Forest–flood relation still tenuous – comment on 'Global evidence that deforestation amplifies flood risk and severity in the developing world' by C. J. A. Bradshaw, N.S. Sodi, K. S.-H. Peh and B.W. Brook

In a recent paper in this journal, Bradshaw and colleagues analyse country statistics on flood characteristics, land cover and land cover change, and conclude that deforestation amplifies flood risk and severity in the developing world. The study addresses an important and long-standing question, but we identify important flaws. Principal among these are difficulties in interpreting country statistics and the correlation between population and floods. We review current knowledge, which suggests that the removal of trees does not affect large flood events, although associated landscape changes can under some circumstances. Reanalysis of the data analysed by Bradshaw and colleagues shows that population density alone already explains up to 83% of the variation in reported flood occurrences, considerably more than forest cover or deforestation (<10%). Feasible explanations for this statistical finding – whether spurious or causative – are not difficult to conceive. We, therefore, consider the conclusion of Bradshaw and colleagues to be unsupported. However, their study is a valuable first step to show how these or similar flood data might be used to further explore the relationship between land cover and flooding.     

Driving factors of a vegetation shift from Scots pine to pubescent oak in dry Alpine forests

An increasing number of studies have reported on forest declines and vegetation shifts triggered by drought. In the Swiss Rhone valley (Valais), one of the driest inner‐Alpine regions, the species composition in low elevation forests is changing: The sub‐boreal Scots pine (Pinus sylvestris L.) dominating the dry forests is showing high mortality rates. Concurrently the sub‐Mediterranean pubescent oak (Quercus pubescens Willd.) has locally increased in abundance. However, it remains unclear whether this local change in species composition is part of a larger‐scale vegetation shift. To study variability in mortality and regeneration in these dry forests we analysed data from the Swiss national forest inventory (NFI) on a regular grid between 1983 and 2003, and combined it with annual mortality data from a monitoring site. Pine mortality was found to be highest at low elevation (below 1000 m a.s.l.). Annual variation in pine mortality was correlated with a drought index computed for the summer months prior to observed tree death. A generalized linear mixed‐effects model indicated for the NFI data increased pine mortality on dryer sites with high stand competition, particularly for small‐diameter trees. Pine regeneration was low in comparison to its occurrence in the overstorey, whereas oak regeneration was comparably abundant. Although both species regenerated well at dry sites, pine regeneration was favoured at cooler sites at higher altitude and oak regeneration was more frequent at warmer sites, indicating a higher adaptation potential of oaks under future warming. Our results thus suggest that an extended shift in species composition is actually occurring in the pine forests in the Valais. The main driving factors are found to be climatic variability, particularly drought, and variability in stand structure and topography. Thus, pine forests at low elevations are developing into oak forests with unknown consequences for these ecosystems and their goods and services.     

Forest Loss in Protected Areas and Intact Forest Landscapes: A Global Analysis

In spite of the high importance of forests, global forest loss has remained alarmingly high during the last decades. Forest loss at a global scale has been unveiled with increasingly finer spatial resolution, but the forest extent and loss in protected areas (PAs) and in large intact forest landscapes (IFLs) have not so far been systematically assessed. Moreover, the impact of protection on preserving the IFLs is not well understood. In this study we conducted a consistent assessment of the global forest loss in PAs and IFLs over the period 2000–2012. We used recently published global remote sensing based spatial forest cover change data, being a uniform and consistent dataset over space and time, together with global datasets on PAs’ and IFLs’ locations. Our analyses revealed that on a global scale 3% of the protected forest, 2.5% of the intact forest, and 1.5% of the protected intact forest were lost during the study period. These forest loss rates are relatively high compared to global total forest loss of 5% for the same time period. The variation in forest losses and in protection effect was large among geographical regions and countries. In some regions the loss in protected forests exceeded 5% (e.g. in Australia and Oceania, and North America) and the relative forest loss was higher inside protected areas than outside those areas (e.g. in Mongolia and parts of Africa, Central Asia, and Europe). At the same time, protection was found to prevent forest loss in several countries (e.g. in South America and Southeast Asia). Globally, high area-weighted forest loss rates of protected and intact forests were associated with high gross domestic product and in the case of protected forests also with high proportions of agricultural land. Our findings reinforce the need for improved understanding of the reasons for the high forest losses in PAs and IFLs and strategies to prevent further losses.     

