Forest disturbance frequency and patch structure from pre-European settlement to present in the Mixed Forest Province of Minnesota, USA

2008 ◽  
Vol 38 (8) ◽  
pp. 2212-2226 ◽  
Author(s):  
M. A. White ◽  
G. E. Host
Keyword(s):  
Spatial Pattern ◽  
Tree Mortality ◽  
Management Practices ◽  
Forest Disturbance ◽  
Mixed Forest ◽  
Strong Relationship ◽  
Timber Harvest ◽  
Study Region ◽  
Disturbance Frequency ◽  
Disturbance Factor

We used General Land Office survey data (1860–1890) and interpreted aerial photography from the 1930s, 1970s, and 1990s to quantify forest disturbance frequency and spatial patterns for four time periods in the Mixed Forest Province of Minnesota. The study region included eight subsections within the Mixed Forest Province of Minnesota’s Ecological Classification System. Presettlement disturbance and spatial pattern estimates varied across the eight subsections indicating a strong relationship to soil and landform characteristics. Land surveyors primarily recorded higher severity disturbances that resulted in significant tree mortality. The 1900–1940 era was characterized by a short-term increase in fire frequency that was relatively uniform across the study region, in contrast to the variability of the presettlement (1860–1890) landscape. In the postsettlement period (1940–1995), timber harvest replaced fire as the dominant disturbance factor. Similar management practices among subsections created similar harvest rates throughout the study region. These management practices imposed a more homogeneous pattern dominated by small (10–25 ha) patches. Management practices now have a greater influence than natural processes in the generation of landscape pattern in the Mixed Forest Province of Minnesota. Information on presettlement forest conditions and subsequent changes can be used by land managers to restore spatial pattern variability in managed forest landscapes.

scholarly journals Over half of western United States' most abundant tree species in decline

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hunter Stanke ◽  
Andrew O. Finley ◽  
Grant M. Domke ◽  
Aaron S. Weed ◽  
David W. MacFarlane
Keyword(s):  
United States ◽  
Tree Species ◽  
Tree Mortality ◽  
Temperate Forests ◽  
Size Structure ◽  
Forest Disturbance ◽  
Population Decline ◽  
Western United States ◽  
Scale Transformation ◽  
Forest Composition

AbstractChanging forest disturbance regimes and climate are driving accelerated tree mortality across temperate forests. However, it remains unknown if elevated mortality has induced decline of tree populations and the ecological, economic, and social benefits they provide. Here, we develop a standardized forest demographic index and use it to quantify trends in tree population dynamics over the last two decades in the western United States. The rate and pattern of change we observe across species and tree size-distributions is alarming and often undesirable. We observe significant population decline in a majority of species examined, show decline was particularly severe, albeit size-dependent, among subalpine tree species, and provide evidence of widespread shifts in the size-structure of montane forests. Our findings offer a stark warning of changing forest composition and structure across the western US, and suggest that sustained anthropogenic and natural stress will likely result in broad-scale transformation of temperate forests globally.

scholarly journals Poleward migration of the destructive effects of tropical cyclones during the 20th century

2018 ◽  
Vol 115 (45) ◽  
pp. 11543-11548 ◽  
Author(s):  
Jan Altman ◽  
Olga N. Ukhvatkina ◽  
Alexander M. Omelko ◽  
Martin Macek ◽  
Tomas Plener ◽  
...  
Keyword(s):  
Forest Disturbance ◽  
Northeast Asia ◽  
Past Century ◽  
Disturbance Frequency ◽  
Proxy Records ◽  
Northern Latitudes ◽  
Term Variation ◽  
Instrumental Records

Determination of long-term tropical cyclone (TC) variability is of enormous importance to society; however, changes in TC activity are poorly understood owing to discrepancies among various datasets and limited span of instrumental records. While the increasing intensity and frequency of TCs have been previously documented on a long-term scale using various proxy records, determination of their poleward migration has been based mostly on short-term instrumental data. Here we present a unique tree-ring–based approach for determination of long-term variability in TC activity via forest disturbance rates in northeast Asia (33–45°N). Our results indicate significant long-term changes in TC activity, with increased rates of disturbances in the northern latitudes over the past century. The disturbance frequency was stable over time in the southern latitudes, however. Our findings of increasing disturbance frequency in the areas formerly situated at the edge of TC activity provide evidence supporting the broad relevance of poleward migration of TCs. Our results significantly enhance our understanding of the effects of climate change on TCs and emphasize the need for determination of long-term variation of past TC activity to improve future TC projections.

