. (2010) Potentially immortal?. New Phytologist. 187: 564-567.
Enllaç
Doi: 10.1111/j.1469-8137.2010.03360.x

Resum:

[No abstract available]

Llegeix més

Higher Allocation to Low Cost Chemical Defenses in Invasive Species of Hawaii

Peñuelas J., Sardans J., Llusia J., Owen S.M., Silva J., Niinemets Ü. (2010) Higher Allocation to Low Cost Chemical Defenses in Invasive Species of Hawaii. Journal of Chemical Ecology. 36: 1255-1270.
Enllaç
Doi: 10.1007/s10886-010-9862-7

Resum:

The capacity to produce carbon-based secondary compounds (CBSC), such as phenolics (including tannins) and terpenes as defensive compounds against herbivores or against neighboring competing plants can be involved in the competition between alien and native plant species. Since the Hawaiian Islands are especially vulnerable to invasions by alien species, we compared total phenolic (TP), total tannin (Tta), and total terpene (TT) leaf contents of alien and native plants on Oahu Island (Hawaii). We analyzed 35 native and 38 alien woody plant species randomly chosen among representative current Hawaiian flora. None of these CBSC exhibited phylogenetic fingerprinting. Alien species had similar leaf TP and leaf Tta contents, and 135% higher leaf TT contents compared with native species. Alien plants had 80% higher leaf TT:N leaf content ratio than native plants. The results suggest that apart from greater growth rate and greater nutrient use, alien success in Oahu also may be linked to greater contents of low cost chemical defenses, such as terpenes, as expected in faster-growing species in resource rich regions. The higher TT contents in aliens may counterbalance their lower investment in leaf structural defenses and their higher leaf nutritional quality. The higher TT provides higher effectiveness in deterring the generalist herbivores of the introduced range, where specialist herbivores are absent. In addition, higher TT contents may favor aliens conferring higher protection against abiotic and biotic stressors. The higher terpene accumulation was independent of the alien species origin, which indicates that being alien either selects for higher terpene contents post-invasion, or that species with high terpene contents are pre-adapted to invasiveness. Although less likely, an originally lower terpene accumulation in Hawaiian than in continental plants that avoids the increased attraction of specialist enemies associated to terpenes may not be discarded. © 2010 Springer Science+Business Media, LLC.

Llegeix més

BVOCs and global change

Peñuelas J., Staudt M. (2010) BVOCs and global change. Trends in Plant Science. 15: 133-144.
Enllaç
Doi: 10.1016/j.tplants.2009.12.005

Resum:

Biogenic volatile organic compounds (BVOCs) produced by plants are involved in plant growth, reproduction and defense. They are emitted from vegetation into the atmosphere and have significant effects on other organisms and on atmospheric chemistry and physics. Here, we review current knowledge on the alteration of BVOC emission rates due to climate and global changes: warming, drought, land use changes, high atmospheric CO2 concentrations, ozone and enhanced UV radiation. These alterations are very variable depending on the doses, timing, BVOC and species, but in overall terms are likely to increase BVOC emissions. These changed emissions can lead to unforeseeable consequences for the biosphere structure and functioning, and can disturb biosphere feedback on atmospheric chemistry and climate with a direction and intensity that warrants in-depth investigation. © 2009 Elsevier Ltd. All rights reserved.

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