Climate change causing big shifts in tropical forests

Below is a repost of an article in Mongabay.com by Apoorva Joshi describing some of our recent finding as reported in PNAS.  Th original mongabay piece can be found HERE.


Climate change causing big shifts in tropical forests

  • Over the last decade, tropical forests in northwestern Colombia have been shrinking and shifting directionally likely due to changing climatic conditions.
  • The researchers warn this may spell doom for species with isolated ranges and nowhere else to go.
  • The study’s findings are probably not isolated to South America, and that tropical forests around the world are shifting in response to climate change.

It’s well known that climate change is significantly affecting the world’s oceans as sea level rise and water acidifies. But forests are also experiencing big impacts. Shifting precipitation patterns are bringing droughts to the Amazon rainforest, and warmer winter temperatures are allowing tree-killing beetles to spread farther north in boreal regions. Now, new research finds that climate change may be making tropical forests “move.”

A study published recently in the Proceedings of the National Academy of Sciences found that over the last decade, tropical forests in north-western Colombia have been shrinking and changing directionally with time as a likely response to climate change. Areas in the northern Andean montane forests and adjacent lowlands of Colombia are experiencing a phenomenon called “thermophilization,” the study says, meaning that the abundance of cold-tolerating highland species is decreasing while only heat-loving, lowland tree species are being left behind. These patterns are consistent with the expectations of upwards species migrations due to climate change, the authors write.

The study found strong links between tree species composition and temperature changes. On the surface, the changes to these forests seem deceptively small, Kenneth Feeley, co-author of the PNAS study and Assistant Professor of Biology at Florida International University, told mongabay.com. “If you were to go to the forest every year and look around, you would see lots of green, healthy vegetation,” he said. “It is only with precise measurements of which species are there, how many of each species is there, and how big each tree is, that the changes are revealed. Once you see the numbers, you realize that the changes are huge.”

Feeley said that some species’ ranges are shifting upwards by an average of two to three meters every year, which equates to a horizontal shift of tens of meters. He attributes most of this change due to dieback at the lower altitudes of their distributions.

“So if you stood at the bottom range of species one year, then returned ten years later, the lowest individual of that species would now be somewhere like 20 meters above you or maybe about 100 meters away,” Feeley said.

In other words, instead of the distributions of tree communities shifting or expanding, they are retreating upwards as it gets too hot for them in lower portions of their ranges. This, the authors say, does not bode well for species persistence or biodiversity.

This study, conducted in Antioquia, Colombia, follows two previous studies; one conducted in Manu National Park, Peru, and the other in Volcan Barva, Costa Rica. “Taken together, the three studies all suggest that widespread upwards species migrations may be occurring throughout many neotropical montane forests,” the authors write.

Feeley says the effects seem to be ubiquitous within these areas studied.

“The relative abundance of lowland species is increasing,” Feeley said. “But this is only because there has been a decrease in the abundance of highland species. The general pattern is that species are dying back from the low, hot portions of their range but they are failing to expand their ranges into the newly-suitable habitats at higher elevations. Over just a decade, the species richness of adult trees decreased in 15 of the 16 study plots in Colombia by an average of four species,” he said.

“In theory, we would expect that species should also invade into higher elevations into the areas that used to be too cold for them but that are now ‘just right’. But in most cases, species are not invading the higher elevations,” Feeley added. This, he said, could be due to a lack of dispersal or several other factors that prevent species from establishing in new areas.

The researchers found that, for adult trees, communities with more mammal, bird or wind-dispersed seeds are changing faster in their composition compared to communities with more ant, water, gravity and ballistic dispersal.

From a conservation point of view, this is important because, “we are simultaneously decreasing the abundance of mammal and bird species and fragmenting habitat in these landscapes,” the authors write.

In the case of juvenile trees, compositional changes are associated more strongly with soil conditions that can influence germination and establishment. The researchers found that juvenile tree communities are changing more quickly than adult communities. Feeley said that this is because juvenile tree communities are more dynamic than adult communities. Individuals die and recruit at faster rates, meaning that you can see faster rates of change in composition through time, he said. Adult communities have a lot of momentum; they have big, old trees that tend to stick around even when the climate is no longer right for them.

Other environmental factors such as species-soil adaptations, as well as anthropogenic disturbances like hunting and habitat loss may limit wildlife migrations and consequently decrease the ability of forest communities to respond to climate change, the study points out.

