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A secondary forest (or second-growth forest) is a
forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
or
woodland
A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the ''plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...
area which has re-grown after a
timber harvest
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars.
Logging is the beginning of a supply chain ...
or clearing for agriculture, until a long enough period has passed so that the effects of the
disturbance are no longer evident. It is distinguished from an
old-growth forest
An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...
(primary or primeval forest), which has not recently undergone such disruption, and complex early
seral
A seral community is an intermediate stage found in ecological succession in an ecosystem advancing towards its climax community. In many cases more than one seral stage evolves until climax conditions are attained. A prisere is a collection of se ...
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
Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction Product (chemistry), products.
At a certain point in the combustion reaction, called the ignition ...
, insect infestation, or
windthrow
In forestry, windthrow refers to trees uprooted by wind. Breakage of the tree bole (trunk) instead of uprooting is called windsnap. Blowdown refers to both windthrow and windsnap.
Causes
Windthrow is common in all forested parts of the w ...
because the dead trees remain to provide nutrients, structure, and water retention after natural disturbances. However, often after natural disturbance the timber is harvested and removed from the system, in which case the system more closely resembles secondary forest rather than seral forest.
Description
Depending on the forest, the development of primary characteristics may take anywhere from a century to several millennia.
Hardwood forests
Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions.
These f ...
of the
eastern United States
The Eastern United States, commonly referred to as the American East, Eastern America, or simply the East, is the region of the United States to the east of the Mississippi River. In some cases the term may refer to a smaller area or the East C ...
, for example, can develop primary characteristics in one or two generations of
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s, or 150–500 years. Often the disruption is the result of human activity, such as
logging
Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidding, on-site processing, and loading of trees or logs onto trucks or skeleton cars.
Logging is the beginning of a supply chain ...
, but natural phenomena that produce the same effect are often included in the definition.
Secondary forests tend to have trees closer spaced than primary forests and contain less
undergrowth
Undergrowth usually refers to the vegetation in the lower part of a forest, which can obstruct passage through the forest. The height of undergrowth is usually considered to be 0.3 – 3 m (1 – 9 ft.). Undergrowth can also refer to all ...
than primary forests. Secondary forests typically were thought to lack
biodiversity
Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
compared to primary forests, however this has been challenged in recent years. Usually, secondary forests have only one
canopy
Canopy may refer to:
Plants
* Canopy (biology), aboveground portion of plant community or crop (including forests)
* Canopy (grape), aboveground portion of grapes
Religion and ceremonies
* Baldachin or canopy of state, typically placed over an a ...
layer, whereas primary forests have several.
Secondary forestation is common in areas where forests have been lost by the
slash-and-burn
Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden. The method begins by cutting down the trees and woody plants in an area. The downed vegeta ...
method, a component of some
shifting cultivation
Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. The period of cul ...
systems of agriculture. Secondary forests may also arise from forest that has been harvested heavily or over a long period of time, forest that is naturally regenerating from fire and from abandoned pastures or areas of agriculture. It takes a secondary forest typically forty to 100 years to begin to resemble the original old-growth forest; however, in some cases a secondary forest will not succeed, due to
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
or
soil nutrient loss in certain
tropical forest
Tropical forests (a.k.a. jungle) are forested landscapes in tropical regions: ''i.e.'' land areas approximately bounded by the tropic of Cancer and Capricorn, but possibly affected by other factors such as prevailing winds.
Some tropical fores ...
s.
Secondary forests re-establish by the process of succession. Openings created in the
forest canopy
In biology, the canopy is the aboveground portion of a plant cropping or crop, formed by the collection of individual plant crowns.
In forest ecology, canopy also refers to the upper layer or habitat zone, formed by mature tree crowns an ...
allow sunlight to reach the forest floor. An area that has been cleared will first be colonized by pioneer species. Even though some species loss may occur with primary forest removal, a secondary forest can protect the watershed from further erosion and provides habitat. Secondary forests may also buffer
edge effect
In ecology, edge effects are changes in population or community structures that occur at the boundary of two or more habitats. Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range. As ...
s around
mature forest fragments and increase connectivity between them. They may also be a source of wood and other forest products.
Today most of the forests of the United States- especially in the eastern part of North America, as well as forests of Europe consist of secondary forest.
When forests are harvested, they either regenerate naturally or artificially (by planting and seeding select tree species). The result is a second growth forest which is less biodiverse than the old growth forest. In order to increase the biodiversity, it is possible to create low to moderate disturbances. Examples of these could be felling certain trees, damaging the tree trunks, and the creating small controlled burns. Low to moderate disturbances have been shown to be extremely beneficial to increase in biodiversity in secondary forests. 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.
Rainforests
In the case of semi-tropical
rainforest
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...
s, where soil
nutrient
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...
levels are characteristically low, the soil quality may be significantly diminished following the removal of
primary forest
An old-growth forestalso termed primary forest, virgin forest, late seral forest, primeval forest, or first-growth forestis a forest that has attained great age without significant disturbance, and thereby exhibits unique ecological featur ...
. In
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
, growth of new forests from abandoned farmland exceeded loss of primary rainforest in 1990.
"New Jungles Prompt a Debate on Rain Forests"
article by Elisabeth Rosenthal in ''The New York Times
''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...
'' January 29, 2009 However, due to the diminished quality of soil, among other factors, the presence of a significant majority of primary forest species fail to recover in these second-growth forests.
See also
* Land use, land-use change and forestry
Land use, land-use change, and forestry (LULUCF), also referred to as Forestry and other land use (FOLU), is defined by the United Nations Climate Change Secretariat as a " greenhouse gas inventory sector that covers emissions and removals of gr ...
* Land use
Land use involves the management and modification of natural environment or wilderness into built environment such as settlements and semi-natural habitats such as arable fields, pastures, and managed woods. Land use by humans has a long h ...
*Overlogging
Overlogging is a form of overexploitation caused by legal or illegal logging activities that lead to unsustainable or irrecoverable deforestation and permanent habitat destruction for forest wildlife.
Causes
The use of poor logging practices a ...
Notes
References
CIFOR Secondary Forest
World Resource Institute
External links
*M. van Breugel, 2007
Dynamics of secondary forests
PhD Thesis Wageningen University.
*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
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Forest ecology
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Reforestation
Environmental issues with forests