The definition of ancient woodland includes several sub-types. Ancient semi-natural woodland (ASNW) is composed of native tree species that have not obviously been planted; features of ancient woodland often survive in many of these woods as well, including characteristic wildlife and structures of archaeological interest. Species which are particularly characteristic of ancient woodland sites are called ancient woodland indicator (AWI) species, representing a type of ecological indicator.[3] The term tends to be applied more usefully to desiccation-sensitive plant species, and particularly lichens and bryophytes, than to animals, as they are slower to colonise planted woodlands, and are thus viewed as more reliable indicators of ancient woodland sites. Sequences of pollen analysis are also indicators of forest continuity. Lists of ancient woodland indicator species among vascular plants were developed by the Nature Conservancy Council (now Natural England) for each region of England, each list containing the hundred most reliable indicators for that region. The methodology involved studying the flora of known woodland sites and analysing patterns of occurrence to determine which species were most indicative of sites from before 1600. Although ancient woodland indicator species can and do occur in post-1600 woodlands, and also in non-woodland sites such as hedgerows, it is uncommon for a site which is not ancient woodland to host a double-figure AWI species total.[4] Wildlife traditionally refers to non-domesticated vertebrates, but has come to broadly reference to all wild plants, animals and other organisms . Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative. Wildlife can be found in all ecosystems. Deserts, forests, rain forests, plains, grasslands, other areas including the most developed urban sites, all have distinct forms of wildlife. While the term in popular culture usually refers to animals that are untouched by human factors,[1] most scientists agree that wildlife around is impacted by human activities. Humans have historically tended to separate civilization from wildlife in a number of ways including the legal, social, and moral sense. Religions have often declared certain animals to be sacred, and in modern times concern for the natural environment has provoked activists to protest the exploitation of wildlife for human benefit or entertainment. Lichens (pron.: /?la?k?n/,[1] sometimes /?l?tn/)[2] are composite organisms consisting of a fungus (the mycobiont) and a photosynthetic partner (the photobiont or phycobiont) growing together in a symbiotic relationship. The photobiont is usually either a green alga (commonly Trebouxia) or cyanobacterium (commonly Nostoc).[3] The morphology, physiology and biochemistry of lichens are very different from those of the isolated fungus and alga in culture. Lichens occur in some of the most extreme environments on Earth—arctic tundra, hot deserts, rocky coasts, and toxic slag heaps. However, they are also abundant as epiphytes on leaves and branches in rain forests and temperate woodland, on bare rock, including walls and gravestones, and on exposed soil surfaces (e.g., Collema) in otherwise mesic habitats. The roofs of many buildings have lichens growing on them. Lichens are widespread and may be long-lived;[4] however, many are also vulnerable to environmental disturbance, and may be useful to scientists in assessing the effects of air pollution,[5][6][7] ozone depletion, and metal contamination. Lichens have also been used in making dyes and perfumes, as well as in traditional medicines.