Organic Olive Groves Research Articles

Testing the Single and Combined Effect of Kaolin and Spinosad against Bactrocera oleae and Its Natural Antagonist Insects in an Organic Olive Grove.

The presence and infestation level of Bactrocera oleae was monitored in an organic olive orchard divided into differently treated parcels with kaolin (K), spinosad (S) and with kaolin and spinosad (K + S) in alternate rows. The treatments did not seem to affect olive fruit fly population dynamics, while statistically significant protective effects were recorded against total and harmful infestation, but not against the active one. Eventually, neither kaolin nor spinosad were shown to have a particular detrimental effect against naturally occurring B. oleae parasitoids.

A Comparison of IPM and Organic Farming Systems Based on the Efficiency of Oophagous Predation on the Olive Moth (Prays oleae Bernard) in Olive Groves of Southern Iberia

The olive moth, Prays oleae (Bernard, 1788) (Lep., Praydidae), is one of the most common insect pests affecting the olives groves of the Mediterranean basin. Current farming practices are largely oriented to optimize the effectiveness of beneficial insects, among which the common green lacewings (Neur., Chrysopidae) stand out. Two different types of management models, organic and IPM, were compared in this study, which was conducted in olive groves in the regions of Andalucía (Spain) and Alentejo (Portugal). During 2020 and 2021, fruit samples were periodically collected, analyzing the population parameters (POP) and potential attack on the fruit (%PA), as well as the predatory impact (%PRED), which has allowed the estimation of the final attack (%FA), and derived fruit recovery rates (%REC). The results show that in organic olive groves of both countries, the infestation parameters (POP, %PA) were significantly higher than in IPM ones. However, predation rates were also higher in organic olive groves, which resulted in REC rates of between 75% and 80%, reducing FA rates to values of approximately 10% and 20% in Portugal and Spain, respectively. In contrast, in the IPM olive groves, significantly lower predation values were recorded, with lower REC rates than in the organic olive groves; the rates were very similar in both countries (ca. 54%), which led to a higher percentage of fruit loss (%FA) equivalent to 22% (Portugal) and to 34% (Spain). This paper discusses potential drivers influencing differences in the population values and percentages of infestation by P. oleae observed, as well as the differences in the final attack rates between olive groves of both countries, subject to the same type of agricultural management.

Impacts of Erosion on the Sustainability of Organic Olive Groves: A Case Study (Estepa Region, Southwestern Spain)

Spain has more than 2.5 M ha of olive groves, with 60% of this area (i.e., 1.5 M ha) concentrated in the region of Andalusia (Southern Spain). Assuming the socio-ecological characteristics of these crops, of which their contribution to ecosystemic services (ES) is fundamental for society, it is highly relevant to direct their management towards practices that guarantee their durability. Organic management of olive groves constitutes a multifunctional model that contributes to ensuring its sustainability and represents 2.4–3.5% of the olive grove area in Spain. Taking the Protected Designation of Origin (PDO) Estepa (Southwestern Spain) as a study model, where organic olive groves are novel, a study of the impacts of erosion on the economic, social, and environmental factors associated with this management was carried out in addition to estimating its impacts. The results showed how organic management promotes edaphic fertility, keeping the levels of diffuse pollution under the legislative limits. Although the increase in erosion has negative effects on the sustainability/durability of agricultural holdings, organic management consolidates a sustainable model that satisfies farmers’ demands. Therefore, organic farming is a model that focuses on the correct use of natural resources associated with the geographical region of study, and contributes to increasing the sustainability of olive groves.

