Assessment of hedge stand types as determinants of woody species richness in rural field margins

Abstract

The woody component along field edges often provides the only permanent elements of structural and biological diversity in landscapes that have lost much of their naturalness to agriculture and urban use. The main aims of this study were (i) to investigate how four hedge stand types, i.e., systems of management distinguished on the basis of the natural and managed growth forms of trees and shrubs (low single-storied, high single-storied, two-storied and multi-storied), differ in their biometric parameters and (ii) to identify the primary management-related determinants of native woody species richness. The study used a large dataset of hedgerows (n=538) sampled in seven sites in Northern Italy. The four hedge stand types exhibited highly significant differences in size and biometric parameters. The multi-storied hedges, associated with the highest stand structural diversity index values, supported the highest number of tree species, followed by high single-storied hedges. The low single-storied hedge stand type contained the lowest number of species. We found a positive effect of hedge area as well as a marginal negative effect of basal area on native woody species richness. The management implications addressed by our study include conversion of single-storied into two- or multi-storied types, increasing hedge size and controlling hedge stand basal area

Topsoil organic matter properties in contrasted hedgerow vegetation types

“…It is a region of ancient cultivation which lies on an homogeneous not differentiated alluvial floodplain, where the management of hedgerows still reflects traditional usages (Sitzia et al 2013;Sitzia 2007). Soils have moderately high runoff potential when thoroughly wet (USDA hydrological group C), high available water capacity, low risk of erosion and they are very slightly salty (ARPAV 2013).…”

“…Then, we randomly selected a sampling fraction of each hedge stand type, which is a good proxy for expected plant diversity in hedgerows, that was proportional to that of the total population: five monolayered, two bi-layered and three multi-layered hedges (see the description by Sitzia et al 2013), a total of 10 hedges (Fig. 2).…”

“…All of the 107 hedges in the study area were surveyed for their stand structural and biophysical attributes, according to the field protocol described by Sitzia et al (2013). Then, we randomly selected a sampling fraction of each hedge stand type, which is a good proxy for expected plant diversity in hedgerows, that was proportional to that of the total population: five monolayered, two bi-layered and three multi-layered hedges (see the description by Sitzia et al 2013), a total of 10 hedges (Fig.…”

Seasonal effects on mortality rates and resprouting of stems treated with glyphosate in the invasive tree of heaven (Ailanthus altissima(Mill.) Swingle)

“…Spread of Ailanthus altissima (Mill.) Swingle is particularly favoured by anthropic disturbances or cutting (Motta, Nola, & Berretti, 2009;Radtke et al, 2013;Sitzia, Trentanovi, Marini, Cattaneo, & Semenzato, 2013). Urgent interventions are therefore needed in order to tackle this global environmental issue, especially focusing on the most harmful species, in order to contain their rising spread and damaging effects.…”

“…Then, it is capable of spreading into relatively undisturbed adjacent forested sites where at first it readily establishes along edges and in clearings (Knapp & Canham, 2000;Sitzia et al, 2013), as a typical heliophilous pioneer plant. A crucial role in the establishment into inner parts of woodlands is played by the remarkable ability of root suckers to propagate vegetatively and resprouts have a higher capacity than seedlings to withstand sub-optimal ecological conditions, such as shade under canopy, or disturbance factors like wildfires (Kowarik, 1995;Lewis, 2007;Maringer et al, 2012;Meggaro & Vilà, 2002).…”