(CN) — Is modern land development catalyzing biodiversity and population decline throughout forested regions of the world? It both is and isn’t. It depends. The solution isn’t as clear-cut as you might imagine.
The authors of a new study published Thursday in the journal Science analyzed a multitude of data sets to answer that question and found certain some species of plants and animals are better able to adapt to forest loss than others, while some exhibit a delayed response by as much as 50 years.
“Surprisingly, we found that forest loss did not always lead to biodiversity declines. When forest cover declined, change intensified, including both gains and losses of biodiversity. We found that forest loss amplified both increases and decreases in the abundance of different plant and animal species,” said Gergana Daskalova, a doctoral candidate in the School of GeoSciences at the University of Edinburgh and lead author of the study.
Depending if their kind has experienced habitat loss in the past, and a range of other factors, certain species are quite resilient. Some experience the changes more slowly, such as certain mammals, birds and large trees — those with a longer interval between generations.
It can take decades for environmental change to manifest in many of these, so alterations to their habitat pose less of a short-term threat. They can even prove beneficial to some, such as the skylark and the red fox.
Others don’t fare so well. Those with shorter intergenerational periods, and those from regions that have seen little past deforestation and land development exhibit the greatest near-term disruptions, like the swift parrot and the tiger.
"Biodiversity, the types of species like different plants and animals around the world, is always changing and the species we see on our forest walks today are likely different from the ones we saw growing up,” Daskalova said.
Nearly 80% of all land-dwelling animals reside in the forest, from bears, beetles, eagles and ocelots. They’re a critical bioregion of our planet. When forests are cleared to make way for human development, some species inevitably decline, typically those with unique adaptations especially well-suited for that particular environment, while others seem to thrive. The result is something of a shuffling — a new order of things.
Tropical regions are currently feeling the greatest impact of deforestation. These areas are often cleared in giant swaths to make way for the palm-oil plantations responsible for 40% of the forest loss occurring around the world today. North America and Europe experienced their greatest loss of forest cover centuries ago, peaking in the early 1800s. That was before scientists began using satellite monitoring to track population and biodiversity across the globe.
The authors studied 2,729 populations of 730 species in 3,361 ecological assemblages. By analyzing the BioTIME and Living Planet databases, covering nearly 5 million records, they were able to traverse a vast spectrum of forest loss and gain across the planet.
"Our new study provides a long-term perspective to how biodiversity is being altered over time as forests are changing across over 6,000 sites,” added Daskalova. “By bringing together data that scientists collect year after year at places around the world, we were able to find signals amidst the noise.”
The authors tested three ways in which forest loss influences species population and richness – historical baselines of forest loss, timing of contemporary forest loss and temporal lags in population and biodiversity. They found the greatest change to populations and ecological assemblages occurred 6 to 13 years after forest loss, while 40% happened within three years.
“The complexity and heterogeneity of forest cover change effects on biodiversity demonstrate that caution is warranted with respect to recent calls for global afforestation as a climate change mitigation tool,” according to the study.
The authors of another study published Thursday in Science may concur. They point out that leaning too heavily on increasing forest cover as a means of carbon sequestration can be a double-edged sword.
While forests absorb and store massive amounts of carbon dioxide from the surrounding air — just under a third of total carbon dioxide emitted worldwide — that leaves them especially vulnerable to the types of wildfires that have ravaged parts of California and Australia in recent years. When a forest burns down, that stored carbon goes up in smoke, which means relying too heavily on them to solve global warming is risky. Forests are also especially vulnerable to insects and other natural disasters.
"There's a very real chance that many of those forest projects could go up in flames or to bugs or drought stress or hurricanes in the coming decades," said William Anderegg, a biologist from the University of Utah.
While the authors still advocate for investing in forest cover, it’s important to take these factors into consideration and minimize risk. Anderegg adds: "If we're worried about fire as a major risk in a certain area, we can start to think about what are the management tools that make a forest more resilient to that disturbance.”
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