Benefits of organic olive farming for the conservation of gleaning bats

Current intensification and expansion of agricultural lands are some of the main anthropogenic processes driving the global decline of biodiversity. Organic farming is generally regarded as a better compromise between production and ecosystems and biodiversity preservation. However, while this practice is gaining popularity worldwide, conventional agriculture is still the main approach, hindering the conservation of many taxa. Bats are poorly studied and generally negatively affected by conventional farming. Their high mobility and long lifespan make them excellent ecological indicators in agroecosystems. We assessed the effect of different crop treatments (conventional and organic olive groves, and sparse coniferous forest as a control) on bat activity, at both guild and species level. In addition, we evaluated whether bat activity was influenced by the abundance of the olive fruit fly Bactrocera oleae, the major insect pest of olive groves worldwide. Bats were surveyed acoustically during autumn 2014 in all treatments using passive ultrasound detectors. In parallel, pheromone traps for B. oleae were used to monitor pest insect abundance. Our results show that aerial hunting bats were significantly more active in sparse coniferous forests compared to the other treatment areas. On the contrary, gleaning bats (those generally more threatened and vulnerable to habitat degradation) showed higher activity rates in organic olive groves. Due to their higher manoeuvrability and slow flight, gleaning species are generally well-adapted to forage in structurally complex and cluttered habitats such as olive groves. A significant negative relation was found between the density of the olive fruit fly and the gleaning bats activity, which were expected to prey on the pest and hence show some positive relation with its density. The reasons are unclear and further research with molecular techniques would be needed to better understand the ecological interaction, if any, between bats and the pest. Organic olive groves, usually more stratified than the conventional ones, are characterized by the presence of spontaneous herbaceous cover and higher diversity of arthropods (either beneficial or deleterious), which favours bat activity. Organic practices should be further prioritised in the agri-environment schemes of the European Union and those of its individual members. If organic farming is not widely implemented, agriculture intensification and the expansion of monocultures may put bat populations at stake, as well as compromise ecosystem quality and the conservation of biodiversity.

Contribution of Agro-Environmental Factors to Yield and Plant Diversity of Olive Grove Ecosystems (Olea europaea L.) in the Mediterranean Landscape

Olive cultivation (Olea europaea L.) is one of the most significant sources of income for agricultural areas in the Mediterranean basin, and the olive oil industry as well as the environmental protection are an important part of the Greek agricultural sector. Generalized Linear Models were applied in order to investigate the predictive strength of several biodiversity components and agro-environmental factors for yield and herbaceous plant diversity (species richness) in organic and conventional olive groves of Greece. Our study highlights an increase in yields of organic olive groves by increasing manure application and the earthworms’ density. In the conventional olive groves, yields increase by increasing soil organic matter and the application of inorganic fertilizer N. Also, the herbaceous plant species richness increases with increasing the Shannon diversity index of herbaceous plants, the field area, the application of organic fertilizer K and the manure in organic olive groves. As for the conventional ones, herbaceous plant species richness increases with the increase of the application of inorganic fertilizer N. Moreover, some plant species could be regarded as indicators of the differently managed olive groves. Conclusively, this study contributes to the integration of biodiversity conservation with ecologically sustainable agriculture and conservation of agroecosystem. Finally, it could be utilized as a decision and management tool to the scientific and agricultural community reinforcing the knowledge about the agro-environmental impact in olive grove management systems.

Changes in the soil due to the use of sheep in cover crop management in organic olive groves

This work studied the effects of cover crop management by livestock on soil properties, comparing it with other managements and uses of soil. For this, two olive-orchards were selected, one an ecological olive-orchard, surrounded by patches of natural vegetation and another under conventional management, both located in Pegalajar (Jaén, Spain). The study area was divided into 7 plots with four management types and three uses: two of the plots were not cultivated, one was lucerne (ESP) and the other one holm oak (ENC); one plot was under conventional management, with bare soil due to the application of herbicides (BL); one plot was managed by mechanical clearing (CON); three plots had a cover crop that was managed in the following ways: two plots with only sheep, for 2 years (G) and six years (GA) and the third plot with a combined management of livestock and mechanical clearing (Mix). The constituents and properties studied were: texture, bulk density, humidity, pH, exchangeable bases and cation exchange capacity (CIC), nitrogen (N), oxidizable organic carbon (CO), soluble organic carbon (COS), assimilable phosphorus (P), enzymatic activities β-glucosidase and dehydrogenase. The organic carbon content was the constituent that most affected the other parameters. As expected, the soils under holm oak, followed by lucerne, showed the highest concentrations of total organic carbon and soluble organic carbon and nitrogen. However, the concentration of total carbon in soils with livestock management was equal to that of the lucerne. The sequences from highest to lowest concentration were ENC > GA, ESP, G > BL for total carbon, and ENC, ESP > CON, G, GA, MIX > Bl for soluble carbon and nitrogen. In general bulk density and pH were lower in the uses and managements with higher CO content. On the contrary, the parameters of humidity, bases and cation exchange capacity were higher when the CO was also higher, although not always with significant differences. The β-Glucosidase activity was lower in holm oak, probably because the organic matter has a lower cellulose content. Finally, the dehydrogenase activity was significantly higher in holm oak and lucerne, which have continuous contributions of organic matter that favour a continual microbial activity, contrary to the rest of treatments that are more time-specific.

