Carbon fluxes resulting from U.S. private timberland management

A carbon budget model was developed to examine the effects of forest management practices on carbon storage in U.S. private timberlands. The model explicitly incorporates the demand for wood products and its impact on harvesting and other management decisions. Forest carbon is divided into four components: carbon stored in trees, soils, forest litter, and understory vegetation. Changes in the forest carbon inventory result from tree growth and management activities, in particular harvesting. Harvesting of timber for wood products is determined by demand and supply forces. The model then tracks carbon in timber removals through primary and secondary processing and disposal stages. Harvesting also has effects on carbon in soils, forest litter, and understory vegetation. A base-run scenario projects increases in carbon storage in U.S. private timberlands by 2040; however, this increase is offset by carbon emissions resulting from harvesting.     

THE POTENTIAL FOR INCREASING CARBON STORAGE IN UNITED STATES UNRESERVED TIMBERLANDS BY REDUCING FOREST FIRE FREQUENCY: AN ECONOMIC AND ECOLOGICAL ANALYSIS

In this paper, we link the impact of fire damage on forests with an economic model of the United States forest sector in order to determine if a reduction in forest fire frequency will increase the projected storage of carbon in United States forests. We first develop a model of forest mortality following fire. We then link this model to an inventory model of United States forests, which allows us to determine how changes in the frequency of fires will impact forest inventories. Changes in inventory levels can be used to project both the amount of carbon stored and an economic response. If fire frequency is reduced from its current level, measured as the average from 1984 to 1990, we find that carbon storage can be increased in unreserved U.S. timberlands over the period 1990 to 2040.     

Global forest products markets and forest sector carbon impacts of projected sea level rise

Sea level rise (SLR) is among the climate-change-related problems of greatest concern, threatening the lives and property of coastal residents and generating far-reaching economic and ecological impacts. We project that SLR will lead to an increase in the rate of new housing construction to replace destroyed structures, impact global wood products supply and demand conditions, and cause changes in global forest sector carbon mitigation potential. Findings indicate that 71 million new units will be built by 2050 to accommodate the SLR-affected global population. More than two-thirds of these new units are projected to be in Asia. The estimated extra wood products needed to build these new residential units is 1,659 million m³, assuming that all these structures would be built mainly with wood, representing a 4 % increase in total wood consumption, compared to projected reference level global wood products consumption. Increased timber removals to meet this higher construction wood demand (alternative scenario) is shown to deplete global forest carbon by 2 % by 2050 compared to the reference scenario. However, all such projected declines in forest biomass carbon could be more than offset by increased carbon sequestration in harvested wood products, avoided emissions due to substitution of wood for non-wood materials in construction, and biomass regrowth on forestland by 2050, with an estimated net emissions reduction benefit of 0.47 tCO₂e/tCO₂e of extra wood used in SLR-related new houses over 30 years. The global net emissions reduction benefit increased to 2.13 tCO₂e/tCO₂e of extra wood when price-induced changes in forest land area were included.     

Overestimated Biomass Carbon Pools of the Northern mid- and High Latitude Forests

The biomass carbon (C) stock of forests is one of key parameters for the study of regional and global carbon cycles. Literature reviews shows that inventory-based forest C stocks documented for major countries in the middle and high northern latitudes fall within a narrow range of 36–56 Mg C ha⁻¹ with an overall area-weighted mean of 43.6 Mg C ha⁻¹. These estimates are 0.40 to 0.71 times smaller than those (61–108 Mg C ha⁻¹) used in previous analysis of balancing the global carbon budget. A statistical analysis, using the global forest biomass database, implies that aboveground biomass per hectare is proportional to forest mean height [biomass in Mg/ha = 10.63 (height in m)] in closed-canopy forests in the study regions, indicating that forest height can be a proxy of regional biomass C stocks. The narrow range of C stocks is likely a result of similar forest height across the northern regions. The lower biomass C stock obtained in this study strongly suggests that the role of the northern forests in the global carbon cycle needs to be re-evaluated. Our findings also suggest that regional estimates of biomass could be readily made from the use of satellite methods such as lidar that can measure forest canopy height over large regions.     

