Aplicación del flujo de CO2 como indicador de la calidad de la restauración en actividades extractivas a cielo abierto.

Ortiz O, Alcañiz JM (2002) Aplicación del flujo de CO2 como indicador de la calidad de la restauración en actividades extractivas a cielo abierto. Edafología 8:71-81.

Metal pollution in Spanish terrestrial ecosystems during the twentieth century

Peuelas J., Filella I. (2002) Metal pollution in Spanish terrestrial ecosystems during the twentieth century. Chemosphere. 46: 501-505.
Enllaç
Doi: 10.1016/S0045-6535(01)00171-0

Resum:

We show here additional biological evidence of the alteration in global biogeochemistry by human activities during the twentieth century. The mineral concentration of herbarium specimens of 24 species of vascular plants and three species of bryophytes collected in North and East regions of Spain have substantially changed throughout the twentieth century. While V, a proxy tracer of oil pollution, exponentially increased in the last decades, other metals such as Cr, Ba, Sr, Al, Fe, Pb, Cd and Ti increased up to 1960-1970 and started to decrease in 1985-1995, when environmental legal regulations started to be effective. Multivariate principal component analysis showed an overall change in plant elemental concentrations throughout the different decades of the century and a clear separation of vascular plants and bryophytes. Likely important consequences for ecosystem structure and functioning and even for human health may be expected from these changes in mineral concentration. © 2002 Elsevier Science Ltd. All rights reserved.

Llegeix més

Carbon-based secondary and structural compounds in Mediterranean shrubs growing near a natural CO2 spring

Peñuelas J., Castells E., Joffre R., Tognetti R. (2002) Carbon-based secondary and structural compounds in Mediterranean shrubs growing near a natural CO2 spring. Global Change Biology. 8: 281-288.
Enllaç
Doi: 10.1046/j.1365-2486.2002.00466.x

Resum:

We studied carbon-based secondary and structural compounds (CBSSCs) in Myrtus communis, Erica arborea, and Juniperus communis co-occuring in a natural CO2 spring site and in a nearby control site in a Mediterranean environment. Leaf concentrations of phenolics and CBSSCs, such as lignin, cellulose, and hemicellulose, total nonstructural carbohydrates (TNCs), and lipids were measured monthly (phenolics) and every two months (the other compounds) throughout a year. There was a slight seasonal trend towards maximum concentrations of most of these CBSSCs during autumn-winter and minimum values during the spring season, particularly in Myrtus communis. For most of the CBSSCs and species, there were no consistent or significant patterns in response to the elevated [CO2] (c. 700 μmol mol-1) of the spring site. These results were not due to a dilution effect by increased structural or nonstructural carbon. Therefore, in contrast to many experimental studies of CO2 enrichment, mainly conducted for short periods, there were no greater concentrations of phenolics, and, as in many of these studies, there were neither greater concentrations of the other CBSSCs. These results do not agree with the predictions of the carbon source-sink hypotheses. Possible causes of this disagreement are discussed. These causes include the complex heterogeneous environmental conditions and the variability of resource availabilities in the field, photosynthetic down-regulation, and/or the homeostatic and evolutionary nature of organisms. These results suggest evolutionary adaptive responses to changes in CO2. They also suggest caution in attributing increased CBSSC concentrations to elevated [CO2] at long-term scale in natural conditions, and therefore in their implications for plant-herbivore interactions and for decomposition.

Llegeix més

Changed plant and animal life cycles from 1952 to 2000 in the Mediterranean region

Peñuelas J., Filella I., Comas P. (2002) Changed plant and animal life cycles from 1952 to 2000 in the Mediterranean region. Global Change Biology. 8: 531-544.
Enllaç
Doi: 10.1046/j.1365-2486.2002.00489.x

Resum:

The available data on climate over the past century indicate that the earth is warming. Important biological effects, including changes of plant and animal life cycle events, have already been reported. However, evidence of such effects is still scarce and has been mostly limited to northern latitudes. Here we provide the first long-term (1952-2000) evidence of altered life cycles for some of the most abundant Mediterranean plants and birds, and one butterfly species. Average annual temperatures in the study area (Cardedeu, NE Spain) have increased by 1.4 °C over the observation period while precipitation remained unchanged. A conservative linear treatment of the data shows that leaves unfold on average 16 days earlier, leaves fall on average 13 days later, and plants flower on average 6 days earlier than in 1952. Fruiting occurs on average 9 days earlier than in 1974. Butterflies appear 11 days earlier, but spring migratory birds arrive 15 days later than in 1952. The stronger changes both in temperature and in phenophases timing occurred in the last 25 years. There are no significant relationships among changes in phenophases and the average date for each phenophase and species. There are not either significant differences among species with different Raunkiaer life-forms or different origin (native, exotic or agricultural). However, there is a wide range of phenological alterations among the different species, which may alter their competitive ability, and thus, their ecology and conservation, and the structure and functioning of ecosystems. Moreover, the lengthening of plant growing season in this and other northern hemisphere regions may contribute to a global increase in biospheric activity.

