Landscape Partnership Resources Library
Managing the whole landscape: historical, hybrid, and novel ecosystems
The reality confronting ecosystem managers today is one of heterogeneous, rapidly transforming landscapes, particularly in the areas more affected by urban and agricultural development. A landscape management framework that incorporates all systems, across the spectrum of degrees of alteration, provides a fuller set of options for how and when to intervene, uses limited resources more effectively, and increases the chances of achieving management goals. That many ecosystems have departed so substantially from their historical trajectory that they defy conventional restoration is not in dispute. Acknowledging novel ecosystems need not constitute a threat to existing policy and management approaches. Rather, the development of an integrated approach to management interventions can provide options that are in tune with the current reality of rapid ecosystem change.
Microhabitats in the tropics buffer temperature in a globally coherent manner
Vegetated habitats contain a variety of fine-scale features that can ameliorate temperate extremes. These buffered microhabitats may be used by species to evade extreme weather and novel climates in the future. Yet, the magnitude and extent of this buffering on a global scale remains unknown. Across all tropical continents and using 36 published studies, we assessed temperature buffering from within microhabitats across various habitat strata and structures (e.g. soil, logs, epiphytes and tree holes) and compared them to non-buffered macro-scale ambient temperatures (the thermal control). Microhabitats buf- fered temperature by 3.98C and reduced maximum temperatures by 3.58C. Buffering was most pronounced in tropical lowlands where temperatures were most variable. With the expected increase in extreme weather events, microhabitats should provide species with a local layer of protection that is not captured by traditional climate assessments, which are typically derived from macro-scale temperatures (e.g. satellites). Our data illustrate the need for a next generation of predictive models that account for species’ ability to move within microhabitats to exploit favourable buffered microclimates.
Saturation-state sensitivity of marine bivalve larvae to ocean acidification
Ocean acidification results in co-varying inorganic carbon system variables. Of these, an explicit focus on pH and organismal acid–base regulation has failed to distinguish the mechanism of failure in highly sensitive bivalve larvae. With unique chemical manipulations of seawater we show definitively that larval shell development and growth are dependent on seawater saturation state, and not on carbon dioxide partial pressure or pH. Although other physiological processes are affected by pH, mineral saturation state thresholds will be crossed decades to centuries ahead of pH thresholds owing to nonlinear changes in the carbonate system variables as carbon dioxide is added. Our findings were repeatable for two species of bivalve larvae could resolve discrepancies in experimental results, are consistent with a previous model of ocean acidification impacts due to rapid calcification in bivalve larvae, and suggest a fundamental ocean acidification bottleneck at early life-history for some marine keystone species.
Nonrandom, diversifying processes are disproportionately strong in the smallest size classes of a tropical forest
Here, we use one of the world’s longest-running, plot-based forest dynamics projects to compare nonrandom outcomes across stage classes. We considered a cohort of 7,977 individuals in 186 species that were alive in 1971 and monitored in 13 mortality censuses over 42 y to 2013. Nonrandom mortality with respect to species identity occurred more often in the smaller rather than the larger size classes. Furthermore, observed nonrandom mortality in the smaller size classes had a diversifying influence; species richness of the survivors was up to 30% greater than expected in the two smallest size classes, but not greater than expected in the larger size classes. These results highlight the importance of early life cycle stages in tropical forest community dynamics. More generally, they add to an accumulating body of evidence for the importance of early-stage nonrandom outcomes to community structure in marine and terrestrial environments. diversity | early life-cycle stages | nonrandom | tropical forest
The Gift of the Dying: The Tragedy of AIDS and the Welfare of Future African Generations
This paper simulates the impact of the AIDS epidemic on future living standards in South Africa. I emphasize two competing effects. On the one hand, the epidemic is likely to have a detrimental impact on the human capital accumulation of orphaned children. On the other hand, widespread community infection lowers fertility, both directly, through a reduction in the willingness to engage in unprotected sexual activity, and indirectly, by increasing the scarcity of labor and the value of a woman’s time. I find that even with the most pessimistic assumptions concerning reductions in educational attainment, the fertility effect dominates. The AIDS epidemic, on net, enhances the future per capita consumption possibilities of the South African economy.