中国森林乔木林碳储量及其固碳潜力预测

加强对我国森林碳储量和固碳潜力的研究,是制定中国增汇减排政策的重要依据,对我国国际气候谈判和全面了解森林碳汇潜力具有重要作用。利用我国第七次和第八次森林资源清查中各优势树种的面积和蓄积量数据,采用IPCC材积源生物量法（volume-biomass method),估算了我国森林（乔木林）碳储量和碳密度及其分布,分析我国不同省份天然乔木林和人工乔木林碳储量龄组结构特征;建立分区域、分起源主要优势树种的单位面积蓄积-林龄Logistic生长方程,结合我国森林2020年和2030年面积蓄积增长目标,预测我国乔木林2010—2050年间碳汇潜力。结果表明：第八次清查期间中国乔木林总碳储量为6135.68 Tg,碳密度为37.28 Mg/hm ²;天然乔木林和人工乔木林的碳储量分别为5246.07 Tg和889.61 Tg,分别占总碳储量的85.50%和14.50%。到2050年,中国乔木林和新造林的总碳储量和平均碳密度将分别达到11125.76 Tg和52.52 Mg/hm ²,与2010年相比分别增加81%和41%。分析结果表明中国乔木林有很大的碳汇潜力,将在应对和减缓全球气候变化中发挥重要作用。     

When the pendulum doesn’t find its center: Environmental narratives,strategies, and forest policy change in the US Pacific Northwest

Since the 1980s, the US Pacific Northwest has been shattered by a major environmental policy conflict related to the management of Federal forests. These “timber wars” were similar to forest environmental policy conflicts in several other countries, but were particularly polarized. They resulted in a significant change in Federal forest policy from timber production orientation to biodiversity conservation. The change occurred suddenly and had significant economic and social consequences within the region and beyond, but was embedded in long-term societal and institutional trends.In this paper, I adopt an interpretive approach in order to, first, understand contemporary interpretations of the 1993 policy change and, second, to reconstruct the contemporary discursive ‘landscape’ of the Pacific Northwest including the major resource management paradigms and narratives that guide policy making in this region today. Empirically, my interpretation is mostly built on 37 qualitative interviews with policy stakeholders that were conducted in the summer of 2011.Based on this evidence, the paper argues that there are four narratives circulating amongst policy stakeholders that represent different conceptualizations of the 1993 policy change. Yet, all narratives highlight the importance of environmental strategy making that mobilized the socio-institutional setting in order to prepare and finally achieve the change.Current forest policy in the region is characterized by a policy stalemate resulting from the confluence of diverse institutional, context-related factors and the inability of stakeholders to create enough contradictions or crisis by combining these factors in order to promote change-enabling narratives. Four resource management paradigms compete in the region and, within these, narratives and counter narratives on physical and social events are developed. Current forest policy is dominated by an ecosystem management paradigm, but forest management practices aim to reconcile demands arising from the different paradigms to a certain degree, for instance via the concept of “ecological restoration”. Yet, given that the material base that feeds such compromises is finite, a new crisis in Pacific Northwest forest policy in the future is likely.In conclusion, this paper offers an interpretation of Pacific Northwest forest policy (change) as a process in which social and physical events are ‘discursively mobilized’ by means of narratives that are produced against the background of major natural resources paradigms. This includes the art of ‘discourse agents’ in constructing problematizations and intervention logics to either defend the current policy state or to increase the likelihood of change.     

