Secondary forest
A secondary forest (or second-growth forest) is a forest or woodland area which has regenerated through largely natural processes after human-caused disturbances, such as timber harvest or agriculture clearing, or equivalently disruptive natural phenomena.[1] It is distinguished from an old-growth forest (primary or primeval forest), which has not recently undergone such disruption, and complex early seral forest, as well as third-growth forests that result from harvest in second growth forests. Secondary forest regrowing after timber harvest differs from forest regrowing after natural disturbances such as fire, insect infestation, or windthrow because the dead trees remain to provide nutrients, structure, and water retention after natural disturbances. Secondary forests are notably different from primary forests in their composition and biodiversity; however, they may still be helpful in providing habitat for native species, preserving watersheds, and restoring connectivity between ecosystems.[2]
Development
Secondary forestation is common in areas where forests have been degraded or destroyed by agriculture or timber harvesting; this includes abandoned pastures or fields that were once forests.
Secondary forests re-establish by the process of
Characteristics
Secondary forests tend to have trees closer spaced than primary forests and contain less
Secondary forests can also be classified by the way in which the original forest was disturbed; examples of these proposed categories include post-extraction secondary forests, rehabilitated secondary forests, and post-abandonment secondary forests.[1]
Biodiversity
When forests are harvested, they either regenerate naturally or artificially (by planting and seeding select tree species). The result is often a second growth forest which is less biodiverse than the old growth forest.[5] Patterns of regeneration in secondary forests show that species richness can quickly recover to pre-disturbance levels via secondary succession; however, relative abundances and identities of species can take much longer to recover.[2] Artificially restored forests, in particular, are highly unlikely to compare to their old-growth counterparts in species composition.[5] Successful recovery of biodiversity is also dependent upon local conditions, such as soil fertility, water availability, forest size, existing vegetation and seed sources, edge effect stressors, toxicity (resulting from human operations like mining), and management strategies (in assisted restoration scenarios).[5]
Low to moderate disturbances have been shown to be extremely beneficial to increase in biodiversity in secondary forests.[7] These secondary disturbances can clear the canopies to encourage lower canopy growth as well as provide habitats for small organisms such as insects, bacteria and fungi which may feed on the decaying plant material. Additionally, forest restoration techniques such as agroforestry and intentionally planting/seeding native species can be combined with natural regeneration to restore biodiversity more effectively.[5] This has also been shown to improve ecosystem service functionality, as well as rural independence and livelihoods.[5] Some of these techniques are less successful at restoring original plant-soil interactions. In certain cases (as in Amazon tropical ecosystems), agroforestry practices have led to soil microbiomes that favor bacterial communities rather than the fungal communities seen in old-growth forests or naturally regenerated secondary forests.[3]
Climate change mitigation
Deforestation is one of the main causes of anthropogenic carbon dioxide emissions, making it one of the largest contributors to climate change. Though preserving old-growth forests is most effective at maintaining biodiversity and ecosystem functionality, secondary forests may play a role in
Though not as effective as primary forests, secondary forests store more
Biomes
Rainforests
In the case of semi-tropical
See also
- Land use, land-use change and forestry
- Land use
- Overlogging
- Old-growth forest
- Ecological succession
Notes
- ^ a b c d e f Chokkalingam, U.; de Jong, W. (2001-11-12). "Array - CIFOR Knowledge". CIFOR. Retrieved 2023-04-02.
- ^ PMID 30854424.
- ^ PMC 10108277.
- ^ "Successional Changes in Communities | Learn Science at Scitable". www.nature.com. Retrieved 2023-04-02.
- ^ PMID 18556551.
- ^ "Global Forest Resource Assessment 2020". www.fao.org. Retrieved 2023-04-02.
- ISSN 1297-966X.
- ^ PMID 23894456.
- ^ PMID 24197410.
- ^ "New Jungles Prompt a Debate on Rain Forests" article by Elisabeth Rosenthal in The New York Times January 29, 2009
General References
External links
- M. van Breugel, 2007, Dynamics of secondary forests. PhD Thesis Wageningen University. ISBN 978-90-8504-693-6
- Uzay. U Sezen, 2007, Parentage analysis of a regenerating palm tree in a tropical second-growth forest. Ecological Society of America, Ecology 88: 3065-3075.
- Rozendaal et al., 2019, Biodiversity recovery of Neotropical secondary forests Science Advances, 2019-03-06