Landscape-scale carbon storage associated with beaver dams
Beaver meadows form when beaver dams promote prolonged overbank flooding and floodplain retention of sediment and organic matter. Extensive beaver meadows form in broad, low-gradient valley segments upstream from glacial terminal moraines. Surveyed sediment volume and total organic carbon content in beaver meadows on the eastern side of Rocky Mountain National Park are extrapolated to create a first-order approximation of landscape-scale carbon storage in these meadows relative to adjacent uplands. Differences in total organic carbon between abandoned and active beaver meadows suggest that valley-bottom carbon storage has declined substantially as beaver have disappeared and meadows have dried. Relict beaver meadows represent ~8% of total carbon storage within the landscape, but the value was closer to 23% when beaver actively maintained wet meadows. These changes reflect the general magnitude of cumulative effects in heterotrophic respiration and organic matter oxidation associated with historical declines in beaver populations across the continent
Large in-stream wood studies: a call for common metrics
During the past decade, research on large in-stream wood has expanded beyond North America’s Pacifi c Northwest to diverse environments and has shifted toward increasingly holistic perspectives that incorporate processes of wood recruitment, retention, and loss at scales from channel segments to entire watersheds. Syntheses of this rapidly expanding literature can be facilitated by agreement on primary variables and methods of measurement. In this paper we address these issues by listing the variables that we consider fundamental to studies of in-stream wood, discussing the sources of variability in their measurement, and suggesting more consistency in future studies. We recommend 23 variables for all studies of in-stream wood, as well as another 12 variables that we suggest for studies with more specifi c objectives. Each of these variables relates either to the size and characteristics of in-stream wood, to the geomorphic features of the channel and valley, or to the ecological characteristics of the riparian zone adjacent to the study reach. The variables were derived from an overview of those cited in the literature and from our collective fi eld experiences.
The anatomy of predator–prey dynamics in a changing climate
1. Humans are increasingly influencing global climate and regional predator assemblages, yet a mechanistic understanding of how climate and predation interact to affect fluctuations in prey populations is currently lacking. 2. Here we develop a modelling framework to explore the effects of different predation strategies on the response of age-structured prey populations to a changing climate. 3. We show that predation acts in opposition to temporal correlation in climatic conditions to suppress prey population fluctuations. 4. Ambush predators such as lions are shown to be more effective at suppressing fluctuations in their prey than cursorial predators such as wolves, which chase down prey over long distances, because they are more effective predators on prime-aged adults. 5. We model climate as a Markov process and explore the consequences of future changes in climatic autocorrelation for population dynamics. We show that the presence of healthy predator populations will be particularly important in dampening prey population fluctuations if temporal correlation in climatic conditions increases in the future.
Wildfire and fuel treatment effects on forest carbon dynamics in the western United States
Sequestration of carbon (C) in forests has the potential to mitigate the effects of climate change by offsetting future emissions of greenhouse gases. However, in dry temperate forests, wildfire is a natural disturbance agent with the potential to release large fluxes of C into the atmosphere. Climate-driven increases in wildfire extent and severity are expected to increase the risks of reversal to C stores and affect the potential of dry forests to sequester C. In the western United States, fuel treatments that successfully reduce surface fuels in dry forests can mitigate the spread and severity of wildfire, while reducing both tree mortality and emissions from wildfire. However, heterogeneous burn environments, site-specific variability in post-fire ecosystem response, and uncertainty in future fire frequency and extent complicate assessments of long-term (decades to centuries) C dynamics across large landscapes. Results of studies on the effects of fuel treatments and wildfires on long-term C retention across large landscapes are limited and equivocal. Stand-scale studies, empirical and modeled, describe a wide range of total treatment costs (12–116 Mg C ha1 ) and reductions in wildfire emissions between treated and untreated stands (1–40 Mg C ha1 ). Conclusions suggest the direction (source, sink) and magnitude of net C effects from fuel treatments are similarly variable (33 Mg C ha1 to +3 Mg C ha1 ). Studies at large spatial and temporal scales suggest that there is a low likelihood of high-severity wildfire events interacting with treated forests, negating any expected C benefit from fuels reduction. The frequency, extent, and severity of wildfire are expected to increase as a result of changing climate, and additional information on C response to management and disturbance scenarios is needed improve the accuracy and usefulness of assessments of fuel treatment and wildfire effects on C dynamics. 20
When It Rains, It Pours Global Warming and the Increase in Extreme Precipitation from 1948 to 2011
Global warming is happening now and its effects are being felt in the United States and around the world. Among the expected consequences of global warming is an increase in the heaviest rain and snow storms, fueled by increased evaporation and the ability of a warmer atmosphere to hold more moisture. An analysis of more than 80 million daily precipitation records from across the contiguous United States reveals that intense rainstorms and snowstorms have already become more frequent and more severe. Extreme downpours are now happening 30 percent more often nationwide than in 1948. In other words, large rain or snowstorms that happened once every 12 months, on average, in the middle of the 20th century now happen every nine months. Moreover, the largest annual storms now produce 10 percent more precipitation, on average.