The potential for short-rotation woody crops to reduce U.S. CO2 emissions

Short-rotation woody crops (SRWC) could potentially displace fossil fuels and thus mitigate CO₂ buildup in the atmosphere. To determine how much fossil fuel SRWC might displace in the United States and what the associated fossil carbon savings might be, a series of assumptions must be made. These assumptions concern the net SRWC biomass yields per hectare (after losses); the amount of suitable land dedicated to SRWC production; wood conversion efficiencies to electricity or liquid fuels; the energy substitution properties of various fuels; and the amount of fossil fuel used in growing, harvesting, transporting, and converting SRWC biomass. Assuming the current climate, present production, and conversion technologies and considering a conservative estimate of the U.S. land base available for SRWC (14 × 10⁶ ha), we calculate that SRWC energy could displace 33.2 to 73.1 × 10⁶ Mg of fossil carbon releases, 3–6% of the current annual U.S. emissions. The carbon mitigation potential per unit of land is larger with the substitution of SRWC for coal-based electricity production than for the substitution of SRWC-derived ethanol for gasoline. Assuming current climate, predicted conversion technology advancements, an optimistic estimate of the U.S. land base available for SRWC (28 × 10⁶ ha), and an optimistic average estimate of net SRWC yields (22.4 dry Mg/ha), we calculate that SRWC energy could displace 148 to 242 × 10⁶ Mg of annual fossil fuel carbon releases. Under this scenario, the carbon mitigation potential of SRWC-based electricity production would be equivalent to about 4.4% of current global fossil fuel emissions and 20% of current U.S. fossil fuel emissions.Research sponsored by the Biofuels Systems Division, U.S. Department of Energy, under contract DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc. Environmental Sciences Division Publication number 3952.     

Regional- and district-level drivers of timber harvesting in European Russia after the collapse of the Soviet Union

After the collapse of the Soviet Union, the forestry sector in Russia underwent substantial changes: the state forestry sector was decentralized, the timber industry was privatized, and timber use rights were allocated through short- and long-term leases. To date, there has been no quantitative assessment of the drivers of timber harvesting in European Russia following these changes. In this paper we estimate an econometric model of timber harvesting using remote sensing estimations of forest disturbance from 1990–2000 to 2000–2005 as our dependent variable. We aggregate forest disturbance to administrative districts – equivalent to counties in the United States – and test the impact of several biophysical and economic factors on timber harvesting. Additionally, we examine the impact that regions – equivalent to states in the United States and the main level of decentralized governance in Russia – have on timber harvesting by estimating the influence of regional-level effects on forest disturbance in our econometric model. Russian regions diverged considerably in political and economic conditions after the collapse of the Soviet Union, and the question is if these variations impacted timber harvesting after controlling for district-level biophysical and economic drivers. We find that the most important drivers of timber harvesting at the district level are road density, the percent of evergreen forest, and the total area of forest. The influence of these variables on timber harvesting changed over time and there was more harvesting closer to urban areas in 2000–2005. Even though district-level variables explain more than 70 percent of the variation in forest disturbance in our econometric model, we find that regional-level effects remain statistically significant. While we cannot identify the exact mechanism through which regional-level effects impact timber harvesting, our results suggest that sub-national differences can have a large and statistically significant impact on land-use outcomes and should be considered in policy design and evaluation.     