Terrestrial isopods as bioindicators for environmental monitoring in olive groves and natural ecosystems

ABSTRACTTerrestrial isopods (Crustacea: Isopoda: Oniscidea) are an important component of biodiversity as they constitute useful bioindicators for monitoring environmental quality in a variety of natural and agricultural ecosystems. In the present study, the predictive strength of several important components of biodiversity (e.g. herbaceous and woody plants, etc.) and agro-environmental factors for isopod species richness in each management system of olive groves and a natural ecosystem in central Greece was investigated. Our study highlights an increase in isopod species richness with increasing air humidity, woody plant species richness and soil organic matter in organic olive groves. It is noteworthy that woody plant species richness could be utilised as the best candidate for monitoring isopod species richness. In the conventional olive groves, isopod species richness decreases possibly due to herbicide and inorganic fertiliser application. In abandoned olive groves, isopod species richness increases with increasing soil plant litter and pH. Moreover, soil organic matter has been proved to be a positive indicator of isopod species richness in maquis ecosystems. The species Porcellio laevis can be regarded as an indicator for organic olive groves. Conclusively, this paper contributes to the integration of biodiversity conservation with ecologically sustainable agriculture, conservation of agroecosystem and natural ecosystem services and preserving landscape.

Evaluation of two different methods to measure the effects of the management regime on the olive-canopy arthropod community

The effects of the management regime, mostly differentiated for using or not insecticides, on biodiversity have frequently been difficult to analyze and understand because of the rapid re-colonization by good-dispersers, the quick recuperation of generalists and the continuity of insecticide-resistant arthropod species. The presence of these different communities may produce values of abundance, diversity indices and species richness which do not reflect the changes caused by the impact of the insecticides in the sprayed area. In this study we assess the impact of the olive tree management on the arthropod community and the changes in this community according to the blooming season. This study has been developed in olive groves subjected to conventional and organic management regimes by two different approaches: (a) the abundance-diversity approach, measuring and comparing abundance, richness and the Shannon-Weaver diversity index (H’) of total arthropods and per guild and (b) the food-web approach, building food-webs and comparing their unweighted quantitative descriptors. We sampled the arthropods in the tree canopy in six conventional and six organic olive groves (12 plots), and in two of the periods of greatest diversity and abundance: pre-blooming and post-blooming seasons. The abundance of total arthropods, but only those within the guild of phytophagous, diminished significantly when insecticides were used. The species richness of total arthropods and specifically predators were also reduced in the conventional plots. These variables were always greater in organic olive groves. Conversely, the total and per guild Shannon-Weaver diversity index (H’) did not detect any management effect on the olive-canopy arthropod community. Furthermore, all the food-web unweighted quantitative descriptors such as size, complexity and prey-predator asymmetries showed the significant effect of the management on the olive-canopy arthropod community and also presented greater values in organic olive groves. We also found that the blooming season did not significantly change the food-web structure, contrary to what we predicted. However, predator, parasitoid and phytophagous abundance, total and predator richness were greater in the post-blooming season. This study shows that the abundance-diversity approach, and especially H’ diversity index, was not useful for describing the effect of different management systems on the canopy arthropod community. On the contrary, the food-web approach emerges as a useful tool for understanding and evaluating the ecological effect of the application of insecticides (and probably other disturbances during the management) affecting the agro-ecosystems.

