People may have to help them
University
of California - Santa Cruz
A new study surveyed the recommendations of scientists for managing biodiversity in the face of climate change, providing a summary of practical guidance and identifying areas in need of further research.
Climate change is already affecting plants and animals worldwide and is a growing threat to biodiversity, adding a new layer to the existing challenges of habitat loss, invasive species, pollution, and overexploitation.
A
new study, published in the April issue of Biological Conservation,
surveyed the recommendations of scientists for managing biodiversity in the
face of climate change, providing a summary of practical guidance and
identifying areas in need of further research.
"There is an enormous need to think ahead and be proactive, as well as a growing recognition that we have to act now," said senior author Erika Zavaleta, professor of ecology and evolutionary biology at UC Santa Cruz.
The
climatic conditions to which species have adapted are shifting across the
geography of a warming planet, leaving plants, animals, and entire ecosystems
in danger of being stranded in places where they can no longer survive.
"Climate
change is causing a mismatch between where species are now and where the
habitat and conditions suitable for them are moving," Zavaleta said.
"We need to think about where suitable habitats for different ecological
communities will be in the future, and how they can get there."
Climate
change is nothing new in the history of our planet, and species have moved and
evolved in response to it. But current changes driven by the burning of fossil
fuels are happening much faster than past climatic shifts. In addition, the
current fragmentation of natural habitats makes it much harder for species to
move than it was in the past.
"The
need to move is greater while the ability to move is less," Zavaleta said.
"Things are changing, and we need to assist the adaptive responses of the
natural world if we don't want to lose both the species and the amenities they
provide for people. We depend on natural ecosystems, and helping them adapt is
not separate from helping people and communities adapt to climate change."
The
new paper updates an earlier survey published in 2009 by Zavaleta and Nicole
Heller, then a postdoctoral researcher in Zavaleta's lab. Blair McLaughlin, an
assistant professor of ecology at Hampshire College in Massachusetts who earned
her Ph.D. in Zavaleta's lab and is currently a visiting scholar at UCSC, led the
new analysis and is first author of the paper.
The
researchers found that current recommendations have gone beyond conceptual
guidance to provide more specific and actionable ideas about strategies to
implement for particular ecosystems or species. "There has been a lot more
on-the-ground implementation of some of these approaches," Zavaleta said.
Longstanding
conservation measures, such as protecting and restoring ecosystems and
increasing their connectivity, remain critically important in the context of climate
change. To address climate-related challenges in particular, however, three
novel strategies have received growing attention in recent years: climate
change refugia, assisted migration, and protecting climate-adaptive genetics.
"If you think of a valley oak, with acorns that are carried only a short distance by birds and are only viable in the year they are dropped, you can have connectivity but the trees are not going to move at the same pace as the drying that's happening in parts of their range," Zavaleta explained.
"So do
we watch their range contract and disappear? Or do we bank them as seedlings in
botanical gardens? And what do we need to be learning now about how to put them
back out into the landscape where they can survive?"
Identifying
and protecting areas that can serve as a refuge for species threatened by
climate change fits easily within the traditional framework of biodiversity
conservation. Creating climate change refugia can include habitat restoration
efforts, such as restoring woodland streams to raise the water table.
Assisted
migration includes "assisted gene flow," which involves moving
organisms between populations within a species' existing range to preserve
genetic diversity, as well as moving species beyond their historical range.
This kind of direct intervention to move threatened species into areas where
they could have a better chance of survival in the future is not without
controversy, however. Concerns include potential impacts on other organisms
after translocation, as well as the possibility of harming the targeted
population if translocated individuals do poorly in the new site.
"I
feel like the devil is in the details, but I also think translocation has been
mischaracterized as an untested strategy, when actually it has been practiced
for over a century and probably longer," Zavaleta said. "Forestry,
for example, has a long practice of planting trees from a wide range of
locations in areas that are being restored. But we do have a lot more to learn,
especially for certain animals and species that are not well understood."
Scientists
also want to protect the genetic diversity of species, especially genetic
variants that might be better adapted to hotter, drier conditions. "These
are the very conditions that we are likely to see more of in the future,"
McLaughlin said. "Preserving the climate-adaptive evolutionary potential
of a species before it's lost is critical to make sure we have the genetic
resources we need to help species adapt to novel climate futures."
For
example, oaks at the southern end of their species' range or that survived a
big die-off during a drought might have genetic traits that enhance survival in
worsening conditions. Seeds and seedlings from those trees could be protected
in a "gene bank" so that those traits are not lost.
McLaughlin
currently leads a pilot project to create a gene bank for blue oaks in
California, which suffered a pronounced die off in the southern part of their
distribution during the last drought.
"We're
planting out seedlings from blue oaks that are adapted to hot dry conditions,
just so they're banked there in case there are more die offs," she said.
"In California, it's become clear that we need to do this now."