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We provide an overview of the current state of knowledge of island frugivory and seed dispersal and identify knowledge gaps that are important for fundamental research on--and applied conservation of--island ecosystems. We conducted a systematic literature search of frugivory and seed dispersal on islands, omitting large, continental islands. This revealed a total of 448 studies, most (75%) published during the last two decades, especially after 2010. Nearly 65% of them were focused on eight archipelagos. There is a paucity of studies in Pacific archipelagos near Asia and Australia, and in the Indian Ocean. Data on island frugivory and seed dispersal are diverse but highly uneven in geographic and conceptual coverage. Despite their limited biodiversity, islands are essential reservoirs of endemic plants and animals and their interactions. Due to the simplicity of insular ecosystems, we can assess the importance of seed dispersal theory and mechanisms at species and community levels. These include the ecological and biogeographical meaning and prevalence of non-standard mechanisms of seed dispersal on islands; the seed dispersal effectiveness and the relative roles of different frugivore guilds (birds and reptiles being the most important); and patterns of community organization and their drivers as revealed by interaction networks. Island systems are characterized by the extinction of many natives and endemics, and high rates of species introductions. Therefore, understanding how these losses and additions alter seed dispersal processes has been a prevailing goal of island studies and an essential foundation for the effective restoration and conservation of islands. Keywords Conservation and restoration * Fleshy-fruited plants * Insular environments * Mutualistic interactions and ecological networks * Non-standard dispersal mechanisms * Seed dispersal effectiveness, Introduction By definition, islands are geographically isolated, which results in lower species richness of plants and animals, but greater levels of endemism and occurrence of relict species when compared to [...]

Globally, subalpine and alpine plant communities are receiving increasing attention owing to disproportionately rapid warming at high altitudes, and the resultant habitat shrinkage leaving high-altitude specialists with nowhere to migrate. The Hawaiian subalpine zone (1,700-3,000 m) is an interesting example of this potential phenomenon because of the high endemism. We analyzed plant species richness, cover, and density from 89 plots (1,000 [m.sup.2]) sampled in 2010-2018 across two volcanic mountains, Haleakala on Maui, and Mauna Loa on Hawai'i. Most of the 139 plant species recorded were non-native (55%), with the remainder endemic (31%) and indigenous (14%). Plot-level richness differed from gamma diversity, with endemic species more abundant than non-native species. Non-native species richness was higher on Haleakala than Mauna Loa. These communities are patchy with low-lying (3,500/ha) and indigenous Leptecophylla tameiameiae (>2,430/ha) shrubs dominant on both volcanoes. Woodland communities were encountered only on Mauna Loa, with endemic trees Metrosideros polymorpha on wetter, south aspects, and Sophora chrysophylla on the drier, leeward side. Hawaiian subalpine vegetation varies among islands, volcanoes, and aspects, yet remains largely native-dominated, though with increasing threats from climate change, invasive non-native species, and wildfire. We recommend continued monitoring of biotic communities and climate in this sensitive zone, in situ physiological studies for the native matrix species, stricter non-native species biosecurity and sanitation protocols, wildfire prevention, and improved documentation of the effects of feral ungulates. Keywords: biodiversity, endemic plants, plant community, high elevation, Hawai'i Volcanoes National Park, Haleakala National Park, island, GLOBALLY, SUBALPINE AND ALPINE plant communities are receiving increasing attention owing to disproportionate rapid warming at high altitudes (MRI 2015), upward shifts in species' optimum elevations (Lenoir et al. 2008), [...]

Aim: Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location: Tropical and subtropical moist forests. Time period: Current. Major taxa studied: Palms (Arecaceae). Methods: We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co-occurring non-palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results: On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long-term climate stability. Life-form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non-tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above-ground biomass, but the magnitude and direction of the effect require additional work. Conclusions: Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests.

Knowledge about the biogeographic affinities of the world's tropical forests helps to better understand regional differences in forest structure, diversity, composition, and dynamics. Such understanding will enable anticipation of region-specific responses to global environmental change. Modern phylogenies, in combination with broad coverage of species inventory data, now allow for global biogeographic analyses that take species evolutionary distance into account. Here we present a classification of the world's tropical forests based on their phylogenetic similarity. We identify five principal floristic regions and their floristic relationships: (i) Indo-Pacific, (ii) Subtropical, (iii) African, (iv) American, and (v) Dry forests. Our results do not support the traditional neo- versus paleotropical forest division but instead separate the combined American and African forests from their Indo-Pacific counterparts. We also find indications for the existence of a global dry forest region, with representatives in America, Africa, Madagascar, and India. Additionally, a northern-hemisphere Subtropical forest region was identified with representatives in Asia and America, providing support for a link between Asian and American northern-hemisphere forests.

WE WERE ALL SADDENED to learn of the passing of Professor Dieter Mueller-Dombois on July 19, 2022. He was a giant in the field of ecology and an inspiration to [...]

Species within tropical alpine treeline ecotones are predicted to be especially sensitive to climate variability because this zone represents tree species' altitudinal limits. Hawaiian volcanoes have distinct treeline ecotones driven by trade wind inversions. The local climate is changing, but little is known about how this influences treeline vegetation. To predict future impacts of climate variability on treelines, we must define the range of variation in treeline ecotone characteristics. Previous studies highlighted an abrupt transition between subalpine grasslands and wet forest on windward Haleakalā, but this site does not represent the diversity of treeline ecotones among volcanoes, lava substrates, and local climatic conditions. To capture this diversity, we used data from 225 plots spanning treelines (1500–2500 m) on Haleakalā and Mauna Loa to characterize ecotonal plant communities. Treeline indicator species differ by moisture and temperature, with common native species important for wet forest, subalpine woodland, and subalpine shrubland. The frequency or abundance of community indicator species may be better predictors of shifting local climates than the presence or absence of tree life forms per se. This study further supports the hypothesis that changes in available moisture, rather than temperature, will dictate the future trajectory of Hawaiian treeline ecotone communities. [ABSTRACT FROM AUTHOR]

Abstract: Little is known regarding pollination webs involving island coastal plants and pollinators, and roles that nonnative flower visitors may play in these interaction networks. Plant-pollinator observations made in March [...]

Abstract: Invasive ants can influence abundance and diversity of insect pollinators, and this effect may be expected to be especially strong on oceanic islands. We examined abundance of native Hylaeus [...]