123 research outputs found
Stomatal Conductance Modeling to Estimate the Evapotranspiration of Natural and Agricultural Ecosystems
This chapter presents some of the available modelling techniques to predict stomatal conductance at leaf and canopy level, the key driver of the transpiration component in the evapotranspiration process of vegetated surfaces. The process-based models reported, are able to predict fast variations of stomatal conductance and the related transpiration and
evapotranspiration rates, e.g. at hourly scale. This high–time resolution is essential for applications which couple the transpiration process with carbon assimilation or air
pollutants uptake by plants.
In these cases, the big-leaf approach, together with the resistive analogy which simulates the gas-exchange between vegetation and atmosphere, is a simple but valid example of a process-based model which includes the stomatal conductance behaviour, as well as a basic representation of the canopy features
(Evapo)Transpiration Measurements Over Vegetated Surfaces as a Key Tool to Assess the Potential Damages of Air Gaseous Pollutant for Plants
Biological damages of a variety of plant organisms are evaluated according their evapotranspiration capacit
An integrated approach shows different use of water resources from Mediterranean maquis species in a coastal dune ecosystem
An integrated approach has been used to analyse the dependence of three Mediterranean species, A. unedo
L., Q. ilex L., and P. latifolia L. co-occurring in a coastal dune ecosystem on two different water resources: groundwater and rainfed upper soil layers. The approach included leaf level gas exchanges, sap flow measurements and structural
adaptations between 15 May and 31 July 2007. During this period it was possible to capture different species-specific response patterns to an environment characterized by a sandy
soil, with a low water retention capacity, and the presence of a water table. The latter did not completely prevent the development of a drought response and, combined with previous
studies in the same area, response differences between species have been partially attributed to different root distributions.
Sap flow of A. unedo decreased rapidly with the decline of soil water content, while that of Q. ilex decreased only moderately. Midday leaf water potential of P. latifolia and A. unedo ranged between 122.2 and 122.7MPa throughout
the measuring period, while in Q. ilex it decreased down to 123.4MPa at the end of the season. A. unedo was the only species that responded to drought with a decrease of its leaf area to sapwood area ratio from 23.9\ub11.2 (May) to
15.2\ub11.5 (July). While A. unedo also underwent an almost stepwise loss on hydraulic conductivity, such a loss did not occur for Q. ilex, whereas P. latifolia was able to slightly increase
its hydraulic conducitivity. These differences show how different plant compartments coordinate differently between species in their responses to drought. The different responses appear to be mediated by different root distributions of the species and their relative resistances to drought
are likely to depend on the duration of the periods in which water remains extractable in the upper soil layers
Operational resilience of reservoirs to climate change, agricultural demand, and tourism: A case study from Sardinia
Copyright © 2015 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Science of the Total Environment. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Science of the Total Environment (2015), DOI: 10.1016/j.scitotenv.2015.04.066Many (semi-) arid locations globally, and particularly islands, rely heavily on reservoirs for water supply. Some reservoirs are particularly vulnerable to climate and development changes (e.g. population change, tourist growth, hydropower demands). Irregularities and uncertainties in the fluvial regime associated with climate change and the continuous increase in water demand by different sectors will add new challenges to the management and to the resilience of these reservoirs. The resilience of vulnerable reservoirs must be studied in detail to prepare for and mitigate potential impacts of these changes. In this paper, a reservoir balance model is developed and presented for the Pedra e' Othoni reservoir in Sardinia, Italy, to assess resilience to climate and development changes. The model was first calibrated and validated, then forced with extensive ensemble climate data for representative concentration pathways (RCPs) 4.5 and 8.5, agricultural data, and with four socio-economic development scenarios. Future projections show a reduction in annual reservoir inflow and an increase in demand, mainly in the agricultural sector. Under no scenario is reservoir resilience significantly affected, the reservoir always achieves refill. However, this occurs at the partial expenses of hydropower production with implications for the production of renewable energy. There is also the possibility of conflict between the agricultural sector and hydropower sector for diminishing water supply. Pedra e' Othoni reservoir shows good resilience to future change mostly because of the disproportionately large basin feeding it. However this is not the case of other Sardinian reservoirs and hence a detailed resilience assessment of all reservoirs is needed, where development plans should carefully account for the trade-offs and potential conflicts among sectors. For Sardinia, the option of physical connection between reservoirs is available, as are alternative water supply measures. Those reservoirs at risk to future change should be identified, and mitigating measures investigated.European Commission Seventh Framework Project ‘WASSERMed’ (Water Availability and Security in Southern EuRope and the Mediterranean
Improved sapflow methodology reveals considerable night-time ozone uptake by Mediterranean species
Due to the evident tropospheric ozone impact on
plant productivity, an accurate ozone risk assessment for the
vegetation has become an issue. There is a growing evidence
that ozone stomatal uptake may also take place at night and
that the night-time uptake may be more damaging than diurnal
uptake. Estimation of night-time uptake in the field is
complicated because of instrumental difficulties. Eddy covariance
technology is not always reliable because of the
low turbulence at night. Leaf level porometry is defective
at relative humidity above 70% which often takes place at
night. Improved sap flow technology allows to estimate also
slow flows that usually take place at night and hence may
be, at present, the most trustworthy technology to measure
night-time transpiration and hence to derive canopy stomatal
conductance and ozone uptake at night. Based on micrometeorological
data and the sap flow of three Mediterranean
woody species, the night-time ozone uptake of these species
was evaluated during a summer season as drought increased.
