Centro MiRT Fondazione Minoprio

Vertemate con Minoprio, Italy

Centro MiRT Fondazione Minoprio

Vertemate con Minoprio, Italy
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Fini A.,University of Florence | Fini A.,University of Milan | Frangi P.,Centro Mirt Fondazione Minoprio | Mori J.,University of Florence | And 2 more authors.
Environmental Research | Year: 2017

Soil sealing is one of the most pervasive forms of soil degradation that follows urbanization and, despite innovative pavements (i.e. pervious) are being installed in urban areas to mitigate it, there is little research on the effects of pervious pavements on soil water and carbon cycle and on the physiology of urban trees. The aim of this 4-year experiment was to assess the effects of three pavements, differing in permeability to water and gases, on some soil physical parameters, and on growth and physiology of newly planted Celtis australis and Fraxinus ornus. Treatments were: 1) impermeable pavement (asphalt on concrete sub-base); 2) permeable pavement (pavers on crushed rock sub-base); 3) porous design (porous pavement on crushed rock sub-base); 4) control (unpaved soil, kept free of weed by chemical control). Soil (temperature, moisture, oxygen content and CO2 efflux) and plant (above- and below-ground growth, leaf gas exchange, chlorophyll fluorescence, water relations) parameters were measured. All types of pavements altered the water cycle compared to unpaved soil plots, but this disturbance was less intense in porous pavements than in other soil cover types. Porous pavements allowed both higher infiltration and evaporation of water than both pavers and asphalt. Reduction of evaporative cooling from soil paved with permeable and impermeable pavements contributed to significant soil warming: at 20 cm depth, soils under concrete pavers and asphalt were 4 and 5 °C warmer than soil covered by porous pavements and unpaved soils, respectively. Thus, enhancing evaporation from paved soil by the use of porous pavements may contribute to mitigating urban heat islands. CO2 greatly accumulated under impermeable and permeable pavements, but not under porous pavements, which showed CO2 efflux rates similar to control. Soil oxygen slightly decreased only beneath asphalt. Growth of newly planted C. australis and F. ornus was little affected by pavement type. Tree transpiration rapidly depleted soil moisture compared to the not-planted scenario, but soil moisture did not fall below wilting point (particularly in the deeper soil layers, i.e. 40–50 cm) in any treatment. While C. australis showed similar leaf gas exchange and water relations in all treatments, F. ornus showed a depression in CO2 assimilation and slight signs of stress of the photosynthetic apparatus when planted in soil covered with impermeable pavement. The effects of soil cover with different materials on tree growth and physiology were little, because newly planted trees have most of their roots still confined in the unpaved planting pit. Still, the reduction of soil sealing around the planting pit triggered the establishment of sensitive species such as ash. Further research is needed to assess the effects of different pavement types on established, larger trees. © 2017 Elsevier Inc.


Fini A.,University of Florence | Frangi P.,Centro MiRT Fondazione Minoprio | Faoro M.,Centro MiRT Fondazione Minoprio | Piatti R.,Centro MiRT Fondazione Minoprio | And 3 more authors.
Urban Forestry and Urban Greening | Year: 2015

The aim of this work was to evaluate the effects of repeated pruning interventions using different pruning methods on growth and physiology of Acer pseudoplatanus L. Trees were pruned in 2008 and 2010 according to widely used pruning techniques for urban trees, such as reduction cut, removal cut and heading (topping) cut. Crown dieback, growth of the plant and of the pruned branches, leaf morphological traits and leaf gas exchange were assessed during the two growing seasons after each pruning cycle. Topping cut (i.e. the pruning treatment which suppressed the primary axis without providing a substitute) induced changes on tree growth pattern (i.e. by increasing the release of adventitious watersprouts and root suckers and decreasing stem diameter growth), which were not observed in the other pruning treatments. At the leaf level only topping cut increased leaf area at the expense of leaf mass per area, which may contribute to explain the higher occurrence of dieback on topped branches than in control and in the other pruning treatments. Also, leaves on topped branches displayed higher chlorophyll content and higher activity of Calvin cycle enzymes, which did not translate in higher CO2 assimilation. We show here that pruning method, not only its severity (i.e. the amount of leaf area removed), modulates the morpho-physiological response of trees to pruning and that maintenance of apical control and apical dominance are key issues to preserve a structurally sound tree structure, as well as the long-term efficiency of the photosynthetic apparatus. © 2015 Elsevier GmbH.

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