Temperate rainforest response to climate change and disturbance agents in northwestern Patagonia (41°S) over the last 2600 years

2012 ◽  
Vol 77 (2) ◽  
pp. 235-244 ◽  
Author(s):  
Ignacio A. Jara ◽  
Patricio I. Moreno
Keyword(s):  
Climate Change ◽  
Summer Drought ◽  
Vegetation Shifts ◽  
Disturbance Regimes ◽  
Composition And Structure ◽  
Cool Temperate ◽  
Dry Conditions ◽  
Primary Driver ◽  
Lowland Rainforest ◽  
Temperate Rainforests

We present detailed pollen and charcoal records from Lago Pichilafquén (~ 41°S) to decipher the effects of climate change and varying disturbance regimes on the composition and structure of the vegetation on the Andean foothills of northwestern Patagonia during the last 2600 yr. Here, temperate rainforests have dominated the landscape since 2600 cal yr BP with variations ranging from cool-temperate and wet north Patagonian rainforests to relatively warm and summer-drought-resistant Valdivian rainforests. We interpret relatively warm/dry conditions between 1900–2600, 690–750 and 320–430 cal yr BP, alternating with cold/wet conditions between 1500–1900, 750–1100 and 430–690 cal yr BP. Rapid deforestation and spread of plants introduced by Europeans occurred at 320 and 140 cal yr BP. The record includes five tephras with ages of 2130, 1460, 1310, 1210, and 340 cal yr BP, all of which precede local fire events and increases in trees favored by disturbance by less than 100 yr. We conclude that centennial-scale changes in the southern westerlies were the primary driver of vegetation shifts in northwestern Patagonia over the last 2600 yr. Within this interval, local disturbance regimes altered the structure, composition, and dynamics of the lowland rainforest vegetation during several discrete, short-lived episodes.

Spatial modelling of "alternative" future landscapes under climate change and fire suppression, Mont Do, New Caledonia

2003 ◽  
Vol 9 (4) ◽  
pp. 248
Author(s):  
George L. W. Perry ◽  
N. J. Enright
Keyword(s):  
Climate Change ◽  
New Caledonia ◽  
Fire Suppression ◽  
Fire Hazard ◽  
Fire Regimes ◽  
The South ◽  
West Pacific ◽  
Disturbance Regimes ◽  
South West ◽  
Composition And Structure

The vegetation dynamics and disturbance regimes of the south-west Pacific have been significantly altered following human settlement. Previously forested landscapes are now dominated by a matrix of flammable early successional vegetation within which patches of mesic, fire-sensitive forest are embedded. Future environmental change, and in particular climate change, will further affect disturbance regimes in these ecosystems. If ignition frequency and fire extent increase, then the persistence of these landscapes in their current composition and structure is uncertain. Using a spatially explicit landscape ecological model, we explored the implications of climatically altered fire regimes for landscape composition and structure in a mountain-top reserve in New Caledonia. The outcomes of the modeling suggest that increased ignition probability and vegetation flammability would lead to a maquis (heathland)-dominated landscape structurally simpler than that seen today. The feasibility of fire suppression as a means of managing altered fire regimes was explored using a series of model experiments. Fire suppression has been problematic in some systems, especially those where fire hazard increases over time. However, in this ecosystem, and others in the south-west Pacific, it may be a viable alternative for managing fire because fire hazard, in terms of flammability, peaks early in the succession and then decreases over successional time.

scholarly journals Oxythermal habitat as a primary driver of ecological niche and genetic diversity in cisco (Coregonus artedi)

2021 ◽  
Author(s):  
Ryan C Grow ◽  
Kyle D Zimmer ◽  
Jennifer L Cruise ◽  
Simon K Emms ◽  
Loren M Miller ◽  
...  
Keyword(s):  
Climate Change ◽  
Genetic Diversity ◽  
Dissolved Oxygen ◽  
Cold Water ◽  
Global Scale ◽  
Isotopic Niche ◽  
Coregonus Artedi ◽  
Primary Driver ◽  
Water Species ◽  
Cold Water Species

Cisco (Coregonus artedi) are threatened by climate change and lake eutrophication, and their oxythermal habitat can be assessed with TDO3, the water temperature at which dissolved oxygen equals 3 mg L-1. We assessed the influence of TDO3 on cisco habitat use, genetic diversity, diets, and isotopic niche in 32 lakes ranging from oligotrophic to eutrophic. Results showed that as TDO3 increased cisco were captured higher in the water column, in a narrower band, with higher minimum temperatures and lower minimum dissolved oxygen. TDO3 was also negatively related to cisco allelic richness and expected heterozygosity, likely driven by summer kill events. Moreover, TDO3 influenced the isotopic niche of cisco, as fish captured deeper were more depleted in δ13C and more enriched in δ15N compared to epilimnetic baselines. Lastly, cisco in high TDO3 lakes consumed more Daphnia, had fewer empty stomachs, and achieved larger body size. Our work identifies specific characteristics of cisco populations that respond to climate change and eutrophication effects, and provides a framework for understanding responses of other cold-water species at the global scale.

