Half of replanted tropical trees don't survive, new study finds

[Still Waters]

On average, about half of trees planted in tropical and sub-tropical forest restoration efforts do not survive more than five years, but there is enormous variation in outcomes, new research has found.

The study analyzed tree survival and growth data from 176 restoration sites in tropical and sub-tropical Asia, where natural forests have suffered degradation. The team found that, on average, 18% of planted saplings died within the first year, rising to 44% after five years. However, survival rates varied greatly amongst sites and species, with some sites seeing over 80% of trees still alive after five years, whereas at others, a similar percentage had died.

About 15% of the world's tropical forests are found in Southeast Asia and they are amongst the most carbon-dense and species-rich in the world, providing habitat for tigers, primates and elephants. However, in recent decades the region has also seen major deforestation, with forest cover reducing by an estimated 32 million hectares between 1990 and 2010.

https://phys.org/news/2022-11-replanted-tropical-trees-dont-survive.html

The findings are published today in the Philosophical Transactions of the Royal Society B: Biological Sciences.

https://royalsocietypublishing.org/doi/10.1098/rstb.2021.0090

[Doug1066]

Results sound about average.

Survival rates for my test ponderosa pine plantings in Colorado were about 50% after twenty years.

Assume 400 seedlings per acre in the initial planting.  That's 200 per acre with 20-year survival.  It's 100 per acre after 40 years.  By that time the trees are sawlog size.  In the tropics, they're even bigger.  So you end up over-stocked with 100 trees per acre.  Now you need to thin them to keep them growing.  So 50% survival after five years is pretty good.

Doug