Effect of the plant protection systems on soil arthropods in olive groves from Alentejo region (South-East of Portugal)

Transcription

1 Effect of the plant protection systems on soil arthropods in olive groves from Alentejo region (South-East of Portugal) Artur Estevão, Sónia A.P. Santos, Andreína Silva, Cláudia Gonçalves, José A. Pereira, M. Isabel Patanita IOBC May 2011

2 Introduction In the last few years, new olive planting systems based on an increase in the density of the trees/ha have been introduced in South Alentejo region. These systems are linked to improvements in harvesting and pruning machinery and irrigation systems and involve a reduction in the number of olive varieties used.

3 Introduction Among these modern planting systems are: The high input intensive system (> trees/ha) The super-intensive or high-density system ( trees/ha) based on hedgerows systems allowing for mechanical harvesting.

4 Introduction These systems are intensively managed through the application of pesticides (insecticides, fungicides, herbicides ), fertilizers or frequent tillages for weed control. It is essential to understand if changes in arthropod abundance and biodiversity can be associated with changes in land use and agricultural practices.

5 Objective To study the abundance and diversity of edaphic arthropods in olive groves following different plant protection systems (organic growing, intensive, super-intensive and traditional); to analyse the seasonal variation of the most abundant groups.

6 Methods - study areas Four olive groves located in South-Alentejo region were sampled Olive grove Irrigation Soil managment Soil coverage Organic Super-highdensity Intensive Conventional Yes Yes Yes No Tillage on the row Weeds removed between rows Bone meal fertilizer in February Herbicide Tillage Ferti-irrigation with binary or ternary fertilizer in March Herbicide on the row Weeds removed between rows Ferti-irrigation Herbicide Tillage Natural vegetation Sown clover No Natural vegetation No Nº trees/ha 238/ha 1976/ha 285/ha 70/ha

7 Methods sampling Soil epigeic arthropods were sampled on a monthly basis from April to October 2010; In each olive grove, 25 pitfall traps with 16 cm height and 9 cm diameter were installed; Traps were placed facing the south side of the canopy at 50 cm apart each tree trunk, at the soil level, and collected after 24 h. All trapped individuals were identified to class, order or family taxa.

8 Methods statistical analysis One way-anova Principal Response Curves (PRC) method was used to analyse the effect of the plant protection system at the community level.

9 Results Total abundance of taxa sampled Taxa Organic Conventional Intensive Super-high density Formicidae Araneae Coleoptera Hemiptera Diptera Collembola Crustacea Chilopoda Orthoptera Lepidoptera Acari Total

10 Abundance of Formicidae Organic Intensive Conventional Super-high-density

11 Abundance of Coleoptera Organic Intensive Conventional Super-high-density

12 Abundance of Araneae Organic Intensive Conventional Super-high-density

13 Principal response curves Canonical coefficient (cdt) Organic Intensive Conventional Super-high-density Species weight (b k ) Formicidae Diptera Araneae Crustacea Orthoptera Coleoptera Hemiptera Acari Collembola Hymenoptera Chilopoda Lepidoptera Dermaptera

14 Conclusions Significantly higher abundances of arthropods were registered in the organic grove when compared with the other three systems. Formicidae family was the most abundant group in all the sampled groves reaching higher abundances in August in the super-intensive system while the other three systems obtained higher abundance of Formicidae in May. Araneae order was more abundant in June in the organic and super-intensive systems and in October in the conventional and intensive systems. Coleoptera order was more abundant in October in the organic, in May in the intensive and super-high-density and in April in the conventional system.

15 Conclusions According the PRC method, Formicidae family was the most affected group by the plant protection system. Moreover, the super-high-density system showed the highest negative impact over arthropod abundance which can be explained by the application of herbicides for the control of Conyza canadensis.

16 Thank you for your attention Acknowledgments: PTDC/AGR-PRO/111123/2009 project UNIÃO EUROPEIA Fundo Europeu de Desenvolvimento Regional

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