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Kauri (Agathis australis), which is one of the world's largest and longest‐living conifer species, is under threat from a root and collar dieback disease caused by the oomycete pathogen Phytophthora agathidicida. The noted incidence of kauri dieback has increased in the past decade, and even trees >1000 years old are not immune. This disease has profound effects on both forest ecosystems and human society, particularly indigenous Māori, for whom kauri is a taonga or treasure of immense significance. This review brings together existing scientific knowledge about the pathogen and the devastating disease it causes, as well as highlighting important knowledge gaps and potential approaches for disease management. The life cycle of P. agathidicida is similar to those of other soilborne Phytophthora pathogens, with roles for vegetative hyphae, zoospores and oospores in the disease. However, there is comparatively little known about many aspects of the biology of P. agathidicida, such as its host range and disease latency, or about the impact on the disease of abiotic and biotic factors such as soil health and co‐occurring Phytophthora species. This review discusses current and emerging tools and strategies for surveillance, diagnostics and management, including a consideration of genomic resources, and the role these play in understanding the pathogen and how it causes this deadly disease. Key aspects of indigenous Māori knowledge, which include rich ecological and historical knowledge of kauri forests and a holistic approach to forest health, are highlighted.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Wiley-Blackwell is collaborating with JSTOR to digitize, preserve and extend access to Journal of Biogeography.Abstract. The emergent conifer Araucaria araucana (Mol.) K. Koch and the small deciduous broadleaved tree Nothofagus antarctica (Forst.) Oerst. occur as mixed post-fire stands in south-central Chile and Argentina. Both species are adapted to survive fire. Adaptations of A. araucana include thick bark, sprouting from epicormic buds and protected terminal buds on branches. N. antarctica resprouts vigorously after fire with multiple shoots. This study investigated the dynamics of this community, particularly in relation to fire. Recently burnt stands were examined for size-related response to fire. All A. araucana < 30 cm d.b.h. were killed with larger trees surviving. The size of these surviving A. araucana is probably related to fire intensity. Stand disturbance histories, population size and age distributions, diameter growth rate patterns and spatial relationships of different size classes, within and between species, were examined in intact stands. Most of these stands contained evidence of past fire. Within the first decade after fire, A. araucana (but not N. antarctica) seedlings or root suckers began to establish beneath the resprouted N. antarctica canopy. However, establishment was spatially clustered around surviving female A. araucana or abandoned caches of unknown seed predators. Once established, A. araucana grew through the sparse N. antarctica canopy, eventually overtopping it. This suppression of N. antarctica, if uninterrupted for more than 150 years, may lead to pure stands of A. araucana. However, fires are common in this region and both species possess attributes that promote accidental fires once ignited. Fire usually leads to formation of stands with clustered 10-20 m tall A. araucana over a 2-5 m tall N. antarctica subcanopy. Therefore, fire acts as a medium of species co-existence between a vigorously sprouting, shade-intolerant species (N. antarctica), and one that partly survives fire above-ground and is more shade-tolerant (A. araucana). The history of fire frequency and intensity on a site largely determine population structures for these species in mixed stands.

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Correlations between environment and tree alpha‐diversity in New Zealand's primary forests were examined using an extensive quantitative dataset (14 540 plots). Generalised additive models were used to examine relationships between species richness and temperature, solar radiation, root‐zone moisture deficit, relative humidity, lithology, drainage, and plot size for all trees (112 species), and separately for broadleaved trees (88 species), conifers (17), and the genus Nothofagus (4). Diversity both for all tree species and for broadleaved trees was predicted to be highest on sites with high temperatures, high solar radiation, and high soil and atmospheric moisture, and on sedimentary and basaltic substrates. Highest conifer diversity was predicted on sites with intermediate temperatures, low solar radiation, high root‐zone and atmospheric moisture, and rhyolitic and Quaternary substrates, particularly where drainage was impeded. Highest Nothofagus diversity was predicted for sites combining low temperatures, high solar radiation, high root‐zone moisture but low atmospheric moisture, and on granitic substrates. Differences in diversity between the species groups on different lithologies are interpreted as rejecting both the effects of variation in large‐scale disturbance histories, and the effects of confounding environmental factors associated with particular substrates. There were also significant interactions between species groups: both broadleaved tree and conifer richness were predicted to be lower on sites where one or more Nothofagus spp. — all of which have marked patchiness in their distribution — are present. Although these results are consistent with the hypothesis that tree diversity is highest on sites conducive to high productivity, history is also indicated as an important determinant of tree diversity in New Zealand.