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What kinds of interesting critters live amongst the forest trees? Adult and child readers can find out together in this new Level 1 co-reader from National Geographic Kids, full of engaging photos and fun facts.

Aim: Primary forests have high conservation value but are rare in Europe due to historic land use. Yet many primary forest patches remain unmapped, and it is unclear to what extent they are effectively protected. Our aim was to (1) compile the most comprehensive European-scale map of currently known primary forests, (2) analyse the spatial determinants characterizing their location and (3) locate areas where so far unmapped primary forests likely occur. Location: Europe. Methods: We aggregated data from a literature review, online questionnaires and 32 datasets of primary forests. We used boosted regression trees to explore which biophysical, socio-economic and forest-related variables explain the current distribution of primary forests. Finally, we predicted and mapped the relative likelihood of primary forest occurrence at a 1-km resolution across Europe. Results: Data on primary forests were frequently incomplete or inconsistent among countries. Known primary forests covered 1.4 Mha in 32 countries (0.7% of Europe's forest area). Most of these forests were protected (89%), but only 46% of them strictly. Primary forests mostly occurred in mountain and boreal areas and were unevenly distributed across countries, biogeographical regions and forest types. Unmapped primary forests likely occur in the least accessible and populated areas, where forests cover a greater share of land, but wood demand historically has been low. Main conclusions: Despite their outstanding conservation value, primary forests are rare and their current distribution is the result of centuries of land use and forest management. The conservation outlook for primary forests is uncertain as many are not strictly protected and most are small and fragmented, making them prone to extinction debt and human disturbance. Predicting where unmapped primary forests likely occur could guide conservation efforts, especially in Eastern Europe where large areas of primary forest still exist but are being lost at an alarming pace.

Aims Primary forests are critical for forest biodiversity and provide key ecosystem services. In Europe, these forests are particularly scarce and it is unclear whether they are sufficiently protected. Here we aim to: (a) understand whether extant primary forests are representative of the range of naturally occurring forest types, (b) identify forest types which host enough primary forest under strict protection to meet conservation targets and (c) highlight areas where restoration is needed and feasible. Location Europe. Methods We combined a unique geodatabase of primary forests with maps of forest cover, potential natural vegetation, biogeographic regions and protected areas to quantify the proportion of extant primary forest across Europe's forest types and to identify gaps in protection. Using spatial predictions of primary forest locations to account for underreporting of primary forests, we then highlighted areas where restoration could complement protection. Results We found a substantial bias in primary forest distribution across forest types. Of the 54 forest types we assessed, six had no primary forest at all, and in two‐thirds of forest types, less than 1% of forest was primary. Even if generally protected, only ten forest types had more than half of their primary forests strictly protected. Protecting all documented primary forests requires expanding the protected area networks by 1,132 km2 (19,194 km2 when including also predicted primary forests). Encouragingly, large areas of non‐primary forest existed inside protected areas for most types, thus presenting restoration opportunities. Main conclusion Europe's primary forests are in a perilous state, as also acknowledged by EU's “Biodiversity Strategy for 2030.” Yet, there are considerable opportunities for ensuring better protection and restoring primary forest structure, composition and functioning, at least partially. We advocate integrated policy reforms that explicitly account for the irreplaceable nature of primary forests and ramp up protection and restoration efforts alike.

Biodiversity loss from deforestation may be partly offset by the expansion of secondary forests and plantation forestry in the tropics. However, our current knowledge of the value of these habitats for biodiversity conservation is limited to very few taxa, and many studies are severely confounded by methodological shortcomings. We examined the conservation value of tropical primary, secondary, and plantation forests for 15 taxonomic groups using a robust and replicated sample design that minimized edge effects. Different taxa varied markedly in their response to patterns of land use in terms of species richness and the percentage of species restricted to primary forest (varying from 5% to 57%), yet almost all between-forest comparisons showed marked differences in community structure and composition. Cross-taxon congruence in response patterns was very weak when evaluated using abundance or species richness data, but much stronger when using metrics based upon community similarity. Our results show that, whereas the biodiversity indicator group concept may hold some validity for several taxa that are frequently sampled (such as birds and fruit-feeding butterflies), it fails for those exhibiting highly idiosyncratic responses to tropical land-use change (including highly vagile species groups such as bats and orchid bees), highlighting the problems associated with quantifying the biodiversity value of anthropogenic habitats. Finally, although we show that areas of native regeneration and exotic tree plantations can provide complementary conservation services, we also provide clear empirical evidence demonstrating the irreplaceable value of primary forests.