Effect of climate change, drought, and insects on oak-pine forests in the Ozark highlands

2020 ◽  
Author(s):  
◽  
Shengwu Duan
Keyword(s):  
Climate Change ◽  
Forest Growth ◽  
Pine Forests ◽  
Spatial And Temporal Variation ◽  
Oak Forests ◽  
Drought Effect ◽  
Ozark Highlands ◽  
Disturbance Regimes ◽  
Warming Climate ◽  
The Impact

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI--COLUMBIA AT REQUEST OF AUTHOR.] Oak-dominated forests in the Ozarks Highlands of Arkansas and Missouri have been suffering severe oak decline and this became a chronic problem since the late 1970s. Such decline became increasingly severe as numerous dense oak forests in this region approaching physiological maturity. Repeated droughts and insect outbreaks in the Ozarks Highlands from 1998 to 2015 accelerate the decline process and resulted in increased mortality of the oaks, particularly those in red oak group. Given these concerns, the overall objective of this dissertation was to conduct a regional scale assessment to evaluate and predict the impact of drought and insects on the oak forests under changing climate. This dissertation contained three main objectives: 1) to evaluate the drought effect on forest growth phenology and productivity by using spatially-explicit drought indices and land surface phenology techniques to capture oak, pine and mixed oak-pine forests' responses to repeated droughts; 2) to develop a climate sensitive biotic disturbance agent (BDA) module in forest landscape modeling framework to quantify the relative importance in determining the insect disturbance regimes under the warming climate; and 3) to predict the effects of insect disturbance, climate change and their interactions on forest composition under alternative climate and insect disturbance scenarios. The dissertation provided a methodology to disassemble the spatial and temporal variation of drought conditions in the Ozark Highlands and provided new insights into improving drought resistance and recovery capacity of forests with different species under climate change. The results from this dissertation also helped to understand the importance of vegetation feedback in predicting inset disturbance regimes under a warming climate as they may mediate or even reverse the expectation of increased insect disturbance in this region. In addition, the projections of how tree species will response to insect disturbance will benefit decision making in silvicultural prescriptions and longterm management plans in the Ozark Highlands.

scholarly journals Potential Arctic tundra vegetation shifts in response to changing temperature, precipitation and permafrost thaw

2016 ◽  
Vol 13 (22) ◽  
pp. 6229-6245 ◽  
Author(s):  
Henk-Jan van der Kolk ◽  
Monique M. P. D. Heijmans ◽  
Jacobus van Huissteden ◽  
Jeroen W. M. Pullens ◽  
Frank Berendse
Keyword(s):  
Climate Change ◽  
The Arctic ◽  
Soil Conditions ◽  
Climate Change Scenarios ◽  
Vegetation Shifts ◽  
Permafrost Thaw ◽  
Temperature And Precipitation ◽  
Tundra Vegetation ◽  
Tundra Ecosystem ◽  
Wide Range

Abstract. Over the past decades, vegetation and climate have changed significantly in the Arctic. Deciduous shrub cover is often assumed to expand in tundra landscapes, but more frequent abrupt permafrost thaw resulting in formation of thaw ponds could lead to vegetation shifts towards graminoid-dominated wetland. Which factors drive vegetation changes in the tundra ecosystem are still not sufficiently clear. In this study, the dynamic tundra vegetation model, NUCOM-tundra (NUtrient and COMpetition), was used to evaluate the consequences of climate change scenarios of warming and increasing precipitation for future tundra vegetation change. The model includes three plant functional types (moss, graminoids and shrubs), carbon and nitrogen cycling, water and permafrost dynamics and a simple thaw pond module. Climate scenario simulations were performed for 16 combinations of temperature and precipitation increases in five vegetation types representing a gradient from dry shrub-dominated to moist mixed and wet graminoid-dominated sites. Vegetation composition dynamics in currently mixed vegetation sites were dependent on both temperature and precipitation changes, with warming favouring shrub dominance and increased precipitation favouring graminoid abundance. Climate change simulations based on greenhouse gas emission scenarios in which temperature and precipitation increases were combined showed increases in biomass of both graminoids and shrubs, with graminoids increasing in abundance. The simulations suggest that shrub growth can be limited by very wet soil conditions and low nutrient supply, whereas graminoids have the advantage of being able to grow in a wide range of soil moisture conditions and have access to nutrients in deeper soil layers. Abrupt permafrost thaw initiating thaw pond formation led to complete domination of graminoids. However, due to increased drainage, shrubs could profit from such changes in adjacent areas. Both climate and thaw pond formation simulations suggest that a wetter tundra can be responsible for local shrub decline instead of shrub expansion.

scholarly journals Water scaling of ecosystem carbon cycle feedback to climate warming

