We assess progress toward the protection of 50% of the terrestrial biosphere to address the species-extinction crisis and conserve a global ecological heritage for future generations. Using a map of Earth's 846 terrestrial ecoregions, we show that 98 ecoregions (12%) exceed Half Protected; 313 ecoregions (37%) fall short of Half Protected but have sufficient unaltered habitat remaining to reach the target; and 207 ecoregions (24%) are in peril, where an average of only 4% of natural habitat remains. We propose a Global Deal for Nature—a companion to the Paris Climate Deal—to promote increased habitat protection and restoration, national- and ecoregion-scale conservation strategies, and the empowerment of indigenous peoples to protect their sovereign lands. The goal of such an accord would be to protect half the terrestrial realm by 2050 to halt the extinction crisis while sustaining human livelihoods.

Both local- and landscape-scale processes drive succession of secondary forests in human-modified tropical landscapes. Nonetheless, until recently successional changes in composition and diversity have been predominantly studied at the patch level. Here, we used a unique dataset with 45 randomly selected sites across a mixed-use tropical landscape in central Panama to study forest succession simultaneously on local and landscape scales and across both life stages (seedling, sapling, juvenile and adult trees) and life forms (shrubs, trees, lianas, and palms). To understand the potential of these secondary forests to conserve tree species diversity, we also evaluated the diversity of species that can persist as viable metapopulations in a dynamic patchwork of short-lived successional forests, using different assumptions about the average relative size at reproductive maturity. We found a deterministic shift in the diversity and composition of the local plant communities as well as the metacommunity, driven by variation in the rate at which species recruited into and disappeared from the secondary forests across the landscape. Our results indicate that dispersal limitation and the successional niche operate simultaneously and shape successional dynamics of the metacommunity of these early secondary forests. A high diversity of plant species across the metacommunity of early secondary forests shows a potential for restoration of diverse forests through natural succession, when trees and fragments of older forests are maintained in the agricultural matrix and land is abandoned or set aside for a long period of time. On the other hand, during the first 32 years the number of species with mature-sized individuals was a relatively small and strongly biased sub-sample of the total species pool. This implies that ephemeral secondary forests have a limited role in the long-term conservation of tree species diversity in human-modified tropical landscapes.

Pichi Sermolli’s work with his more than 2750 collections of plants from nearly 150 localities on the Lake Tana expedition in Ethiopia in 1937 was interrupted by World War II, but completed in 1947 at the Royal Botanic Gardens, Kew, and the British Museum (Natural History), UK. It resulted in preliminary accounts of the vegetation published 1938-40 and a taxonomically arranged account in 1951, all in Italian. Pichi Sermolli’s observations are difficult to locate due to the imperfect maps of the time, but in this book the authors have reconstructed the sequence of the collections, georeferenced the localities, and updated the identifications of the species. By reconstructing Pichi Sermolli’s observations, it is possible to draw conclusions about the vegetation and compare with a recent model of the vegetation of Ethiopia. According to this, the vegetation of the Lake Tana Basin was a complex mosaic of woodland, scrub, forest, farmland and lake shore vegetation now difficult to interpret in detail. Pichi Sermolli’s study of the vegetation in the Semien Mountains demonstrated for the first time the zonation of Ericaceous woodland and Afroalpine vegetation, within which he distinguished Carex monostachya bogs, Afroalpine grasslands with Lobelia rhynchopetalum, and stony and rocky Afroalpine vegetation. This book interprets Pichi Sermolli’s observations in English and compares them with modern knowledge of the region, partly obtained by the present authors’ own field work. It demonstrates how Pichi Sermolli’s studies form a valuable contribution to the understanding of the Ethiopian flora and vegetation.

Rethinking the logic of institutional environments aiming to facilitate agroforestry smallholders in economic development, this article compares smallholder input supply systems for crop and tree seeds in sub-Saharan Africa and reflects on two basic challenges: (1) how to develop a large number of relevant tree crops for different agroecologies, (2) how to reach smallholders in rural areas. Policy options for improving agroforestry input supply systems are discussed, whereby our article concludes with suggestions how sectoral approaches for crop seed systems can be modified to agroforestry seed-seedling systems. Biophysical differences have practical implications for how the logic of the 'African green revolution' would be translated into a corresponding revolution for agroforestry. K E Y W O R D SAGRA, agroforestry, institutions, productivity, seed systems | INTRODUCTIONGreat opportunities for producing value from agroforestry seeds are currently wasted.1 To allow smallholders to realize the full productive potential of quality agroforestry seeds, institutional environ-1 We use the term 'seed' to include seed and also vegetatively propagated planting stockThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Competition between neighboring plants plays a major role in the population dynamics of tree species in the early phases of humid tropical forest succession. We evaluated the relative importance of above-versus below-ground competition during the first years of old-field succession on soil with low fertility in Southern Mexico, using the premise that competition for light is size-asymmetric, unlike competition for nutrients. Plant growth is thus expected to be disproportionally impeded by larger neighbors. We studied how growth and survival of 3.5-5.5 m tall saplings of Cecropia peltata and Trichospermum mexicanum, two pioneer species that dominate the secondary forests in the study region, varied with the abundance and size of neighboring trees in 1-2 year old secondary vegetation. We found that local neighborhood basal area varied 10-fold (3 to 30 cm 2 m -2 ) and explained most of the variation in diameter and height growth of the target saplings. Most growth variables were strongly affected by the neighbors bigger than the focal trees with no significant additive effect of the smaller neighbors, indicating asymmetric competition. Smaller neighbors did have a small but significant additive effect on the diameter growth of Cecropia saplings and stem slenderness of Trichospermum saplings. We conclude that competition for light was more important than belowground competition in this initial phase of moist tropical forest successional, despite the low soil fertility.