afforestation

Aug

2023

The impacts of land degradation

This graphics [1] very nicely outline the consequences of large-scale logging – and then later monocultural afforestation – on the landscape. Without forest, no more soil, no water absorption, ergo soil erosion, silting, (flash) floods. Coniferous forest monocultures do only help in the short term – they do not form fertile soil, and are harvested in clear-cutting. Solution: Diverse permanent forests. Hmm, that’s not so difficult to understand, is it?!

[1] https://thespinoff.co.nz/society/28-07-2023/the-side-eye-deeper-roots

Jul

2022

Local temperature response to land cover and management change driven by non-radiative processes

Cooling forests: Here, we combine extensive records of remote sensing and in situ observation to show that non-radiative mechanisms dominate the local response in most regions for eight of nine common LCMC perturbations. We find that forest cover gains lead to an annual cooling in all regions south of the upper conterminous United States, northern Europe, and Siberia—reinforcing the attractiveness of re-/afforestation as a local mitigation and adaptation measure in these regions. Our results affirm the importance of accounting for non-radiative mechanisms when evaluating local land-based mitigation or adaptation policies.

Jul

2022

Large-scale semi-arid afforestation can enhance precipitation and carbon sequestration potential

More forests, more rain: …that implementing measured characteristics of a successful semi-arid afforestation system (2000 ha, ~300 mm mean annual precipitation) over large areas (~200 million ha) of similar precipitation levels in the Sahel and North Australia leads to the weakening and shifting of regional low-level jets, enhancing moisture penetration and precipitation (+0.8 ± 0.1 mm d−1 over the Sahel and +0.4 ± 0.1 mm d−1 over North Australia), influencing areas larger than the original afforestation. These effects are associated with increasing root depth and surface roughness and with decreasing albedo. This results in enhanced evapotranspiration, surface cooling and the modification of the latitudinal temperature gradient. It is estimated that the carbon sequestration potential of such large-scale semi-arid afforestation can be on the order of ~10% of the global carbon sink of the land biosphere and would overwhelm any biogeophysical warming effects within ~6 years.

Jun

2022

Cloud cooling effects of afforestation and reforestation at midlatitudes

Interesting analysis:

Here, we carefully analyze the situation for reforestation and afforestation (R&A) at midlatitudes, where the warming effects due to vegetation albedo are regarded to be almost balanced by the cooling effects from an increased carbon storage. Using both satellite data and atmospheric boundary-layer models, we show that by including cloudalbedo effects due to land–atmosphere interactions, the R&A cooling at midlatitudes becomes prevalent. This points to a much greater potential of R&A for wet temperate regions than previously considered.

Apr

2022

Revealing the widespread potential of forests to increase low level cloud cover

Forests, afforestation, evapotranspiration, and its cooling effect:

However, changing the forest cover can further affect the climate system through biophysical effects. One such effect that is seldom studied is how afforestation can alter the cloud regime, which can potentially have repercussions on the hydrological cycle, the surface radiation budget and on planetary albedo itself. Here we provide a global scale assessment of this effect derived from satellite remote sensing observations. We show that for 67% of sampled areas across the world, afforestation would increase low level cloud cover, which should have a cooling effect on the planet. We further reveal a dependency of this effect on forest type, notably in Europe where needleleaf forests generate more clouds than broadleaf forests.

The scientists emphasize that land-based climate mitigation through afforestation, forest restoration and avoided deforestation should not be reasoned purely in terms of carbon capture. Instead, policies should include the wider climate benefits that forests offer, including increasing cloud cover for localized cooling and generating rainfall, giving forests additional hydrological value.