Forests in crisis
Over the past three decades ,
420 million hectares of the world ’ s forests have vanished , according to estimates from the United Nations ’ Food and Agriculture Organization ( FAO ). That area represents a little more than half the contiguous United States .
These are losses the world can ’ t afford . Trees are a critical buffer against climate change . Forests absorb an estimated 7.6 billion metric tonnes of carbon dioxide a year from the planet ’ s atmosphere , or one and a half times the US annual total ,
according to a recent study by the World Resources Institute .
Trees are being destroyed by building development , wildfires , landslides , and other environmental
factors , but agriculture drives almost 90 % of deforestation ,
according to a recent FAO study : Conversion to cropland accounts for more than half , livestock grazing almost 40 %.
Recognizing the crisis , leaders of 140 countries representing 91 % of the world ’ s forests agreed to “
halt and reverse forest loss and land degradation by 2030 ” at the COP26 climate talks in Glasgow last year .
“ Nature-based solutions for forests and land — things like forest protection , improved forest management , and forest restoration — can help reverse all those trends that we ’ re seeing around the world ,” says Linda Walker , senior director of corporate engagement , forests , for World Wildlife Fund ( WWF ).
A broad group that includes scientists , governments , nonprofits , and businesses is exploring what reforestation actually means when done right .
Learning the right way to reforest
Reforestation has gotten some big boosts in recent years , such as the World Economic Forum ’ s 1t . org initiative , a plan to conserve , restore , and grow 1 trillion trees globally by 2030 , and the Jane Goodall Institute , an organization founded by renowned scientist and conservationist Dr . Jane Goodall to protect and restore forests . WWF ’ s Walker says that even though much of the world ’ s forestland remains at risk , the opportunity to reverse course is promising .
Several companies , including HP , are part of the 1t . org project , which emphasizes the word “
grow ” over “ plant ,” its website notes , because “ simply putting a seedling in the ground is not sufficient — that tree needs to be supported to maturity to reach its full potential . It also needs to be the right species , planted in the right conditions .”
Reforestation means restoring a forest to where it once was , not creating a new forest where there never was one , which might mean destroying a different , but critical , ecosystem . The consequences for ignoring this fundamental premise can be costly in terms of both carbon and cash , and ongoing scientific research offers clues about what works and what doesn ’ t .
In South Africa , non-native Australian acacias planted in the 19th and 20th centuries ended up taking over natural grasslands and lowering the water table , and now the annual chore of clearing them costs
millions of dollars . Scientists from the Botanic Gardens Conservation International and the Royal Botanic Gardens , Kew , cite the acacia example in a post introducing “
10 Golden Rules for Restoring Forests ,” which lays out simple best practices , such as selecting the right area and planting species that can maximize biodiversity .
Paying attention to these lessons will determine the success or failure of the many public and private reforestation efforts now underway around the world .
“
We can only effectively plant trees in locations where at some point in time they were cut down or destroyed ,” notes Ansgar Kahmen , a botanist and professor of environmental science at the University of Basel who studies
how reforestation changes in the face of a changing climate . “ I think we ’ re fooling ourselves if we think we can keep burning fossil fuels and planting a tree will compensate for it .”
Complications of climate change
The challenge of what to plant , and where , becomes trickier with climate change . Ongoing research is aimed at discovering which trees will thrive in a warming world .
At a research site in northern Switzerland equipped with a crane that hoists researchers into the canopy , Kahmen and colleagues are simulating drought on a subset of trees by putting a roof over them , diminishing the amount of rain they get . The goal is to see not only how species respond , but which might be most adaptable .
“ There ’ s a big debate in Europe at the moment : What are the appropriate trees that we should reforest with ? And there is no consensus ,” Kahmen says . “ It actually opens a big ecological discussion . What is a native tree in the future ?”
These kinds of questions are relevant far beyond Europe , as forests are being planted in different regions , with varying objectives , worldwide . Between 2000 and 2018 , 46 million hectares of forest were planted , almost a quarter of which replaced naturally regenerating forests , according to a
2020 remote sensing survey from the FAO .
But merely restoring tree cover does not guarantee long-term success , particularly as saplings face conditions that might be different from those of their ancestors . “ Ecosystems do have some resilience , but we don ’ t really know what this resilience is for different species that we work with , and how fast they can actually acclimate ,” Kahmen says .
Scientists like Kahmen and Stewart are developing the research and technology needed to inform planted trees ’ survival in the decades to come . Stewart has built computer-based tools that can help ecosystem managers identify , for example ,
which wildfire-scarred areas are not likely to regenerate on their own and may need intervention , and
which species are likely to thrive as environmental and climate conditions evolve .
“ With the climate changing as fast as it has , tree populations often aren ’ t adapted to the local conditions anymore ,” Stewart says . For example , climate models predict that conifer forests like the one destroyed by the Camp Fire , made up of ponderosa pine and Douglas fir , will be replaced by mixed forests of oaks and pines , chaparral , or grassland .
In such cases , seeds might come from slightly different locations than where they are being replanted . The Bureau of Land Management ’ s
reforestation plan for the Camp Fire includes a
OPPOSITE PAGE : PHOTOGRAPH BY BOYOUNG LEE
HP / INNOVATION / SUMMER 2022 48