Impacts of climate variability on tree demography in second growth tropical forests: the importance of regional context for predicting successional trajectories

Naturally regenerating and restored second growth forests account for over 70% of tropical forest cover and provide key ecosystem services. Understanding climate change impacts on successional trajectories of these ecosystems is critical for developing effective large‐scale forest landscape restoration (FLR) programs. Differences in environmental conditions, species composition, dynamics, and landscape context from old growth forests may exacerbate climate impacts on second growth stands. We compile data from 112 studies on the effects of natural climate variability, including warming, droughts, fires, and cyclonic storms, on demography and dynamics of second growth forest trees and identify variation in forest responses across biomes, regions, and landscapes. Across studies, drought decreases tree growth, survival, and recruitment, particularly during early succession, but the effects of temperature remain unexplored. Shifts in the frequency and severity of disturbance alter successional trajectories and increase the extent of second growth forests. Vulnerability to climate extremes is generally inversely related to long‐term exposure, which varies with historical climate and biogeography. The majority of studies, however, have been conducted in the Neotropics hindering generalization. Effects of fire and cyclonic storms often lead to positive feedbacks, increasing vulnerability to climate extremes and subsequent disturbance. Fragmentation increases forests’ vulnerability to fires, wind, and drought, while land use and other human activities influence the frequency and intensity of fire, potentially retarding succession. Comparative studies of climate effects on tropical forest succession across biogeographic regions are required to forecast the response of tropical forest landscapes to future climates and to implement effective FLR policies and programs in these landscapes.     

Natural regeneration as a tool for large‐scale forest restoration in the tropics: prospects and challenges

A major global effort to enable cost‐effective natural regeneration is needed to achieve ambitious forest and landscape restoration goals. Natural forest regeneration can potentially play a major role in large‐scale landscape restoration in tropical regions. Here, we focus on the conditions that favor natural regeneration within tropical forest landscapes. We illustrate cases where large‐scale natural regeneration followed forest clearing and non‐forest land use, and describe the social and ecological factors that drove these local forest transitions. The self‐organizing processes that create naturally regenerating forests and natural regeneration in planted forests promote local genetic adaptation, foster native species with known traditional uses, create spatial and temporal heterogeneity, and sustain local biodiversity and biotic interactions. These features confer greater ecosystem resilience in the face of future shocks and disturbances. We discuss economic, social, and legal issues that challenge natural regeneration in tropical landscapes. We conclude by suggesting ways to enable natural regeneration to become an effective tool for implementing large‐scale forest and landscape restoration. Major research and policy priorities include: identifying and modeling the ecological and economic conditions where natural regeneration is a viable and favorable land‐use option, developing monitoring protocols for natural regeneration that can be carried out by local communities, and developing enabling incentives, governance structures, and regulatory conditions that promote the stewardship of naturally regenerating forests. Aligning restoration goals and practices with natural regeneration can achieve the best possible outcome for achieving multiple social and environmental benefits at minimal cost.     

Tree species composition and diversity gradients in white-water forests across the Amazon Basin