Litter dynamics of Olea europaea subsp. Europaea residues related to soil properties and microbial N-biomass in a Mediterranean agroecosystem

Residues decomposition is an important process for plant nutritional demands. The present work was conducted in order to investigate the olive tree residues decomposition (leaves and shoots: buried in a horizontal and a sloping site of an organic olive grove) and its impact on soil properties and microbial N-biomass as affected by soil slope. Mean mass loss and C, N, K, and Mg release rates were higher in leaf than in shoots residues in both soil slopes. The incorporation of leaves and shoots in the soil of the olive grove contributed to its enrichment in certain nutrients such as N, K, Ca, and Mg. Soil organic carbon losses were compensated by the residue released soluble C compounds. The macroaggregates formed by fungal hyphae were not stable in water as Water Aggregate Stability tended to decline in the horizontal site and showed no change in the sloping site. The added amounts of N, P, and K by olive tree residues soil incorporation were 6.1, 0.4, and 7.2 kg ha−1 y−1 (sloping site) and 6.8, 0.3, and 8.8 kg ha−1 y−1 (horizontal site), respectively. These amounts are lower than the needed ones for olive trees (15–35 N, 8 P, ≤50 K kg ha−1 y−1), so olive tree growers should use additional fertilization in order to have strong and productive olive trees.

Behavioural Resistance in Insects: Its Potential Use as Bio Indicator of Organic Agriculture

Most of the investigations carried out on the resistance of insects to pesticides have been focused on the physiological and biochemical mechanisms. However, the behavioural answers that pesticide induces in the insects have received very little attention. The symptoms from getting pesticides on the cuticular surface of insects, as neurotoxical pre mortem effects, include spasmodic activity, hyperactivity and leak of the surfaces impregnated by the pesticides. These reactions provides a first barrier of defense, named behavioural resistance. Previous experiments carried out on olive groves usually subjected to pesticide application have allowed to visualize a reaction of leak of the natural enemies from treated areas, which is reflected as an increase of its rate of capture in sticky chromatic traps, in relation to the free of pesticides areas, on olive groves, usually subjected to pesticide application. The aim of this investigation is to evaluate the reaction of these insects’ species under different agricultural pest management: i- A conventional olive grove, where pesticides are usually applied; and ii- An organic olive grove, where pest management depends exclusively on the role of the natural enemies. During the spring of 2016, experimental applications have been carried out in two olive groves of the province of Jaén (south of Spain) by means of a commercial pesticide application, in order to evaluate the reactions induced in the main species of olive predators. Six pairs of plots were randomly selected in both conventional and organic olive groves, three of these were pesticide sprayed, whereas a second series of three plots were free of pesticide application. Sticky yellow traps were installed in both treated and control plots just after application of pesticide. The results allow to determine the existence of two different reactions of the predators in both types of olive groves. In the plots of the conventional management, a significant increase of the capture values was observed. However, in the ecological groves, the same insects’ species showed a lack of behavioural resistance. The ecological implications of this study open a new field of research, which provides new criteria to assess the qualification of the organic agriculture.

From which soil metal fractions Fe, Mn, Zn and Cu are taken up by olive trees (Olea europaea L., cv. ‘Chondrolia Chalkidikis’) in organic groves?

Organic farming has been proposed as an alternative agricultural system to help solve environmental problems, like the sustainable management of soil micronutrients, without inputs of chemical fertilizers. The purposes of this study were: i) to assess Fe, Mn, Zn and Cu bioavailability through the determination of sequentially extracted chemical forms (fractions) and their correlation with foliar micronutrient concentrations in mature organic olive (cv. ‘Chondrolia Chalkidikis’) groves; ii) to determine the soil depth and the available forms (fractions) by which the 4 metals are taken up by olive trees. DTPA extractable (from the soil layers 0–20, 20–40 and 40–60 cm) and foliar micronutrient concentrations were determined in two organic olive groves. Using the Tessier fractionation, five fractions, for all the metals, were found: exchangeable, bound to carbonates (acid–soluble), bound to Fe-Mn oxides (reducible), organic (oxidizable), as well as residual form. Our results indicated that Fe was taken up by the olive trees as organic complex, mainly from the soil layer 40–60 cm. Manganese was taken up from the exchangeable fraction (0–20 cm); Zinc was taken up as organic complex from the layers 0–20 and 40–60 cm, as well as in the exchangeable form from the upper 20 cm. Copper was taken up from the soil layers 0–20 and 40–60 cm as soluble organic complex, and as exchangeable ion from the upper 20 cm. Our data reveal the crucial role of organic matter to sustain metal (Fe, Zn and Cu) uptake -as soluble complexes-by olive trees, in mature organic groves grown on calcareous soils; it is also expected that these data will constitute a thorough insight and useful tool towards a successful nutrient and organic C management for organic olive groves, since no serious nutritional deficiencies were found.