Projections of Future Drought in the Continental United States and Mexico
Using the Palmer drought severity index, the ability of 19 state-of-the-art climate models to reproduce observed statistics of drought over North America is examined. It is found that correction of substantial biases in the models’ surface air temperature and precipitation fields is necessary. However, even after a bias correction, there are significant differences in the models’ ability to reproduce observations. Using metrics based on the ability to reproduce observed temporal and spatial patterns of drought, the relationship between model performance in simulating present-day drought characteristics and their differences in projections of future drought changes is investigated. It is found that all models project increases in future drought frequency and severity. However, using the metrics presented here to increase confidence in the multimodel projection is complicated by a correlation between models’ drought metric skill and climate sensitivity. The effect of this sampling error can be removed by changing how the projection is presented, from a projection based on a specific time interval to a projection based on a specified temperature change. This modified class of projections has reduced intermodel uncertainty and could be suitable for a wide range of climate change impacts projections.
Safe Havens, Safe Passages for Vulnerable Fish and Wildlife
Some of the best-known and most-cherished mountains on Earth are set in the Canadian Rockies of British Columbia and Alberta. Indeed, the mention of Banff, Jasper, Kootenay or Yoho National Parks evokes images of snow-capped peaks, thundering falls and turquoise waters, numerous natural wonders and majestic wildlife. The adjoining Provincial Parks in British Columbia – Mount Robson, Mount Assiniboine, and Hamber – are just as spectacular, if not quite as renowned. Waterton Lakes National Park in Alberta and Glacier National Park in Montana – brought together in 1931 as an International Peace Park by the respective Rotary Clubs – exemplify international cooperation and wilderness and wildlife without borders. All 9 of these parks have been designated as World Heritage Sites in recognition of their outstanding natural importance to the common heritage of humanity.
Spatial patterns and policy implications for residential water use
The front yard makes a powerful visual statement about the occupants of the residence. As visible statements, yards are likely to induce a behavioral response on the part of neighboring residents. As an example, residents may strive to keep their yard as green and lush as their neighbors. For Kelowna, British Columbia, a highly significant positive spatial lag for summer water use implies some degree of spatial emulation in water using behavior. Other variables such as lot size, building size, assessed value, presence of a pool, etc. impact on water use as expected. The presence of a spatial lag implies a spatial multiplier for water saving innovations. If local water managers and policy makers can influence the spatial pattern of water saving innovations, they may be able to increase the size of the multiplier effect. Similar spatial policies may also be applicable to other socially influenced behaviors that leave a spatial signature, such as protecting ecologically significant habitats in urban areas
How Much More Rain Will Global Warming Bring?
Climate models and satellite observations both indicate that the total amount of water in the atmosphere will increase at a rate of 7% per kelvin of surface warming. However, the climate models predict that global precipitation will increase at a much slower rate of 1 to 3% per kelvin. A recent analysis of satellite observations does not support this prediction of a muted response of precipitation to global warming. Rather, the observations suggest that precipitation and total atmospheric water have increased at about the same rate over the past two decades. SCIENCE VOL 317 13 JULY 2007
Predicting satellite-derived patterns of large-scale disturbances in forests of the Pacific Northwest Region in response to recent climatic variation
Across the Pacific Northwest, the climate between 1950 and 1975 was exceptionally cool and wet compared with more recent conditions (1995–2005). We reasoned that the changes in climate could result in expanded outbreaks of insects, diseases, and fire. To test this premise, we first modeled monthly variation in photosynthesis and growth of the most widely distributed species, Douglas-fir (Pseudotsuga menziesii), using a process-based model (3-PG) for the two periods. To compare with remotely sensed variables, we converted modeled growth potential into maximum leaf area index (LAImax), which was predicted to range from 1 to 9 across the region. On most sites, varying soil moisture storage capacity (θcap) from 200 to 300 mm while holding soil fertility constant, made slight but insignificant difference in simulated LAImax patterns. Both values of θcap correlated well with LAI estimates acquired from NASA's MODIS satellites in June, 2005 (r2= 0.7). To evaluate where 15 coniferous tree species might be prone to wide-scale disturbance, we used climatically-driven decision-tree models, calibrated in the 1950–1975 period, to identify vulnerable areas in 1995–2005. We stratified predictions within 34 recognized ecoregions and compared these results with large-scale disturbances recorded on MODIS imagery acquired between 2005 and 2009. The correlation between the percent of species judged as vulnerable within each ecoregion and the percent of forested areas recorded as disturbed with a MODIS-derived Global Disturbance Index was linear and accounted for 65 to 73% of the observed variation, depending on whether or not disturbance by fire was excluded from the analysis. Based on climate projections through the rest of the rest of the 21st century, we expect continued high levels of disturbance in ecoregions located beyond the climatically buffering influence of the Pacific Ocean.