Aim Attention has increasingly been focused on the floristic variation within forests of the Amazon Basin. Variations in species composition and diversity are poorly understood, especially in Amazonian floodplain forests. We investigated tree species composition, richness and α diversity in the Amazonian white‐water (várzea) forest, looking particularly at: (1) the flood‐level gradient, (2) the successional stage (stand age), and (3) the geographical location of the forests. Location Eastern Amazonia, central Amazonia, equatorial western Amazonia and the southern part of western Amazonia. Methods The data originate from 16 permanent várzea forest plots in the central and western Brazilian Amazon and in the northern Bolivian Amazon. In addition, revised species lists of 28 várzea forest inventories from across the Amazon Basin were used. Most important families and species were determined using importance values. Floristic similarity between plots was calculated to detect similarity variations between forest types and over geographical distances. To check for spatial diversity gradients, α diversity (Fisher) of the plots was correlated with stand age, longitudinal and latitudinal plot location, and flood‐level gradient. Results More than 900 flood‐tolerant tree species were recorded, which indicates that Amazonian várzea forests are the most species‐rich floodplain forests worldwide. The most important plant families recorded also dominate most Neotropical upland forests, and c. 31% of the tree species listed also occur in the uplands. Species distribution and diversity varied: (1) on the flood‐level gradient, with a distinct separation between low‐várzea forests and high‐várzea forests, (2) in relation to natural forest succession, with species‐poor forests in early stages of succession and species‐rich forests in later stages, and (3) as a function of geographical distance between sites, indicating an increasing α diversity from eastern to western Amazonia, and simultaneously from the southern part of western Amazonia to equatorial western Amazonia. Main conclusions The east‐to‐west gradient of increasing species diversity in várzea forests reflects the diversity patterns also described for Amazonian terra firme. Despite the fine‐scale geomorphological heterogeneity of the floodplains, and despite high disturbance of the different forest types by sedimentation and erosion, várzea forests are dominated by a high proportion of generalistic, widely distributed tree species. In contrast to high‐várzea forests, where floristic dissimilarity increases significantly with increasing distance between the sites, low‐várzea forests can exhibit high floristic similarity over large geographical distances. The high várzea may be an important transitional zone for lateral immigration of terra firme species to the floodplains, thus contributing to comparatively high species richness. However, long‐distance dispersal of many low‐várzea trees contributes to comparatively low species richness in highly flooded low várzea.     

Is forest landscape restoration socially desirable? A discrete choice experiment applied to the Scandinavian transboundary Fulufjället National Park Area

Using an economic valuation approach, we assessed people's stated preferences for policy aimed at enhancing restoration of functional networks of naturally dynamic boreal forest habitats as a public good. Active landscape restoration can improve the functionality of boreal forest habitats as green infrastructure, which is essential for biodiversity conservation and delivery of multiple ecosystem services that production forests are poor at providing. In contrast, so far designation of protected areas in Fennoscandia has focused on remnant patches of near‐natural forests, and not on forest landscape restoration. We assessed citizens' preferences for forest landscape restoration in a transboundary region primarily managed for sustained‐yield wood production for the forest industry, and which hosts the transboundary Fulufjället National Parks in Sweden and Norway. We conducted a discrete choice experiment by asking Swedish and Norwegian citizens to choose among two options for the Fulufjället area, including (1) extension of passive protection on one side or both sides of the border, by additional area protection and restoration of forest naturalness, and (2) a status quo option. The scenario assumed that extension of the protected forest area would imply a compulsory tax administered bilaterally by the two countries. Just over half of the sample, in both countries expressed willingness to pay for forest landscape restoration. Alternatives that contemplated larger extensions of forest landscape restoration were assigned higher willingness‐to‐pay. Public awareness and support, combined with spatial planning, are necessary for forest landscape restoration to become a viable tool for biodiversity conservation in Scandinavia.     

Understanding and predicting frost‐induced tropical tree mortality patterns

Extreme climatic and weather events are increasing in frequency and intensity across the world causing episodes of widespread tree mortality in many forested ecosystems. However, we have a limited understanding about which local factors influence tree mortality patterns, restricting our ability to predict tree mortality, especially within topographically complex tropical landscapes with a matrix of mature and secondary forests. We investigated the effects of two major local factors, topography and forest successional type, on climate‐induced tropical tree mortality patterns using an observational and modeling approach. The northernmost Neotropical dry forest endured an unprecedented episode of frost‐induced tree mortality after the historic February 2011 cold wave hit northwestern Mexico. In a moderately hilly landscape covering mature and secondary tropical dry forests, we surveyed 454 sites for the presence or absence of frost‐induced tree mortality. In addition, across forty‐eight 1 ha plots equally split into the two forest types, we examined 6,981 woody plants to estimate a frost‐disturbance severity metric using the density of frost‐killed trees. Elevation is the main factor modulating frost effects regardless of forest type. Higher occurrence probabilities of frost‐induced tree mortality at lowland forests can be explained by the strong influence of elevation on temperature distribution since heavier cold air masses move downhill during advective frosts. Holding elevation constant, the probability of frost‐induced tree mortality in mature forests was twice that of secondary forests but severity showed the opposite pattern, suggesting a cautious use of occurrence probabilities of tree mortality to infer severity of climate‐driven disturbances. Extreme frost events, in addition to altering forest successional pathways and ecosystem services, likely maintain and could ultimately shift latitudinal and altitudinal range margins of Neotropical dry forests.     

