Marine heatwaves in the dynamics of the Pantanal´s historical drought and unprecedented fires

2021 ◽  
Author(s):  
Dirk Thielen ◽  
Paolo Ramoni-Perazzi ◽  
Marco Marquez ◽  
José I. Quintero ◽  
Wilmer Rojas ◽  
...  
Keyword(s):  
Climate Change ◽  
Northern Hemisphere ◽  
Temporal Dynamics ◽  
Fire Regime ◽  
Natural Disturbance ◽  
Extreme Drought ◽  
Northeast Pacific ◽  
Paraguay River ◽  
Floodplain Inundation ◽  
Precipitation Anomalies

<p>Fire is a natural disturbance in the Neotropical savannas, and rather frequent in the relatively<br>dry and well-drained seasonal savannas of the Brazilian Cerrado. The neighboring Pantanal, on<br>the other hand, is a seasonally flooded savanna and the largest wetland in the world (≈138,000<br>km 2 ). Due to its wetter condition, fires in the Pantanal are much less frequent and spatially<br>restricted. But, given an ongoing extreme drought, the 2020’s fires in the Pantanal have been<br>unprecedented in extent and duration: About one third (≈45,000 km 2 ) of the area of this<br>important wetland has gone up in flames since last January. Regarding this historical drought,<br>climate change has been identified as one of the most important threats to the Pantanal.<br>Reductions in precipitation may cause significant disturbances in its ecological functioning,<br>affecting hydrological, floodplain inundation dynamics, as well as fire regime. Climate change<br>models from a recent study (Thielen et al. 2020, doi:10.1371/journal.pone.0227437) indicate<br>that, for the Pantanal, extended severe droughts are to be expected from the warming of Sea<br>Surface Temperatures (SST) at Northern Hemisphere oceans.<br>The present study analyses the spatial and temporal dynamics of precipitations during the<br>series 1981-2020 in the Upper Paraguay River Basin (UPRB), which comprises the Pantanal and<br>the neighboring Highlands, along with a co-evaluation of the SST trends at three oceanic<br>regions from Northern Hemisphere. Precipitation anomalies were analyzed by mean of the<br>Standardized Precipitation Drought Index (SPDI) based on the 1981-2010 climate normals.<br>Results show that for the UPRB, negative precipitation anomalies occur in pulses lasting<br>several years. A drought starting in 2019 has been the strongest and most extended on record,<br>persistently reaching the Extremely Dry condition (SPDI≤-2.0) during 2020. As early as Mar,<br>over 64% of the Pantanal is affected by such drought, and around 83% by Dec. For the UPRB,<br>four distinctive groups of subregions were identified according to their temporal dynamics of<br>mean SPDI values, mainly during Sep2019/Feb2020 and Mar2020/Dec2020. Here, precipitation<br>anomalies from southernmost subregions of the Pantanal were less intense and even not<br>affected by the drought.<br>As for SST, the Northeast Pacific region (PAC-NE) showed the most important dynamics. In this<br>region, SSTs have been anomalously warm since Jun 2019, with 64% of the time SSTA<br>surpassing the 90 th percentile: reaching the Heatwave condition. With a lead of one to two<br>months, PAC-NE showed the strongest (and negative) correlation with precipitation at UPRB<br>(r=-0.87) during Jan2019 to Dec2020. There is a significant trend for an increase in SST at the</p><p>Northeast Pacific, a trend that will certainly generate a rather continuous Heatwave in PAC-NE.<br>As a result, one expects an extension of the current extreme drought in the Pantanal area, at<br>least during 2021, and the intensification of fires with unprecedented duration and intensity,<br>extending now to areas historically flooded or perhumid. Concomitantly, we predict a most<br>definite impact on non-fire-resistant vegetation cover, as well as ecosystem functioning and<br>biodiversity.</p>

How fire and climate shaped grass-dominated vegetation and forest mosaics in northern South Africa during past millennia

The Holocene ◽  
2011 ◽  
Vol 22 (12) ◽  
pp. 1427-1439 ◽  
Author(s):  
Elinor Breman ◽  
Lindsey Gillson ◽  
Kathy Willis
Keyword(s):  
Climate Change ◽  
South Africa ◽  
Anthropogenic Impact ◽  
Temporal Dynamics ◽  
Fire Regime ◽  
Anthropogenic Activities ◽  
Stable State ◽  
Future Climate Change ◽  
Lower Altitude ◽  
Stress Changes