Humic acid adsorption and its role in colloidal‐scale aggregation determined with the zeta potential, surface free energy and the extended‐DLVOtheory

SummaryThe effect of colloidal forces involved in the adsorption of commercial humic acids (HAs) and particle cohesion was studied in the soil of an organic olive grove with the extendedDerjaguin,Landau,Verwey andOverbeek (extended‐DLVO) theory. Total interaction energy was determined from the zeta potential (ζ) and surface free energy, measured under different experimental conditions [natural and hydrogen peroxide (H2O2) organic matter‐free mineral surfaces]. The soil was clayey, dominated by illite and vermiculite. It showed electron‐donor behaviour, with negatively charged surfaces and zeta potential < 0 mV. DecreasingmVin the zeta potential,ζ, curves and electron‐donor component,γ–, when addingHAto natural surfaces showed effectiveHAadsorption, but only when soil organic matter had not been removed previously. Isotherms confirmed adsorption by natural soil (> 2.5 mg C g−1). Because the isotherms showed no relation with temperature, adsorption would be better attributed to weak physical interactions. On natural surfaces withHA, soil particle attraction forces increased slightly (≈50kT) through decreasing soil wettability. However, this effect on total surface energy was overcome largely by increasing electrostatic repulsive energy caused by the adsorption of negatively chargedHA(> 300 kT). TheDLVO‐extended model showed that natural surfaces withoutH2O2treatment or addedHAseem to be the most favourable state for colloidal aggregate stability. We recommend some caution about the type and quality of organic matter added to increase organic carbon in soil.HighlightsWe applied the extendedDLVOmodel to study humic acid adsorption and its effects on soil structure.Adsorption on soil surfaces with their natural organic matter was mostly by weak physical forces.Adsorption increased the total particle interaction energy through an increase in electrostatic repulsion.Adsorption of some types of organic matter might decrease the colloidal stability of aggregates.

Comparing organic and conventional olive groves relative to energy use and greenhouse gas emissions associated with the cultivation of two varieties

Abstract Organic farming is applied in olive groves in Lesvos Island the last 20 years. “Kolovi” and “Adramitiani”, two dominant varieties are cultivated. Since there is limited research for energy inputs in olive groves, 62 conventional and 26 organic farms were selected during 2011–2013 in order to (a) determine the differences in energy flow among farming systems and varieties, (b) group olive groves based on energy flow indicators, (c) compare the CO2-equivalent emissions among farming systems and varieties. A combination of univariate and multivariate statistical methods was applied. Hierarchical Cluster Analysis (HCA) revealed three farm groups, all consisted of conventional and/or organic olive groves and included both varieties. Group 1 had the lowest energy inputs, while Group 3 the highest. Fuels and transportation, as energy inputs, had the highest contribution in farms’ grouping. A large number of external variables was studied, most of which (fruit production, olive oil production, pomace production, shoot production, olive oil energy production, pomace energy production, shoot energy production, total energy inputs, total energy outputs, intensity, energy efficiency, and energy productivity) had statistically significant differences among the three Groups. Management practices along with geographical location could be a reasonable explanation for the differences between the groups of studied olive groves. Group 3 had the highest non-renewable energy inputs (14,683.5 MJ ha−1) and consumption (2.4 MJ kg−1) and gas emissions (1.27 Mg ha−1 CO2, 0.17 kg ha−1 CH4, and 10.31 g ha−1 N2O). Group 2 had the highest renewable energy inputs (7065.8 MJ ha−1) and consumption (0.9 MJ kg−1), and low CO2-equivalent per fruit production (0.12 kg kg−1). The above mentioned results show that best management farming practices introduce the use of renewable energy inputs and lead to lower gas emissions.

