Climate Variability and Ecosystem Response at the H. J. Andrews Long-Term Ecological Research Site

Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites ◽

10.1093/oso/9780195150599.003.0037 ◽

2003 ◽

Author(s):

David Greenland ◽

Frederick Bierlmaier

Keyword(s):

Climate Variability ◽

Pacific Northwest ◽

Ecological Research ◽

Ecosystem Response ◽

Red Cedar ◽

The Pacific ◽

Long Term Ecological Research ◽

General Climate ◽

Guiding Questions

The H. J. Andrews (AND) Long-Term Ecological Research (LTER) site represents the temperate coniferous forest of the Pacific Northwest (PNW) of the United States. The general climate of the area is highly dynamic, displaying variability at a variety of timescales ranging from daily to millennial. AND, and its surrounding region, is therefore an ideal site for examining some of the guiding questions of climate variability and ecosystem response addressed by this volume (see chapter 1). A legacy of more than 50 years of research at the site and its surrounding area ensures that several of the questions can be investigated in some depth. Here we organize our discussion within a timescale framework that is consistent with the structure of this volume. Thus, following a brief description of the general climate of the site, we discuss climate variability and ecosystem response at the daily, multidecadal, and century to millennial scale. This discussion for the PNW is supplemented in chapters 6 and 13 by a consideration of the quasi-quintennial scale and an additional ecosystem response at the decadal scale. Having described some of the climate variability and ecosystem response at the selected timescales, we will consider what this information can tell us regarding some of the guiding questions of this book. The questions that we specifically address include the following: What preexisting conditions affect the impact of the climatic event or episode? Is the climatic effect on the ecosystems direct or cascading? Does the system return to its original state? We also consider potential future climate change and its possible ecosystem effects. Located at latitude 44.2º N and longitude 122.2º W, the Andrews Forest is situated in the western Cascade Range of Oregon in the 6400-ha (15,800-acre) drainage basin of Lookout Creek, a tributary of the Blue River and the McKenzie River (figure 19.1). Elevation ranges from 410 m (1350 feet) to 1630 m (5340 feet). Broadly representative of the rugged mountainous landscape of the Pacific Northwest (PNW), the Andrews Forest contains excellent examples of the region’s conifer forests and associated wildlife and stream ecosystems. Lower elevation forests are dominated by Douglas-fir (Pseudotsuga menziesii), western hemlock (Tsuga heterophylla), and western red cedar (Thuja plicata).

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Seasonal Climate Variability and Change in the Pacific Northwest of the United States

Journal of Climate ◽

10.1175/jcli-d-13-00218.1 ◽

2014 ◽

Vol 27 (5) ◽

pp. 2125-2142 ◽

Cited By ~ 128

Author(s):

John T. Abatzoglou ◽

David E. Rupp ◽

Philip W. Mote

Keyword(s):

Climate Variability ◽

Pacific Northwest ◽

Time Scales ◽

Potential Evapotranspiration ◽

Seasonal Precipitation ◽

Seasonal Temperature ◽

Temperature Trends ◽

The Pacific ◽

Precipitation Trends

Abstract Observed changes in climate of the U.S. Pacific Northwest since the early twentieth century were examined using four different datasets. Annual mean temperature increased by approximately 0.6°–0.8°C from 1901 to 2012, with corroborating indicators including a lengthened freeze-free season, increased temperature of the coldest night of the year, and increased growing-season potential evapotranspiration. Seasonal temperature trends over shorter time scales (<50 yr) were variable. Despite increased warming rates in most seasons over the last half century, nonsignificant cooling was observed during spring from 1980 to 2012. Observations show a long-term increase in spring precipitation; however, decreased summer and autumn precipitation and increased potential evapotranspiration have resulted in larger climatic water deficits over the past four decades. A bootstrapped multiple linear regression model was used to better resolve the temporal heterogeneity of seasonal temperature and precipitation trends and to apportion trends to internal climate variability, solar variability, volcanic aerosols, and anthropogenic forcing. The El Niño–Southern Oscillation and the Pacific–North American pattern were the primary modulators of seasonal temperature trends on multidecadal time scales: solar and volcanic forcing were nonsignificant predictors and contributed weakly to observed trends. Anthropogenic forcing was a significant predictor of, and the leading contributor to, long-term warming; natural factors alone fail to explain the observed warming. Conversely, poor model skill for seasonal precipitation suggests that other factors need to be considered to understand the sources of seasonal precipitation trends.