Phylogenetic patterns of species loss in Thoreau’s woods are driven by climate change
Climate change has led to major changes in the phenology (the timing of seasonal activities, such as flowering) of some species but not others. The extent to which flowering-time response to temperature is shared among closely related species might have important consequences for community-wide patterns of species loss under rapid climate change. Henry David Thoreau initiated a dataset of the Concord, Massachusetts, flora that spans !150 years and provides information on changes in species abundance and flowering time. When these data are analyzed in a phylogenetic context, they indicate that change in abundance is strongly correlated with flowering-time response. Species that do not respond to temperature have decreased greatly in abundance, and include among others anemones and buttercups [Ranunculaceae pro parte (p.p.)], asters and campanulas (Asterales), bluets (Rubiaceae p.p.), bladderworts (Lentibulariaceae), dogwoods (Cornaceae), lilies (Liliales), mints (Lamiaceae p.p.), orchids (Orchidaceae), roses (Rosaceae p.p.), saxifrages (Saxifragales), and violets (Malpighiales). Because flowering-time response traits are shared among closely related species, our findings suggest that climate change has affected and will likely continue to shape the phylogenetically biased pattern of species loss in Thoreau’s woods PNAS ! November 4, 2008 ! vol. 105 ! no. 44 ! 17029–17033
Are we in the midst of the sixth mass extinction? A view from the world of amphibians
Many scientists argue that we are either entering or in the midst of the sixth great mass extinction. Intense human pressure, both direct and indirect, is having profound effects on natural environments. The amphibians—frogs, salamanders, and caecilians—may be the only major group currently at risk globally. A detailed worldwide assessment and subsequent updates show that onethird or more of the 6,300 species are threatened with extinction. This trend is likely to accelerate because most amphibians occur in the tropics and have small geographic ranges that make them susceptible to extinction. The increasing pressure from habitat destruction and climate change is likely to have major impacts on narrowly adapted and distributed species. We show that salamanders on tropical mountains are particularly at risk. A new and significant threat to amphibians is a virulent, emerging infectious disease, chytridiomycosis, which appears to be globally distributed, and its effects may be exacerbated by global warming. This disease, which is caused by a fungal pathogen and implicated in serious declines and extinctions of >200 species of amphibians, poses the greatest threat to biodiversity of any known disease. Our data for frogs in the Sierra Nevada of California show that the fungus is having a devastating impact on native species, already weakened by the effects of pollution and introduced predators. A general message from amphibians is that we may have little time to stave off a potential mass extinction. 11466–11473 PNAS August 12, 2008 vol. 105 suppl. 1
Volcanic cause of catastrophe
From the timing, it looks as if an episode of marked oceanic oxygen deficiency during the Cretaceous was the result of undersea volcanism. Studies of such events are relevant to the warming world of today. NATURE|Vol 454|17 July 2008
Why Is Climate Sensitivity So Unpredictable?
Uncertainties in projections of future climate change have not lessened substantially in past decades. Both models and observations yield broad probability distributions for long-term increases in global mean temperature expected from the doubling of atmospheric carbon dioxide, with small but finite probabilities of very large increases. We show that the shape of these probability distributions is an inevitable and general consequence of the nature of the climate system, and we derive a simple analytic form for the shape that fits recent published distributions very well. We show that the breadth of the distribution and, in particular, the probability of large temperature increases are relatively insensitive to decreases in uncertainties associated with the underlying climate processes. VOL 318 26 OCTOBER 2007
Scenario Planning: a Tool for Conservation in an Uncertain World
: Conservation decisions about how, when, and where to act are typically based on our expectations for the future. When the world is highly unpredictable and we are working from a limited range of expectations, however, our expectations will frequently be proved wrong. Scenario planning offers a framework for developing more resilient conservation policies when faced with uncontrollable, irreducible uncertainty. A scenario in this context is an account of a plausible future. Scenario planning consists of using a few contrasting scenarios to explore the uncertainty surrounding the future consequences of a decision. Ideally, scenarios should be constructed by a diverse group of people for a single, stated purpose. Scenario planning can incorporate a variety of quantitative and qualitative information in the decision-making process. Often, consideration of this diverse information in a systemic way leads to better decisions. Furthermore, the participation of a diverse group of people in a systemic process of collecting, discussing, and analyzing scenarios builds shared understanding. The robustness provided by the consideration of multiple possible futures has served several groups well; we present examples from business, government, and conservation planning that illustrate the value of scenario planning. For conservation, major benefits of using scenario planning are (1) increased understanding of key uncertainties, (2) incorporation of alternative perspectives into conservation planning, and (3) greater resilience of decisions to surprise.
