Search

Understanding what controls global leaf type variation in trees is crucial for comprehending their role in terrestrial ecosystems, including carbon, water and nutrient dynamics. Yet our understanding of the factors influencing forest leaf types remains incomplete, leaving us uncertain about the global proportions of needle-leaved, broadleaved, evergreen and deciduous trees. To address these gaps, we conducted a global, ground-sourced assessment of forest leaf-type variation by integrating forest inventory data with comprehensive leaf form (broadleaf vs needle-leaf) and habit (evergreen vs deciduous) records. We found that global variation in leaf habit is primarily driven by isothermality and soil characteristics, while leaf form is predominantly driven by temperature. Given these relationships, we estimate that 38% of global tree individuals are needle-leaved evergreen, 29% are broadleaved evergreen, 27% are broadleaved deciduous and 5% are needle-leaved deciduous. The aboveground biomass distribution among these tree types is approximately 21% (126.4 Gt), 54% (335.7 Gt), 22% (136.2 Gt) and 3% (18.7 Gt), respectively. We further project that, depending on future emissions pathways, 17–34% of forested areas will experience climate conditions by the end of the century that currently support a different forest type, highlighting the intensification of climatic stress on existing forests. By quantifying the distribution of tree leaf types and their corresponding biomass, and identifying regions where climate change will exert greatest pressure on current leaf types, our results can help improve predictions of future terrestrial ecosystem functioning and carbon cycling.

Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2–5are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6and satellite-derived approaches2,7,8to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151–363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets.

In the framework of the RECCAP2 initiative, we present the greenhouse gas (GHG) and carbon (C) budget of Europe. For the decade of the 2010s, we present a bottom‐up (BU) estimate of GHG net‐emissions of 3.9 Pg CO2‐eq. yr−1(using a global warming potential on a 100 years horizon), which are largely dominated by fossil fuel emissions. In this decade, terrestrial ecosystems acted as a net GHG sink of 0.9 Pg CO2‐eq. yr−1, dominated by a CO2sink that was partially counterbalanced by net emissions of CH4and N2O. For CH4and N2O, we find good agreement between BU and top‐down (TD) estimates from atmospheric inversions. However, our BU land CO2sink is significantly higher than the TD estimates. We further show that decadal averages of GHG net‐emissions have declined by 1.2 Pg CO2‐eq. yr−1since the 1990s, mainly due to a reduction in fossil fuel emissions. In addition, based on both data driven BU and TD estimates, we also find that the land CO2sink has weakened over the past two decades. A large part of the European CO2and C sinks is located in Northern Europe. At the same time, we find a decreasing trend in sink strength in Scandinavia, which can be attributed to an increase in forest management intensity. These are partly offset by increasing CO2sinks in parts of Eastern Europe and Northern Spain, attributed in part to land use change. Extensive regions of high CH4and N2O emissions are mainly attributed to agricultural activities and are found in Belgium, the Netherlands and the southern UK. We further analyzed interannual variability in the GHG budgets. The drought year of 2003 shows the highest net‐emissions of CO2and of all GHGs combined. We have synthesized the European budgets of carbon and the greenhouse gases (GHG) carbon dioxide, methane and nitrous oxide. This synthesis includes estimates of direct emissions from fossil fuel burning, industrial production, waste management and agriculture, as well as of sources and sinks in the terrestrial biosphere. Summing up the sources and sinks of the three GHGs, we estimate for the decade of the 2010s an average annual net‐emission of 3.9 billion tons of carbon dioxide equivalents. These net‐emissions are dominated by carbon dioxide from fossil fuel emissions (4.1 billion tons of carbon dioxide). In contrast, the terrestrial biosphere acts as a net sink of carbon dioxide, the effect of which is only partly counterbalanced by net emissions of methane and nitrous oxide. The net‐effect of the terrestrial biosphere's GHG budget is a sink of 0.9 billion tons of carbon dioxide equivalents per year. Over the last three decades, European GHG emissions have declined by 1.2 billion tons carbon dioxide equivalents per year, mainly due to reductions in fossil fuel emissions. However, the sink capacity of the terrestrial biosphere has diminished since the 2000s. We provide a bottom‐up estimate of CO2, CH4, N2O emissions of 3.9 Pg CO2‐eq. yr−1over Europe, 2010–2019Terrestrial ecosystems acted as a greenhouse gas net sink of 0.9 Pg CO2‐eq. yr−1, dominated by CO2sinkNet‐greenhouse gas emissions decreased by ∼1/4 since the 1990s, but land carbon sink is weakening since the 2000s We provide a bottom‐up estimate of CO2, CH4, N2O emissions of 3.9 Pg CO2‐eq. yr−1over Europe, 2010–2019 Terrestrial ecosystems acted as a greenhouse gas net sink of 0.9 Pg CO2‐eq. yr−1, dominated by CO2sink Net‐greenhouse gas emissions decreased by ∼1/4 since the 1990s, but land carbon sink is weakening since the 2000s

