scholarly journals Past and projected future changes in moisture conditions in the Canadian boreal forest

2014 ◽  
Vol 90 (05) ◽  
pp. 678-691 ◽  
Author(s):  
Yonghe Wang ◽  
Edward H. Hogg ◽  
David T. Price ◽  
Jason Edwards ◽  
Tim Williamson
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Spatial Data ◽  
General Circulation ◽  
General Circulation Models ◽  
Drought Severity ◽  
Linear Regression Models ◽  
Moisture Index ◽  
Forest Management Planning ◽  
Canadian Boreal Forest

Spatial data for the Climate Moisture Index and the Palmer Drought Severity Index were generated from gridded temperature and precipitation data for the Canadian boreal zone over the period 1951–2010. Annual values for the indices for 2011–2100 were generated from projections of future climate derived from four general circulation models forced by three greenhouse gas emissions scenarios. Linear regression models between the indices and time were fitted to examine long-term trends. Results indicated that several large regions of the Canadian boreal forest experienced substantial drying during 1951–2010. Future projections indicated a general trend toward drier conditions during the 21st century. Overall, the analysis indicated more frequent and/or more severe droughts across managed western and central portions of the boreal forest in coming decades. These projections of indices are relevant to forest management because soil moisture availability is an important determinant of forest distribution, tree health, and regeneration success. Knowledge of the range of potential future changes in drought occurrence and intensity will aid forest managers and decisionmakers in incorporating climate change considerations into forest management planning and practices.

scholarly journals Twenty-First Century Drought Analysis Across China using CMIP6 Under Climate Change

2021 ◽  
Author(s):  
Gengxi Zhang ◽  
Thian Yew Gan ◽  
Xiaoling Su
Keyword(s):  
Soil Moisture ◽  
General Circulation ◽  
Coupled Model ◽  
Severity Index ◽  
General Circulation Models ◽  
Mitigation Strategies ◽  
Drought Indices ◽  
Drought Severity ◽  
Moisture Index ◽  
Arid Northwestern China

Abstract Under global warming, according to results obtained from offline drought indices driven by projections of general circulation models (GCMs), future droughts in China will worsen but the results are not consistent. We analyzed changes in droughts covering the entire hydrologic cycle using outputs of GCMs of the 6th Coupled Model Intercomparison Project (CMIP6) for SSP2-4.5 and SSP5-8.5 climate scenarios, and compared the results with that of popular, offline drought indices (the self-calibrating Palmer Drought Severity Index (scPDSI), Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Actual Evapotranspiration Index (SPAEI)). Among meteorological, agricultural, and hydrological drought indices tested under both SSP scenarios, the results obtained from SPAEI and scPDSI agree better with univariate drought indices than SPEI. scPDSI generally agrees well with agricultural droughts (Standardized Soil Moisture Index with the surface soil moisture content; SSIS). Future droughts estimated using soil moisture analysis are more widespread than that from precipitation and runoff analysis in humid regions of South China by the end of the 21st century. In arid northwestern China and Inner Mongolia, drought areas and severity based on scPDSI and SSIS forced with the SSP scenarios show obvious decreasing trends, in contrast to increasing trends projected in humid regions. Trends projected using SPEI contradict those projected by other drought indices in non-humid regions. Therefore, selecting appropriate drought indices are crucial in project representative future droughts and meaningful information needed to achieve effective regional drought mitigation strategies under climate warming impact.

scholarly journals How do Alberta's, Ontario's and Quebec's forest operation laws respect ecological sustainable forest management criteria in the boreal forest?

2007 ◽  
Vol 83 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Laurence Bourgeois ◽  
Daniel Kneeshaw ◽  
Louis Imbeau ◽  
Nicolas Bélanger ◽  
Stephen Yamasaki ◽  
...  
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Aquatic Environment ◽  
Sustainable Forest Management ◽  
Forest Certification ◽  
Forest Operations ◽  
Ecological Criteria ◽  
Canadian Boreal Forest ◽  
Forest Operation ◽  
To Receive

