Fluxes of Carbon, Water and Energy of European Forests
However, recent findings cast doubt on the sustainability of this offset. First, the strength of the U. Second, climate change is expected to further increase frequencies of insect outbreaks and wildfire, and alter species composition in forest ecosystems, consequently influencing forest carbon pools in a significant way. Integrating Landscape-scale Forest Measurements with Remote Sensing and Ecosystem Models to Improve Carbon Management Decisions Managing forests to increase carbon stocks and reduce emissions requires knowledge of how management practices and natural disturbances affect carbon pools over time, and cost-effective techniques for monitoring and reporting.
Tools for Carbon Inventory, Management and Reporting Much of our science is used to provide information for policymakers and planning. We have developed tools so that others may apply this information, or work with our tools to further the science. Poplars are dedicated energy crops that can be strategically placed in the landscape to conserve soil and water, recycle nutrients, and sequester carbon. Therefore, building on decades of research conducted at our Institute and throughout the region, we are evaluating the fate of carbon in soils and woody biomass, soil greenhouse gas emissions, and conversion efficiency barriers throughout the energy supply chain.
Coarse Woody Debris A proportion of the carbon in forest ecosystems is contained in coarse woody debris on the forest floor.
Estimating the carbon stock and other attributes of coarse woody debris can be time consuming and error-prone. New methods for field sampling of coarse woody debris are needed for efficient estimation of the carbon stock in this forest pool. Effects of Insect Defoliation on Regional Carbon Dynamics of Forests On an annual basis, insects severely defoliate more than 20 million acres of forested land in the conterminous United States, affecting a larger area and incurring higher economic costs than any other disturbance.
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However, the long-term costs and ecosystem consequences of insect outbreaks on forest health and productivity are difficult to quantify at the regional scale because of the variety of pests involved, differences in forest types affected, and varying spatial scale and intensity of the impacts. In particular, the effect of insect activity on carbon cycling and sequestration at the annual and decadal scale is poorly characterized.
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Mid-Atlantic Forests and the Chesapeake Bay Watershed Forest landscapes are changing as a consequence of climate and environmental change. These changes affect people and the forest ecosystems they depend on for clean water, clean air and forest products, and recreation. How can we best manage our forest resources to sustain this array of ecosystem services under increasing environmental stress and a changing climate?
Because forests store large quantities of carbon and these stocks are affected by many factors, accurate monitoring of forest carbon stocks and fluxes is a critical component of strategies to manage greenhouse gas emissions and sequestration. Dothistroma needle blight, lodgepole pine dwarf mistletoe, several root diseases, and other pathogens are predicted to respond to climate change; but with complex disease host interactions, the impacts are difficult to forecast. Aspen dieback or decline in Alberta and Saskatchewan in the southern boreal zone could possibly be the beginning of widespread species dieback in the boreal zone attributed to changing weather and climate patterns and interactions with defoliating insects Hogg et al.
While these impacts of climate change will be difficult to diagnose and quantify, it is generally accepted that the risk of large-scale disease outbreaks will increase with increased climate variability partly because pathogens and disease can adapt to new climate conditions faster than tree species Sturrock et al. Responses of the boreal forest to insects, pathogens, and drought under a changing climate are discussed in further detail by Price et al.
Windthrow has been reported as one of the most important factors driving succession in Russian boreal forests Ulanova and extreme windthrow events in Scandinavian boreal forests have been shown to affect C budgets Lindroth et al. However, uncertainties remain because windthrow extent is typically not monitored or reported by provincial resource management agencies. The explicit C accounting of additional disturbance types would require the monitoring of areas affected by these disturbance types, as well as their effects on growth, mortality, and transfers to DOM or HWPs following salvage logging.
However, based on the limited data available, the magnitude of this reduction is currently expected to be well within the overall uncertainty of existing C balance estimates. But if the frequency or intensity of these disturbances increases with climate change, then their impacts on C balances could become much more significant and they should then be included in NFCMARS. Mineral soils are distinguished from organics soils that are classified in the Organic order or the Organic great group of the Cryosolic order Soil Classification Working Group that in the boreal zone are largely composed of moss-derived peat.
