Short-term effects of overstory reduction and slash mulching on ground vegetation in a Mediterranean Aleppo pine woodland

Abstract

The short-term effects of forest overstory reduction and slash mulching on ground vegetation were analysed in a Mediterranean Aleppo pine reforested woodland on degraded agricultural land in south-east Spain. This sort of practice is becoming common in the Mediterranean basin to guard against forest fires, but very few attempts have been made to analyse its effect upon biodiversity. The data concerning floristic richness and above-ground biomass of species were measured as dependent variables in 0.5 9 0.5 m quadrats in an overstory reduction versus control area (treatment factor) during the spring of 2006. The data were analysed by ANCOVA, in which slash-mulch weight was introduced as covariate. Relationships between dependent variables and slash-mulch weight were examined using linear regression, and variations in floristic composition were ascertained by means of principal component analysis (PCA). A total of 32 ruderal herbaceous species were recorded, none of which was exotic. In spite of some methodological constraints (i.e. low number of samples and data from a non-replicated case study), the results of our study point to the conclusion that most of these species were found more frequently in the overstory-reduction treatment compared to the control area, and that only a few species clearly preferred the control treatment. In general, overstory reduction led to a significant increase both in floristic richness and above-ground biomass. Slash mulching, on the other hand, encouraged the appearance of a greater quantity of above-ground biomass (in different ways depending upon treatment), although species richness did not improve, even to the extent of declining in the control area. On the basis of our findings, overstory reduction seems to increase species richness and productivity in dense Mediterranean afforestations on degraded agricultural land, at least in the shortterm. Large quantities of mulch accompanied by high tree density would seem not to favour species richness.

Stand management to reduce fire risk promotes understorey plant diversity and biomass in a semi‐aridPinus halepensisplantation

“…Plantation management techniques to reduce these risks and to promote seedling recruitment are used widely throughout the region, and have become increasing in popularity (Navarro et al. ; Prévosto et al. ; Molina & Del Campo ; Ruiz‐Mirazo & Robles ).…”

Stones and Organic Mulches Improve theQuercus IlexL. Afforestation Success Under Mediterranean Climatic Conditions

“…Mulches have been widely used as post-planting treatments in agriculture, forestry systems, and environmental restoration to improve seedling establishment or yields (Navarro et al, 2010;García-Moreno et al, 2013). Mulches are also used as a key strategy to reduce soil erosion and surface overland flow (Alegre et al, 2013).…”

Effects of pre-commercial thinning on growth and reproduction in post-fire regeneration of Pinus halepensis Mill

“…In the first phases, this species improves the vertical structure of the forest, but the richness and diversity of undergrowth species is diminished (Chirino et al 2006). However, timely treatments such as thinning or pruning could improve conditions for understory plant species in mono-specific plantations (Navarro et al 2010a). However, the benefits and risks of thinning to reduce sapling density after a fire are not well-defined.…”