Nonlinear dynamics in ecosystem response to climatic change: Case studies and policy implications (original) (raw)
Related papers
2005
Many biological, hydrological, and geological processes are interactively linked in ecosystems. These ecological phenomena normally vary within bounded ranges, but rapid, nonlinear changes to markedly different conditions can be triggered by even small differences if threshold values are exceeded. Intrinsic and extrinsic ecological thresholds can lead to effects that cascade among systems, precluding accurate modeling and prediction of system response to climate change. Ten case studies from North America illustrate how changes in climate can lead to rapid, threshold-type responses within ecological communities; the case studies also highlight the role of human activities that alter the rate or direction of system response to climate change. Understanding and anticipating nonlinear dynamics are important aspects of adaptation planning since responses of biological resources to changes in the physical climate system are not necessarily proportional and sometimes, as in the case of co...
Ecological Applications, 2008
It is commonly acknowledged that ecosystem responses to global climate change are nonlinear. However, patterns of the nonlinearity have not been well characterized on ecosystem carbon and water processes. We used a terrestrial ecosystem (TECO) model to examine nonlinear patterns of ecosystem responses to changes in temperature, CO 2 , and precipitation individually or in combination. The TECO model was calibrated against experimental data obtained from a grassland ecosystem in the central United States and ran for 100 years with gradual change at 252 different scenarios. We primarily used the 100th-year results to explore nonlinearity of ecosystem responses. Variables examined in this study are net primary production (NPP), heterotrophic respiration (R h ), net ecosystem carbon exchange (NEE), runoff, and evapotranspiration (ET). Our modeling results show that nonlinear patterns were parabolic, asymptotic, and threshold-like in response to temperature, CO 2 , and precipitation anomalies, respectively, for NPP, NEE, and R h . Runoff and ET exhibited threshold-like pattern in response to both temperature and precipitation anomalies but were less sensitive to CO 2 changes. Ecosystem responses to combined temperature, CO 2 , and precipitation anomalies differed considerably from the responses to individual factors in terms of response patterns and/or critical points of nonlinearity. Our results suggest that nonlinear patterns in response to multiple global-change factors were diverse and were considerably affected by combined climate anomalies on ecosystem carbon and water processes. The diverse response patterns in nonlinearity have profound implications for both experimental design and theoretical development.
Biology letters, 2012
Most studies that forecast the ecological consequences of climate change target a single species and a single life stage. Depending on climatic impacts on other life stages and on interacting species, however, the results from simple experiments may not translate into accurate predictions of future ecological change. Research needs to move beyond simple experimental studies and environmental envelope projections for single species towards identifying where ecosystem change is likely to occur and the drivers for this change. For this to happen, we advocate research directions that (i) identify the critical species within the target ecosystem, and the life stage(s) most susceptible to changing conditions and (ii) the key interactions between these species and components of their broader ecosystem. A combined approach using macroecology, experimentally derived data and modelling that incorporates energy budgets in life cycle models may identify critical abiotic conditions that disproportionately alter important ecological processes under forecasted climates.
The impacts of climate change on ecosystem structure and function
Frontiers in Ecology and the Environment, 2013
C limate fundamentally controls the distribution of ecosystems, species ranges, and process rates on Earth. As a component of the US National Climate Assessment, to be released in 2014, a group of over 60 ecological experts from academic, governmental, and nongovernmental organizations assessed the state of knowledge about how climate change has affected and will affect species, biodiversity, and ecosystem structure, function, and services in the US. Here, we summarize key findings on the impacts of climate change on ecosystems, focusing on the fluxes of matter and energy and the biotic and abiotic parts of ecosystems that contribute most to those fluxes. Ecosystem patterns and processes, such as rates of primary productivity or input-output balance of chemical elements, respond in complex ways to climate change because of multiple controlling factors. For example, whether a forest is a carbon (C) source or sink depends on the balance of primary production and ecosystem respiration, processes that respond to different drivers. Physical changes in ecosystems-for instance, changes in thermal stratification patterns in lakes and oceans, flood and drying regimes in streams and rivers, or intensification of the hydrologic cycle across large basinslead to changes in ecosystem structure and function that have economic and human consequences. Often the extremes or changes in timing have greater impact than changes in average conditions and incur greater societal impacts and costs. Recognizing these issues, climate-change action plans and management strategies have begun to account for forecasted changes in extremes or seasonality. n Seven key impacts Although climate change is affecting US ecosystems in numerous ways, seven findings emerged from our assessment as representing the most critical climate-change impacts on ecosystem structure and function in the US, supported by compelling evidence from the past 4 years (Figure 1). Only a few of the important references can be cited in this article due to space limitations, and we refer US CLIMATE-CHANGE IMPACTS