新冠疫情对全球生物多样性热点地区森林面积的影响

森林是维持生物多样性的重要保障,森林面积的损失常常会导致区域生物多样性的降低或丧失。为探讨新冠疫情对全球生物多样性的影响,该文利用Image J软件筛选出全球生物多样性热点地区占国土面积超60%的国家作为研究对象,以全球生物多样性热点地区的森林损失面积、生物多样性完整性数据、年度(2020年和2021年)新冠疫情感染数据、国内生产总值(GDP)为研究对象,进行关联分析、线性混合效应模型构建和回归预测。结果表明:虽然新冠病毒的每百万人口感染数量与森林损失面积表现为显著负相关,具体表现为新冠疫情显著减少了因城市和农业大规模扩张而导致的森林损失面积,但在新冠疫情暴发的2年(2020年和2021年)期间,全球生物多样性热点地区的森林损失总量仍然持续上升,主要原因是新冠疫情间接加速了人工林和天然林的采伐。回归模型预测显示,新冠疫情期间,全球生物多样性热点地区的森林损失面积在2020年和2021年分别增加了5.83%和21.78%。综上表明,虽然新冠疫情对生物多样性热点地区的森林损失具有一定的抑制作用,但森林损失面积仍然在增加。该研究结果为制定生物多样性的保护措施提供了数据支撑。     

Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest

Drought‐induced, regional‐scale dieback of forests has emerged as a global concern that is expected to escalate under model projections of climate change. Since 2000, drought of unusual severity, extent, and duration has affected large areas of western North America, leading to regional‐scale dieback of forests in the southwestern US. We report on drought impacts on forests in a region farther north, encompassing the transition between boreal forest and prairie in western Canada. A central question is the significance of drought as an agent of large‐scale tree mortality and its potential future impact on carbon cycling in this cold region. We used a combination of plot‐based, meteorological, and remote sensing measures to map and quantify aboveground, dead biomass of trembling aspen (Populus tremuloides Michx.) across an 11.5 Mha survey area where drought was exceptionally severe during 2001–2002. Within this area, a satellite‐based land cover map showed that aspen‐dominated broadleaf forests occupied 2.3 Mha. Aerial surveys revealed extensive patches of severe mortality (>55%) resembling the impacts of fire. Dead aboveground biomass was estimated at 45 Mt, representing 20% of the total aboveground biomass, based on a spatial interpolation of plot‐based measurements. Spatial variation in percentage dead biomass showed a moderately strong correlation with drought severity. In the prairie‐like, southern half of the study area where the drought was most severe, 35% of aspen biomass was dead, compared with an estimated 7% dead biomass in the absence of drought. Drought led to an estimated 29 Mt increase in dead biomass across the survey area, corresponding to 14 Mt of potential future carbon emissions following decomposition. Many recent, comparable episodes of drought‐induced forest dieback have been reported from around the world, which points to an emerging need for multiscale monitoring approaches to quantify drought effects on woody biomass and carbon cycling across large areas.     

