Mountain forests deserve special attention from ecologists and conservation biologists given the ecosystem services they provide to society, and their threat under global change. In the subalpine region of the Andes, Polylepis woodlands occur as arboreal islands in a matrix of grassland and scrub. Due to overgrazing and burning, however, these woodland patches are believed to cover only 11% of their potential area in Bolivia, core area for Polylepis. We reviewed the knowledge on the species diversity for the Bolivian Polylepis woodland remnants, assessed the conservation status of the occurring species, determined their trophic niche, and related species richness with climatic variables and elevation. Based in 31 publications, we found 780 identified species occurring in Polylepis woodlands: 425 plants, 266 birds, 46 mammals, 35 butterflies and 8 reptiles. Ten of the 13 Bolivian Polylepis species, as well as 7 other plant species, 14 bird species and 4 mammal species were categorized as threatened or near threatened according to IUCN criteria. In general, plant species richness increased with increased precipitation and length of the growth season, while it decreased with increasing elevation. There was a positive relationship between bird species richness, precipitation and length of the growth season. The highest bird endemism in Polylepis woodland remnants occurred at intermediate elevations, temperatures and Electronic supplementary material The online version of this article (precipitation. Mammal species richness decreased with increasing maximum temperature. Finally, we discuss the most important knowledge gaps regarding biodiversity in Bolivian Polylepis woodland remnants.

The establishment of exotic trees such as Pinus radiata (radiata pine, Pinaceae) and Eucalyptus globulus (eucalyptus, Myrtaceae) in fragments of native vegetation at the Parque Nacional Tunari (PNT, Cochabamba-Bolivia), can affect the regeneration of the native species that live there. Polylepis subtusalbida's (kewiñ a, Rosaceae) regeneration was surveyed, evaluating the density of seedlings, their size structure, and growth forms, as well as variables of growth and survival in fragments of pure forests (P. subtusalbida fragments without exotic trees) and mixed fragments (P. subtusalbida fragments with exotic trees). Sixty-four permanent study plots were established in mixed fragments of P. subtusalbida-P. radiata, P. subtusalbida-E. globulus and fragments with only P. subtusalbida, in three locations within the Parque Nacional Tunari. Mixed fragments with both native and exotic trees and native pure fragments did not present differences in seedling density. Differences in density were related to adult native tree densities. A greater proportion of P. subtusalbida's seedlings exhibited lateral growth and adventitious roots in mixed fragments than in pure fragments. The size structure only varied between locations and not between fragmenttypes. Smaller individuals grew more, in both pure and mixed fragments. Greater survival of seedlings was observed in the larger individuals and in the ones that exhibited lateral growth. P. subtusalbida's regeneration in the PNT is complex and varies at two spatial scales: between locations and between fragment type. If conservation of P. subtusalbida fragments in the PNT is considered a priority, their regeneration should be favored and different measures for the management of forests must be in accordance with the specific needs given the locations and fragment type.

There is a long‐standing debate on whether the occurrence of the iconic high‐Andes Polylepis woodlands as small and isolated fragments is of natural or anthropogenic origin. We make inferences regarding the fragmentation history based on both a new population genetic study on P. besseri and a synthesis of available studies on the population genetics of Polylepis woodlands. We infer the timing of the main woodland fragmentation event by analysing: (1) the remaining levels of population genetic diversity and the relation to population size; (2) among‐population genetic differentiation; and (3) the difference in genetic diversity between the offspring and adult generation. We retrieved seven publications on the population genetics of five Polylepis spp. We did not find a relationship between population size and genetic diversity, and genetic differentiation was low compared with that reported for similar plant species. These findings do not support a history of long‐term fragmentation. The offspring showed a loss of genetic diversity and increasing differentiation compared with adults, suggesting that the main habitat fragmentation event is of relatively recent origin. For P. besseri, no significant differences were found between the adult and offspring genetic variation. We discuss the conservation and restoration consequences for this important high‐Andean genus. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172, 544–554.

High-altitude Polylepis besseri woodlands in Bolivia are under increasing threat from human use and disturbance. Currently, there is no information regarding P. besseri growth rates, age structures or the relationship between environmental variables and growth. Such information would be useful for effective management and conservation of the remaining woodlands. We used standard dendrochronological techniques to determine the age and radial growth rates for 23 trees from two Polylepis besseri populations in Sacha Loma (mountains Uypa and Chutu Senega), and investigated the relationship between climate and radial growth. Wood samples exhibited semicircular porosity and visible tree-ring boundaries. The sample trees were young (mean age 40 years, max age 63 years) and growing slowly (\1 mm/year). Trees at Chutu Senega were older and growing more slowly than those at Uypa. The strong linearity of cumulated radial increments suggest that P. besseri may maintain consistent growth rates beyond 60 years. Our results indicate that radial growth is limited by the accumulation of reserves the year before ring formation, and that a warm period before the growing season (humid period) can increase P. besseri's growth in the Bolivian-Tucuman biogeographic Province. It seems that local factors are more important than regional factors in these high Andean woodlands. This study improves our understanding of the biology of Polylepis and demonstrates the usefulness of dendrochronology for investigating the biotic, abiotic and anthropogenic effects on woodlands in areas lacking long term historical data.