Night-time ozone uptake was from 10% to 18% of the total
daily uptake when plants were exposed to a weak drought,
but increased up to 24% as the drought became more pronounced.
The percentage increase is due to a stronger reduction
of diurnal stomatal conductance than night-time stomatal
conductance
The ACCENT-VOCBAS field campaign on biosphere-atmosphere interactions in a Mediterranean ecosystem of Castelporziano (Rome): site characteristics, climatic and meteorological conditions, and eco-physiology of vegetation
Biosphere-atmosphere interactions were investigated
on a sandy dune Mediterranean ecosystem in a field
campaign held in 2007 within the frame of the European
Projects ACCENT and VOCBAS. The campaign was carried
out in the Presidential estate of Castelporziano, a periurban
park close to Rome. Former campaigns (e.g. BEMA)
performed in Castelporziano investigated the emission of
biogenic volatile organic compounds (BVOC). These campaigns
focused on pseudosteppe and evergreen oak groves
whereas the contribution of the largely biodiverse dune vegetation,
a prominent component of the Mediterranean ecosystem,
was overlooked. While specific aspects of the campaign
will be discussed in companion papers, the general climatic
and physiological aspects are presented here, together with
information regarding BVOC emission from the most common
plant species of the dune ecosystem. During the campaign
regular air movements were observed, dominated by
moderate nocturnal land breeze and diurnal sea breeze. A
regular daily increase of ozone concentration in the air was
also observed, but daily peaks of ozone were lower than those
measured in summer on the same site. The site was ideal as a natural photochemical reactor to observe reaction, transport
and deposition processes occurring in the Mediterranean
basin, since the sea-land breeze circulation allowed a strong
mixing between biogenic and anthropogenic emissions and
secondary pollutants. Measurements were run in May, when
plant physiological conditions were optimal, in absence of
severe drought and heat stress. Foliar rates of photosynthesis
and transpiration were as high as generally recorded
in unstressed Mediterranean sclerophyllous plants. Most of
the plant species emitted high level of monoterpenes, despite
measurements being made in a period in which emissions
of volatile isoprenoids could be restrained by developmental
and environmental factors, such as leaf age and relatively
low air temperature. Emission of isoprene was generally low.