In the continuous permafrost zone, permafrost occurs everywhere beneath the ground surface except below large bodies of water, whereas it underlies varying proportions of the land area in the discontinuous permafrost zone Hegginbottom et al. Aboveground productivity in these zones tends to be low, but decomposition rates are even lower so that larger amounts of ecosystem C are stored in mineral soils and organic soils of peatlands Wieder et al.
For example, Vitt et al. This may even be an underestimate given that some of the permafrost soils are of deltaic or paleozoic origin, which contain extraordinarily high organic C stocks matching those found in deep organic soils Sanborn et al. The addition of these soil types to a recent re-estimation of C stocks in the northern circumpolar permafrost region contributed to a doubling of previous C stock estimates Tarnocai et al.
Zimov et al. Therefore, even though these soils occupy a small area of the boreal zone, their contribution to the C budget of the Canadian boreal zone is expected to be significant both nationally and regionally, although little is known about their C dynamics in Canada. The discontinuous permafrost zone is where permafrost thaw is of greatest concern to contemporary and future see section 4. The majority of the discontinuous permafrost zone lies within the boreal zone. Much of the area is dominated by mineral soils with relatively good drainage or as mineral soils within in a complex of peatlands with frozen and unfrozen organic soils.
Despite their smaller area, the majority of C stocks are found within the organic soils of the peatlands. The C dynamics of northern peatlands frozen or not have been extensively reviewed over the last decade, particularly in relation to global change Blodau ; Lavoie et al.
In a recent review, Strack et al. Carlson et al. Recently, Wania et al. After introducing permafrost effects, they concluded that NEP was reduced from 1.
The effect of introducing peatlands as well as permafrost was to double the soil C stock increase to 80 Pg. Most lines of evidence suggest that the consequence of not including forested permafrost and peatland areas in national-scale accounting is to underestimate C stocks and exclude uncertainty associated with under- or over-estimation of net GHG exchange in response to disturbance or climate change. Readers are referred to section 4 and Price et al. Bryophytes, predominantly mosses and lichens, are ubiquitous throughout the boreal forest in upland forests and peatlands Brodo et al.
The physiology and ecology of bryophytes differ from vascular plants Turetsky ; Turetsky et al.kiibreadnuerece.gq
Fluxes of Carbon, Water and Energy of European Forests
In the context of C dynamics and climate change, the importance of mosses and lichens in peatlands is well studied, but less attention, particularly with respect to C dynamics, has been paid to forests with significant bryophyte associations. These would include peaty, mainly black spruce forests Lavoie et al. Although the bryophyte layer is not sufficiently thick to be classified as an organic soil or peatland, it imparts unique ecosystem characteristics interacting with trees and shrubs Turetsky ; Turetsky et al.
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Ecosystems of this type commonly occur in the transition zone between upland forest and peatlands and where drainage is poor because of landscape position or because the underlying mineral soil has poor drainage characteristics Bhatti et al. Exclusion of the bryophyte component from the C budget of these forest types will clearly lead to the underestimation of soil C and ecosystem C stocks Bona et al.
Turetsky et al. Across all upland and wetland types, moss NPP ranged from 0. Peaty forests are also important because they are potentially very responsive to disturbance from fire or harvesting and climate change Hartshorn et al. The bryophyte layer can have significant impacts on forest C dynamics.
Research over the last decade indicates the need to understand the response of the balance between peat moss Sphagnum subsp. Cornwell et al. In the case of bryophytes, it has been shown that the compositional change can affect key ecosystem processes including maximum photosynthetic rate of the forest floor and soil base respiration rates Bergeron et al. In most cases, the interactions between bryophyte species, hydrology, permafrost, and vascular plants are very complex Hobbie et al.
Inclusion of the bryophyte component of peaty forests in national-scale forest C budgets and forest ecosystem models Bond-Lamberty et al. Including bryophyte contributions to peaty forests and lichen woodlands in models requires improved data on their spatial distribution in relation to forested and nonforested areas, abundance, type, productivity, interactions with decomposers, and decomposition rates, as well as their indirect impacts on soil thermal regimes and interactions with hydrological regimes.
Clear-cut harvesting produces a short-term pulse of slash and other DOM stumps and roots and reduces the annual input of biomass C foliage, fine roots, and other biomass turnover to DOM pools see section 2. The net C balance of DOM and soil pools with the atmosphere is often negative for some years after harvest, leading to net reductions in litter, dead wood, and soil C pools. The effect of harvesting on C transfers between pools and their subsequent decomposition is reflected in the NFCMARS, but its impact on C stock changes remains the subject of ongoing research.