Taking the Pulse of Mountains: Ecosystem Responses to Climatic Variability

An integrated program of ecosystem modeling and field studies in the mountains of the Pacific Northwest (U.S.A.) has quantified many of the ecological processes affected by climatic variability. Paleoecological and contemporary ecological data in forest ecosystems provided model parameterization and validation at broad spatial and temporal scales for tree growth, tree regeneration and treeline movement. For subalpine tree species, winter precipitation has a strong negative correlation with growth; this relationship is stronger at higher elevations and west-side sites (which have more precipitation). Temperature affects tree growth at some locations with respect to length of growing season (spring) and severity of drought at drier sites (summer). Furthermore, variable but predictable climate-growth relationships across elevation gradients suggest that tree species respond differently to climate at different locations, making a uniform response of these species to future climatic change unlikely. Multi-decadal variability in climate also affects ecosystem processes. Mountain hemlock growth at high-elevation sites is negatively correlated with winter snow depth and positively correlated with the winter Pacific Decadal Oscillation (PDO) index. At low elevations, the reverse is true. Glacier mass balance and fire severity are also linked to PDO. Rapid establishment of trees in subalpine ecosystems during this century is increasing forest cover and reducing meadow cover at many subalpine locations in the western U.S.A. and precipitation (snow depth) is a critical variable regulating conifer expansion. Lastly, modeling potential future ecosystem conditions suggests that increased climatic variability will result in increasing forest fire size and frequency, and reduced net primary productivity in drier, east-side forest ecosystems. As additional empirical data and modeling output become available, we will improve our ability to predict the effects of climatic change across a broad range of climates and mountain ecosystems in the northwestern U.S.A.     

Carbon Stores,Sinks, and Sources in Forests of Northwestern Russia: Can We Reconcile Forest Inventories with Remote Sensing Results?

Forest inventories and remote sensing are the two principal data sources used to estimate carbon (C) stocks and fluxes for large forest regions. National governments have historically relied on forest inventories for assessments but developments in remote sensing technology provide additional opportunities for operational C monitoring. The estimate of total C stock in live forest biomass modeled from Landsat imagery for the St. Petersburg region was consistent with estimates derived from forest inventory data for the early 1990s (272 and 269 TgC, respectively). The estimates of mean C sink in live forest biomass also agreed well (0.36 and 0.34 Mg C ha^–1 yr^–1). Virtually all forest lands were accumulating C in live biomass, however when the net change in total ecosystem C stock was considered, 19% of the forest area were a net source of C. The average net C sink in total ecosystem biomass is quite weak (0.08 MgC ha^–1 yr^–1 and could be reversed by minor increases in harvest rates or a small decline in biomass growth rates.     

Carbon Stores, Sinks, and Sources in Forests of Northwestern Russia: Can We Reconcile Forest Inventories with Remote Sensing Results?

Forest inventories and remote sensing are the two principal data sources used to estimate carbon (C) stocks and fluxes for large forest regions. National governments have historically relied on forest inventories for assessments but developments in remote sensing technology provide additional opportunities for operational C monitoring. The estimate of total C stock in live forest biomass modeled from Landsat imagery for the St. Petersburg region was consistent with estimates derived from forest inventory data for the early 1990s (272 and 269 TgC, respectively). The estimates of mean C sink in live forest biomass also agreed well (0.36 and 0.34 Mg C ha^–1 yr^–1). Virtually all forest lands were accumulating C in live biomass, however when the net change in total ecosystem C stock was considered, 19% of the forest area were a net source of C. The average net C sink in total ecosystem biomass is quite weak (0.08 MgC ha^–1 yr^–1 and could be reversed by minor increases in harvest rates or a small decline in biomass growth rates.     

Paper 3. impacts and responses to climate change in forests of the mink region

The adaptability of forests in the U.S. midwest to a changing climate is assessed. The forests of Missouri are simulated with a forest-gap model, a stochastic model of the annual growth and mortality of trees within mixed-species forest plots. The development of representative forest plots under an analog climate like that of the 1930s is compared to development under baseline climate conditions. With no management response, average forest biomass in the region declines by 11% within ten years, primarily due to moisture-stress induced mortality. Longer term declines in forest productivity on the order of 30% are simulated. A variety of possible management responses through planting or harvesting practices were evaluated. None of these adaptations appear to be practical, although the salvage harvest of stressed trees would offset the economifc losses associated with the early mortality. An investigation of anticipated trends in the broader forest products sector suggests that opportunities for further adaptation to offset the decline in primary productivity of this region's forest are quite limited. However, a shift to wood powered electrical generation in the region might justify a level of management that would allow some adaptation to the analog climate change.Acknowledgments: Support from the U.S. Department of Energy through the Pacific Northwest Laboratory is gratefully acknowledged. We thank Alan Solomon for providing the FORENA forest simulation model.     

