Search results for " Primary production"
showing 10 items of 18 documents
Reference growth charts for assessing growth performance of Posidonia oceanica (L.) Delile
2016
Posidonia oceanica is considered a key species due to its different roles as primary producer, substrate for many species, shoreline erosion protector and long-term carbon store (1).The importance of P. oceanicahas stimulated several studies aimed at quantifying its status. In particular growth performance of rhizomes has become among the most used descriptors for monitoring changes of P. oceanicameadows induced by human or naturalexogenous factors (2). However, ability to detect any change of growth in space or in time is often confounded by natural age-induced variations, which involves serious interpretation problems (3). A general approach adopted to overcome this problem is to build gr…
Constraining Uncertainty in Projected Gross Primary Production With Machine Learning
2020
The terrestrial biosphere is currently slowing down global warming by absorbing about 30% of human emissions of carbon dioxide (CO2). The largest flux of the terrestrial carbon uptake is gross primary production (GPP) defined as the production of carbohydrates by photosynthesis. Elevated atmospheric CO2 concentration is expected to increase GPP (“CO2 fertilization effect”). However, Earth system models (ESMs) exhibit a large range in simulated GPP projections. In this study, we combine an existing emergent constraint on CO2 fertilization with a machine learning approach to constrain the spatial variations of multimodel GPP projections. In a first step, we use observed changes in the CO2 sea…
Climate change and Mediterranean seagrass meadows: a synopsis for environmental managers
2014
12 páginas, 3 figuras
The importance of phytoplankton production for carbon budgets in a semiarid floodplain wetland
2011
Phytoplankton production (PP) in wetlands is not measured as often as that of macrophytes. A three year-study during a period of sustained high flooding was undertaken in a central Spanish floodplain wetland (Las Tablas de Daimiel National Park) to determine net PP, its spatial heterogeneity and controlling factors, and compare it with primary production in macrophyte communities. This enabled us to estimate carbon budgets for each community. All PP variables showed high spatial and temporal variability among sites, resulting in low coherence even when flooding connected all sites. Net PP corresponded to 25- 36% of submerged plant production and 3-10% of helophyte production. Net PP was con…
Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks
2020
Abstract The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co‐acting…
Filtration pressure by bivalves affects the trophic conditions in Mediterranean shallow ecosystems
2009
Bivalve filtration may control the amount of seston in coastal waters, reducing local euthrophication and keeping degrading phenomena like hypoxia and anthropogenic pollution under control. Two Sicilian brackish-marine ponds (Ganzirri and Faro) present us with the opportunity to gain data on the effect of bivalve filtration on the amount of particulate organic matter in the field. The cultivation of bivalves has been carried out in both of the ponds since the early 1990s but stopped in Ganzirri in 1995.We tested whether the cessation of bivalve cultivation influenced features of organic matter available to suspension feeders (total suspended matter, its inorganic and organic fractions, chlo…
Effects of a small seagull colony on trophic status and primary production in a Mediterranean coastal system (Marinello ponds, Italy)
2012
Abstract Colonies of seabirds have been shown to influence nutrient cycling and primary production of coastal areas, but knowledge is still limited above all for smaller colonies. This study evaluates the influence of a small resident seagull colony (Larus michahellis Naumann, 1840) on a Mediterranean coastal system (Marinello ponds, Sicily, Italy). The presence of ornithogenic organic matter from seagull guano was first assessed at increasing distances from the colony using δ15N to indicate the effects of guano on the trophic status and primary production. The pond directly affected by guano deposition showed an anomalous water and sediment chemistry, especially regarding physico-chemical …
A survey of carbon sequestration potential of orchards and vineyards in Italy
2016
Orchards and vineyards are important land use types in Southern Europe. In spite of their potential to sequester atmospheric C and to mitigate climate change, relatively little is known regarding the influx and outflux of C in these systems. The aim of this work is to provide data on the C budget, including net primary production (NPP), C removal through production, and C sequestration potential for the vineyards and the main fruit tree species (apple, citrus, olive, and peach) grown in Italy. Standing biomass and NPP were measured, and net ecosystem exchange and net C balance assessed directly, through either eddy covariance technique, or considering NPP and heterotrophic respiration. Abov…
Global sensitivity analysis of the SCOPE model : what drives simulated canopy - leaving sun - induced fluorescence?
2015
This study provides insight into the key variables that drive sun-induced chlorophyll fluorescence (SIF) emanating from vegetation canopies, based on a global sensitivity analysis (GSA) of the Soil-Canopy Observation of Photosynthesis and Energy (SCOPE) balance model. An updated version of the SCOPE model was used here (v1.53) which contains novel leaf physiological modules for determination of the steady state fluorescence yield: a photosynthesis model coupled with (a) submodels having empirically derived relationships, identified as TB12 for unstressed and TB12-D for drought conditions and (b) a mechanistic (MD12) submodel based on theoretical relationships. By inspecting Sobol's total or…
CEFLES2: The remote sensing component to quantify photosynthetic efficiency from the leaf to the region by measuring sun-induced fluorescence in the …
2009
The CEFLES2 campaign during the Carbo Europe Regional Experiment Strategy was designed to provide simultaneous airborne measurements of solar induced fluorescence and CO<sub>2</sub> fluxes. It was combined with extensive ground-based quantification of leaf- and canopy-level processes in support of ESA's Candidate Earth Explorer Mission of the "Fluorescence Explorer" (FLEX). The aim of this campaign was to test if fluorescence signal detected from an airborne platform can be used to improve estimates of plant mediated exchange on the mesoscale. Canopy fluorescence was quantified from four airborne platforms using a combination of novel sensors: (i) the prototype ai…