The frequently cited decline in forest soil C stocks in response to harvesting was primarily attributed to the observations of Covington in a temperate forest ecosystem, but Yanai et al. However, Nave et al. Variability in responses was high and explained mainly by soil taxonomic order, species composition, and time since harvest. Similar meta-analyses have not been conducted for the Canadian boreal forests, which differ significantly from temperate forests in species composition, soil taxa, NPP, decomposition rates, and harvesting practices.
Soil C stocks in boreal systems are typically higher than those in temperate systems because site conditions in the boreal forest are often conducive to accumulation of soil C Wieder et al. Bhatti and Tarnocai estimated that, in boreal ecozones, C stocks range from These values are higher than those estimated by Nave et al. A recent review Thiffault et al. However, when pool size is small temperate and some boreal forest floor C stocks , the loss of a small amount of C can translate into a high proportional loss Nave et al.
Applying such high proportional losses to the boreal zone where forest floor C stocks are mostly large could lead to the potentially erroneous conclusion that harvesting in the boreal results in large losses of soil C to the atmosphere. The high proportional loss of soil C in response to harvesting estimated for temperate systems may not occur in some of the dominant forest types of the Canadian boreal zone.
This is especially true for black spruce forests, the most common coniferous forest cover type in the boreal forest Lavoie et al. The dominant natural disturbance type in black spruce systems is wildfire, and consensus is emerging that harvesting has a less negative impact on the C budget of black spruce forests compared with wildfire Bergeron et al.
This is primarily because harvesting practices in most black spruce forests are less disruptive than wildfire Amiro et al. Studies examining black spruce stands in Ontario and Quebec generally indicated no response of mineral soil C to harvest disturbance. In some cases, reduction in forest floor C in younger stands was attributed to a change in harvest practices during the past several decades from horses to more disruptive mechanical logging Brumelis and Carleton or post-harvest burns Scheuner et al.
In black spruce systems conducive to paludification a shift from non-peatland to peatland caused mainly by a change in the hydrologic balance to wetter conditions Fenton et al.
Two emerging themes in temperate forest soil C research that may affect this conclusion are i most studies to date focus on C stock changes in the surface soil and do not account for the response of soil C at depth to cm or greater and ii the apparent stability of mineral soil C may change in response to change in the environment, which can occur because of harvesting Harrison et al. However, no research, to our knowledge, has been conducted in the Canadian boreal forest to study C dynamics at depth in response to harvesting or distinguish C that has accumulated from that which is stabilized Jandl et al.
In particular, we know little of the degree of stabilization of C Marschner et al. Since the time of Darwin it has been known that earthworms are important agents of soil formation and nutrient dynamics. However, the Canadian boreal forest zone has evolved in the absence of this significant ecosystem engineer Evers et al.
Non-native, primarily European, earthworms are being introduced to areas of boreal forest following the regional extinction of native species during the last ice age Addison The primary vectors of spread are associated with human recreational and resource development activities Cameron et al. Earthworms can have large impacts on GHG emissions Lubbers et al.
They can reduce forest floor C stocks either through an increase in decomposition rates or transfer rates to the mineral soil Langmaid ; Hale et al. Reduction in forest floor C stocks by earthworms has implications for estimation of C emissions from fire that originate mainly from the combustion of the forest floor Letang and de Groot Although a model of the effects of earthworms on soil C was recently developed for temperate forests Huang et al.
Further to this, effects of earthworms are currently not included in landscape-scale models of boreal forest C dynamics because of insufficient data on the spatial distribution and rates of spread of earthworms in the boreal zone of Canada and because of an inadequate understanding of their effects on net C fluxes in boreal forests. However, given their site-level effects on forest floor and mineral soil C dynamics and their expansion in many parts of the boreal zone, the omissions of earthworm impacts in national-scale analyses of forest C budgets could contribute significant uncertainties to present and future estimates.
The future C balance of the Canadian boreal forest will affect the global atmospheric C budget and influence the level of global mitigation efforts required to attain atmospheric CO 2 stabilization targets Allen et al.