In order to receive forest certification and to respond to societal desires, many forest companies are attempting to demonstrate that their forest activities are «sustainable». The main objective of this paper is to qualitatively evaluate the ways in which forestry-related provincial regulations in the three provinces (Alberta, Ontario and Quebec) that contain most of the Canadian boreal forest help forest companies achieve certification with respect to ecological criteria. In the process of continually evolving towards sustainable forest management, we evaluate how these provincial regulations governing forest operations can be helpful in maintaining three criteria: biodiversity, the aquatic environment and soils. This study shows that the regulations evaluated have varied in their approach and thus have different strengths that must be underlined: (1) Ontario's approach is the strongest in terms of biodiversity, (2) Alberta and Ontario provide measures to abandon roads after harvesting, (3) Quebec provides the greatest specific measures for protecting waterways and aquatic species, (4) Alberta shows the greatest consideration for maintaining the most soil properties and functions. Better links between different regulations are necessary in all jurisdictions. The continual improvement of Canadian forest rules is often slow and advances at a different pace depending on regulators but it should be supported in all provinces. Key words: sustainable forest management, biodiversity, aquatic environment, soils, Alberta, Ontario, Quebec

Opportunities and costs of intensification and clustering of forest management activities

2008 ◽  
Vol 38 (4) ◽  
pp. 711-720 ◽  
Author(s):  
Anne-Hélène Mathey ◽  
Emina Krcmar ◽  
John Innes ◽  
Ilan Vertinsky
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Timber Harvesting ◽  
Conservation Areas ◽  
Intensive Forest Management ◽  
Trade Offs ◽  
Planning Approach ◽  
Increasing Demand ◽  
Canadian Boreal Forest ◽  
The Cost

The intensification of forest management in Canada has been advocated as a possible solution to the conundrum that increasing demand for conservation areas and increasing pressure for timber production have created. The benefits and disadvantages of intensive forest management in the context of the Canadian boreal forest are unclear and reaching conclusions about its general value from stand analyses may be difficult. In this study, a boreal forest in Ontario has been used to investigate the potential of intensive management to generate financial revenues and meet management constraints on volume flow and old-growth retention. Two aspects of intensive forest management are considered: intensive silviculture and concentrated harvest activities. The plans are generated with a decentralized planning approach based on cellular automata. The results for the case study show that increasing silviculture intensity can help fulfill high timber flow requirements under strict conservation requirements. This comes at the cost of reduced net revenues but from a smaller timber harvesting landbase. The main trade-offs found were those between harvest flow and financial benefits. Clustering both protected areas and harvest operations could help achieve the conservation and timber-related objectives simultaneously by improving the habitat value of conserved areas and decreasing the operational costs in harvested areas.

scholarly journals Historical droughts in Mediterranean regions during the last 500 years: a data/model approach

2007 ◽  
Vol 3 (2) ◽  
pp. 355-366 ◽  
Author(s):  
S. Brewer ◽  
S. Alleaume ◽  
J. Guiot ◽  
A. Nicault
Keyword(s):  
Drought Stress ◽  
General Circulation ◽  
Distance Measure ◽  
Severity Index ◽  
General Circulation Models ◽  
Ice Age ◽  
Drought Severity ◽  
Atmospheric Circulation Patterns ◽  
Dry Conditions ◽  
Simulated Climate

Abstract. We present here a new method for comparing the output of General Circulation Models (GCMs) with proxy-based reconstructions, using time series of reconstructed and simulated climate parameters. The method uses k-means clustering to allow comparison between different periods that have similar spatial patterns, and a fuzzy logic-based distance measure in order to take reconstruction errors into account. The method has been used to test two coupled ocean-atmosphere GCMs over the Mediterranean region for the last 500 years, using an index of drought stress, the Palmer Drought Severity Index. The results showed that, whilst no model exactly simulated the reconstructed changes, all simulations were an improvement over using the mean climate, and a good match was found after 1650 with a model run that took into account changes in volcanic forcing, solar irradiance, and greenhouse gases. A more detailed investigation of the output of this model showed the existence of a set of atmospheric circulation patterns linked to the patterns of drought stress: 1) a blocking pattern over northern Europe linked to dry conditions in the south prior to the Little Ice Age (LIA) and during the 20th century; 2) a NAO-positive like pattern with increased westerlies during the LIA; 3) a NAO-negative like period shown in the model prior to the LIA, but that occurs most frequently in the data during the LIA. The results of the comparison show the improvement in simulated climate as various forcings are included and help to understand the atmospheric changes that are linked to the observed reconstructed climate changes.

Is regulated even-aged management the right strategy for the Canadian boreal forest?