Grassland and savanna are globally important ecosystems, both ecologically and economically. These grass-dominated systems are at risk from current and future climate change and increasing anthropogenic impact. Key questions for understanding the resilience and variability of grass-dominated ecosystems under current and future environmental conditions include: How have these systems responded to climate change and disturbance in the past? What are the principal driving agents responsible for their present-day composition and distribution? Do the palaeoecological data provide evidence for feedbacks between climate, fire and anthropogenic activities? In this study, the temporal dynamics of grassland, savanna and forest in the summer rainfall region of northern South Africa were reconstructed for the last ~6500 years. Palaeoecological techniques used include analyses of fossil pollen, charcoal and stable isotopes. Data from two sites located at the present-day grassland-savanna ecotone in Mpumalanga province of South Africa are reported. Results indicate that a mosaic of grassland, savanna and Podocarpus forest occupied the landscape throughout the late Holocene, with grassland and forest dominating higher altitudes, and savanna and forest lower altitudes. Podocarpus forest retreated and grass-dominated vegetation expanded its range around 1800 cal. yr BP at the lower altitude site (Lowveld) and 600 cal. yr BP at the higher altitude site (Highveld), representing a change from a stable state forest savanna/grassland mosaic to an increasingly grass-dominated system. Climatic stress, changes in fire regime and anthropogenic impact led to the vegetation transitions recorded, and resulted in changes in water and nutrient cycles. In an increasingly warm world, with fluctuating water availability and heightened anthropogenic use of natural resources, the future of grass-dominated ecosystems appears far from stable.

scholarly journals Climate change alters temporal dynamics of alpine soil microbial functioning and biogeochemical cycling via earlier snowmelt

2021 ◽  
Author(s):  
Arthur A. D. Broadbent ◽  
Helen S. K. Snell ◽  
Antonios Michas ◽  
William J. Pritchard ◽  
Lindsay Newbold ◽  
...  
Keyword(s):  
Climate Change ◽  
Temporal Dynamics ◽  
Biogeochemical Cycling ◽  
Soil Microbial ◽  
Alpine Soil

scholarly journals Simulating the Effects of Intensifying Silviculture on Desired Species Yields across a Broad Environmental Gradient

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 755
Author(s):  
Eric B. Searle ◽  
F. Wayne Bell ◽  
Guy R. Larocque ◽  
Mathieu Fortin ◽  
Jennifer Dacosta ◽  
...  
Keyword(s):  
Climate Change ◽  
Forest Management ◽  
Planning Process ◽  
Mechanistic Model ◽  
Natural Disturbance ◽  
Fine Tuning ◽  
Mechanistic Models ◽  
Paradigm Shifts ◽  
Ecological Processes ◽  
Forest Modelling

In the past two decades, forest management has undergone major paradigm shifts that are challenging the current forest modelling architecture. New silvicultural systems, guidelines for natural disturbance emulation, a desire to enhance structural complexity, major advances in successional theory, and climate change have all highlighted the limitations of current empirical models in covering this range of conditions. Mechanistic models, which focus on modelling underlying ecological processes rather than specific forest conditions, have the potential to meet these new paradigm shifts in a consistent framework, thereby streamlining the planning process. Here we use the NEBIE (a silvicultural intervention scale that classifies management intensities as natural, extensive, basic, intensive, and elite) plot network, from across Ontario, Canada, to examine the applicability of a mechanistic model, ZELIG-CFS (a version of the ZELIG tree growth model developed by the Canadian Forest Service), to simulate yields and species compositions. As silvicultural intensity increased, overall yield generally increased. Species compositions met the desired outcomes when specific silvicultural treatments were implemented and otherwise generally moved from more shade-intolerant to more shade-tolerant species through time. Our results indicated that a mechanistic model can simulate complex stands across a range of forest types and silvicultural systems while accounting for climate change. Finally, we highlight the need to improve the modelling of regeneration processes in ZELIG-CFS to better represent regeneration dynamics in plantations. While fine-tuning is needed, mechanistic models present an option to incorporate adaptive complexity into modelling forest management outcomes.

scholarly journals Impact of Extreme Drought Climate on Water Security in North Borneo: Case Study of Sabah