Short-term effects of timber harvest and forest edges on ground-layer mosses and liverworts

2005 ◽  
Vol 83 (6) ◽  
pp. 610-620 ◽  
Author(s):  
Cara R Nelson ◽  
Charles B Halpern
Keyword(s):  
Forest Management ◽  
Edge Effects ◽  
Management Practices ◽  
Timber Harvest ◽  
Ground Layer ◽  
Limited Information ◽  
Short Term ◽  
Before And After ◽  
Logging Effects ◽  
Structural Retention

Limited information exists on the effects of forest management practices on bryophytes, despite their importance to forest ecosystems. We examined short-term responses of ground-layer bryophytes to logging disturbance and creation of edges in mature Pseudotsuga forests of western Washington (USA). The abundance and richness of species were measured in four 1-ha forest aggregates (patches of intact forest) and in surrounding logged areas before and after structural retention harvests. One year after treatment, species richness, total cover, and frequency of most moss and liverwort taxa declined within harvest areas. Within forest aggregates, mosses did not show significant edge effects; however, richness and abundance of liverworts declined with proximity to the aggregate edge. Our results suggest that, over short time frames, 1-ha-sized aggregates are sufficient to maintain most common mosses through structural retention harvests but are not large enough to prevent declines or losses of liverworts. Thus, current standards for structural retention, which allow for aggregates as small as 0.2 ha, may be inadequate to retain the diversity and abundance of species found in mature, undisturbed forests.Key words: bryophyte, edge effects, forest borders, forest management, logging effects, structural retention harvest.

Integrating remote sensing and climate data with process-based models to map forest productivity within west-central Alberta's boreal forest: Ecoleap-West

2006 ◽  
Vol 82 (2) ◽  
pp. 159-176 ◽  
Author(s):  
R J Hall ◽  
F. Raulier ◽  
D T Price ◽  
E. Arsenault ◽  
P Y Bernier ◽  
...  
Keyword(s):  
Climate Change ◽  
Remote Sensing ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Management Practices ◽  
Forest Productivity ◽  
Process Models ◽  
Growth And Yield ◽  
Area Index ◽  
Study Region

Forest yield forecasting typically employs statistically derived growth and yield (G&Y) functions that will yield biased growth estimates if changes in climate seriously influence future site conditions. Significant climate warming anticipated for the Prairie Provinces may result in increased moisture deficits, reductions in average site productivity and changes to natural species composition. Process-based stand growth models that respond realistically to simulated changes in climate can be used to assess the potential impacts of climate change on forest productivity, and hence can provide information for adapting forest management practices. We present an application of such a model, StandLEAP, to estimate stand-level net primary productivity (NPP) within a 2700 km2 study region in western Alberta. StandLEAP requires satellite remote-sensing derived estimates of canopy light absorption or leaf area index, in addition to spatial data on climate, topography and soil physical characteristics. The model was applied to some 80 000 stand-level inventory polygons across the study region. The resulting estimates of NPP correlate well with timber productivity values based on stand-level site index (height in metres at 50 years). This agreement demonstrates the potential to make site-based G&Y estimates using process models and to further investigate possible effects of climate change on future timber supply. Key words: forest productivity, NPP, climate change, process-based model, StandLEAP, leaf area index, above-ground biomass

scholarly journals Spatial variability of mean daily estimates of actual evaporation from remotely sensed imagery and surface reference data

2019 ◽  
Vol 23 (12) ◽  
pp. 4891-4907 ◽  
Author(s):  
Robert N. Armstrong ◽  
John W. Pomeroy ◽  
Lawrence W. Martz
Keyword(s):  
Remote Sensing ◽  
Spatial Variability ◽  
Land Surface ◽  
Management Practices ◽  
Reference Data ◽  
Meteorological Data ◽  
Net Radiation ◽  
Study Region ◽  
Evaporation Model ◽  
Actual Evaporation

