Old Growth

Old growth forest, sometimes called '''late seral forest''', '''ancient forest''', '''primary forest''' or ''' Ancient Woodland ''' is an area of Forest that has attained great age and exhibits unique Biological features. Old growth forests typically contain large live Tree s, large dead trees (sometimes called " Snags "), and large Log s. Old growth forests usually have multiple vertical layers of Vegetation representing a variety of tree Species and a variety of different age classes.

Concepts of ''old growth'' vary widely and are not always easily applied or reconcilable with one another. Ancient Woodland is a term used in the United Kingdom to refer specifically to Woodland dating back to at least 1600 in England and Wales , (or 1750 in Scotland ). Before this, planting of new woodland was uncommon, so a wood present in 1600 was likely to have developed naturally. By contrast, in the U.S., ''old growth'' is often used to imply a forest has experienced little or no direct disruption by Euro-Americans and looks about as it would had not Europeans come to America. However, this criterion is difficult to apply, since it is often impossible to determine the history of human management (Euro-American or Native American). Further, since landscapes are naturally dynamic, there can be no certainty what forests would look like now had pre-Columbian regimes been uninterrupted. While it is generally agreed that old forests defined as old growth have not been subject to Logging , the role of natural disturbances in defining old growth is more ambiguous. Some definitions, for example, exclude recently burned forests, even where Fire has been part of the natural dynamics for millennia; in other cases, such natural disturbance is incorporated in the old growth concept. However, it is often difficult to distinguish between the ecological effects of natural disruption and human-caused disruption. Finally, even forests that have never experienced direct manipulation by Euro-Americans have been subjected to indirect effects in the form of Invasive Species , climate change, and regional modifications of Ecological Disturbance regimes (e.g., fire suppression).

Forest regenerated after severe disruptions, such as Clear-cut or Fire is often referred to as Second-growth or ''regeneration'' until a long enough period has passed that the effects of the disturbance are no longer evident. Depending on the forest, this may take anywhere from a century to several millennia. Hardwood forests of the eastern United States can develop old-growth characteristics in one or two generations of trees, or 150-500 years.

Old growth forests may be home to rare species which are dependent on this now-rare habitat. For this reason they have great Environmental importance. Biodiversity may be higher or lower in old growth forests than in second-growth forests depending on specific circumstances. Logging in old growth forests is a contentious issue in many parts of the world.

CHARACTERISTICS OF OLD GROWTH FOREST

Many botanists specifically define old growth in terms of meeting several criteria, under which system forests with sufficient age and minimal disturbance are considered old growth. Typical characteristics of old-growth forest include presence of older trees, minimal signs of human disturbance, mixed-age stands, presence of Canopy openings due to tree falls, pit-and-mound Topography , down wood in various stages of Decay , standing snags (dead trees), multi-layered canopies, intact Soil s, a healthy Fungal ecosystem, and presence of indicator species.

Mixed age

The mixed age of the forest is an important criterion in ensuring that the forest is a stable ecosystem in the long term. A Climax forest that is a uniformly-aged stand becomes senescent and degrades within a relatively short time-period to result in a new cycle of forest Succession . Thus, it is not a stable ecosystem, but one very much in flux.

Canopy openings

Canopy openings are essential in creating and maintaining the mixed-age stands. In addition, some Herbaceous Plant s only become established in canopy openings although they are able to persist thereafter in the darker understory. Canopy openings created by natural disturbance events such as wind, ice, and mixed-severity fire retain significant structural enrichment from dead trees, whereas canopy opening created by logging are structurally simplified and deprived of the legacy structures that normally occur in healthy old-growth forests.

Topography

Pit-and-mound topography is the characteristic lay of the land after trees that have fallen due to natural causes create pits where roots have pulled out and mounds where the Root mass decays (with the soil clinging to the roots). These places provide, in the pit, fresh exposure of Humus -poor, Mineral -rich soil, often a place where moisture may collect and in which fallen leaves soon form a thick Organic layer and so able to nurture certain types of organisms, while the mound provides a place free from leaf inundation and saturation where other types of organisms may thrive.

Decaying ground layer

Down wood directly contributes Carbon -rich organic material directly to the soil, in providing a substrate for Moss es and fungi and for Seedling s, and in creating microhabitats by creating relief on the forest floor. Down wood which is significant in some ecosystems, such as the temperate Rain Forest of the Pacific Coast , for providing a seedling substrate is termed ''nurse logs''.

Standing snags

Standing snags provide food sources and habitat for many types of organisms. Several species of Woodpecker s, in particular, must have standing snags available for feeding. The Spotted Owl is well-known for needing standing snags for nesting habitat.

Soil

Intact soils harbor many life-forms that rely on them. Intact soils generally have very well-defined horizons, or Soil Profile s. Different organisms may need certain well-defined soil horizons in order to live, while many trees need well-structured soils free of disturbance in order to thrive. Some herbaceous plants in northern hardwood forests must have thick duff layers (which are part of the soil profile).

Fungal ecosystems are essential for efficient '' In-situ '' recycling of nutrients back into the entire ecosystem.

IMPORTANCE OF OLD GROWTH FORESTS

Due to the lack of severe disturbance, old growth is often associated with rich communities of Plant s and Animal s that may be dependent upon the unique environmental conditions created by these forests. The age of the oldest trees indicates that disturbance events during the long period of development were of moderate intensity at most and did not kill all vegetation. This long period of pseudostability allows the old growth forest to become occupied over time by a wide variety of species, some of them rare.

Old growth forest serves as a reservoir for species which cannot thrive or easily regenerate in younger forest, and as such can be used as a baseline for research.

Old growth forests also store large amounts of Carbon , both above and below ground. These forests collectively represent a significant pool of climate gases. Continued liquidation of these forests may increase the risk of global Climate Change .

LOGGING IN OLD GROWTH FORESTS

Despite the ecological importance of old growth forests they are logged in many parts of the world. The large trees in old growth forests are economically valuable, so these forests have been subjected to aggressive logging almost everywhere they occur.

It is a major issue around the world where old growth forests stand. For example, in South America logging companies provide the local people a pittance to log the trees that have stood for (in some cases) thousands of years.

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Old Growth