Management linked to ecological intensification supports insect pollinators in Iberian wood-pastures

ABSTRACT: Context - Iberian wood-pastures (dehesas) constitute important habitats for flower-visiting insects, thus supporting the delivery of essential ecosystem services. However, dehesas have been experiencing increasing degradation either by farming intensification or abandonment. Objectives - We assess if alternative management strategies linked to ecological intensification, designed to maximize productivity in Iberian dehesas, are also favorable for biodiversity, specifically pollinators. Methods - We carried surveys in nine dehesas located across western and southwestern Spain. Each site comprised five paddocks under different management: conventional grazing, alternative systems linked to ecological intensification (rotational grazing, legume-enriched young and old pastures) and abandonment. We surveyed bees and hoverflies along fixed transects, together with flower cover and botanical composition, and we assessed landscape configuration. Results - Results showed that rotational grazing, legume-enriched and abandonment enhanced pollinator abundance compared to conventional management. Yet, ecological intensification practices were the most beneficial, showing a positive impact also on pollinator richness. Flower cover, together with plant diversity and landscape composition, were important drivers of pollinator diversity metrics. These patterns varied among pollinator groups, e.g., hoverflies were less impacted by management than bees, while being more affected by plant diversity. Conclusions - Our findings suggest that alternative management linked to ecological intensification has potential in low-input farming systems such as Iberian dehesas. These measures can help to maximize productivity, whilst preserving biodiversity and essential ecosystem services such as pollination. Complementary measures, such as the preservation or restoration of semi-natural habitats, also appear to be crucial for effectively safeguarding pollinating insects in this High Nature Value farming system.info:eu-repo/semantics/publishedVersio

Gains to species diversity in organically farmed fields are not propagated at the farm level

Organic farming is promoted to reduce environmental impacts of agriculture, but surprisingly little is known about its effects at the farm level, the primary unit of decision making. Here we report the effects of organic farming on species diversity at the field, farm and regional levels by sampling plants, earthworms, spiders and bees in 1470 fields of 205 randomly selected organic and nonorganic farms in twelve European and African regions. Species richness is, on average, 10.5% higher in organic than nonorganic production fields, with highest gains in intensive arable fields (around +45%). Gains to species richness are partly caused by higher organism abundance and are common in plants and bees but intermittent in earthworms and spiders. Average gains are marginal +4.6% at the farm and +3.1% at the regional level, even in intensive arable regions. Additional, targeted measures are therefore needed to fulfil the commitment of organic farming to benefit farmland biodiversity