Conservation of Mediterranean oak woodlands: understorey dynamics under different shrub management

Abstract

The effect of experimental disturbances on the dynamics of a shrub community was studied on a'Montado' ecosystem, in southern Portugal. The evolution of the community physiognomy, composition and diversity were monitored after shrub clearing followed by biomass removal, deposition on soil surface and incorporation with the soil, over a 9-year period. Maximum shrub density was recorded in the first year after the disturbances, excepting in mulched plots which showed the greatest number of individuals 1 year later. The increment of shrub leaf biomass was very fast in the first 3 years, whereas wood production was slower but occurred along the whole study period. At the end of the study, leaf and wood biomass was still significantly lower than in the predisturbance situation. The variation pattern of leaf area index was similar to that of leaf biomass. The evolution of total plant cover and diversity was similar across treatments. The highest species richness and diversity were recorded 2 years after cutting, decreasing afterwards with the increasing dominance of shrubs. Thus it seems likely that, although a 9 year period is too short for these communities to reach steady equilibrium, they are very resistant and resilient to disturbances, as regeneration was fast and vegetation dynamics was not influenced by differences among treatments. We can conclude that shrub clearing promotes biodiversity and the time of permanence of shrub patches depends on the particular goal we want to achieve.

Long-term sustainability of cork oak agro-forests in the Iberian Peninsula: A model-based approach aimed at supporting the best management options for the montado conservation

“…This agrees with our results, where short periods between clearings would inhibit the regeneration of trees, since mechanical clearing is a non-selective tool that destroys most seedlings (Arosa et al, 2015), thus the absence of immature trees directly affects negatively the population of adult trees. According to our long term results, we assume that extending shrub clearing for longer periods would benefit natural regeneration, which is in agreement with other short term studies (Canteiro et al, 2011;Godinho et al, 2014;Simões et al, 2016). In fact, other authors' conclusions suggest maintaining shrub cover for a period between 7 and 12 years to help cork oak regeneration and promote tree nursery and soil rehabilitation.…”

“…In fact, other authors' conclusions suggest maintaining shrub cover for a period between 7 and 12 years to help cork oak regeneration and promote tree nursery and soil rehabilitation. Conversely, periods longer than 12 years could facilitate fire spread due to the accumulation of dead material (Canteiro et al, 2011). EU programs have only been subsidizing planting young cork oak trees but results obtained by Arosa et al (2015) confirmed that direct seeding (or natural regeneration) of cork oak is a good alternative to facilitate regeneration, because emergence success ranged between 43.5% and 63.9%.…”

“…Shrub clearing might hinder landscape heterogeneity and damage the fungal community in montado, decreasing the mycorrhizal community that is part of the symbiosis most intimately connected to the soil and most directly involved in uptaking nutrients and influencing soil properties (Azul, 2002;Azul et al, 2010). The period between consecutive shrub clearings supports different management objectives: intensive shrub clearing every three years will favour pastureland for livestock grazing and decreasing shrub growing will neglect its positive protector effect over regeneration (Canteiro et al, 2011;Simões et al, 2015). This agrees with our results, where short periods between clearings would inhibit the regeneration of trees, since mechanical clearing is a non-selective tool that destroys most seedlings (Arosa et al, 2015), thus the absence of immature trees directly affects negatively the population of adult trees.…”

Evaluation of the effects of various factors on aboveground and belowground biomass storage capacity of eastern mediterranean maquis vegetation

“…Plant biologists generally dry the leaves and fruits at 60-70 °C, because high temperatures cause decreases in organic compounds (Westerman, 1990). Cornelissen et al (2003) have recommended drying the herbaceous stems at 60 °C for 72 hours or at s 80 °C for 48-72 hours, and extended this recommendation to woody stems. Since maquis societies consists of high-level of leaves and thin material, the temperature of drying was set to 65°C in order to prevent any failures due to high temperature.…”

Biomass residues for energy production and habitat preservation. Case study in a montado area in Southwestern Europe

“…Its main forest tree species are the cork oak (Quercus suber L.) and the holm oak (Quercus rotundifolia Lam.). For a detailed characterization of this ecosystem, which is known as dehesa in Spain, see, for example, Joffre et al (1999) and Canteiro et al (2011).…”