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The natural range of the moose, Alces alces in Europe had been reduced during historical times and the species became extinct in western Europe. In Poland, being the edge of the species' natural range the moose population survived in the wild. After the Second World War, the moose was critically endangered in Poland. Fortunately, its number considerably increased, most probably due to immigration of large numbers of individuals from the former Soviet Union and the demographic expansion of autochthonous, relic population at the Biebrza valley. Starting for 1952 the species was strictly protected and in 1967, when population was about 600 individuals, the sustainable harvest (hunting) was established. Demographic expansion of moose populations continued through 60. and 70-ties of the XXth century and resulted in its maximum (ca 6200 individuals) in 1981. The moose was present at Polish lowlands and reached the German boundary. Unfortunately, overhunting that continued for over 20 years became a considerable threat to a species and their numbers were reduced by over 70%. Many populations in western and central Poland became extinct till 2001. The reduction was explained by demands of forest protection, as moose in Poland caused significant damages in young-growth forests. As the species became endangered, no hunting is allowed since 2001. This decision of the Ministry of Environment resulted in the recovery of moose populations and the species is now abundant, especially in eastern part of Poland. The future of the moose in Poland will depend on "The strategy for moose protection and management", being prepared by a team of scientists, National Forest Holding and Polish Hunting Association. This evidence based-management plans should help to maintain viable populations and lower the damages in young-growth forests as well as the risk of car accidents with moose.
The insects' behaviour and development of pest populations are closely related to the host plant separation in respect of the time or space. The more food-specialization of pests could mean the greater possibilities to control them and may affect less damages of host plants, when they are growing together with non-host plants. Monophagous insects, strictly connected with one species very often couldn't find out their food, shelter and oviposition requirements within the crops consisted of different species. Population densities of olygophagous insects (botanical family is spectrum of hosts) are strongly restricted by the mixtures composed with taxonomically unrelated species, such as Poaceae and Papilionaceae. For example, the cereal leaf beetles - dangerous pest for all cereal species may damage about 50% more cereal plants in pure stand than in the cereal-leguminous mixtures. The numerous empirical data and several theoretical arguments are presented that suggest that the differences in pest abundance between diverse and simple annual crops can be accounted for by the response of herbivore host-finding behaviour to the patterns of recourse availability rather than the activities of natural enemies. The multicropping systems, especially inter-species mixtures, may provide short-term benefits such as: - reduced insect-pest populations, - decreased losses of plant yield, - decreased pest control costs.
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