Thermophilization is occurring in trees at rates consistent with concurrent temperature increases, the study found. The findings support the hypothesis that these observed compositional changes are part of a long-term process, such a global warming, and are not a response to any single episodic event. The results all indicate that tropical forests are being strongly affected by climate change and suggest that many species will be at an elevated risk of extinction as warming continues.

Since the 1960s, mean annual temperatures in the province of Antioquia, Colombia, have been increasing. The rate of warming throughout the Neotropics is accelerating and temperatures are expected to increase by two to four degrees Celsius by the end of this century.

Researchers say it is important to keep in mind that climate change involves many variables other than just mean annual temperature. For example, changes in the timing or amount of precipitation can potentially drive species migrations as well. “In other words, the thermophilization of the north Andean tree communities may have the adverse effect of making these forests more moisture-demanding and susceptible to future drought,” the study says. That is bad news for the persistence of these systems because most climate models predict decreasing rainfall, especially over dry season periods, in this region over the coming decades. Changes in the juvenile tree communities also indicate that these forests will continue to undergo compositional shifts long into the future.

Tropical forests are systematically underrepresented in studies examining the effects of climate change, Feeley said. “We tend to focus our attention on systems such as the Arctic or Antarctic where changes are easily visible in the form of melting ice or rising sea levels. But in reality, some of the strongest and most dire effects of climate change are likely to be in the tropical forests,” he said.

Often considered the hottest of all biodiversity hotspots, according to Feeley, the Andes Mountain region is one of the most biologically diverse and threatened regions of the world. Most Andean species have small ranges and many are restricted to narrow elevation bands or even to single valleys or ridges.

“The Andes Mountains contain huge numbers of endemic species which are inherently more sensitive to changes in their environment than widespread generalist species,” Feeley said.

According to the Alliance for Zero Extinction, the study site is home to a number of endangered species like the chestnut-capped piha (Lipaugus weberi) and the chestnut-bellied flowerpiercer (Diglossa gloriosissima), both birds that are native to Colombia. Among the critically endangered species are amphibians like the Antado stubfoot toad (Atelopus galactogaster) that is known only from 10 specimens, the Niceforo’s stubfoot toad (Atelopus nicefori), and the Argelia robber frog (Pristimantis bernali), which occupies an area less than 10 square kilometres (four square miles) in size. Handley’s slender mouse opossum (Marmops handleyi) is another critically endangered species, known only from two individuals that were found within the Antioquia study site.

According to Global Forest Watch, the region encompassing the study site (outlined in green) lost nearly 4 percent — 369,000 hectares — of its tree cover to deforestation and plantation activity between 2001 and 2013. The area features many Alliance for Zero Extinction (AZE) sites, which indicate the ranges of endangered species with limited distributions and populations found nowhere else on the planet.Global Forest Watch data show that the region encompassing the study site (outlined in green) lost nearly 4 percent — 369,000 hectares — of its tree cover to deforestation and plantation activity between 2001 and 2013. The area features many Alliance for Zero Extinction (AZE) sites, which indicate the ranges of endangered species with limited distributions and populations found nowhere else on the planet.

“If tree species are dying back, then the animals that depend on them will inevitably dieback as well,” Feeley said. Indeed, a previous study in Peru showed that bird species are changing their distributions at about the same rates as the tree species.

Many of the thousands of species supported by tropical forests are specialized and adapted to highly stable climates and are therefore very sensitive to changes in climate that we are now causing, Feeley said.

The fact that results from all three independent studies conducted in different parts of the Neotropics are all so consistent between different forests has two big implications: that the driver of these compositional shifts is global warming, and that they are likely occurring in other tropical forests around the world.

“The effects of climate change are ubiquitous and pervasive – they cannot be escaped and they care little about isolation or protection,” Feeley said.

According to the study, high rates of deforestation and loss of wildlife in the study area will likely further decrease forest connectivity and diminish many plant species’ ability to reach new suitable areas in the future.

“Reduced connectivity coupled with accelerating climate change (including both increases in temperatures and reductions in water availability) will result in faster range retractions and may increase the likelihood of local and global extinctions,” the authors write.

But knowing how forests are shifting may help conservationists prepare for a changing world.

“Understanding how species respond to climate change is crucial to the development of effective conservation strategies,” write the authors.

Citations:

  • Feeley, K. J., Hurtado, J., Saatchi, S., Silman, M. R., & Clark, D. B. (2013). Compositional shifts in Costa Rican forests due to climate‐driven species migrations. Global change biology, 19(11), 3472-3480.
  • Feeley, K. J., Silman, M. R., Bush, M. B., Farfan, W., Cabrera, K. G., Malhi, Y., … & Saatchi, S. (2011). Upslope migration of Andean trees. Journal of Biogeography, 38(4), 783-791.