We identify policies that would provide a solid foundation in key international negotiations to ensure that primary forests persist into the 21st Century. A novel compilation of primary forest cover and other data revealed that protection of primary forests is a matter of global concern being equally distributed between developed and developing countries. Almost all (98%) of primary forest is found within 25 countries with around half in five developed ones (USA, Canada, Russia, Australia, and NZ). Only ∼22% of primary forest is found in IUCN Protected Areas Categories I–VI, which is approximately 5% of preagriculture natural forest cover. Rates of deforestation and forest degradation are rapid and extensive, and the long‐term integrity of primary forest cannot be assumed. We recommend four new actions that could be included in climate change, biodiversity, and sustainable development negotiations: (1) recognize primary forests as a matter of global concern within international negotiations; (2) incorporate primary forests into environmental accounting; (3) prioritize the principle of avoided loss; and (4) universally accept the important role of indigenous and community conserved areas. In the absence of specific policies for primary forest protection, their unique biodiversity values and ecosystem services will continue to erode.

Given the short time-frame to limit global warming, and the current emissions gap, it is critical to prioritise mitigation actions. To date, scant attention has been paid to the mitigation benefits of primary forest protection. We estimated tropical forest ecosystem carbon stocks and flows. The ecosystem carbon stock of primary tropical forests is estimated at 141–159 Pg C (billion tonnes of carbon) which is some 49–53% of all tropical forest carbon, the living biomass component of which alone is 91–103% of the remaining carbon budget to limit global warming to below 1.5 degrees above pre-industrial levels. Furthermore, tropical forests have ongoing sequestration rates 0.47–1.3 Pg C yr−1, equivalent to 8–13% of annual global anthropogenic CO2 (carbon dioxide) emissions. We examined three main forest-based strategies used in the land sector—halting deforestation, increasing forest restoration and improving the sustainable management of production forests. The mitigation benefits of primary forest protection are contingent upon how degradation is defined and accounted for, while those from restoration also depend on how restoration is understood and applied. Through proforestation, reduced carbon stocks in secondary forests can regrow to their natural carbon carrying capacity or primary forest state. We evaluated published data from studies comparing logged and unlogged forests. On average, primary forests store around 35% more carbon. While comparisons are confounded by a range of factors, reported biomass carbon recovery rates were from 40 to 100+ years. There is a substantive portfolio of forest-based mitigation actions and interventions available to policy and decision-makers, depending on national circumstances, in addition to SFM and plantation focused approaches, that can be grouped into four main strategies: protection; proforestation, reforestation and restoration; reform of guidelines, accounting rules and default values; landscape conservation planning. Given the emissions gap, mitigation strategies that merely reduce the rate of emissions against historic or projected reference levels are insufficient. Mitigation strategies are needed that explicitly avoid emissions where possible as well as enabling ongoing sequestration.