2004 ◽  
Vol 80 (4) ◽  
pp. 458-462 ◽  
Author(s):  
Yves Bergeron
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Biological Diversity ◽  
Fire Regime ◽  
Age Distribution ◽  
Fire Frequency ◽  
Stand Age ◽  
Old Growth ◽  
Old Growth Forests ◽  
Canadian Boreal Forest

Over the past decade, there has been an increasing interest in the development of forest management approaches that are based on an understanding of historical natural disturbance dynamics. The rationale for such an approach is that management to favour landscape compositions and stand structures similar to those of natural ecosystems should also maintain biological diversity and essential ecological functions. In fire-dominated landscapes, this approach is possible only if current and future fire frequencies are sufficiently low, in comparison to pre-industrial fire frequency, that we can substitute fire with forest management. I address this question by comparing current and future fire frequency to historical reconstruction of fire frequency from studies in the Canadian boreal forest. Current and simulated future fire frequencies using 2× and 3×CO2 scenarios are lower than the historical fire frequency for most sites, suggesting that forest management could potentially be used to recreate the forest age structure of fire-controlled pre-industrial landscapes. Current even-aged management, however, tends to reduce forest variability: for example, fully regulated, even-aged management will tend to truncate the natural forest stand age distribution and eliminate overmature and old-growth forests from the landscape. The development of silvicultural techniques that maintain a spectrum of forest compositions and structures at different scales in the landscape is one avenue to maintain this variability. Key words: boreal forest, even aged management, fire regime, old-growth forests, climate change, partial cutting

scholarly journals Historical droughts in Mediterranean regions during the last 500 years: a data/model approach

2006 ◽  
Vol 2 (5) ◽  
pp. 771-800 ◽  
Author(s):  
S. Brewer ◽  
S. Alleaume ◽  
J. Guiot ◽  
A. Nicault
Keyword(s):  
Drought Stress ◽  
General Circulation ◽  
Distance Measure ◽  
Severity Index ◽  
General Circulation Models ◽  
Ice Age ◽  
Drought Severity ◽  
Atmospheric Circulation Patterns ◽  
Mediterranean Regions ◽  
Dry Conditions

Abstract. We present here a new method for comparing the output of General Circulation Models (GCMs) with proxy-based reconstructions, using time series of reconstructed and simulated climate parameters. The method uses k-means clustering to allow comparison between different periods that have similar spatial patterns, and a fuzzy logic-based distance measure in order to take reconstruction errors into account. The method has been used to test two coupled ocean-atmosphere GCMs over the Mediterranean region for the last 500 years, using an index of drought stress, the Palmer Drought Severity Index. The results showed that, whilst no model was able to exactly simulate the reconstructed changes, all simulations were an improvement over using the mean climate. Further, a good match was found after 1650 with a model run that took into account changes in volcanic forcing, solar irradiance, and greenhouse gases. A more detailed investigation of the output of this model showed the existence of a set of atmospheric circulation patterns linked to the patterns of drought stress: 1) a blocking pattern over northern Europe linked to dry conditions in the south prior to the Little Ice Age (LIA) and during the 20th century; 2) a NAO-positive like pattern with increased westerlies during the LIA; 3) a NAO-negative like period shown in the model prior to the LIA, but that occurs most frequently in the data during this period. The results of the comparison emphasise the importance of the inclusion of the various forcings in the models and help to understand the atmospheric changes connected to reconstructed climate changes.

Trends and periodicities in the Canadian Drought Code and their relationships with atmospheric circulation for the southern Canadian boreal forest

2004 ◽  
Vol 34 (1) ◽  
pp. 103-119 ◽  
Author(s):  
Martin-Philippe Girardin ◽  
Jacques Tardif ◽  
Mike D Flannigan ◽  
B Mike Wotton ◽  
Yves Bergeron
Keyword(s):  
Boreal Forest ◽  
Gulf Of Alaska ◽  
Drought Severity ◽  
Severe Drought ◽  
Summer Drought ◽  
Eastern Canada ◽  
The North ◽  
Circulation Patterns ◽  
Decadal Scale ◽  
Canadian Boreal Forest