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1135
Author(s):  
Carolyn Payus ◽  
Lim Ann Huey ◽  
Farrah Adnan ◽  
Andi Besse Rimba ◽  
Geetha Mohan ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Resource ◽  
Supply And Demand ◽  
Water Security ◽  
Water Levels ◽  
Extreme Drought ◽  
Northeast Monsoon ◽  
Water Insecurity ◽  
The North ◽  
North Borneo

For countries in Southeast Asia that mainly rely on surface water as their water resource, changes in weather patterns and hydrological systems due to climate change will cause severely decreased water resource availability. Warm weather triggers more water use and exacerbates the extraction of water resources, which will change the operation patterns of water usage and increase demand, resulting in water scarcity. The occurrence of prolonged drought upsets the balance between water supply and demand, significantly increasing the vulnerability of regions to damaging impacts. The objectives of this study are to identify trends and determine the impacts of extreme drought events on water levels for the major important water dams in the northern part of Borneo, and to assess the risk of water insecurity for the dams. In this context, remote sensing images are used to determine the degree of risk of water insecurity in the regions. Statistical methods are used in the analysis of daily water levels and rainfall data. The findings show that water levels in dams on the North and Northeast Coasts of Borneo are greatly affected by the extreme drought climate caused by the Northeast Monsoon, with mild to the high risk recorded in terms of water insecurity, with only two of the water dams being water-secure. This study shows how climate change has affected water availability throughout the regions.

Fire regime impacts on post-fire diurnal land surface temperature change over North American boreal forest

2021 ◽  
Author(s):  
Jie Zhao ◽  
Chao Yue ◽  
Philippe Ciais ◽  
Xin Hou ◽  
Qi Tian
Keyword(s):  
Climate Change ◽  
Regression Analysis ◽  
Land Surface ◽  
Fire Regime ◽  
Fire Severity ◽  
Linear Regression Analysis ◽  
Fire Regimes ◽  
Fire Intensity ◽  
Surface Temperature Change ◽  
One Year

<p>Wildfire is the most prevalent natural disturbance in the North American boreal (BNA) forest and can cause post-fire land surface temperature change (ΔLST<sub>fire</sub>) through biophysical processes. Fire regimes, such as fire severity, fire intensity and percentage of burned area (PBA), might affect ΔLST<sub>fire</sub> through their impacts on post-fire vegetation damage. However, the difference of the influence of different fire regimes on the ΔLST<sub>fire</sub> has not been quantified in previous studies, despite ongoing and projected changes in fire regimes in BNA in association with climate change. Here we employed satellite observations and a space-and-time approach to investigate diurnal ΔLST<sub>fire</sub> one year after fire across BNA. We further examined potential impacts of three fire regimes (i.e., fire intensity, fire severity and PBA) and latitude on ΔLST<sub>fire</sub> by simple linear regression analysis and multiple linear regression analysis in a stepwise manner. Our results demonstrated pronounced asymmetry in diurnal ΔLST<sub>fire</sub>, characterized by daytime warming in contrast to nighttime cooling over most BNA. Such diurnal ΔLST<sub>fire</sub> also exhibits a clear latitudinal pattern, with stronger daytime warming and nighttime cooling one year after fire in lower latitudes, whereas in high latitudes fire effects are almost neutral. Among the fire regimes, fire severity accounted for the most (43.65%) of the variation of daytime ΔLST<sub>fire</sub>, followed by PBA (11.6%) and fire intensity (8.5%). The latitude is an important factor affecting the influence of fire regimes on daytime ΔLST<sub>fire</sub>. The sensitivity of fire intensity and PBA impact on daytime ΔLST<sub>fire</sub> decreases with latitude. But only fire severity had a significant effect on nighttime ΔLST<sub>fire</sub> among three fire regimes. Our results highlight important fire regime impacts on daytime ΔLST<sub>fire</sub>, which might play a critical role in catalyzing future boreal climate change through positive feedbacks between fire regime and post-fire surface warming.</p>

Five new deep-sea species of nudibranchs (Gastropoda: Heterobranchia: Cladobranchia) from the Northeast Pacific

