We created small-scale artificial canopy gaps to accelerate the growth of mature indigenous forest canopy species for restoration of an 18-year-old exotic Pinus radiata plantation forest, in the Marlborough Sounds, New Zealand. Small and large circular gaps were formed by felling. Seedlings of two indigenous forest canopy species, Podocarpus totara (Podocarpaceae) and Beilschmiedia tawa (Lauraceae), were planted within artificial gaps and undisturbed plantation canopy. Seedling height growth, mortality, and occurrence of animal browse were monitored at approximately 6-month intervals over 17 months. Both P. totara and B. tawa differed significantly in height growth and in animal browse occurrence among artificial gap treatments. Growth of the light-demanding P. totara was better under large canopy gaps, whereas growth of the shade-tolerant B. tawa increased under gaps of any size but was most consistent under small gaps. For P. totara, any significant restoration benefit of gap formation on height growth was lost when browsed seedlings were taken into account. Animal browse significantly limited B. tawa height growth in large but not in small gaps. Small-scale canopy gap creation is an effective method of modifying light transmission to the plantation understorey and accelerating seedling growth rates. Canopy gap size can be used to optimize understorey illumination according to species-specific light requirements. The increased occurrence of animal browse in gaps requires consideration. Artificial canopy gaps within planted monocultures create structural heterogeneity that would otherwise take an extended period of time to develop. These results further support the role of plantations as indigenous forest restoration sites.

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New Zealand's formerly extensive lowland native forests have been comprehensively cleared or modified, and large areas of secondary-growth vegetation have subsequently established. These areas are comprised of native, exotic, and mixed tree and shrub species assemblages. The mature-phase canopy and emergent tree species representative of pre-human New Zealand forests are often rare or locally extinct in these forests, indicating negative ramifications for long-term biodiversity conservation and ecosystem service provision, especially such as carbon sequestration. The successful recruitment of mature-phase canopy and emergent tree species may be prevented by biotic and abiotic filters related to dispersal (e.g. lack of seed sources or lack of dispersal agents), environmental variation (e.g. unsuitable germination microclimate or light availability), and competition (e.g. exotic weed competition). Failure of mature-phase tree species to cross through these filters may halt forest succession and cause arrested development of the ecosystem. There are also social and cultural imperatives for restoring mature-phase tree species, such as reassembling desired forest habitat and landscapes and providing lost natural heritage and cultural resources. Therefore, to restore secondary forests, depauperate remnant forests and create new forests that have complex structure, high biomass, and natural canopy tree diversity, mature-phase canopy and emergent species should be reintroduced through human interventions (i.e. enrichment planting). Experiments demonstrate that mature-phase tree species establishment can be optimised through canopy manipulation to address competition for light. Such targeted management can determine successful recruitment of mature-phase tree species, as can weed maintenance post-enrichment planting and landscape-level pest animal control. Currently political focus is emphasising planting of new early-successional native forests. However, support from scientific research and policy development is essential to actively recruit mature-phase tree species where they are now poorly represented and hence forest succession may be arrested. Afforestation and emissions trading policies need to support the reinstatement of mature-phase tree species within existing regenerating and degraded forests and newly created forests to facilitate the substantial ecological and ecosystem service benefits they provide over the long-term.

Summary We propose that nonharvest plantations could provide important opportunities for restoration of indigenous forest cover and related ecosystem services. We assessed the relative performance of three Podocarpaceae (podocarps) species planted into a degraded Ponderosa Pine (Pinus ponderosa) plantation, central North Island, New Zealand. We hypothesised that the degraded pine plantation overstorey could provide suitable conditions for the development of a podocarp‐dominated forest structure within ca. 50 years of underplanting and that podocarp growth would differ depending on the species suitability to the site. Rimu (Dacrydium cupressinum) significantly outperformed both Totara (Podocarpus totara) and Kahikatea (Dacrycarpus dacrydioides) in height and diameter growth. Rimu was now the structurally dominant tree where it occurred rather than pine. Per annum scaled carbon storage within Rimu stands was significantly greater than the Totara, Kahikatea or Pine stands. All podocarp species had attained a greater stand density compared to the pine overstorey. Possible reasons for the differing podocarp growth performance include different light requirements, response to soil nutrients, elevational distributions and frost susceptibility. There were significant differences in understorey species richness among the different stands of podocarp species. Underplanting accelerated successional development by incorporating late‐successional indigenous canopy dominants within the forest succession and overcame limitations imposed on forest succession at the site from its isolation from indigenous forest tree seed sources.

Pastoral farming is the dominant land use in New Zealand today and is under considerable domestic social and political pressure to reduce its environmental footprint. In this article, we explore options to enhance native biodiversity conservation within New Zealand pastoral systems. We argue that there is strong synergistic interdependence between biodiversity conservation and pastoral farming and suggest that it is possible to have win-win outcomes for both. Landowners need to be incentivised and rewarded for good biodiversity management, rather than relying on a strict rules-based approach. To bring integrity and objective support to this incentive-based approach, farmers need to adopt environmental management planning that is supported by good biodiversity extension resources. Alongside this, a verification system is required that shows farmers are doing what they say they are doing and reflects agreed management targets for biodiversity. This approach requires trust and partnership among all players in agroecosystems-farmers, government, food and fibre processors, scientists, conservationists, NGOs, and the wider New Zealand population. We suggest that if we change the way we think about how farming and biodiversity interact, then we will achieve substantial biodiversity gains across the 50% of New Zealand under pastoral farming. This then brings integrity to the existing and expanding market story for pastoral farming and creates a stronger connection between all New Zealanders and the farming sector. Advancing our thinking in this way will enable New Zealand to maintain a premium for our farming products internationally while supporting conservation of our native biodiversity.