Product Code Database
An oak savanna is a type of savanna (or lightly forested grassland), where ( Quercus spp.) are the dominant trees. It is also generally characterized by an understory that is lush with grass and herb-related plants. The terms "oakery" or "" are also used commonly, though the former is more prevalent when referencing the Mediterranean area. Oak savannas typically exist in areas with low precipitation and feature poor soils. Predominant land uses include rangeland agriculture. Naturally, these savannas depend on natural wildfires (e.g. caused by lightning) to maintain their open vegetation.
According to the findings of Victoria A. Nuzzo, since there is much variation per state, other names used for the Midwestern oak savanna are oak opening, scrub prairie, oak barrens, and brush savanna.
The bur oak ( Quercus macrocarpa) is the dominant species in northern oak savannas, although black oak ( Quercus velutina), white oak ( Quercus alba), and Hill's oak ( Quercus ellipsoidalis) are sometimes present. The dominant tree in the south is usually black oak, although the chinquapin oak ( Quercus muhlenbergii), post oak ( Quercus stellata), and black-jack oak ( Quercus marilandica) are also common.
The flora of the herbaceous layer generally consists of species associated with tallgrass prairies, both grasses and flowering plants, although some woodland species may be present. Some of these plants can include white wild indigo plant ( Baptista lucantha), purple coneflower ( Echinacea purpurea) and pasture rose ( Rosa carolina). There are also a few species that are unique to oak savannas. Some important species in the midwest oak savanna include a variety of bats, like the evening bat ( Nycticeius humeralis) found in Missouri, and many types of birds, including the blue winged warbler ( Vermivora cyanoptera), field sparrow ( Spizella pusilla), and summer tanager ( Piranga rubra). Oak savannas, because of their mixture of grassland, woodland, and unique savanna species, typically have a higher plant diversity than grasslands and woodlands combined.
Research by Granado-Díaz, Villanueva, & Colombo (2024) on land manager preferences for environmental services in oak savannas offers historical insights into the evolution of conservation strategies. This study illuminates the critical role of managing understory vegetation for ecological health, integrating seamlessly with the natural that shaped these ecosystems. These findings underscore the importance of preserving the intricate balance between fire, vegetation, and wildlife that defines the oak savanna's unique ecological identity. The understory flourishes from exposure, as the oaks tend to be scattered, making for a less dense canopy. Fires contain the oak population, as too much shade would eliminate the grasses underneath.
The most fire-tolerant of the oak species is the bur oak ( Quercus macrocarpa), which is especially common in hill-country savannas in the Midwest.
European settlers cleared much of the savanna for agricultural use. In addition, they suppressed the fire cycle. Thus surviving pockets of savanna typically became less like savannas and more like forests or thickets. Many oak savanna plant and animal species became extinct or rare.
However, a lack of generalized terminology or documentation in historical records has made it difficult to know about the past state of oak savannas.
Two separate studies done by Garrastatxu et al. (2024) and Encinas‐Valero et al. (2024) have identified the crucial role of fungal Symbiosis and the tree-soil microbial system in the health of oak savannas, underlining the importance of these factors in restoration practices. This insight is pivotal, as it highlights the interconnectedness of all elements within the oak savanna ecosystem, emphasizing that successful restoration efforts must account for the complexity of biological relationships. Similarly, the study by Hsiao et al. (2024) on the impact of vegetation and geology on soil nutrient storage in juniper–oak savannas emphasizes the need to consider soil health in restoration efforts.
Restoration work in the US began in the 1970s in Illinois, followed by work in Wisconsin, Indiana, Iowa, Missouri, and Minnesota. (1996). 9780671780456, Gallery Books. ISBN 9780671780456 The Bald Hill Natural Area in Corvallis, Oregon, was established in the 1990s in part to protect oak savanna remnants. At one point in time the oak savanna was the most common type of vegetation found in the midwest, but it is now endangered with many ecologists every year working on replacing the oak savannas that have been destroyed in the past.
For centuries, the issue of oak regeneration failure has been acknowledged. Historical records, such as French ordinances dating back to the 13th century, illustrate early recognition of obstacles to oak regeneration. These ordinances required the planting of oak seedlings to prevent overharvesting, given oak's significant timber worth and adaptability.
Valadi et al. have explored the conflicting edge influences on herbaceous species in oak savannas, shedding light on the complex interactions that impact the distribution and conservation status of these ecosystems today. This research underscores the need for nuanced conservation strategies that address both the macro and microecological pressures impacting oak savanna preservation.
Many sites are protected and maintained by government bodies or non-profit organizations such as The Nature Conservancy, the Wisconsin and Minnesota Departments of Natural Resources, and the Iowa Natural Heritage Foundation. In the midwest, about only 30,000 acres total of oak savanna still exist. The savannas that remain are fairly small at about 100 acres and this rarity has caused them to be categorized as “globally imperilled”. It is estimated that about only less than 0.02% of the original savannas remain due to human interaction and many organizations and conservations are prioritizing restoring and recreating these ecosystems in the midwest.
Examples of remnant oak savanna include:
Examples of restored oak savanna sites:
In the Eastern Mediterranean, oak rangelands are still common landscape elements in Greece, Anatolia and the Levant. They are formed by a number of oak species, including pedunculate oak ( Quercus robur), sessile oak ( Quercus petraea subsp. polycarpa), downy oak ( Quercus pubescens), Hungarian oak ( Quercus frainetto), Quercus dalechampii, Strandzha oak ( Quercus hartwissiana), Austrian oak ( Quercus cerris), Macedonian oak ( Quercus trojana), holly oak ( Quercus ilex), Kasnak oak ( Quercus vulcanica), Aleppo oak ( Quercus infectoria), Lebanon oak ( Quercus libani), Tabor oak ( Quercus ithaburensis), Valonia oak ( Quercus ithaburensis subsp. macrolepis), Brant's oak ( Quercus brantii), Quercus aucheri, Quercus look and kermes oak ( Quercus coccifera).
|
|