Accounting for the high monoterpene spring emission of the
dune ecosystem may be important to correct algorithms at regional
and ecosystem levels, and to interpret measurements
of fluxes of volatile isoprenoids and secondary pollutants
Evaluation of Borderline Ovarian Tumor Recurrence Rate after Surgery with or without Fertility-Sparing Approach: Results of a Retrospective Analysis
Borderline ovarian tumors (BOTs) comprise 15-20% of primary ovarian neoplasms and represent an independent disease entity among epithelial ovarian cancers. The present study (Clinical Trial ID: NCT05791838) aimed to report a retrospective analysis of the management and outcomes of 86 consecutive BOTs patients, 54 of which were at a reproductive age. All patients with BOTs undergoing surgical treatment from January 2010 to December 2017 were included. Data were retrospectively reviewed. High levels of Ca-125 were observed in 25.6% of the FIGO stage I patients and 58.3% of the advanced disease patients. Fertility-sparing surgery and comprehensive surgical staging were performed in 36.7% and 49.3% of the patients, respectively. Laparotomy was the most frequent surgical approach (65.1%). The most common diagnosis at frozen sections was serous BOT (50.6%). Serous BOTs have significantly smaller tumor diameters than mucinous BOTs (p < 0.0001). The mean postoperative follow-up was 29.8 months (range 6-87 months). Three patients experienced a recurrence, with an overall recurrence rate of 3.5% (10% considering only the patients who underwent fertility-sparing treatment). BOTs have low recurrence rates, with excellent prognosis. Surgery with proper staging is the main treatment. Conservative surgery is a valid option for women with reproductive potential
(Evapo)transpiration measurements over vegetated surfaces as a key tool to assess the potential damages of air gaseous pollutants for plants
Biological damages of a variety of plant organisms are evaluated according their evapotranspiration capacit
Interactions among vegetation and ozone, water and nitrogen fluxes in a coastal Mediterranean maquis ecosystem
Ozone, water and energy fluxes were measured
over a Mediterranean maquis ecosystem from 5 May until 31
July 2007 by means of the eddy covariance technique. Additional
measurements of NOx fluxes were performed by the
aerodynamic gradient technique. Stomatal ozone fluxes were
obtained from water fluxes by a Dry Deposition Inferential
Method based on a big leaf concept.
The maquis ecosystem acted as a net sink for ozone. The
different water availability between late spring and summer
was the major cause of the changes observed in stomatal
fluxes, which decreased, together with evapotranspiration,
when the season became drier.
NOx concentrations were significantly dependent on the
local meteorology. NOx fluxes resulted less intense than the
ozone fluxes. However an average upward flux of both NO
and NO2 was measured.
The non-stomatal pathways of ozone deposition were investigated.
A correlation of non-stomatal deposition with air
humidity and, in a minor way, with NO2 fluxes was found.
Ozone risk assessment was performed by comparing the
exposure and the dose metrics: AOT40 (Accumulated dose
over a threshold of 40 ppb) and AFst 1.6 (Accumulated stomatal
flux of ozone over a threshold of 1.6 nmolm 122 s 121).
AOT40, both at the measurement height and at canopy height
was greater than the Critical Level for the protection of
forests and semi-natural vegetation (5000 ppb h) adopted by
UN-ECE. Also the AFst 1.6 value (12.6 mmolm 122 PLA, Projected
Leaf Area) was higher than the provisional critical
dose of 4 mmolm 122 PLA for forests. The cumulated dose
showed two different growth rates in the spring and in the
summer periods, while the exposure showed a more irregular
behavior in both periods
Nitrogen Deposition Effects on Soil Properties, Microbial Abundance, and Litter Decomposition Across Three Shrublands Ecosystems From the Mediterranean Basin
Atmospheric nitrogen (N) inputs in the Mediterranean Basin are projected to increase due to fossil fuel combustion, fertilizer use, and the exacerbation of agricultural production processes. Although increasing N deposition is recognized as a major threat to ecosystem functioning, little is known about how local environmental conditions modulate ecosystem function response to N addition, particularly in the context of Mediterranean-Basin ecosystems. Here, we assess how N addition affects important ecosystem properties associated with litter decomposition, soil physical-chemical properties, soil extracellular enzymatic activity and microbial abundance across three long-term N addition experimental sites in the Mediterranean Basin. Sites were located in El Regajal (Madrid, Spain), Capo Caccia (Alghero, Italy), and Arrábida (Lisbon, Portugal) and are all representative of Mediterranean shrublands. No common pattern for litter decomposition process or other studied variables emerged among the control plots of the studied sites. Nitrogen supply only affected soil pH, a major driver of decomposition, in two out of three experimental sites. Moreover, when we explored the role of N addition and soil pH in controlling litter decay, we found that the effects of these factors were site-dependent. Our results point out to local ecosystem features modulating N addition effects in controlling litter decomposition rates in Mediterranean ecosystems, suggesting that the responses of soil functioning to N deposition are site-dependent. These findings provide further knowledge to understand contrasting ecosystem responses to N additions based on a single field experiments
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