GLADES

I posted earlier about the FIU ecology club, GLADES being named by ESA as their SEEDS chapter of the year.  To follow on that post, I am including below an article written about GLADES and the award, written but Evelyn Perez for FIU NEWS.

Student ecology club named chapter of the year

When Christine Pardo ’14 set out to create a club for students interested in ecological sciences in 2013, she never imagined it would achieve as much success as it has in such a short amount of time.

Christine Prado '14

GLADES — or Growth of Leadership, Academics and Diversity in Ecological Sciences —provides students with a network to explore research, professional development, community outreach and leadership opportunities in ecology, an interdisciplinary field that studies the interactions among organisms and their environment. As a student chapter of the Ecological Society of America (ESA), GLADES’ mission is to diversify the ecology profession by exposing students to the field early on in their college careers.

“The majority of biology majors I had met were on the pre-med track,” said Pardo, GLADES’ founding president. “I knew early on I wanted to pursue ecology research, but felt there weren’t a lot of resources for students like me. Thanks to my mentors, I was inspired to do something about it.”

Conducting research on the cloud forests of the Andes Mountains in Peru during the summer of her junior year, the young field assistant shared her ambitions with her biology professor Kenneth Feeley and doctoral researcher Evan Rehm. Pardo credits them with giving her the confidence she needed to create what she felt was missing on campus; Feeley serves as the club’s faculty adviser.

Since its creation, GLADES has organized a variety of events and initiatives, including panel discussions and lectures on topics ranging from solar energy to climate change and sea level rise; a banquet introducing students to FIU faculty and graduate researchers and their projects; beach clean-ups and other community service events; and an adopt-a-tree program in the community.

Valeria Paz accepts the Ecological Society of America’s Strategies for Ecology Education, Diversity and Sustainability Chapter of the Year award in August.

Now in its second year at FIU, GLADES was named the ESA’sStrategies for Ecology Education, Diversity and Sustainability (SEEDS) Chapter of the Year. SEEDS is the flagship education program of the ESA dedicated to advancing and diversifying the ecology profession through opportunities that nurture the interest of underrepresented students to participate in and lead in ecology.

Ph.D. biology student Valeria Paz ’14 traveled to Baltimore to accept the award on behalf of the club at the 2015 ESA Annual Meeting in August. Paz, a researcher in the Heithaus Lab, presented a research poster on her research on dolphin habitats in the Everglades at the meeting, her first major networking event.

“I had the chance to experience what big questions are being asked in our field,” Paz said. “There’s a lot of great research being done on topics ranging from the effects of climate change, to urban ecology and ecology on invasive species. It’s important to know what’s going on, because it can be relevant to your particular area of study.”

GLADES President Ana Rojas, an environmental studies student, hopes to expand on the club’s momentum by organizing student research panel discussions and outdoor adventure trips; partnering more undergraduate students with graduate students and faculty for mentorship and research experience in the lab and in the field; developing a program advocating for the use of renewable energy on campus; building an orchid garden on campus; and further collaborate with other student clubs on campus.

Pardo, who now works for Miami-Dade County as an environmental regulator, is still actively involved in advising GLADES. She prefers to stay behind-the-scenes, providing information and guidance to help the next generation of club leaders build the foundation for success.

GLADES members attend an environmental leadership workshop at Deering Estate in where they went kayaking and participated in other team-building activities.

“I really wanted to leave a mark at FIU before I graduated. I hope to have empowered young people to create opportunities for themselves and pursue something they love,” Pardo said. “There are so many different pathways to a career in science. I hope GLADES serves as a vehicle for young people in our community to become the next generation of environmental professionals and stewards.”

Please get it right NPR – climate change is real everywhere and not just in the arctic

Over the past couple of days, NPR has given a lot of coverage to climate change associated with President Obama’s visit to the Arctic.  While I appreciate any attention they bring to these important issues, I am very disappointed in some of the statements that they have made which are misleading and simply inaccurate.  In yesterday’s Takeaway program they stated that Obama is in the arctic where “climate change is a reality and not just a theory” and today they again stated that Obama is in the arctic “where climate change is a reality” (or something to that effect). Climate change is a reality everywhere and nowhere is it just a theory.  Climate change is happening in tropical rainforests, beaches, alpine meadows, deserts, boreal forests and arctic tundras.  It is having strong effects everywhere and people livelihoods are being impacted by climate change (although they don’t alway realize it).  What they should be saying is that the effects climate change are ‘more visible‘ in the arctic.