Trends and periodicities in summer drought severity are investigated on a network of Canadian Drought Code (CDC) monthly average indices extending from central Quebec to western Manitoba and covering the instrumental period 1913–1998. The relationship and coherency between CDC indices and ocean–atmosphere circulation patterns are also examined. Trend analyses indicate that drought severity is unchanged in eastern and central Canada. Composite analyses indicate that for most of the corridor, severe drought seasons occur with a combination of positive 500-hPa geopotential height anomalies centered over the Gulf of Alaska and over the Baffin Bay. Additional severe drought seasons develop across the corridor in the presence of positive height anomalies located over or upstream of the affected regions. According to spectral analyses, the North Atlantic and the North Pacific circulation patterns modulate the drought variability at the decadal scale. Our results lead us to conclude that climate warming and the increases in the amount and frequency of precipitation in eastern Canada during the last century had no significant impact on summer drought severity. It is unlikely that linear climate change contributed to the change in the boreal forest dynamics observed over the past 150 years.

Using spatially explicit simulations to explore size distribution and spacing of regenerating areas produced by wildfires: recommendations for designing harvest agglomerations for the Canadian boreal forest

2007 ◽  
Vol 83 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Annie Belleau ◽  
Yves Bergeron ◽  
Alain Leduc ◽  
Sylvie Gauthier ◽  
Andrew Fall
Keyword(s):  
Forest Management ◽  
Boreal Forest ◽  
Size Distribution ◽  
Temporal Variability ◽  
Fire Regime ◽  
Natural Disturbance ◽  
Fire Regimes ◽  
Spatially Explicit ◽  
Fire Size ◽  
Canadian Boreal Forest

It is now recognized that in the Canadian boreal forest, timber harvesting activities have replaced wildfires as the main stand-replacing disturbance. Differences in landscape patterns derived from these two sources of disturbance have, however, raised concerns that the way forest harvesting has been dispersed is potentially shifting patterns away from the natural range. In the context of natural disturbance-based management, we used a spatially explicit model designed to capture general fire regimes in order to quantify temporal variability associated with regenerating areas (burnt areas of 25 years or younger), and to develop strategic objectives for harvest agglomeration sizes and dispersion. We first evaluated temporal variability in the proportion of stands younger than 100 years (assumed to be even-aged stands) for various fire regimes (seven fire cycles: 50 to 400 years, and three mean fires sizes: 3000, 15 000 and 60 000 ha). Secondly, we quantified the size distribution and dispersion of regenerating areas for each fire regime. As expected by theoretical fire frequencies and size distributions, the importance of even-aged stands at the forest management unit level was found to decrease with longer fire cycles. However, the temporal variability associated with these proportions is shown to increase with mean fire size. It was also observed that the size distribution and dispersion of regenerating areas was primarily influenced by mean fire size. Based on these observations, natural disturbance-based management objectives were formulated, providing guidelines on harvest agglomeration size and dispersion. Key words: temporal variability, boreal forest, fire regime, forest management, age distribution, fire size distribution, clearcut agglomeration size distribution

scholarly journals Unprecedented 21st century drought risk in the American Southwest and Central Plains

2015 ◽  
Vol 1 (1) ◽  
pp. e1400082 ◽  
Author(s):  
Benjamin I. Cook ◽  
Toby R. Ault ◽  
Jason E. Smerdon
Keyword(s):  
21St Century ◽  
General Circulation ◽  
General Circulation Models ◽  
American Southwest ◽  
Drought Severity ◽  
Historical Event ◽  
Drought Risk ◽  
Central Plains ◽  
Emissions Scenarios ◽  
Rcp 8.5

In the Southwest and Central Plains of Western North America, climate change is expected to increase drought severity in the coming decades. These regions nevertheless experienced extended Medieval-era droughts that were more persistent than any historical event, providing crucial targets in the paleoclimate record for benchmarking the severity of future drought risks. We use an empirical drought reconstruction and three soil moisture metrics from 17 state-of-the-art general circulation models to show that these models project significantly drier conditions in the later half of the 21st century compared to the 20th century and earlier paleoclimatic intervals. This desiccation is consistent across most of the models and moisture balance variables, indicating a coherent and robust drying response to warming despite the diversity of models and metrics analyzed. Notably, future drought risk will likely exceed even the driest centuries of the Medieval Climate Anomaly (1100–1300 CE) in both moderate (RCP 4.5) and high (RCP 8.5) future emissions scenarios, leading to unprecedented drought conditions during the last millennium.

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