Radar vision in the mapping of forest biodiversity from space.

Recent progress in remote sensing provides much-needed, large-scale spatio-temporal information on habitat structures important for biodiversity conservation. Here we examine the potential of a newly launched satellite-borne radar system (Sentinel-1) to map the biodiversity of twelve taxa across five temperate forest regions in central Europe. We show that the sensitivity of radar to habitat structure is similar to that of airborne laser scanning (ALS), the current gold standard in the measurement of forest structure. Our models of different facets of biodiversity reveal that radar performs as well as ALS; median R² over twelve taxa by ALS and radar are 0.51 and 0.57 respectively for the first non-metric multidimensional scaling axes representing assemblage composition. We further demonstrate the promising predictive ability of radar-derived data with external validation based on the species composition of birds and saproxylic beetles. Establishing new area-wide biodiversity monitoring by remote sensing will require the coupling of radar data to stratified and standardized collected local species data.

Phylogenetic classification of the world's tropical 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.

Five new species of Syzygium (Myrtaceae) from Sulawesi, Indonesia.

Following ongoing ecological research on the tree diversity of the Indonesian island of Sulawesi, we describe five new species of Syzygium. These are the first descriptions of Syzygium species from the island since Blume (1850, Jambosa celebica and J. cornifolia), highlighting the significant lack of taxonomic research on the genus for the region. The five species proposed as new are Syzygium balgooyisp. nov., Syzygium contiguumsp. nov., Syzygium devogeliisp. nov., Syzygium eymaesp. nov., and Syzygium galanthumsp. nov. All species are illustrated and information on their distribution, ecology, and conservation status is given.

Elaeocarpus firdausii (Elaeocarpaceae), a new species from tropical mountain forests of Sulawesi.

Based on ongoing ecological research in mountain forests of Sulawesi, a new species, Elaeocarpus firdausii Brambach, Coode, Biagioni & Culmsee, sp. nov. is described and illustrated from mossy forests at > 2000 m and information provided on the species' distribution, ecology and pollen morphology. Elaeocarpus firdausii is similar to Elaeocarpus luteolignum Coode but differs from the latter in having glabrous terminal buds, leaves with black gland dots, 4-merous, larger flowers, and more numerous stamens.

An estimate of the number of tropical tree species.

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between ∼ 40,000 and ∼ 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of ∼ 19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of ∼ 4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.