The impacts of land-use change on biodiversity in the Himalayas are poorly known, notwithstanding widespread deforestation and agricultural intensification in this highly biodiverse region. Although intact primary forests harbor many Himalayan birds during breeding, a large number of bird species use agricultural lands during winter. We assessed how Himalayan bird species richness, abundance, and composition during winter are affected by forest loss stemming from agriculture and grazing. Bird surveys along 12 elevational transects within primary forest, low-intensity agriculture, mixed subsistence agriculture, and intensively grazed pastures in winter revealed that bird species richness and abundance were greatest in low-intensity and mixed agriculture, intermediate in grazed pastures, and lowest in primary forest at both local and landscape scales; over twice as many species and individuals were recorded in low-intensity agriculture than in primary forest. Bird communities in primary forests were distinct from those in all other land-use classes, but only 4 species were unique to primary forests. Low-, medium-, and high-intensity agriculture harbored 32 unique species. Of the species observed in primary forest, 80% had equal or greater abundance in low-intensity agricultural lands, underscoring the value of these lands in retaining diverse community assemblages at high densities in winter. Among disturbed landscapes, bird species richness and abundance declined as land-use intensity increased, especially in high-intensity pastures. Our results suggest that agricultural landscapes are important for most Himalayan bird species in winter. But agricultural intensification—especially increased grazing—will likely result in biodiversity losses. Given that forest reserves alone may inadequately conserve Himalayan birds in winter, comprehensive conservation strategies in the region must go beyond protecting intact primary forests and ensure that low-intensity agricultural lands are not extensively converted to highintensity pastures. Los impactos del cambio de uso de suelo sobre la biodiversidad en el Himalaya son poco conocidos, a pesar de la deforestación extendida y la intensificación agrícola en esta región altamente biodiversa. Aunque los bosques primarios intactos albergan a muchas aves del Himalaya durante la época reproductiva, un gran número de especies de aves utilizan las tierras agrícolas durante el invierno. Valoramos cómo la riqueza, abundancia y composición de especies de aves del Himalaya durante el invierno son afectadas por la pérdida del bosque a partir de la agricultura y el pastoreo. Los censos de aves a lo largo de doce transectos de altitud dentro del bosque primario, de la agricultura de baja intensidad, de la agricultura de subsistencia mixta y de las zonas de pastoreo intensivo en invierno revelaron que la riqueza de especies de aves y la abundancia fueron mayores en la agricultura de baja intensidad y en la mixta, intermedias en las zonas de pastoreo, y más bajas en el bosque primario tanto en la escala local como la de paisaje; más del doble de especies y de individuos se registraron en la agricultura de baja intensidad que en el bosque primario. Las comunidades de aves en el bosque primario fueron distintas de aquellas en todos los demás tipos de uso de suelo, pero sólo cuatro especies fueron únicas de los bosques primarios. La agricultura de intensidad baja, media y alta albergó 32 especies únicas. De las especies observadas en el bosque primario, el 80 % tuvo una abundancia igual o mayor en los suelos de baja intensidad agrícola, enfatizando el valor de estos suelos en la retención de ensamblajes diversos de comunidades a densidades altas durante el invierno. Entre los paisajes perturbados, la riqueza de especies y la abundancia declinaron conforme incrementó la intensidad del uso de suelo, especialmente en las pasturas de alta intensidad. Nuestros resultados sugieren que los paisajes agrícolas son importantes para la mayoría de las especies de aves del Himalaya durante el inverno; aunque la intensificación agrícola - especialmente el pastoreo incrementado - probablemente resultará en la pérdida de la biodiversidad. Dado que las reservas de bosques por sí solas pueden conservar inadecuadamente a las aves del Himalaya en invernó, las estrategias integrales de conservación en la región deben ir más allá de proteger los bosques primarios intactos y asegurar que los suelos de uso agrícola de baja intensidad no sean convertidos extensivamente a zonas de pastoreo de alta intensidad.

One of the main goals of modern silviculture is to emulate the structural complexity of old-growth forests. In this context, it is of advantage to identify a target state of structural complexity at the stand level and to analyze the spatial characteristics that led to the desired complexity of forest structures in primary forest references. In this study, we used 3D forest scenes captured by terrestrial laser scanning (TLS) to identify spatial patterns of structural complexity of differently managed and unmanaged European forests dominated by beech (Fagus sylvatica L.). We scanned in managed even-aged and uneven-aged stands, as well as in formerly managed forests (National Parks) and primary forests. For three different forest strata, representing the understory, the midstory, and the overstory of a forest stand, we determined the structural complexity mathematically using fractal analysis. Beyond that, we analyzed the density, as well as the horizontal and vertical distribution of plant material. For all three forest strata, we observed differences in structural complexity between the different forest types. Within the lower and middle strata, the investigated primary forests showed a random to regular distribution of plant material, as well as a complex understory structure as a result of pronounced natural decay. Compared to the primary forests, the managed uneven-aged stands showed quite similar spatial patterns of distribution of plant material, but on average a higher space occupation in the lower and middle forest stratum. Our results suggest that single tree or group selection cutting is a useful management tool to imitate old-growth structures of undisturbed beech-dominated forests.