2019 ◽  
Vol 5 (8) ◽  
pp. eaav1131 ◽  
Author(s):  
Quan Quan ◽  
Dashuan Tian ◽  
Yiqi Luo ◽  
Fangyue Zhang ◽  
Tom W. Crowther ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Water Availability ◽  
Field Experiments ◽  
Climate Feedback ◽  
Carbon Uptake ◽  
Scaling Effects ◽  
Ecosystem Carbon ◽  
Improve Model ◽  
Dry Conditions

It has been well established by field experiments that warming stimulates either net ecosystem carbon uptake or release, leading to negative or positive carbon cycle–climate change feedback, respectively. This variation in carbon-climate feedback has been partially attributed to water availability. However, it remains unclear under what conditions water availability enhances or weakens carbon-climate feedback or even changes its direction. Combining a field experiment with a global synthesis, we show that warming stimulates net carbon uptake (negative feedback) under wet conditions, but depresses it (positive feedback) under very dry conditions. This switch in carbon-climate feedback direction arises mainly from scaling effects of warming-induced decreases in soil water content on net ecosystem productivity. This water scaling of warming effects offers generalizable mechanisms not only to help explain varying magnitudes and directions of observed carbon-climate feedback but also to improve model prediction of ecosystem carbon dynamics in response to climate change.

scholarly journals Long-term effects of elevated CO2, nighttime warming and drought on plant secondary metabolites in a temperate heath ecosystem

2020 ◽  
Vol 125 (7) ◽  
pp. 1065-1075
Author(s):  
Tao Li ◽  
Päivi Tiiva ◽  
Åsmund Rinnan ◽  
Riitta Julkunen-Tiitto ◽  
Anders Michelsen ◽  
...  
Keyword(s):  
Climate Change ◽  
Secondary Metabolites ◽  
Elevated Co2 ◽  
Chemical Constituents ◽  
Plant Secondary Metabolites ◽  
Plant Secondary Metabolite ◽  
Summer Drought ◽  
Voc Emissions ◽  
Nighttime Warming ◽  
Change Components

Abstract Background and Aims Plant secondary metabolites play critical roles in plant stress tolerance and adaptation, and are known to be influenced by the environment and climate changes, yet the impacts and interactions of multiple climate change components are poorly understood, particularly under natural conditions. Methods Accumulation of phenolics and emissions of volatile organic compounds (VOCs) were assessed on heather, Calluna vulgaris, an abundant evergreen dwarf shrub in European heathlands, after 6 years of exposure to elevated CO2, summer drought and nighttime warming. Key Results Drought alone had the strongest effects on phenolic concentrations and compositions, with moderate effects of elevated CO2 and temperature. Elevated CO2 exerted the greatest impact on VOC emissions, mainly by increasing monoterpene emissions. The response magnitudes varied among plant tissue types and chemical constituents, and across time. With respect to interactive effects of the studied climate change components, the interaction between drought and elevated CO2 was most apparent. Drought mainly reduced phenolic accumulation and VOC emissions, while elevated CO2 mitigated such effects. Conclusions In natural ecosystems, co-occurring climate factors can exert complex impacts on plant secondary metabolite profiles, which may in turn alter ecosystem processes.

scholarly journals Precipitation and Temperature in Costa Rica at the End of the Century Based on NEX-GDDP Projected Scenarios

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1323
Author(s):  
Rodrigo Castillo ◽  
Jorge A. Amador
Keyword(s):  
Climate Change ◽  
Costa Rica ◽  
Regional Climate ◽  
Climate Change Impacts ◽  
Summer Drought ◽  
Climate Change Scenarios ◽  
Economic Activities ◽  
Temperature Range ◽  
Past Data ◽  
Precipitation And Temperature

The evaluation of intraseasonal, seasonal, and annual variability of rainfall and temperature extremes, while using climate change scenarios data, is extremely important for socio-economic activities, such as water resources management. Costa Rica, a climate change hotspot, is largely dependent on rainfall for socioeconomic activities; hence, the relevance of this study. Based on the NEX-GDDP, rainfall and temperature range were analyzed for Costa Rica at the end of the century (2070–2099), while using 1970–1999 as a baseline for six available meteorological stations. Differences between the multimodel ensembles of two prospective scenarios (RCP 4.5 and 8.5) and the historical information were computed. This study highlights Costa Rica as an inflexion region for climate change impacts in Central America, for which projected scenarios suggest an early onset of the rainy season, and a decline in the mid-summer drought (MSD) minimum. The assessment of model data in some regions of Costa Rica, for which historical data were available, suggests that the latter does not capture a well-known regional climate feature, the MSD, in both precipitation and temperature range well. The availability of observed past data sources is a major limitation of this research; however, with the station data used, it is still possible to draw some conclusions regarding future climate in some regions of Costa Rica, especially in the northwest side of the country, where past data are consistent with model information, providing a more reliable picture of changes in climate there that has potential implications for socioeconomic sectors.

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