The 27 countries in the European Union have a combined total of 177 million ha of forested and other wooded land. These are mainly characterised as semi-natural, multi-functional forests. Only about 13 million ha are characterised as plantationsi, although an additional 47 million ha are regarded as planted forests (Forest Europe 2011). European forests are highly diverse due to centuries of management in countries with different cultural objectives. Often the current management is nature oriented and so forests may not be used primarily for wood production. Wood provides only a small part of the income for many of the 16 million private owners according to the Confédération Européenne des Propriétaires Forestiers (CEPF 2013). These circumstances, plus sluggish demand for wood brought about by the current economic crisis, have generated challenges for the forestry sector. Demand for wood is expected to increase with expansion of the green economy and an increased emphasis on the use of bioenergy. Three forest management scenarios (analysed with the EFISCEN model) were used to project supply in response to demand for wood from EU forests over the next 50 years. Shortening of broadleaved forest rotation length and planting 50% of the felled area with fast-growing coniferous species could increase coniferous wood supply from 473 to 561 million m3y-1. Demand could reach more than 1200 million m3y-1by 2065. Conversion of 50% of broadleaved forest in EU27 countries to coniferous forest is not likely to satisfy the increased demand for wood expected by 2065.

Disturbances from wind, bark beetles and wildfires have increased in Europe’s forests throughout the twentieth century. Climatic changes were identified as a key driver behind this increase, yet how the expected continuation of climate change will affect Europe’s forest disturbance regime remains unresolved. Increasing disturbances could strongly impact the forest carbon budget, and are suggested to contribute to the recently observed carbon sink saturation in Europe’s forests. Here we show that forest disturbance damage in Europe has continued to increase in the first decade of the twenty-first century. On the basis of an ensemble of climate change scenarios we find that damage from wind, bark beetles and forest fires is likely to increase further in coming decades, and estimate the rate of increase to be +0.91 × 106m3of timber per year until 2030. We show that this intensification can offset the effect of management strategies aiming to increase the forest carbon sink, and calculate the disturbance-related reduction of the carbon storage potential in Europe’s forests to be 503.4 Tg C in 2021–2030. Our results highlight the considerable carbon cycle feedbacks of changing disturbance regimes, and underline that future forest policy and management will require a stronger focus on disturbance risk and resilience.

European forests, covering more than 2 million km2or 32% of the land surface, are to a large extent intensively managed and support an important timber industry. Climate change is expected to strongly affect tree species distribution within these forests. Climate and land use are undergoing rapid changes at present, with initial range shifts already visible. However, discussions on the consequences of biome shifts have concentrated on ecological issues. Here we show that forecasted changes in temperature and precipitation may have severe economic consequences. On the basis of our model results, the expected value of European forest land will decrease owing to the decline of economically valuable species in the absence of effective countermeasures. We found that by 2100—depending on the interest rate and climate scenario applied—this loss varies between 14 and 50% (mean: 28% for an interest rate of 2%) of the present value of forest land in Europe, excluding Russia, and may total several hundred billion Euros. Our model shows that—depending on different realizations of three climate scenarios—by 2100, between 21 and 60% (mean: 34%) of European forest lands will be suitable only for a Mediterranean oak forest type with low economic returns for forest owners and the timber industry and reduced carbon sequestration.