Zootaxa ◽  
2018 ◽  
Vol 4526 (4) ◽  
pp. 401 ◽  
Author(s):  
ÁNGEL VALDÉS ◽  
LONNY LUNDSTEN ◽  
NERIDA G. WILSON
Keyword(s):  
Climate Change ◽  
New Species ◽  
Deep Sea ◽  
Undescribed Species ◽  
Invertebrate Community ◽  
Nuclear Markers ◽  
Mitochondrial Coi ◽  
Northeast Pacific ◽  
Northeastern Pacific ◽  
System Information

Increased exploration of northeastern Pacific deep-sea habitats has revealed a diverse and often poorly-known invertebrate community, including a number of undescribed species of nudibranchs studied herein. We used morphology to distinguish several new species from their congeners, and generated data where possible for mitochondrial (COI, 16S) and nuclear markers (H3) to place them in a phylogenetic context. We described here Tritonia nigritigris sp. nov., Dendronotus claguei sp. nov., Ziminella vrijenhoeki sp. nov., Cuthona methana sp. nov., Aeolidia libitinaria sp. nov. and redescribed Zeusia herculea (Bergh, 1894). Another species of Tritonia is described but not named due to the absence of reproductive system information. Although there are difficulties in collection from deep-sea habitats, only two of our new species are known from single specimens. As with many other deep-sea regions, we expect the number of new species from this region to increase with further exploration. Because the deep regions of the northeast Pacific are particularly vulnerable to the effects of decreasing oxygenation due to climate change, we consider that documenting this fauna has some level of urgency. 

The role of short-term weather conditions in temporal dynamics of fire regime features in mainland Spain

2019 ◽  
Vol 241 ◽  
pp. 575-586 ◽  
Author(s):  
Adrián Jiménez-Ruano ◽  
Marcos Rodrigues Mimbrero ◽  
W. Matt Jolly ◽  
Juan de la Riva Fernández
Keyword(s):  
Temporal Dynamics ◽  
Fire Regime ◽  
Weather Conditions ◽  
Short Term

Is the END (emulation of natural disturbance) a new beginning? A critical analysis of the use of fire regimes as the basis of forest ecosystem management with examples from the Canadian western Cordillera

2016 ◽  
Vol 24 (3) ◽  
pp. 233-243 ◽  
Author(s):  
Chris Stockdale ◽  
Mike Flannigan ◽  
Ellen Macdonald
Keyword(s):  
Forest Management ◽  
Ecosystem Management ◽  
Forest Structure ◽  
Fire Regime ◽  
Natural Disturbance ◽  
Fire Regimes ◽  
Disturbance Regime ◽  
Ecological Processes ◽  
High Severity ◽  
Management Actions

As our view of disturbances such as wildfire has shifted from prevention to recognizing their ecological necessity, so too forest management has evolved from timber-focused even-aged management to more holistic paradigms like ecosystem-based management. Emulation of natural disturbance (END) is a variant of ecosystem management that recognizes the importance of disturbance for maintaining ecological integrity. For END to be a successful model for forest management we need to describe disturbance regimes and implement management actions that emulate them, in turn achieving our objectives for forest structure and function. We review the different components of fire regimes (cause, frequency, extent, timing, and magnitude), we describe low-, mixed-, and high-severity fire regimes, and we discuss key issues related to describing these regimes. When characterizing fire regimes, different methods and spatial and temporal extents result in wide variation of estimates for different fire regime components. Comparing studies is difficult as few measure the same components; some methods are based on the assumption of a high-severity fire regime and are not suited to detecting mixed- or low-severity regimes, which are critical to END management, as this would affect retention in harvested areas. We outline some difficulties with using fire regimes as coarse filters for forest management, including (i) not fully understanding the interactions between fire and other disturbance agents, (ii) assuming that fire is strictly an exogenous disturbance agent that exerts top-down control of forest structure while ignoring numerous endogenous and bottom-up feedbacks on fire effects, and (iii) assuming by only replicating natural disturbance patterns we preserve ecological processes and vital ecosystem components. Even with a good understanding of a fire regime, we would still be challenged with choosing the temporal and spatial scope for the disturbance regime we are trying to emulate. We cannot yet define forest conditions that will arise from variations in disturbance regime; this then limits our ability to implement management actions that will achieve those conditions. We end by highlighting some important knowledge gaps about fire regimes and how the END model could be strengthened to achieve a more sustainable form of forest management.

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