Selection and characterization of the olive groves

Objective of this task:

Selection and characterization of various olive groves in the two main olive growing regions,Trás-os-Montes and Alentejo.

The seletion of the olive groves was based in a gradient of land use intensity that corresponds to the management regimes most frequently followed by the olive growers:organic farming and integrated production. Nine olive groves were selected in Trás-os-Montes region and eight in Alentejo region.

Olive groves selected in Tras-os-Montes region

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Olive groves selected in Alentejo region

The characterization of each olive grove involved several variables such as, the grove area,altitude,age,density (trees per ha),olive tree variety or average height of the trees (<2.5 m or ≥ 2.5 m).

Additionally,the surrounding landscape buffer of 0.5-1.0 km diameter was established at each olive grove and characterized regarding landscape diversity and structure using aerial photographs of the sites and validation in the field. The characterization of each buffer is based on land use types (coniferous,broadleaved,mixed forest with closed,open,and very open stands,agro-forestry,artificial surfaces like villages or roads,open spaces with no vegetation,agricultural crops – which include other olive groves,agricultural and natural grasslands,shrub land and heath land,wetland,and water bodies). Landscape structure is quantified using metric parameters (number,area,shape and spatial configuration  metrics) and derived at patch and class levels. Special attention is given to a detailed spatial analysis of ecological structures (e.g.,hedgerows,stone-walls),since they are key landscape features hosting populations of important predatory arthropod groups.

Sampling of arthropods

The objective of this task is to collect arthropod specimens in the study sites previously selected.

In each region,the collection of arthropods includes two compartments of the ecosystem (tree canopy and soil) and the following techniques:

1. Canopy arthropods using the beating technique.

  

 

2. Epigeal arthropods using pitfall traps.

 

3. Mesofauna using a sample core (5 cm diameter and 5 cm depth).

Species and morphospecies identification

The objective of this task is:

Identify the arthropods collected in soil and canopy compartments using both eco-morphological and taxonomic criteria.

The identification of arthropods is focused on the following taxonomic groups:

Order Araneae

Class Collembola

Order Coleoptera

Family Formicidae

After taxonomic identification,an eco-morphotype database based on morphological and ecological traits is under construction.

Identification of environmental variables

The objective of this task is to obtain a set of environmental variables collected from the study sites

The following environmental variables will be obtained:

1. Management practices:(i) number of pesticide applications per year,(ii) number of fertilizations per year,(iii) conventional tillage or conservation tillage.

2. Pest population levels.

3. Soil properties:(i) determination of soil pH (in 1M KCl and water 1:6 v:v),(ii) moisture content (dried overnight at 105ºC) (iii) carbon content (iv) nitrogen content and (v) organic matter.

Development of biological indicators

The objective of this task is to develop biological indicators of quality and sustainability for the olive grove.

This task involves the use of:

1. structural biodiversity descriptors (abundance,frequency,species richness,diversity indexes).

2. multivariate analyses to evaluate the influence of the landscape metrics on biodiversity descriptors.

3. analyses of similarity to compare average similarity values of biodiversity descriptors among olive groves (land-use intensity) and regions.

4. IndVal methodology and Soil Quality Indexes to search for indicator species

After this, the species are ranked in order to obtain potential indicator species that could be used in olive grove.