The Himalayas are a global biodiversity hotspot threatened by widespread agriculture and pasture expansion. To determine the impact of these threats on biodiversity and toformulate appropriate conservation strategies, we surveyed birds along elevational gradients in primary forest and in human-dominated lands spanning a gradient of habitat alteration, including forest-agriculture mosaics, mixed agriculture mosaics, and pasture. We surveyed birds during the breeding season and in winter to account for pronounced seasonal migrations. Bird abundance and richness in forest-agriculture and mixed agriculture mosaics were equal to or greater than in primary forest and greater than in pasture at local and landscape scales during both seasons. Pasture had greater abundance and richness of birds in winter than primary forest, but richness was greater in primary forest at the landscape scale during the breeding season. All 4 land-use types held unique species, suggesting that all must be retained in the landscape to conserve the entire avifauna. Our results suggest forest-agriculture and mixed agriculture mosaics are particularly important for sustaining Himalayan bird communities during winter and primary forests are vital for sustaining Himalayan bird communities during the breeding season. Further conversion of forest-agriculture and mixed agriculture mosaics to pasture would likely result in significant biodiversity losses that would disproportionately affect breeding species. To ensure comprehensive conservation, strategies in the western Himalayas must balance the protection of intact primary forest with the minimization of pasture expansion. La cordillera del Himalaya es un punto caliente de biodiversidad que está amenazado por la agricultura extensiva y la expansión de las pasturas. Para determinar el impacto de estas amenazas sobre la biodiversidad y para formular estrategias de conservación apropiadas, realizamos un censo de aves a lo largo del gradiente de elevación en bosques primarios y en tierras dominadas por humanos que abarcan un gradiente de alteración de habitat, incluyendo los mosaicos de agricultura forestal, los mosaicos de agricultura mixta, y las pasturas. Censamos a las aves durante la temporada de reproducción y durante el invierno para explicar la migración estacional pronunciada. La riqueza y abundancia de aves en los terrenos agrícolas y forestales y en los mosaicos de agricultura mixta fueron iguales o mayores que en los bosques primarios, y mayores que en las pasturas a escala local y de paisaje durante ambas temporadas. Durante el invierno las pasturas tuvieron mayor abundancia y riqueza de aves que los bosques primarios, pero la riqueza fue mayor en los bosques primarios a escala de paisaje durante la temporada de reproducción. Los cuatros tipos de uso de suelo albergaron a especies únicas, lo que sugiere que todas deben ser retenidas dentro del paisaje para conservar a toda la avifauna. Nuestros resultados sugieren que la agricultura forestal y los mosaicos de agricultura mixta son particularmente importantes para mantener a las comunidades de aves del Himalaya durante el invierno y los bosques primarios son vitales para mantener a estas comunidades durante la época reproductiva. Una mayor conversión de la agricultura forestal y los mosaicos de agricultura mixta a pasturas probablemente resultaría en pérdidas significativas de biodiversidad que podrían afectar desproporcionadamente a las especies en reproducción. Para asegurar una conservación completa, las estrategias en el oeste del Himalaya deben balancear a la protección del bosque primario intacto con la reducción de la expansión de las pasturas. 喜马拉雅山脉是全球生物多祥性保护热点地区，但受到农业和牧场大規模扩张的威胁。为了确定这些威 胁对生物多祥性的影响，并制定合适的保护策略，我们沿海拔梯度，对原始林和人类利用的土地间的一系列生境 包括森林农业镶嵌区、混合农业镶嵌区和牧场中的鸟类进行了调查。考虑到鸟类明显的季节性迁徒，我们分别 在繁殖期和冬季进行了调查。在这两个季节中，森林-农业镶嵌区和混合农业镶嵌区局部水平和景观尺度上的鸟 类丰度和丰富度等于或髙于原始林中的情况，同时都高于牧场的水平。在冬季牧场的鸟类丰度和丰富度比原始 林高，但在繁殖季，原始林景观尺度上的丰富度更高。这四种土地利用类型的生境中都有特有种，这意味着要保 护整个鸟类动物群就应在景观中把各种生境都保留下来。我们的结果表明, 森林-农业镶嵌区和混合农业镶嵌区 对于在冬季維持喜马拉雅的鸟类群落尤为重要，而原始林则在繁殖季十分重要。将森林-农业镶嵌区和混合农业 镶嵌区进ー步转化为牧场很可能导致严重的生物多样性丧失，而且对繁殖的物种影响更大。为了进行全面的保 护，西喜马拉雅地区的保护策略必须在原始林的完整保护和最小化牧场扩张间找到平衡。

Economists are increasingly using impact evaluation methods to measure the effectiveness of forest conservation programs. Theoretical analysis of two complementary economic models demonstrates that the average treatment effect on the treated (ATT) typically reported by these studies can be related to an economic measure of program performance only under very restrictive conditions. This is because the ATT is usually expressed in purely physical terms (e.g., avoided deforestation) and ignores heterogeneity in the costs and benefits of conservation programs. For the same reasons, clinical trials are a misleading analogy for the evaluation of conservation programs. To be more useful for economic analyses of conservation programs, impact evaluations should work toward developing measures of program outcomes that are economically more relevant, data that would enable the evaluation of impacts on forest degradation (not just deforestation) and primary forests (not forests in general), better estimates of spatially disaggregated treatment effects (not program-wide averages), and better information on the accuracy of estimated treatment effects as predictors of future risks.