Storage of carbon in U.S. forests predicted from satellite data,ecosystem modeling,and inventory summaries

A plant and soil simulation model based on satellite observations of vegetation and climate data was used to estimate the potential carbon pools in standing wood biomass across all forest ecosystems of the conterminous United States up to the year 1997. These modeled estimates of vegetative carbon potential were compared to aggregated measurements of standing wood biomass from the U. S. Forest Service’s national Forest Inventory and Analysis (FIA) data set and the Carbon Online Estimator (COLE) to understand: 1) predominant geographic variations in tree growth rate and 2) local land cover and land use history including the time since the last stand-replacing disturbance (e.g., from wildfire or harvest). Results suggest that although wood appears to be accumulating at high rates in many areas of the U.S. (Northwest and Southeast), there are still extensive areas of relatively low biomass forest in the late 1990s according to FIA records. We attribute these low biomass accumulation levels to the high frequency of disturbances, which can be observed even in high production areas such as the Southeast due to frequent forest harvests. Ecosystem models like the one presented in this study have been coupled with satellite observations of land cover and green plant density to uniquely differentiate areas with a high potential for vegetative carbon storage at relatively fine spatial resolution.     

Increased Carbon Sink in Temperate and Boreal Forests

An intense search is under way to identify the `missing sink' in the world carbon budget of perhaps 2 Pg year^–1 (petagrams, or billiontonnes) of carbon, but its location and mechanism have proved elusive. Here we use a new forest inventory data set to estimate the carbon sink and the carbon pool of woody biomass in 55 countries that account for nearly all temperate or boreal forests and approximately half the world's total forest area. In each country there was a net accumulation of biomass; together, the carbon sink of woody biomass was 0.88 Pg year^–1 during the 1990swith estimated uncertainty from 0.71 to 1.1 Pg year^–1. Thisestimate, already about half of the missing sink, would probably be even larger if carbon accumulation in soil and detritus were also accounted for, but we are unable to quantify that additional sink. The sink is twice that estimated for the woody biomass of these forests a decade ago due to higher estimates for tree growth throughout the region and decreased timber harvests in Russia. In contrast, the new data indicate a carbon pool that is smaller than earlier estimates because of improved data for Russia and Australia.     

The Consequences of CO2 Stabilisation for the Impacts of Climate Change

This paper reports the main results of an assessment of the global-scale implications of the stabilisation of atmospheric CO₂ concentrations at 750 ppm (by 2250) and 550 ppm (by 2150), in relationto a scenario of unmitigated emissions. The climate change scenarios were derived from simulation experiments conducted with the HadCM2 global climate model and forced with the IPCC IS92a, S750 and S550 emissions scenarios. The simulated changes in climate were applied to an observed global baseline climatology, and applied with impacts models to estimate impacts on natural vegetation, water resources, coastal flood risk and wetland loss, crop yield and food security, and malaria. The studies used a single set of population and socio-economic scenarios about the future that are similar to those adopted in the IS92a emissions scenario.An emissions pathway which stabilises CO₂ concentrations at 750 ppmby the 2230s delays the 2050 temperature increase under unmitigated emissions by around 50 years. The loss of tropical forest and grassland which occurs by the 2050s under unmitigated emissions is delayed to the 22nd century, and the switch from carbon sink to carbon source is delayed from the 2050s to the 2170s. Coastal wetland loss is slowed. Stabilisation at 750 ppm generally has relatively little effect on the impacts of climate change on water resource stress, and populations at risk of hunger or falciparum malaria until the 2080s.A pathway which stabilises CO₂ concentrations at 550 ppm by the 2170s delays the 2050 temperature increase under unmitigated emissions by around 100 years. There is no substantial loss of tropical forest or grassland, even by the 2230s, although the terrestrial carbon store ceases to act as a net carbon sink by around 2170 (this time because the vegetation has reached a new equilibrium with the atmosphere). Coastal wetland loss is slowed considerably, and the increase in coastal flood risk is considerably lower than under unmitigated emissions. CO₂ stabilisation at 550 ppm reduces substantially water resource stress, relative to unmitigated emissions, but has relatively little impact on populations at risk of falciparum malaria, and may even cause more people to be at risk of hunger. While this study shows that mitigation avoids many impacts, particularly in the longer-term (beyond the 2080s), stabilisation at 550 ppm appears to be necessary to avoid or significantly reduce most of the projected impacts in the unmitigated case.     