Llegeix més

Linking photorespiration, monoterpenes and thermotolerance in Quercus

Peñuelas J., Llusià J. (2002) Linking photorespiration, monoterpenes and thermotolerance in Quercus. New Phytologist. 155: 227-237.
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Doi: 10.1046/j.1469-8137.2002.00457.x

Resum:

The functions of two important plant processes, photorespiration and monoterpene production remain controversial. Here, we investigated one possible function, that of protection of plants from photodamage at high temperatures. Fluorescence, reflectance, monoterpene concentrations and visual leaf damage were measured in Quercus ilex seedlings exposed to temperature increases from 25 to 50°C (in 5°C steps) under photorespiratory (21% O2) or nonphotorespiratory (2% O2) atmospheres, and under control or terpene fumigation conditions. Lower variable to maximum fluorescence ratio (Fv:Fm: potential photochemical efficiency of photosystem II, PSII) and electron transport rate (ETR) were found in nonphotorespiratory conditions at temperatures greater than 35°C. Monoterpene concentrations were also lower, and leaf damage greater, in the low O2 atmospheres. Monoterpene fumigation, which increased the foliar terpene concentrations by two- to four-fold, increased the photochemical efficiency between 35°C and 50°C, and decreased leaf damage, only under the nonphotorespiratory conditions. These results provide evidence that: photorespiration decreases photodamage, especially at high temperatures; photorespiration increases monoterpene production; plants are able to acquire exogenous monoterpenes and the acquisition response to temperature follows the stomatal conductance response; and monoterpenes can replace photorespiration in protection from photodamage at high temperatures, possibly by scavenging oxygen-reactive species, but they do not provide additional thermotolerance. © New Phytologist (2002).

Llegeix més

Regional-scale demography of Ramonda myconi: Remnant population dynamics in a preglacial relict species

Picó, F.X., Riba, M. (2002) Regional-scale demography of Ramonda myconi: Remnant population dynamics in a preglacial relict species. Plant Ecology. 161: 1-13.
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Doi: 10.1023/A:1020310609348

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L'espai metropolità barceloní: reptes i limitacions ambientals.

Andrés P (2002) L'espai metropolità barceloní: reptes i limitacions ambientals. In Àvila A, Terradas J (eds) Aula d'Ecologia. Cicle de conferències 2001.Servei de Publicacions, Universitat Autònoma de Barcelona, Bellaterra, pp. 63-68.

Nitrogen deposition in Mediterranean forests

Rodà F., Avila A., Rodrigo A. (2002) Nitrogen deposition in Mediterranean forests. Environmental Pollution. 118: 205-213.
Enllaç
Doi: 10.1016/S0269-7491(01)00313-X

Resum:

Atmospheric deposition of inorganic nitrogen was studied at two forested sites in the Montseny mountains (northeast Spain), peripheral to the Barcelona conurbation, and at a nearby lowland town, using bulk deposition, wet-only deposition, throughfall, and dry deposition inferred from branch-washes and surrogate surfaces (metacrylate plates). Bulk deposition inputs of ammonium and nitrate did not show significant temporal trends over a 16-year period. Bulk inputs of inorganic N were moderate, ranging from 6 to 10 kg N ha-1 year-1 depending on the time period considered and the degree of site exposure to polluted air masses from the Barcelona conurbation. Large dry-sedimented particles played a minor role, since wet-only inputs were virtually identical to bulk inputs. On the contrary, branch- and plate-washes indicated substantial dry inputs of N gases and small particles. Total atmospheric deposition was estimated at 15-22 kg N ha-1 year-1, most of it being retained within the studied broadleaved evergreen forests. Ecosystem N availability is thus likely to be increasing in these forests. © 2002 Elsevier Science Ltd. All rights reserved.

Llegeix més

Testing taxonomic and biogeographical relationships in a narrow Mediterranean endemic complex (Hippocrepis balearica) using RAPD markers

Rosselló J.A., Cebrián M.C., Mayol M. (2002) Testing taxonomic and biogeographical relationships in a narrow Mediterranean endemic complex (Hippocrepis balearica) using RAPD markers. Annals of Botany. 89: 321-327.
Enllaç
Doi: 10.1093/aob/mcf044

Resum:

Analyses of RAPD profiles from 17 populations of the Hippacrepis balearica complex revealed a highly structured geographic pattern, not only among continental-insular areas but also within the eastern Balearic islands. In marked contrast to previous morphometric results, a clear separation between continental and insular samples was found, and intermediates between H. balearica and H. valentina samples were not detected. Molecular data indicated that western and eastern Balearic populations of the complex (H. grosii and H. balearica) were more closely related to each other than to continental populations (H. valentina). Multivariate analyses of the RAPD data clearly indicated that the similarities between continental and eastern Balearic samples of the H. balearica complex recovered by morphometric methods are due either to parallel evolution or to retention of plesiomorphic features. © 2002 Annals of Botany Company.

Llegeix més

Seed germination and reproductive features of Lysimachia minoricensis (Primulaceae), a wild-extinct plant

Rosselló J.A., Mayol M. (2002) Seed germination and reproductive features of Lysimachia minoricensis (Primulaceae), a wild-extinct plant. Annals of Botany. 89: 559-562.
Enllaç
Doi: 10.1093/aob/mcf083

Resum:

Lysimachia minoricensis is one of the few Mediterranean endemic plants (Minorca, Balearic islands) that has gone extinct in the wild but which persists as extant germplasm or cultivated plants in several botanical gardens. Reproductive features (seed set, number of seeds per capsule, seed weight) and germination responses to constant temperatures, sea water and dry-heat pre-treatments were investigated to determine the extent to which they may have influenced the extinction of the species. Seed set in Lysimachia is not dependent on pollinators, suggesting a functional selfer breeding system. Most plants produced a large mean number of fruits (23.2) and seeds (46.6), and the mean production of seeds per individual was estimated to be almost 1100. Overall, no highly specific requirements were observed for seed germination. Seed germination was not inhibited in the dark, and a high germinability (over 87 % in all cases) was recorded in most experiments, with the exception of those performed at low temperatures (5 and 10°C). These data suggest that fertility and seed viability were not the major causes of extinction. The high reproductive performance of L. minoricensis is in striking contrast to its status as a wild-extinct plant, suggesting that extrinsic factors were responsible for its extinction. © 2002 Annals of Botany Company.

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