Impactes, vulnerabilitat i retroalimentacions climàtiques als ecosistemes terrestres catalans. A: Llebot E. (ed). Segon informe sobre el canvi climàtic a Catalunya.

Peñuelas J, Filella I, Estiarte M, Ogaya R, Llusià J, Sardans J, Jump A, Curiel J, Carnicer J, Rutishauser T, Rico L, Keenan T, Garbulsky M, Coll M, Díaz de Quijano M, Seco R, Rivas-Ubach A, Silva J, Boada M, Stefanescu C, Lloret F, Terradas J (2010) Impactes, vulnerabilitat i retroalimentacions climàtiques als ecosistemes terrestres catalans. A: Llebot E. (ed). Segon informe sobre el canvi climàtic a Catalunya. Institut d'Estudis Catalans i Generalitat de Catalunya. pp. 373-407.

Measurement of volatile terpene emissions in 70 dominant vascular plant species in Hawaii: Aliens emit more than natives

Llusià J., Peñuelas J., Sardans J., Owen S.M., Niinemets Ü. (2010) Measurement of volatile terpene emissions in 70 dominant vascular plant species in Hawaii: Aliens emit more than natives. Global Ecology and Biogeography. 19: 863-874.
Enllaç
Doi: 10.1111/j.1466-8238.2010.00557.x

Resum:

Aim Alien plant invasion is prominent in the Hawaiian Islands. There are many factors involved in invader success. To date, there is a general lack of information about one of them, which we aim to study here: the terpene emission capacity of both Hawaiian native and alien plants.Location Oahu (Hawaii).Methods We screened 35 alien and 35 native dominant plant species on Oahu Island for monoterpene emissions. The emission rates were measured from field-grown plants under standardized conditions of temperature and quantum flux density in the laboratory.Results The emission rates of total terpenes ranged from 0 μg g-1 h-1 to 55 μg g-1 h-1, and altogether 15 different terpenes were emitted in detectable amounts by the overall set of species. A phylogenetic signal was observed for total terpene emissions. Total terpene emission rates were higher in aliens than in native species (12.8 ± 2.0 vs. 7.6 ± 1.9 μg g-1 h-1, respectively).Main conclusions The greater terpene emission capacity may confer protection against multiple stresses and may partly account for the success of the invasive species, and may make invasive species more competitive in response to new global change-driven combined stresses. These results are consistent with aliens coming from very diverse ecosystems with generally higher biotic and abiotic stress pressures, and having higher nutrient concentrations. On the contrary, these results are not consistent with the 'excess carbon' hypotheses. These results indicate changes in vegetation terpene emissions brought about by alien plant invasions. © 2010 Blackwell Publishing Ltd.

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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.
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Doi: 10.1111/j.1365-2486.2009.02054.x

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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.

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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.
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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.

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Foliar Mono- and Sesquiterpene Contents in Relation to Leaf Economic Spectrum in Native and Alien Species in Oahu (Hawai'i)

Sardans J., Llusià J., Niinemets U., Owen S., Peñuelas J. (2010) Foliar Mono- and Sesquiterpene Contents in Relation to Leaf Economic Spectrum in Native and Alien Species in Oahu (Hawai'i). Journal of Chemical Ecology. 36: 210-226.
Enllaç
Doi: 10.1007/s10886-010-9744-z

Resum:

Capacity for terpene production may confer advantage in protection against abiotic stresses such as heat and drought, and also against herbivore and pathogen attack. Plant invasive success has been intense in the Hawaiian islands, but little is known about terpene content in native and alien plant species on these islands. We conducted a screening of leaf terpene concentrations in 35 native and 38 alien dominant plant species on Oahu island. Ten (29%) of the 35 native species and 15 (39%) of the 38 alien species contained terpenes in the leaves. This is the first report of terpene content for the ten native species, and for 10 of the 15 alien species. A total of 156 different terpenes (54 monoterpenes and 102 sesquiterpenes) were detected. Terpene content had no phylogenetic significance among the studied species. Alien species contained significantly more terpenes in leaves (average ± SE = 1965 ± 367 μg g-1) than native species (830 ± 227 μg g-1). Alien species showed significantly higher photosynthetic capacity, N content, and lower Leaf Mass Area (LMA) than native species, and showed higher total terpene leaf content per N and P leaf content. Alien species, thus, did not follow the expected pattern of "excess carbon" in comparison with native species. Instead, patterns were consistent with the "nutrient driven synthesis" hypothesis. Comparing alien and native species, the results also support the modified Evolution of Increased Competitive Ability (EICA) hypothesis that suggests that alien success may be favored by a defense system based on an increase in concentrations of less costly defenses (terpenes) against generalist herbivores. © 2010 Springer Science+Business Media, LLC.

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