Patterns of shrub diversity and tree regeneration across topographic and stand-structural gradients in a Mediterranean forest

Abstract

Aim of study: This study aimed to determine the influence of topography and stand-structure on the characteristics of shrub communities and tree regeneration in a Mediterranean forest.Area of study: The Navahondona forest in Cazorla mountain range (SE Spain).Material and Methods: Data from 298 inventory plots were analysed by means of Generalized Linear Models (GLM) to test the effects of aspect, altitude and stand basal area on shrub cover and diversity. Likewise, the effects of these three factors plus shrub cover on the recruitment of Spanish black pine (Pinus nigra spp. salzmannii) and two oak species (Quercus ilex and Q. faginea) were analysed by GLMs. Additionally, the influence of topography and forest structure on the specific distribution of shrub species was analysed with multivariate methods.Main results: Shrub cover and diversity were generally low and did not change across the topographic gradient. Tree density was the only study variable affecting (negatively) shrub cover. However, shrub composition changed with aspect and altitude. Both pine and oak regeneration benefited from partial tree cover at intermediate values of stand density, but only oak regeneration was facilitated by shrubs.Research highlights: Altitude, aspect and stand basal area influence the characteristics of shrub communities and tree regeneration. Proactive management of dense pinewoods might be needed to increase shrub and tree diversity.Key words Pinus nigra; Quercus sp.; altitude; aspect; facilitation; Shannon diversity index.

Regeneration of Native Forest Species in Mainland Portugal: Identifying Main Drivers

“…Basal area (G) affected Q. suber regeneration positively, in agreement with other studies where a nursing effect of tree cover was reported [39,100]. It is striking to note that Q. suber was the only taxon for which saplings density did not increase with the density of stands dominated or co-dominated by Q. suber adult trees in the neighbourhood (SeedAvail).…”

Regeneration of submediterranean species Euonymus latifolius (L.) Mill. at its southernmost limit in Europe

“…Grazing, especially from wild ungulates, is among the main threats for most populations, both for species and habitat. Overgrazing by domestic and wild ungulates (García-González & Cuartas, 1989;Soriguer et al, 2003), affecting significantly the structure, composition and regeneration of the vegetation (Tíscar-Oliver, 2015). It was also the main threat factor in many endangered species and acted synergistically with other threat factors (Lorite et al, 2007).…”

“…The total amount of vascular plants accounted for the area is 2,200, with 360 endemics to the Baetic-Rifan complex, 35 of them being narrow endemics of these mountains (Benavente, 2005). This mountain range has typically been overgrazed by domestic and wild ungulates (García-González & Cuartas, 1989;Soriguer et al, 2003), affecting significantly the structure, composition, and regeneration of the vegetation (Tíscar-Oliver, 2015). It is the main threat factor in the area acting synergistically with other threat factors such as climatic change, land use changes, or forestry (Lorite et al, 2007;Heywood, 2014).…”

Factors influencing the establishment and growth of tree seedlings at Subarctic alpine treelines

“…, Harper et al. , Tiscar‐oliver ). That said, further study is required to differentiate whether seedlings are responding to differences in environmental conditions or to the influence of shrubs, which are themselves responding to the environment.…”