Impact of Climate Change on Biodiversity, Forestry and Conservation

Current scientific and empirical evidence on impact of climate change on biodiversity, forestry and conservation

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The Effect of Climate Change on Biodiversity, Forestry and Conservation

Recommendations for DPI/NGO.   This report is preliminary and In 2009, this working group plans to explore this question in depth.

Current authors: Jennifer Lanier, Paul Leadley, Dominique Bachelet, Larry Roeder

I. Introduction

Climate change is an issue as complex and challenging as any that humans have yet faced.  Methods to predict global climate change are growing more sophisticated, and projections increasingly anticipate severe consequences for a wide range of biota, including climate-related extinctions (Root et al. 2003; Parmesan and Yohe 2003; Walther 2004; Walther et al. 2002; Pounds et al. 1999, 2006). Whether these effects may have both positive and negative results is outside the purview of this paper. What is within our remit is the expected dramatic evolution shift that will push the limits of survivability.   However, few evidence-based strategies exist that may help human and natural systems adapt to climate change. The existing static network of protected areas, and associated conservation strategies, is inadequate for helping dynamic systems and their current assemblages of species to persist in the fact of abrupt climate change.  Even optimistic carbon mitigation and sequestration scenarios estimate that global temperatures will continue to increase for 80-100 years. Clearly, we cannot wait and expect that someone else will solve the dilemmas presented to human and natural systems by climate change.

II. Problem Statement

Evolution generally occurs naturally, everyday in small almost unperceivable steps. There are numerous events that speed up or otherwise change the dynamics of evolution, either on a global (asteroid strike) or regional (Industrial Revolution) scale. There are at least three general assumptions about Climate Change: 1) That the effects will be global but unevenly distributed; 2) That change will be punctuated by abrupt events (e.g. droughts, floods, outbreaks,, human conflicts); and 3) in relation to normal evolution changes will be very rapid with the potential to push every living organism and system to their limits. It is this extreme and rapid change that is of greatest concern.

As the effects will be global and will affect human habitat and economies, it is important to identify where these effects may and may not occur. It is most certain that niche environments (tundra), jurisdictions with limited resources or influence (developing world), boundary locked people and animals (islands, mountain tops) will potentially be affected the most. Agreements of cooperation and action-based preparedness are critical to mitigate these aggravating circumstances. For example, water is already the most limiting resource for human activities and native species. With increased predicted temperatures and periods of drought, the competition between individuals (humans, fauna, and flora) for water will increase. This has the potential for greater conflict between individuals, and for putting additional pressure on communities and nations. These conflicts and pressure will be evident at all levels of life for all species and systems affected, from soil organisms, to humans, from plant communities to nations. .An alternate way to look at the complexities and issues is to look at the niche instead at a single issue such as water availability.

The Greater Yellowstone Ecosystem (GYE), in the USA, is a macro niche spanning 73,000 km2 and three states. It is a mosaic of state, federal, and private lands, and contains two national parks, seven national forests, and three national wildlife refuges. The ecosystem is home to the highest concentration of mammals in the lower 48 states. The Rocky Mountains, with their complex topography, are the core of the GYE and are expected to act as important refugia for wildlife and plants in the face of climate change. Aggravation of any one critical stressor such as increased fragmentation, due to human activities or Climate Change, of the GYE will hinder floral and faunal responses to climate change in general. The GYE case study can provide insight into how climate change strategies might be applied across multiple jurisdictions, and how barriers to coordination can be overcome. This macro niche and extant importance becomes greater when considering migratory species.

Without some form of agreement and mitigation planning most responses to the pressures and conflicts will remain reactionary responses and not address the underlying issue. As it is true that in the overall timetable of earth, societies, species (Alley et al. 2003; Benton and Twitchett 2003) and environmental systems will find balance, as a species, under stress, we can not afford to sit and wait a few hundred or million years for a ‘natural equilibrium’. As we are partially responsible for the current climate change, and have a vested interest in the short and long term future, constructive strategies and actions are needed to diminish negative and enhance positive effects of Climate Change.

The following are areas of concern or understanding needed to address the underlying issues:

Novel climates, uncharted portions of the climate space, novel flora communities, possible mismatch with preserves, static parks delineation (Williams and Jackson 2007)
Uncertainty about where species will move because we know about realized niche not necessarily fundamental niche (Loehle 1996)
Corollary to previous statement: There is no equilibrium, nature is dynamic and so is species range (Hannah et al. 2007)
Refugia will maintain some species, how do we identify refugia and at what scale?
Complex topography will help buffer Climate Change impacts: quote from Hamann and Aitken
“Protected areas that have a large elevation range may be able to buffer against climate change because species can migrate over short distances to entirely different habitat conditions.”

Mortality/establishment depend on extreme events (wet year in desert area for seedling establishment, LT drought for diebacks, fire for serotinous cone species, combination of fuel-building wet years and fuel-drying year for stand replacement fires)
Migration vs adaptation
Invasives with long distance dispersal can rapidly occupy new potential habitat under climate change and successfully outcompete remnant native populations and transform biogeochemical cycles affecting the direction of natural succession.

III. Current Situation

**Are there examples of static, territory based, myopic efforts?** Example, of good but limited efforts? Do we want examples?**  In 2009, this working group plans to explore this question in depth.

Innovative processes are being developed. For example, in the US a group of varied stakeholders with international experience have formed The Climate Change Conservation Collaborative Solutions Group (C4) to actively address potential issues.