Bird community characteristics as indicators of sustainable management in olive grove ecosystems of Central Greece

The role of breeding birds as indicators of sustainable management in olive groves was investigated. The data revealed significantly higher alpha diversity in organic and abandoned olive groves and maquis than in conventional ones. The highest beta diversity was found between the following pairs: organic olive groves–maquis, and abandoned olive groves–maquis. Breeding bird diversity, Heteroptera, Hymenoptera, Hemiptera and Coleoptera densities positively influenced bird species richness in organic olive groves and maquis, and additionally, manure application positively influenced bird species richness in organic ones. Bird species richness was negatively influenced by pesticide and inorganic fertilizer application in conventional ones. Moreover, isopod density was unimportant in explaining breeding bird richness in organic olive groves. Finally, our study suggests a difference in bird communities of various olive groves as a result of different management and practices, and concludes that birds might serve as indicators of overall olive grove health. Furthermore, these findings could be used as a tool for prediction of breeding bird species richness probability in different olive grove management systems and maquis. Finally, the results of the present study may contribute to highlighting some aspects of the effect of different farming practices on the dynamics of Mediterranean bird communities.

Suitability of Untreated and Composted Olive Mill By-Products as Amendments in Organic Olive Orchards

ABSTRACT.In the Mediterranean area, the proper soil application of olive pomace compost (OPC) and olive mill wastewater (OWW) could play a crucial role in replacing the annual losses of organic matter, thus sustaining agriculture. Therefore, the objectives of this five-year field trial were: (i) to investigate the effects of OWW and OPC, applied at different doses, on soil fertility in an organic Mediterranean olive grove; (ii) to assess the influence of treatments on production and quality responses of olive trees. In a randomized block experimental design, the following experimental treatments were compared: (i) OWW; (ii) OPC; (iii) the same olive pomace compost used in treatment (ii) distributed to supply a double rate of N per plant (OPCx2). These treatments were compared to: (a) commercial NPK organic-mineral fertilizer (Org-min); and (b) green manure of broad bean (GM). Soil parameters were analyzed to assess soil fertility at the beginning of the field trial and in the medium and longer term. At harvest, agronomical performance of treatments was also evaluated. At the end of the field trial, olive pomace compost (mean of OPC and OPCx2) significantly increased total organic carbon by 47.5% compared to Org-min, and the humified organic carbon values were significantly higher for OWW, OPC, and OPCx2, as compared to GM. The values for olive yield components in GM were lower than in OPC and OWW. Therefore, results showed that OWW and OPC application could be a suitable substitute of traditional methods (GM) to improve overall soil fertility and sustain yield in organic olive grove.

Species Richness and Density of Earthworms in Relation to Soil Factors in Olive Orchard Production Systems in Central Greece

Earthworms can be used as bioindicators of soil management as they are easy to classify and very sensitive to changes of both physical and chemical soil parameters. The aim of this work was to study relations between earthworm species (richness and density) and the physicochemical soil properties such as pH, organic matter, soil moisture, and texture (percentages of sand, silt, and clay) under different farming practices (organic and conventional) in olive groves in central Greece. The data revealed significantly greater values of earthworm species richness, density, soil organic matter, and moisture in the organic olive groves than in the conventional ones. Furthermore, total earthworm density was positively correlated to earthworm Shannon diversity index, soil moisture, organic matter, nitrogen, phosphorus, and potassium in organic olive groves. However, total earthworm density was negatively correlated to soil pH and silt in conventional olive groves. It can be concluded that species richness and density of earthworms in olive groves can be considered as sensitive indicators of management practices.

Effects of Organic Farming on Winter Plant Composition, Cover and Diversity in Olive Grove Ecosystems in Central Greece

The present study aimed to assess the effects of organic farming in comparison with conventional on plant composition, plant cover (%), diversity [species richness, Shannon, Simpson, and evenness (Pielou's) indexes] and investigate and describe the relations among plant species richness, plant cover, indexes, and soil parameters (pH and temperature) in olive grove ecosystems during the winter. Organic olive groves had significantly greater values of cover, species richness, and Shannon and Simpson indexes than the conventional ones. Plant species richness was positively correlated to plant cover and Shannon and Simpson indexes but negatively correlated to evenness index for both farming system. Finally, plant cover was positively correlated to the Shannon and Simpson indexes for both farming systems. According to principal component analysis (PCA), for axis 1, positive correlation was detected among the plant species richness, soil temperature, and Shannon and Simpson diversity indexes, whereas for axis 2, negative correlation was detected between plant cover and soil pH. It can be concluded that the organic management system enhances herbaceous plant cover and diversity (species richness, Shannon and Simpson indexes) in olive grove ecosystems during the winter.