A process-based approach to estimate lodgepole pine (Pinus contorta Dougl.) distribution in the Pacific Northwest under climate change

Lodgepole pine (Pinus contorta Dougl.) is a widely distributed species in the Pacific Northwest of North America. The extent that the current distribution of this species may be altered under a changing climate is an important question for managers of wood supply as well as those interested in conservation of subalpine ecosystems. In this paper, we address the question, how much might the current range of the species shift under a changing climate? We first assessed the extent that suboptimal temperature, frost, drought, and humidity deficits affect photosynthesis and growth of the species across the Pacific Northwest with a process-based model (3-PG). We then entered the same set of climatic variables into a decision-tree model, which creates a suite of rules that differentially rank the variables, to provide a basis for predicting presence or absence of the species under current climatic conditions. The derived decision-tree model successfully predicted weighted presence and absence recorded on 12,660 field survey plots with an accuracy of ~70%. The analysis indicated that sites with significant spring frost, summer temperatures averaging <15°C and soils that fully recharged from snowmelt were most likely to support lodgepole pine. Based on these criteria, we projected climatic conditions through the twenty-first century as they might develop without additional efforts to reduce carbon emissions using the Canadian Climate Centre model (CGCM2). In the 30-year period centered around 2020, the area suitable for lodgepole pine in the Pacific Northwest was projected to be reduced only slightly (8%). Thereafter, however, the projected climatic conditions appear to progressively favor other species, so that by the last 30 years of twenty-first century, lodgepole pine could be nearly absent from much of its current range. We conclude that process-based models, because they are highly sensitive to seasonal variation in solar radiation, are well adapted to identify the importance of different climatic variables on photosynthesis and growth. These same variables, once indentified, and run through a decision-tree model, provide a reasonable approach to predict current and future patterns in a species?? distribution.     

Global exposure to river and coastal flooding: Long term trends and changes

Flood damage modelling has traditionally been limited to the local, regional or national scale. Recent flood events, population growth and climate change concerns have increased the need for global methods with both spatial and temporal dynamics. This paper presents a first estimation of global economic exposure to both river and coastal flooding for the period 1970–2050, using two different methods for damage assessment. One method is based on population and the second is based on land-use within areas subject to 1/100 year flood events. On the basis of population density and GDP per capita, we estimate a total global exposure to river and coastal flooding of 46 trillion USD in 2010. By 2050, these numbers are projected to increase to 158 trillion USD. Using a land-use based assessment, we estimated a total flood exposure of 27 trillion USD in 2010. For 2050 we simulate a total exposure of 80 trillion USD. The largest absolute exposure changes between 1970 and 2050 are simulated in North America and Asia. In relative terms we project the largest increases in North Africa and Sub-Saharan Africa. The models also show systematically larger growth in the population living within hazard zones compared to total population growth. While the methods unveil similar overall trends in flood exposure, there are significant differences in the estimates and geographical distribution. These differences result from inherent model characteristics and the varying relationship between population density and the total urban area in the regions of analysis. We propose further research on the modelling of inundation characteristics and flood protection standards, which can complement the methodologies presented in this paper to enable the development of a global flood risk framework.     