Persistence of fishers in riparian forests in North Dakota,USA following a severe flood event

Historically, the distribution of fishers (Martes pennanti) in North America included portions of eastern North Dakota, USA; however, the population was reported to have become extirpated by the early 1900s. Verified reports, road-killed and incidentally trapped individuals, indicate that fishers have been re-establishing populations in riparian forests (the only areas with substantive forest cover in the region) over the last 10 years. During the summers of 2008 (16 Jun–1 Aug) and 2009 (1 Jun–18 Aug), we conducted presence–absence sampling using remote cameras and enclosed track-plates to determine the distribution of fishers along 237 km of the Red River of the North in North Dakota. Between sampling events, the Red River experienced an extreme flood with peak flooding above major flood stage, which inundated all riparian forests within the study area from approximately 23 Mar–22 May. Because of the severity of the flood, we anticipated that fishers could have perished or been displaced from much of the study area, resulting in lower detection rates in 2009 than 2008. However, fishers were detected throughout the study area during both years and, unexpectedly, detection rates were higher in 2009 than 2008 (28 out of 35 sites [80%] and 25 out of 57 sites [44%], respectively). Our study demonstrates that fishers existing in what traditionally would have been considered marginal habitat for the species were able to persist following a severe, multi-month flood that inundated >95% of the forest habitat.     

Climate regime shift and forest loss amplify fire in Amazonian forests

Frequent Amazonian fires over the last decade have raised the alarm about the fate of the Earth's most biodiverse forest. The increased fire frequency has been attributed to altered hydrological cycles. However, observations over the past few decades have demonstrated hydrological changes that may have opposing impacts on fire, including higher basin‐wide precipitation and increased drought frequency and severity. Here, we use multiple satellite observations and climate reanalysis datasets to demonstrate compelling evidence of increased fire susceptibility in response to climate regime shifts across Amazonia. We show that accumulated forest loss since 2000 warmed and dried the lower atmosphere, which reduced moisture recycling and resulted in increased drought extent and severity, and subsequent fire. Extremely dry and wet events accompanied with hot days have been more frequent in Amazonia due to climate shift and forest loss. Simultaneously, intensified water vapor transport from the tropical Pacific and Atlantic increased high‐altitude atmospheric humidity and heavy rainfall events, but those events did not alleviate severe and long‐lasting droughts. Amazonia fire risk is most significant in the southeastern region where tropical savannas undergo long seasonally dry periods. We also find that fires have been expanding through the wet–dry transition season and northward to savanna–forest transition and tropical seasonal forest regions in response to increased forest loss at the “Arc of Deforestation.” Tropical forests, which have adapted to historically moist conditions, are less resilient and easily tip into an alternative state. Our results imply forest conservation and fire protection options to reduce the stress from positive feedback between forest loss, climate change, and fire.     

Where are Europe’s last primary forests?

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.     

Rainforest and savanna landscape dynamics in New Caledonia: Towards a mosaic of stable rainforest and savanna states?

Stable forested environments can be converted to savanna in response to changes in environmental disturbances. New Caledonia is a biodiversity hotspot; significant ecological and economic resources would be lost if forests were turned into savanna by anthropogenic environmental changes. On the landscape scale, systems that have undergone shifts of this kind are characterized by sharp forest–savanna boundaries and mosaic‐like distributions of savanna and forest. Understanding the locations and the dynamics of such boundaries is a challenge for ecologists and is critical for landscape management and biodiversity conservation. Using a time series of aerial photographs (1955–2000) and a forest habitat suitability map, we tested the hypothesis that topography and spatial processes, especially those relating to fire spread and seed dispersal, are the main determinants of the spatial distribution of rainforest and savanna in a New Caledonian landscape covering 24 km². Within the studied landscape, the overall forest coverage decreased by 24% between 1976 and 2000. This was primarily due to the contraction of forests on west‐facing slopes, which accounted for about 90% of the total loss. Conversely, the east‐facing forests seemed to have contracted extensively prior to the studied period, and were confined to refuges. A habitat suitability index calculated from the landscape's topographical features using generalized additive models accurately predicted both the presence of forests and the probability of forest expansion/contraction. We also provide evidence that spatial processes such as fire spread and seed dispersal limit the expansion and contraction of forests. Our results suggest that rainforests on west‐facing slopes in New Caledonia will be progressively destroyed by fire until they are restricted to refuges along thalwegs and creeks, as appears to have already happened for their east‐facing counterparts.     