Abstract. Land surface evaporation has considerable spatial variability that is not captured by point-scale estimates calculated from meteorological data alone. Knowing how evaporation varies spatially remains an important issue for improving parameterisations of land surface schemes and hydrological models and various land management practices. Satellite-based and aerial remote sensing has been crucial for capturing moderate- to larger-scale surface variables to indirectly estimate evaporative fluxes. However, more recent advances for field research via unmanned aerial vehicles (UAVs) now allow for the acquisition of more highly detailed surface data. Integrating models that can estimate “actual” evaporation from higher-resolution imagery and surface reference data would be valuable to better examine potential impacts of local variations in evaporation on upscaled estimates. This study introduces a novel approach for computing a normalised ratiometric index from surface variables that can be used to obtain more-realistic distributed estimates of actual evaporation. For demonstration purposes the Granger–Gray evaporation model (Granger and Gray, 1989) was applied at a rolling prairie agricultural site in central Saskatchewan, Canada. Visible and thermal images and meteorological reference data required to parameterise the model were obtained at midday. Ratiometric indexes were computed for the key surface variables albedo and net radiation at midday. This allowed point observations of albedo and mean daily net radiation to be scaled across high-resolution images over a large study region. Albedo and net radiation estimates were within 5 %–10 % of measured values. A daily evaporation estimate for a grassed surface was 0.5 mm (23 %) larger than eddy covariance measurements. Spatial variations in key factors driving evaporation and their impacts on upscaled evaporation estimates are also discussed. The methods applied have two key advantages for estimating evaporation over previous remote-sensing approaches: (1) detailed daily estimates of actual evaporation can be directly obtained using a physically based evaporation model, and (2) analysis of more-detailed and more-reliable evaporation estimates may lead to improved methods for upscaling evaporative fluxes to larger areas.

scholarly journals Supplied Sediment Tracking for Bridge Collapse with Large-Scale Channel Migration

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1881
Author(s):  
Takuya Inoue ◽  
Jagriti Mishra ◽  
Kazuo Kato ◽  
Tamaki Sumner ◽  
Yasuyuki Shimizu
Keyword(s):  
Erosion Rate ◽  
Large Scale ◽  
Bank Erosion ◽  
Strong Relationship ◽  
Sediment Supply ◽  
Study Region ◽  
Flow Discharge ◽  
Bridge Abutment ◽  
Bridge Collapse ◽  
Flooding Events

Here, we provide a numerical model that assigns an identification number to trace sediments and also identify the source of sediment supply. We analyze the efficacy of our model by reproducing the reach-scale field observations from flooding events in 2010 and 2016 that affected Kyusen Bridge over the Bebetsu River, Hokkaido, Japan. Our simulation results can successfully reproduce and trace the formation of bars caused by sediment supply in the study region. Our study also suggests a strong relationship between bank erosion rate, sediment supply and flow-discharge. The bank erosion rate is higher when sediment supply increases, and bank erosion reduces as flow discharge goes down. The model can also replicate the changes in a bed concerning sediment supply and was used to reproduce the bridge-abutment failure caused by the 2016 flooding with large sediment supply and the bridge-pier failure caused by the 2010 flooding with less sediment supply.

scholarly journals Abundance and genetic diversity responses of a lizard (Eulamprus heatwolei) to logging disturbance

2017 ◽  
Vol 65 (6) ◽  
pp. 362
Author(s):  
Francesca Lyndon-Gee ◽  
Joanna Sumner ◽  
Yang Hu ◽  
Claudio Ciofi ◽  
Tim S. Jessop
Keyword(s):  
Genetic Diversity ◽  
Forest Management ◽  
Management Practices ◽  
Forest Disturbance ◽  
Population Level ◽  
Landscape Scale ◽  
Population Abundance ◽  
Animal Populations ◽  
Eastern Australia ◽  
Logging Disturbance