Consequences of climate change for the soil climate in Central Europe and the central plains of the United States

This study aims to evaluate soil climate quantitatively under present and projected climatic conditions across Central Europe (12.1°–18.9° E and 46.8°–51.1° N) and the U.S. Central Plains (90°–104° W and 37°–49° N), with a special focus on soil temperature, hydric regime, drought risk and potential productivity (assessed as a period suitable for crop growth). The analysis was completed for the baselines (1961–1990 for Europe and 1985–2005 for the U.S.) and time horizons of 2025, 2050 and 2100 based on the outputs of three global circulation models using two levels of climate sensitivity. The results indicate that the soil climate (soil temperature and hydric soil regimes) will change dramatically in both regions, with significant consequences for soil genesis. However, the predicted changes of the pathways are very uncertain because of the range of future climate systems predicted by climate models. Nevertheless, our findings suggest that the risk of unfavourable dry years will increase, resulting in greater risk of soil erosion and lower productivity. The projected increase in the variability of dry and wet events combined with the uncertainty (particularly in the U.S.) poses a challenge for selecting the most appropriate adaptation strategies and for setting adequate policies. The results also suggest that the soil resources are likely be under increased pressure from changes in climate.     

西北太平洋热带气旋移动路径的年际变化及其机理研究

利用JTWC的热带气旋资料、NCEP/NCAR再分析的风场资料以及Scripps海洋研究所的海温资料分析了西北太平洋热带气旋(TC)移动路径的年际变化及其机理。结果表明,西北太平洋TC移动路径有明显的年际变化并与西太平洋暖池热状态有很密切的关系。当西太平洋暖池处于暖状态,西北太平洋上空TC移动路径偏西,影响中国的台风个数偏多;相反,当西太平洋暖池处于冷状态,西北太平洋的TC移动路径偏东,影响日本的台风个数偏多,而影响中国的台风个数可能偏少。本研究以西太平洋暖池处于冷状态的2004年与西太平洋暖池处于暖状态的2006年的西北太平洋TC移动路径的差别进一步论证了这一分析结果并从动力理论方面分析了在西太平洋暖池不同热状态下,季风槽对赤道西传天气尺度的Rossby重力混合波转变成热带低压型波动(TD型波动)的影响,以此揭示西太平洋暖池的热状态对西北太平洋TC生成位置与移动路径年际变化的影响机理。分析结果表明,当西北太平洋暖池处于暖状态时,季风槽偏西,使得热带太平洋上空对流层低层Rossby重力混合波转变成TD型波动的位置也偏西,从而造成TC生成平均位置偏西,并易于出现西行路径;相反,当西太平洋暖池处于冷状态时,季风槽偏东,这造成了对流层低层Rossby重力混合波转变成TD型波动的区域,以及TC生成的平均位置都偏东,从而导致TC移动路径以东北转向为主。     

Climate change vulnerability of sustainable forest management in the Eastern Alps

Considering climatic uncertainties in management planning is a prerequisite for sustainable forest management (SFM). The aim of the study was to evaluate climate change vulnerability of the current SFM strategy for commercial forests managed by the Austrian Federal Forests. To that end vulnerability indicators were defined in a stakeholder process (selected indicators were productivity, timber and carbon stocks, biodiversity, disturbances, a tree species’ position in fundamental niche space, silvicultural flexibility and cost intensity) and their performance under climate change scenarios assessed with an ecosystem model. Multi criteria analysis techniques were employed in a partial aggregation of indicators to locate forest stands on a vulnerability surface. Results revealed high vulnerability particularly in the second half of the twenty-first century, where 39.6% of the 164.550 ha study area were assessed highly vulnerable to climate change, indicating a strong decline in the functions and services represented by the indicator system. Water-limited sites on calcareous bedrock were most negatively affected whereas assessment units at higher altitudes responded predominately positive to climate warming. The presented approach, transparently integrating multiple management objectives and allowing a quantitative comparison of vulnerabilities between sites and management strategies, contributes to the development of operational and efficient climate change adaptation measures in forest management.