The Utility of Spectral Indices from Landsat ETM+ for Measuring the Structure and Composition of Tropical Dry Forests1

There is a growing emphasis on developing methods for quantifying the structure and composition of tropical forests that can be applied over large landscapes, especially for tropical dry forests that are severely fragmented and have a high conservation priority. This study investigates the relationships between various measures of forest structure (annual woody increment, canopy closure, stand density, stand basal area) and composition (tree species diversity, tree community composition) measured in semi‐deciduous tropical dry forests on islands in Lago Guri, Venezuela and three spectral indices derived from Landsat ETM+: Normalized Difference Vegetation Index (NDVI), Infrared Index (IRI), and Mid‐Infrared Index (MIRI). Even though there were significant autocorrelations among spectral indices, there were significant differences in the relationships between spectral indices and forest attributes. IRI was not significantly correlated with any of the structural variables while MIRI was correlated with canopy closure and NDVI values were correlated with canopy closure as well as annual woody increment. NDVI and MIRI were both related to relative tree diversity and all three indices were associated with aspects of tree species composition. Based on the results of this study, it appears that spectral indices, and in particular NDVI, may be useful indicators of forest attributes in tropical dry forest habitats. Further research needs to be undertaken to identify if the results of this study can be applied to other tropical dry forests at a global spatial scale.     

Native plantations as an important element for biodiversity in vanishing forested landscapes: A study of the near threatened araucaria tit spinetail (Leptasthenura setaria,Furnariidae)

Although forest loss is still a problem worldwide, estimated rates of deforestation have declined in the last decade, primarily because of an increase in the area of tree plantations. This leads to the central question of how suitable plantations are for indigenous species. Native plantations are thought to have higher value for biodiversity than plantations of non‐native trees; however, not all studies support this view. We assessed occupancy and density of the araucaria tit spinetail (Leptasthenura setaria, Furnariidae), a near threatened species, in the highly endangered araucaria forests of north‐eastern Argentina and in araucaria plantations, which comprise 90% of the remaining habitat for this species. All natural forest remnants were occupied by araucaria tit spinetails. Only 85% of the plantations were occupied; however, density was almost threefold higher in plantations compared with natural forests. Our models indicated that stand age was the most important factor in determining occupancy and density of this bird species in plantations. Plantations <10 years old exhibited lower densities than older plantations. This species does not occur in plantations of non‐native trees, but our results indicate that native plantations may provide important habitat for the araucaria tit spinetail, particularly given that most native forest has been removed. Restoration of natural remnants and conservation of old, connected plantations may assure the protection of significant populations of spinetails. The role of native araucaria plantations as habitat for other species merits further examination.     

Impending disaster or sliver of hope for Southeast Asian forests? The devil may lie in the details

Here, I report on how forest area in Southeast Asia has changed for different types of forest and across different countries between the periods of 1990–2000 and 2000–2005. The loss of old growth forests has accelerated in Indonesia, Cambodia and Vietnam but have ceased in Thailand, Malaysia, Laos and the Philippines. Secondary forests continue to be lost in Malaysia, Cambodia, Laos, Myanmar, Indonesia, Thailand and the Philippines. Plantation forests have increased in area by 25.0% from 1990 to 2005 but still comprise only 6.2% of the total forest area in Southeast Asia. Overall, the loss of native forests (old growth and secondary forests) has slowed down in Thailand, the Philippines and Brunei but has worsened in Laos, Myanmar, Indonesia, Malaysia and Cambodia.     