***Need examples from around the world****   In 2009, this working group plans to explore this question in depth.

The tools: strengths and limitations

Species distribution models (Araujo et al. 2004, Williams et al 2005, Lawler et al.) are useful tools to simulate potential range shifts but they assume that species ranges are in equilibrium with climate. These models are based on the realized niche of the various species and can thus underestimate future ranges as new climates create new conditions these species may thrive in. On the other hand, these models are static and may overestimate future ranges if between two periods of projections of range, extreme events (ex. droughts) causes the extinction of the species. Several efforts are now underway to link dynamic vegetation models that can be used to track habitat response to climate with species models projection range contractions and expansion.
GARP: genetic algorithm for rule set prediction – species distrib model using multiple statistical and rule based techniques to project range changes
GAM: generalized additive modeling – statistical modeling technique
climate envelope modeling (Schwartz et al. 2001, Hamann and Wang 2005)
conservation planning software systems
SITES (Williams et al 2000)
Climate change scenarios
general circulation models (GCMs)
GCMs were designed to simulate the climate of the earth. They include state-of-the-art understanding of atmospheric and ocean physics and chemistry principles. Given their level of complexity, they are computer-intensive and provide coarse-scale projections of future climate on the planet. Ecologists have been downscaling these large scale projections to the regional and even local level for which climate models were not designed to simulate. Because GCMs assume homogenous vegetation cover and topography, downscaled information continues to assume limited feedbacks between actual land cover or ocean fluxes and the atmosphere. Coastal areas are either represented as pure ocean cells or pure land cells in climate models at coarse scale. Complex topography also renders projections inadequate to project the future of potential refugia such as valley bottoms protected from regional warming by cold air drainage, inversion layers and other locally important cloud cover dynamics.

regional climate models (RCMs)
RCMs which provide finer resolution projections are initialized with boundary conditions driven by GCM output and thus include similar limitations.

arbitrary scenarios
The vast majority of models of the impacts of climate change on biodiversity have focused on the effects of long-term climatic trends. There is growing concern that the occurrence of extreme climatic events such as drought, extreme ocean temperatures and hurricanes may increase in the future and that these events will play an important role in driving mortality. Examples of this include the recent episodes of severe coral reef bleaching due to extreme sea surface temperature anomalies (Hoegh-Guldberg et al 2007) or forest dieback in temperate forests due to extreme heat and drought (Breda et al 2006, Breshears et al 2005). Extreme climatic events pose two challenges for biodiversity modelers.

First, extreme climatic events are difficult to model because of their very nature of being rare events in space or in time. The simulation of extreme events is an area of active research within the climate community, but much of the most recent work has not yet been used by the biodiversity modeling community. Secondly, many models are not designed to handle extreme events. In particular, the statistical relationships between distribution and climate in niche-based models are typically based on long-term averages of climate and distribution making them difficult to apply to extreme climatic events. However models such as forest gap-dynamic models or DGVMs contain the mechanisms to account for some types of extreme events on trees or plant functional groups,. Several novel types of models are also now under development and may provide the mechanisms to simulate the response of a large number of species or functional groups to extreme events.

Emission scenarios: predictability of societal and political choices

Climate change impacts models

Dynamic global vegetation models: PFTs vs species: DGVMs were designed to simulate the impacts of climate change on global land cover to eventually provide biofeedbacks to the GCMs. Instead of providing snapshots of species location on the surface of the planet like species (climate envelope) or biogeography models do, they provide a continuous projection of how vegetation shifts and their associated biogeochemical cycles may respond to a change in climate and associated disturbance regimes (fires, permafrost melting). DGVMs however do not include species characteristics. They focus on functions and are more closely related to the notion of ecosytem services than biodiversity. They can however provide valuable information on how habitats may change with time following abrupt changes such as decadal droughts, stand replacing fires etc. It is unrealistic to think that increasing DGVM complexity by replacing plant functional types (PFTs) by species will give us a better tool to simulate biodiversity. Several efforts (IGBP DIVERSITAS) are underway to increase the number of PFTs to represent underrepresented organisms such as mosses and lichens which play an important role in the carbon cycle and fire regime of boreal forests or such as wetland plants which have not been included in most global carbon accounting based on simulations despite the extreme importance of their importance as a conduit for methane fluxes.
Forest gap-dynamic models simulate the dynamics of species succession in forests using empirical relationships describing the growth and regeneration of tree species in gaps created by the death or removal of trees. These models have been relatively successfully used to reproduce past and current species composition of temperate forests and therefore are powerful tools for simulating the effects of global change on temperate tree species. They have been less successful in describing species dynamics in tropical forests where a variety of other models including "neutral" models have been applied. There are currently a variety of efforts to improve the representation of the functional response of trees to global change and to simulate mortality and migration in gap-dynamic models (Rickebusch et al 2007).
Gene flow models simulate the flow of genes within and among populations (see "NCEAS web site" for review). These models can be combined with models of population demography to simulate the long-term viability of populations in response to human disturbances such as habitat fragmentation. More recently these models have been adapted to explore the genetic and phenotypic adaptation of species to climate change (Kramer A, pers comm.). Few other types of models account for the possible adaptation of plants and animals to a changing environment. These models are, however, difficult to parameterize and test for more than a few species and generally have very limited representations of the functional response of plants or animals to their environment.
c. Sea level rise models: SLR vs local subsidence

d. Earth system models: biofeedbacks, local climate, complex topography  In 2009, this working group plans to explore this question in depth.





(1) Winter Ecard: Polar bear, Churchill, Canada, © Lindsey P. Martin