Herbaceous Plant Diversity and Identification of Indicator Species in Olive Groves in Central Greece

The present study is aimed at assessing the herbaceous plant diversity and determining the specific species related to different management systems in olive grove ecosystems [organic, conventional (unsprayed), and conventional (sprayed)] in two sites (Nies and Pteleos) of Magnesia Prefecture (central Greece). The sampling of herbaceous vegetation was carried out in randomly selected plots of 0.25 m2 (0.5 m × 0.5 m) each. The results showed that the organic system in Pteleos favored plant species richness and Shannon–Weiner, Simpson, Margalef, Brilluin, McIntosh, and Menhinick indexes more than the other management systems (P < 0.05). A Renyi diagram revealed the greatest plant diversity in the organic system in Pteleos site. According to cluster analysis results, the organic and the conventional (unsprayed) olive groves in Pteleos exhibited a strong similarity regarding plant diversity. The same was detected in the pairs: Nies conventional (unsprayed) and Nies organic, and in Nies conventional (sprayed) and Pteleos conventional (sprayed). IndVal analysis revealed three “characteristic” types of indices, Chenopodium album in the organic olive groves in Pteleos, Sinapis arvensis in the organic ones in Nies, and Aegilops geniculata in the conventional (unsprayed) olive groves in Nies.

The effects of farming practices on earthworm dynamics in olive groves of central Greece

We compared species richness, species composition, density and biomass of earthworm communities in organically and conventionally managed olive groves in central Greece. Earthworm biomass and density was significantly higher (p<0.05) in organic olive groves than in conventional olive groves. The highest species richness was recorded in the organic olive groves. Six species were recorded in total: Octodrilus complanatus, O. croaticus, Dendrobaena byblica, D. veneta, Aporrectodea caliginosa, and Microscolex phosphoreus. Only four of these were found in conventional olive groves, where D. veneta and M. phosphoreus were absent. The most abundant species were O. complanatus, D. veneta, and D. byblica.

Comparing conventional and organic olive groves in central Greece: plant and bird diversity and abundance

AbstractThe present study was conducted in Magnesia Prefecture, central Greece, during the period May–June 2007. It aimed at the comparison between conventional and certified organic olive groves with regard to olive and olive oil production, diversity of plants (herbaceous and woody) and diversity and abundance of avifauna. Correlations between variables within herbaceous plants (linear regression) and woody plants (Principal Component Analysis), and the role of integration time of olive groves to the organic system were investigated. Also, finding easily measurable parameters indicating high bird diversity levels within organic and conventional management systems was a main target of the study. According to our findings, neither edible olive yield nor olive oil yield showed significant differences between conventional and certified organic olive groves. There is an increasing trend for alpha and beta diversity of herbaceous plant species, woody plant beta diversity, density and cover of woody plants, and density of breeding birds in certified organic olive groves (10 years) in comparison with conventional ones. The effect of time since the adoption of organic procedures is very important and produces benefits for the biodiversity. In the total olive groves 15 insectivorous, six granivorous and three insectivorous/granivorous birds species were recorded. Nine bird species distinguished by Ward's hierarchical clustering were identified as typical (indicator value, IndVal&gt;50%) of specific farming systems. Among them, the Eurasian jay, associated with the 10-year certified organic olive groves, and the common cuckoo, Orphean warbler and Red-backed shrike, associated with the 6-year certified organic olive groves, should be regarded as characteristic species (IndVal&gt;70%). Conclusively, organic farming favors some aspects of diversity of herbaceous and woody plants of olive grove ecosystems. On the contrary, similar effects on breeding bird diversity and density were not clearly recorded. However, breeding bird density proved a good indicator of their richness.