Human and natural impacts on forests along lower Tana river,Kenya: implications towards conservation and management of endemic primate species and their habitat

Seventy-three forest patches were assessed to determine the effects of human and natural impact on native forests along the Lower Tana River flood plains in Kenya between January and March 2001. Seventeen of these forests were within the Tana River Primate National Reserve (TRPNR) while 56 were outside the protected area. Cultivation and dyke construction had the most devastating human impact, which involved partial or complete forest clearing resulting in further fragmentation of forest patches [Suleman MA, Wahungu GM, Mouria PK, Karere GM, Oguge N, Moinde NN (2001) Tana River primate census and forest evaluation. A report to Kenya Wildlife Services]. Natural impacts were either die back or flooding, which appeared to cause progressive degradation of forest structure and biodiversity. Overall, forest area in the Lower Tana significantly reduced by 34.5% (P < 0.001) over a 21-year period. Forest loss was greater outside the reserve (38%) than inside (29.2%) reiterating the significant role played by this protected area in habitat and species conservation. Continued forest loss increases extinction risks for the endemic primate species the Tana River Red Colobus (Procolobus rufomitratus) and the Crested Mangabey sub-species (Cercocebus galeritus galeritus). Initiation of community conservation programmes outside the reserve and introduction of sustainable micro-economic projects were recommended to enhance sustainable livelihoods and the environment.     

Ecological outcomes and livelihood benefits of community‐managed agroforests and second growth forests in Southeast Brazil

The Forest and Landscape Restoration movement has emerged as an approach to reconcile biodiversity conservation, ecosystem services provisioning and human well‐being in degraded landscapes, but little is known so far about the potential of different reforestation methods to achieve these objectives. Based on this gap, we assessed the ecological outcomes and local livelihood benefits of community‐managed agroforests and second growth forests to assist natural regeneration in the coastal Atlantic Forest of Brazil. We investigated and compared agroforests and secondary forests according to their structure and floristic composition in 51 circular plots of 314 m², their role in supporting local livelihoods (45 semi‐structured interviews) and the use and cultural importance of plant species (61 interviews). Agroforests and, more remarkably, managed secondary forests (1) re‐established a well‐developed forest structure, with a higher density of tree‐sized individuals and similar basal area compared to nearby old growth forests; (2) were composed by a rich array of native species, including five threatened species, but had lower species richness than old growth remnants; and (3) improved local livelihoods by supplying market valuable and culturally important plants, including 231 native ethnospecies. Overall, local production systems showed remarkable potential to engage smallholders of developing tropical countries in Forest and Landscape Restoration and contribute to achieve its overall goals. We advocate the promotion of these systems as effective Forest and Landscape Restoration approaches in multi‐scale programs and policies.     

Rainforest expansion reduces understorey plant diversity and density in open forest of eastern Australia

The expansion of rainforest pioneer trees into long‐unburnt open forests has become increasingly widespread across high rainfall regions of Australia. Increasing tree cover can limit resource availability for understorey plant communities and reduce understorey diversity. However, it remains unclear if sclerophyll and rainforest trees differ in their competitive exclusion of understory plant communities, which contain most of the floristic diversity of open forests. Here, we examine dry open forest across contrasting fire histories (burnt and unburnt) and levels of rainforest invasion (sclerophyll or rainforest midstorey) to hindcast changes in understorey plant density, richness and composition. The influence of these treatments and other site variables (midstorey structure, midstorey composition and soil parameters) on understorey plant communities were all examined. This study is the first to demonstrate significantly greater losses of understorey species richness, particularly of dry open‐forest specialists, under an invading rainforest midstorey compared to a typical sclerophyll midstorey. Rainforest pioneers displaced over half of the understorey plant species, and reduced ground cover and density of dry forest specialists by ~90%. Significant understorey declines also occurred with increased sclerophyll midstorey cover following fire exclusion, although losses were typically less than half that of rainforest‐invaded sites over the same period. Understorey declines were closely related to leaf area index and basal area of rainforest and wattle trees, suggesting competitive exclusion through shading and potentially belowground competition for water. Around 20% of displaced species lacked any capacity for population recovery, while transient seed banks or distance‐limited dispersal may hinder recovery for a further 68%. We conclude that rainforest invasion leads to significant declines in understorey plant diversity and cover in open forests. To avoid elimination of local native plant populations in open forests, fires should occur with sufficient frequency to prevent overstorey cover from reaching a level where shade‐intolerant species fail to thrive.