El cambio climático y la reducción de la reserva de agua en el bosque mediterráneo.

Gracia C, Sabaté S, Sánchez A (2002) El cambio climático y la reducción de la reserva de agua en el bosque mediterráneo. Ecosistemas 2002/2 (URL: http//www.aeet.org/ecosistemas/022/investigacion4.htm)

Intraspecific variability of phenolic concentrations and their responses to elevated CO2 in two mediterranean perennial grasses

Castells E., Roumet C., Peñuelas J., Roy J. (2002) Intraspecific variability of phenolic concentrations and their responses to elevated CO2 in two mediterranean perennial grasses. Environmental and Experimental Botany. 47: 205-216.
Enllaç
Doi: 10.1016/S0098-8472(01)00123-X

Resum:

Intraspecific variability of total phenolic compound concentrations and their responses to elevated CO2 were studied in two wild Mediterranean perennial grasses, Dactylis glomerata and Bromus erectus. Ten and nine genotypes of each species were grown in climate-controlled naturally-lit glasshouses under plant intergenotypic and interspecific competition for water, light and nutrients. Carbon source-sink balance hypotheses of resource allocation were also tested. Elevated CO2 induced changes in dry shoot biomass (DM), leaf total non-structural carbohydrate concentrations [TNC] and leaf nitrogen concentrations [N] found in a previous study (New Phytol. 143 (1999) 73) were related to changes in phenolic compound concentrations. Phenolic compound concentrations increased to 15.2% DM in D. glomerata and 86.9% DM in B. erectus under elevated CO2. These changes were more pronounced when expressed on a structural dry mass basis (DMst). Increases in DMst and [TNCst] and decreases in [Nst] were also found according to current resource allocation hypotheses. However, there were no proportional changes between phenolic responses to elevated CO2 and DMst, [TNCst] and [Nst] responses. Phenolic concentrations were highly determined by genetics in both species, but all studied genotypes responded in a similar way to elevated CO2. Considering the present experimental conditions with plants growing in intraspecific and interspecific competition, the absence of CO2 × genotype interaction would lead to little changes of fitness in terms of antiherbivore chemical defence, and, therefore, to low evolutionary consequences in CBSC under the increasing atmospheric CO2 concentrations of the next decades. © 2002 Elsevier Science B.V. All rights reserved.

Llegeix més

Spatial patterns, temporal variability, and the role of multi-nest colonies in a monogynous Spanish desert ant

Cerdá X., Dahbi A., Retana J. (2002) Spatial patterns, temporal variability, and the role of multi-nest colonies in a monogynous Spanish desert ant. Ecological Entomology. 27: 7-15.
Enllaç
Doi: 10.1046/j.0307-6946.2001.00386.x

Resum:

1. The colonies of the Spanish desert ant Cataglyphis iberica are polydomous. This study describes the temporal and spatial patterns of the polydomy in this species at two different sites, and presents analyses of its role in reducing the attacks of the queen over sexual brood, and in allowing better habitat exploitation. 2. The spatial distribution of nests was clumped while colonies were distributed randomly. Mean nearest neighbour distance ranged from 3.4 to 7.0 m for nests and from 12.3 to 14.1 m for colonies. Distance of foragers searching for food varied among nests: mean values were between 6.1 and 12.6 m. 3. At both sites, the maximum number of nests per colony occurred in summer, during the maximum activity period of the species. Colonies regrouped at the end of this period but overwintered in several nests. 4. Nest renewal in C. iberica colonies was high and showed great temporal variability: nests changed (open, close, re-open) continuously through the activity season and/or among years. The lifetime of up to 55% of nests was only 1-3 months. 5. Polydomy in C. iberica might decrease the interactions between the queen and the sexual brood. In all colonies excavated just before the mating period, the nest containing the queen did not contain any virgin female. Females were in the queenless nests of the colony. 6. The results also suggest that polydomous C. iberica colonies may enhance habitat exploitation because foraging activity per colony increases with nest number. The relationship between total prey input and foraging efficiency and number of nests per colony attains a plateau or even decreases after a certain colony size (four to six nests). This value agrees with the observed mean number of nests per colony in C. iberica.

Llegeix més

Organic matter dynamics in soils with different types of sewage sludge amendments.

Tarrasón D, Ortiz O, Ojeda G, Alcañiz JM (2002) Organic matter dynamics in soils with different types of sewage sludge amendments. In Faz (ed) Sustainable Use and Management of Soils in Arid and Semiarid Regions, Vol. II, pp. 201-202.

El CREAF i la formació forestal.

Rodà F (2002) El CREAF i la formació forestal. Silvicultura 35:7.

Assessing decadal changes in rainwater alkalinity at a rural Mediterranean site in the Montseny Mountains (NE Spain).

Avila A, Rodà F (2002) Assessing decadal changes in rainwater alkalinity at a rural Mediterranean site in the Montseny Mountains (NE Spain). Atmospheric Environment 36:2881-2890.

Ética, conocimiento científico y naturaleza en la cultura occidental.

Lloret F (2002) Ética, conocimiento científico y naturaleza en la cultura occidental. Ecosistemas (edició electrònica). Revista de la Asociación Española de Ecología Terrestre. Any XI, Núm. 1. (http://www.aeet.org/ecosistemas/opinion3.htm).

Fire management and Conservation in Mediterranean Ecosystems

Lloret F (2002) Fire management and Conservation in Mediterranean Ecosystems Fire and Nature Management. Whitmore G (ed)

Satellite evidence of decreasing resilience in Mediterranean plant communities after recurrent wildfires.

Díaz-Delgado R, Lloret F, Pons X, Terradas J (2002) Satellite evidence of decreasing resilience in Mediterranean plant communities after recurrent wildfires. Ecology 83:2293-2303.

Effects of three types of sewage sludge on soil erodibility.

Ojeda G, Alcañiz JM, Ortiz O, Tarrasón D (2002) Effects of three types of sewage sludge on soil erodibility. In Faz (ed) Sustainable Use and Management of Soils in Arid and Semiarid Regions, Vol. II, p. 110-111.

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