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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Fire ecology | 3/7 | https://en.wikipedia.org/wiki/Fire_ecology | reference | science, encyclopedia | 2026-05-05T07:18:10.171501+00:00 | kb-cron |
== Fire and ecological succession == Fire behavior is different in every ecosystem and the organisms in those ecosystems have adapted accordingly. One sweeping generality is that in all ecosystems, fire creates a mosaic of different habitat patches, with areas ranging from those having just been burned to those that have been untouched by fire for many years. This is a form of ecological succession in which a freshly burned site will progress through continuous and directional phases of colonization following the destruction caused by the fire. Ecologists usually characterize succession through the changes in vegetation that successively arise. After a fire, the first species to re-colonize will be those with seeds are already present in the soil, or those with seeds are able to travel into the burned area quickly. These are generally fast-growing herbaceous plants that require light and are intolerant of shading. As time passes, more slowly growing, shade-tolerant woody species will suppress some of the herbaceous plants. Conifers are often early successional species, while broad leaf trees frequently replace them in the absence of fire. Hence, many conifer forests are themselves dependent upon recurring fire. Both natural and human fires affect all ecosystems from peatlands to shrublands to forests and tropical landscapes. This impacts the way that the ecosystem is structured and functions. Though there have always been wildfires naturally, the frequency of wildfires has increased at a rapid rate in recent years. This is largely due to decreases in precipitation, increases in temperature, and increases in human ignitions. Different species of plants, animals, and microbes specialize in exploiting different stages in this process of succession, and by creating these different types of patches, fire allows a greater number of species to exist within a landscape. Soil characteristics will be a factor in determining the specific nature of a fire-adapted ecosystem, as will climate and topography. Different frequencies of fire also result in different successional pathways; short intervals between fires often eliminate tree species due to the time required to rebuild a seed bank, resulting in replacement by lighter seeded species like grasses and forbs.
== Genetic Diversity ==
=== Genetic Tools === Fire regime has a range of impacts on genetic trends by influencing reproduction, survival, natural selection, and dispersal in individuals, populations, and metapopulations.. Genetic and genomic tools can be used to understand fire's evolutionary role in individuals and populations. The study of genes and their role in inheritance is called genetics. Genetics focuses on how genes direct cell activity and body functions through the proteins they instruct for. Genomics, on the other hand, studies all of the genes within an individual and how that unit of heredity interacts with the individual's environment and with other genes. A few of these genetic technologies are microsatellites (STRs), single-nucleotide polymorphisms (SNPs), and mitochondrial and nuclear genomic sequencing data. STRs allow for genetic variation to be tracked across populations. This is done using short sequences of repeating nucleotides and comparing these sequences across a population. Providing further knowledge of how the disturbance of fire affects population structure and genetic diversity over an immediate and long-term period. SNPs are another method for tracking small DNA changes that show how gene patterns change over time. SNPs are used more to study populations across different regions that display varying fire regimes. This enables the understanding of how fire tolerances are adapted across populations. Mitochondrial and nuclear genomic sequencing data can be used to comprehend both the short-term adaptive responses and the long-term evolutionary effects of fire pressures. Mitochondrial sequencing data can be used to study recent genetic variations in female lineages. Nuclear genomic sequencing, although more susceptible to damage from intense heat, is used to study the entire population's history of adaptations from the combination of maternal and paternal genetic inheritance.
=== Biodiversity === The influence of fire on biodiversity is complex and varies depending on the ecosystem and context of the disturbance. Mortality, immigration, accessibility to affected habitat, fire intensity, and adaptations of species are examples of factors that influence the biodiversity of an area post-disturbance . In some cases, fires reduce genetic diversity. High mortality rates caused by a fire may result in a population bottleneck. This reduces a species' gene pool and may result in decreased genetic diversity in that species, especially if immigration to the disturbed area after the fire is low . The increased occurrence of large and intense fires may also have an effect on biodiversity in burned areas. While more research is needed to understand the effects of these types of fires, some studies suggest they may have a negative impact on biodiversity, especially the effects of human-induced wildfires on species in tropical or temperate broad leaved forests . Wildfires can also promote invasive species, which force out native species and decrease biodiversity by altering nutrients such as nitrogen in the environment . In other cases, fire can increase biodiversity. Many ecosystems rely on fire or other disturbances to drive succession and biodiversity. Organisms living in these ecosystems have adaptations to help them survive fires. For example, some plant species can re-establish themselves post-fire by resprouting. The ability to resprout leads to various mutations accruing within individuals because this trait is hereditary. This can result in beneficial combinations of genes and quicker adaptations . Large, intense fires can be harmful to biodiversity, but smaller, less intense fires can promote biodiversity. These smaller-scale disturbances promote heterogeneity of ecosystems. These heterogenous habitats created by fire disturbances can create niches that promote biodiversity .