Rotational logging practices are used with the goal of reducing forest disturbance impacts on biodiversity. However, it is poorly understood whether such forest management practices conserve the demographic and genetic composition of animal populations across logged landscapes. Here we investigated whether rotational logging practices alter patterns of landscape-scale population abundance and genetic diversity of a forest-dwelling lizard (Eulamprus heatwolei) in south-eastern Australia. We sampled lizards (n = 407) at up to 48 sites across a chronosequence of logging disturbance intervals (<10 to >60 years after logging) to assess site-specific population changes and genetic diversity parameters. Lizard abundances exhibited a significant curvilinear response to time since logging, with decreased numbers following logging (<10 years), increased abundance as the forest regenerated (10–20 years), before decreasing again in older regenerated forest sites (>30 years). Lizard genetic diversity parameters were not significantly influenced by logging disturbance. These results suggest that logging practices, whilst inducing short-term changes to population abundance, had no measurable effects on the landscape-scale genetic diversity of E. heatwolei. These results are important as they demonstrate the value of monitoring for evaluating forest management efficacy, and the use of different population-level markers to make stronger inference about the potential impacts of logging activities.

scholarly journals Factors affecting post-fire regeneration after coppicing of cork oak (Quercus suber) trees in northeastern Algeria

2020 ◽  
Vol 50 (4) ◽  
pp. 371-379
Author(s):  
Salah Eddine Roula ◽  
Rachid T. Bouhraoua ◽  
Filipe X. Catry
Keyword(s):  
Tree Mortality ◽  
Management Practices ◽  
Negative Impact ◽  
Quercus Suber ◽  
Grazing Pressure ◽  
Cork Oak ◽  
Ecological Impacts ◽  
Factors Affecting ◽  
Growing Seasons ◽  
Oak Trees

Wildfires may have serious and long-lasting impacts in Mediterranean Basin oak forests. Although cork oak (Quercus suber L.) is usually considered a highly fire-resistant tree species, post-fire recovery is not guaranteed. We assessed the mortality and regeneration of 729 cork oak trees that burned and were cut in six sites with the objective of identifying the main factors affecting the short- to medium-term post-fire recovery. We used linear mixed models to investigate potential relationships among tree stump status at the end of the second and fifth growing seasons and several tree- and site-level variables. Overall tree mortality in the second year was 44% and was negatively affected by bark thickness and positively affected by root exposure, trunk injuries, and diameter, in decreasing order of importance. Between the second and fifth years, mortality increased to 53%, but this increase was only observed in sites with high grazing pressure. Grazing also had a strong negative impact on the growth of basal resprouts, thereby compromising tree recovery. The results give useful information on the need for application of adequate forest management practices (particularly avoiding debarking injuries, soil erosion, and grazing pressure) to increase the resilience of these ecosystems and reduce the negative economic and ecological impacts of wildfires.

Mixed method approaches to evaluate conservation impact: evidence from decentralized forest management in Tanzania

2014 ◽  
Vol 42 (2) ◽  
pp. 162-170 ◽  
Author(s):  
JENS FRIIS LUND ◽  
NEIL D. BURGESS ◽  
SHABANI A. O. CHAMSHAMA ◽  
KLAUS DONS ◽  
JACK A. ISANGO ◽  
...  
Keyword(s):  
Forest Management ◽  
Mixed Method ◽  
Management Practices ◽  
Forest Disturbance ◽  
Good Condition ◽  
Policy Outcomes ◽  
Landsat Images ◽  
Forest Condition ◽  
Before And After ◽  
Forest Use

SUMMARYNearly 10% of the world's total forest area is formally owned by communities and indigenous groups, yet knowledge of the effects of decentralized forest management approaches on conservation (and livelihood) impacts remains elusive. In this paper, the conservation impact of decentralized forest management on two forests in Tanzania was evaluated using a mixed method approach. Current forest condition, forest increment and forest use patterns were assessed through forest inventories, and changes in forest disturbance levels before and after the implementation of decentralized forest management were assessed on the basis of analyses of Landsat images. This biophysical evidence was then linked to changes in actual management practices, assessed through records, interviews and participatory observations, to provide a measure of the conservation impact of the policy change. Both forests in the study were found to be in good condition, and extraction was lower than overall forest increment. Divergent changes in forest disturbance levels were in evidence following the implementation of decentralized forest management. The evidence from records, interviews and participatory observations indicated that decentralized management had led to increased control of forest use and the observed divergence in forest disturbance levels appeared to be linked to differences in the way that village-level forest managers prioritized conservation objectives and forest-based livelihood strategies. The study illustrates that a mixed methods approach comprises a valid and promising way to evaluate impacts of conservation policies, even in the absence of control sites. By carefully linking policy outcomes to policy outputs, such an approach not only identifies whether such policies work as intended, but also potential mechanisms.

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