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An Introduction to Climate Variability and Ecosystem Response

Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites ◽

10.1093/oso/9780195150599.003.0005 ◽

2003 ◽

Author(s):

David Greenland ◽

Douglas G. Goodin

Keyword(s):

Climate Variability ◽

Ecological Research ◽

Tree Species Composition ◽

Mean Values ◽

Individual Fitness ◽

Long Term Ecological Research ◽

Decadal Climate ◽

Definition Of ◽

And Function

The regularities of our planet’s climate determine a large part of the form and function of Earth’s ecosystems. The frequently nonlinear operation of the atmosphere gives rise to a rich complexity of variability superimposed on the fundamental regularities. A traditional definition of climate is “the long-term state of the atmosphere encompassing the aggregate effect of weather phenomena—the extremes as well as the mean values” (Barry and Chorley 1987). Ecosystems share some of the same properties as the climate system. At one level their operation is fairly straightforward. Ecologists, to a certain extent, understand the flows of energy and matter through these systems. A good deal of ecosystem operation over time is characterized by some degree of homeostasis. On the other hand, nonlinear change and multiple variables have placed uncertainty and surprise at the forefront of much ecological research. In both the climate and the ecosystem the only certainty often appears to be change. The task of this book is to focus on some of this change at the interface between the climate and the ecosystem and by doing so gain insights into the operation of both systems. Millennial-scale (1000-year) climate variability has driven large changes of vegetation and fauna at almost all of the Long-Term Ecological Research (LTER) sites. Decadal climate variability at some sites has seen dramatic changes in fish catches and has altered tree species composition. During the first two decades of study, LTER sites have been affected by two super El Niño events and several more “normal” El Niños and La Niñas. Major droughts have affected species diversity and killed some trees. Severe storms and floods have damaged stream restoration structures. Coastal sites have measured a rise in sea level. Antarctic sites have documented the decrease of some penguin populations and a rise in other populations as a result of climatic warming over 50 or more years. Climate variability has constantly been on investigators’ minds. It is little wonder that ecologists clearly recognize climate as a driver of biotic systems. Parmesan and her coworkers describe how climate affects individual fitness, population dynamics, and the distribution and abundance of species, as well as ecosystem structure and function (Parmesan et al. 2000).

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Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites

10.1093/oso/9780195150599.001.0001 ◽

2003 ◽

Keyword(s):

Climate Change ◽

Global Climate ◽

Research Community ◽

Research Network ◽

Ecological Research ◽

Ecosystem Response ◽

Climate Change Research ◽

Wide Range ◽

Long Term Ecological Research

This volume in the Long-Term Ecological Research Network Series would present the work that has been done and the understanding and database that have been developed by work on climate change done at all the LTER sites. Global climate change is a central issue facing the world, which is being worked on by a very large number of scientists across a wide range of fields. The LTER sites hold some of the best available data measuring long term impacts and changes in the environment, and the research done at these sites has not previously been made widely available to the broader climate change research community. This book should appeal reasonably widely outside the ecological community, and because it pulls together information from all 20 research sites, it should capture the interest of virtually the entire LTER research community.

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Climate Variability and Ecosystem Response—Synthesis

Climate Variability and Ecosystem Response in Long-Term Ecological Research Sites ◽

10.1093/oso/9780195150599.003.0039 ◽

2003 ◽

Author(s):

Greenland David ◽

Douglas G. Goodin

Keyword(s):

Climate Variability ◽

Pacific Northwest ◽

Southern Oscillation ◽

Ecosystem Response ◽

The Pacific ◽

Climate Event ◽

Almost All ◽

Positive And Negative Feedbacks ◽

Climate Events ◽

The Relationship

At the outset we identified the theme of this book as how ecosystems respond to climate variability. We have examined this theme at a variety of LTER sites and at a variety of timescales. The subject matter of the book was also to be focused on a series of framework questions. We noted that the theme of climate variability and ecosystem response is inherently deterministic and implicitly carries with it the notion of climate cause and ecosystem result. The analyses in this volume demonstrated that this is a valid and fruitful working assumption. However, the idea of a simple single climate cause and effect might be true in some cases, but it is obviously simplistic. More realistically, the effects of climate variability cascade through ecosystems. In almost all cases there is the probability of many secondary and associated effects accompanying the primary effects. As an example, the possible results of potential warming in the Pacific Northwest forests include changes in global carbon dioxide input, nutrient cycling between the plants and the soil, and feedback links between the plant and soil organisms (Perry and Borchers 1990). In general there seem to be at least three broad classes of interaction between climate and ecosystems. First, the ecosystem simply responds to individual climate events or episodes that exceed some threshold for response. Second, ecosystems may buffer climate variability. In this sense they are filtering the effect of the climate event or episode. The same component in an ecosystem can sometimes act as a buffer and sometimes not, according to the nature of the climate event. Thus a riparian environment might provide soil moisture that acts as a buffer to a drought, but the whole environment might be destroyed by a large flood event. Third, we hypothesize that the ecosystem may move into resonance with the climate variability with positive and negative feedbacks that produce a strong ecosystem response. The relationship between fire and the Southern Oscillation indicates that the South west United States (Swetnam and Betancourt 1990) may provide an example of such resonance. Other examples of resonance, discussed subsequently, may exist in the forests of Interior Alaska and Puerto Rico. If there is indeed an ecosystem response to climate variability, the response tends to occur in cascades.

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