Valencia, Spain
Valencia, Spain

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Cano A.,University of Valencia | Saleh K.,University of Cambridge | Wigneron J.-P.,French National Institute for Agricultural Research | Antolin C.,CIDE CSIC UV GV | And 7 more authors.
Remote Sensing of Environment | Year: 2010

In the framework of ESA's SMOS mission (Soil Moisture and Ocean Salinity), many studies have been carried out over different land surface types to model their microwave emission at L-band (1.4 GHz). Results of these studies have been integrated in the emission model L-MEB (L-Band Microwave Emission of the Biosphere), which is the core of the SMOS Level 2 soil moisture retrieval algorithm. The Mediterranean Ecosystem L-Band characterisation EXperiment (MELBEX-I) was carried out at the SMOS validation site near Valencia in autumn 2005. The main objective of MELBEX-I was to calibrate L-MEB over Mediterranean shrub land, as no data were available over this biome. For that purpose, multi-angular and dual polarimetric measurements (H, V) were obtained by the EMIRAD L-band radiometer from a 14-m tower. Results of this study indicate a small and constant impact of vegetation on the microwave emission of shrub land, and L-MEB parameters for shrub land were obtained. In addition, the study highlights the need for calibrating microwave soil roughness, which was found to be constant at the site. Depending on the number of retrieved parameters, soil moisture (SM) near the surface could be estimated with errors between 0.035 m3 m- 3 (if only SM was retrieved) and 0.057 m3 m- 3 (if SM, optical depth and a roughness parameter were simultaneously retrieved). Finally, no modelling improvements were observed when coarse estimates of the fraction of exposed rocks were accounted for in the model. © 2009 Elsevier Inc. All rights reserved.

Montesinos D.,CIDE CSIC UV GV | Montesinos D.,University of Coimbra | Villar-Salvador P.,University of Alcalá | Garcia-Fayos P.,CIDE CSIC UV GV | Verdu M.,CIDE CSIC UV GV
New Phytologist | Year: 2012

• Differences in reproductive investment can trigger asymmetric, context-dependent, functional strategies between genders in dioecious species. However, little is known about the gender responses of dioecious species to nutrient availability. • We experimentally fertirrigated a set of male and female Juniperus thurifera trees monthly for 2yr. Water potential, photosynthesis rate and stomatal conductance were measured monthly for 2yr, while shoot nitrogen (N) concentration, carbon isotopic composition (δ 13C), branch growth, trunk radial growth and reproductive investment per branch were measured yearly. • Control males had lower gas exchange rates and radial growth but greater reproductive investment and higher water use efficiency (WUE; as inferred from more positive δ 13C values) than females. Fertirrigation did not affect water potential or WUE but genders responded differently to increased nutrient availability. The two genders similarly increased shoot N concentration when fertilized. The increase in shoot N was associated with increased photosynthesis in males but not in females, which presented consistently high photosynthetic rates across treatments. • Our results suggest that genders invest N surplus in different functions, with females presenting a long-term strategy by increasing N storage to compensate for massive reproductive masting events, while males seem to be more reactive to current nutrient availability, promoting gas-exchange capacity. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

Montesinos D.,CIDE CSIC UV GV | Montesinos D.,University of Coimbra | Garcia-Fayos P.,CIDE CSIC UV GV | Verdu M.,CIDE CSIC UV GV
Oikos | Year: 2012

Evolutionary selective forces, like predator satiation and pollination efficiency, are acknowledged to be major causes of masting (the variable, periodic and synchronic production of seeds in a population). However, a number of recent studies indicate that resources might also play an important role on shaping masting patterns. Dioecious masting species offer a privileged framework to study the role of resources on masting variation, since male and female plants often experience different reproductive costs and selective pressures. We followed masting and reproductive investment (RI) of the dioecious tree Juniperus thurifera in two populations along 10 years and studied the different response of males and females to experimentally increased water and nutrient availability in a third population. Juniperus thurifera females invested in reproduction three times more resources than males. Such disparity generated different resource-use strategies in male and female trees. Tree-ring growth and water use efficiency (WUE) confirmed that sexes differed in their resource investment temporal pattern, with males using current resources for reproduction and females using resources accumulated during longer periods. Watered and fertilized female trees presented significantly higher flowering reproductive investments than males and experienced an extraordinary mast-flowering event. However, seeding RI and mast seeding were not affected by the treatment. This suggests that although resource availability affects the reproductive output of this species, there are other major forces regulating masting on J. thurifera. During 10 years, J. thurifera male and female trees presented high and low flowering years more or less synchronously. However, not all mast flowering episodes resulted in mast seeding, leading to masting uncoupling between flowering and seeding. Since flowering costs represent only 1% of females' total reproductive investments, masting uncoupling could be a beneficial bet-hedging strategy to maximize reproductive output in spite of unpredictable catastrophic events. © 2012 The Authors. Oikos © 2012 Nordic Society Oikos.

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