Inter‐row flowering strips enhance pest suppression and improve tree physiological performance in pine nurseries

Commercial tree nurseries face intense economic pressure to produce high‐quality, marketable planting stock with minimal pest damage. Because dense monocultures of young saplings are highly susceptible to pest outbreaks, this sector has traditionally relied on synthetic pesticides. Although flowering strips are widely recognised for strengthening conservation biological control in annual cropping systems, their capacity to support sustainable pest regulation and improve crop physiological performance in perennial woody nurseries remains untested.

We investigated whether flowering strips enhance biocontrol in a commercial ornamental pine nursery by comparing plots with inter‐row flowering strips to control plots with regularly mown grass. Arthropods were sampled from inter‐rows and pine canopies to assess community‐level patterns consistent with their spillover. Tree vitality was evaluated using complementary indicators of physiological performance and pest impact, including relative chlorophyll content, chlorophyll fluorescence parameters (linear electron flow and non‐photochemical quenching), needle biomass, and herbivore damage.

Flowering strips increased natural enemy abundance, particularly spiders, in inter‐rows and canopies. Beta‐diversity revealed stronger habitat separation for herbivores than predators, consistent with selective spillover: predator communities overlapped, whereas herbivores remained distinct, probably reflecting host specificity. Strips were dominated by herb‐layer feeders, likely alternative prey, while canopies hosted pine‐associated sap‐sucking pests. In parallel, adjacent trees showed reduced herbivore damage, greater needle biomass, higher chlorophyll content, enhanced linear electron flow, and lower non‐photochemical quenching.

Our study provides evidence that habitat diversification in nurseries can strengthen conservation biological control and contribute to agronomically valuable improvements in crop physiological performance.

Synthesis and applications . To reduce reliance on synthetic pesticides and improve planting‐stock quality, nursery managers may consider integrating perennial flowering strips into inter‐rows, particularly under comparable pine nursery conditions. This nature‐based intervention was associated with reduced sap‐sucking pest pressure, probably mediated by increased natural enemy abundance and community patterns consistent with predator spillover. To realise these benefits and avoid strips acting as ecological traps, practitioners should adopt tailored maintenance regimes: retain uncut refugia during mowing and prevent chemical drift into strips if canopy‐targeted pesticides are needed. More broadly, this strategy supports resilient forestry production and aligns nursery operations with growing policy pressure for biodiversity‐friendly practices.