مقاله انگلیسی رایگان در مورد تحت تاثیر قرار گرفتن علف های هرز محیط زیست با وراثت – اسپرینگر 2017

Ecologists have recognized two important successions: initial succession, which is the occurrence of ecosystem expansion on the sites that have not been previously occupied by living organisms (such as bare rocks and frozen surfaces); and secondary succession, which happens in the ecosystems, which have been previously occupied by organisms. Tilled felds, clear-cut forests, and burned areas are all exposed to secondary succession (Letcher 2010; Podda et al. 2011; Rezvani et al. 2013). During the succession, vegetative variations are not coincidental, and spread of vegetation is regularly carried out with the following functional variations (Dölle et al. 2008; Schmid et al. 2017). The early stages in succession include species, which have light seeds (Rockwood 1985), high seed production (Hyatt and Casper 2000), extensive distribution (Samuel and Hart 1994), and rapid growth rate (Lambers et al. 2008). Species with large seeds have longer life period, meaning they are more competitive and dominant in the fnal stages of succession (Fenesi et al. 2014). In such stages, perennial weed species replace the annual ones (Corbin and D’Antonio 2004) in a period of one (Brown et al. 1987) to 40 years (Bornkamm 1981). The rate of these events depends on factors such as soil (Dzwonko and Loster 1997; Fanelli and Lucchese 1998), climate (Calvo et al. 2005), weed seed bank (Bekker et al. 2000), and the initial density of perennial weed species (Turner et al. 1998). The establishment of juvenile plants, bush, and weed under the tree shadow idiomatically is called ‘understory’ (Leopold and Solozar 2008) that have interference with trees. The interactions between weed growth and tree behaviour have been addressed by diferent studies (Cantarelli et al. 2006; Rondon 2006; Bonari et al. 2017). For example, Larpkern et al. (2010) have identifed specifc species of weeds under the trees after tillage. It is preferable that such weeds be controlled at the early stage of growth, or the use of repair trends become difcult. Increased frequency of species is largely controlled by seed production, species growth rate (Chapin et al. 1997), and competitiveness (Tilman 1988). The chemicals characteristics of soil such as nutrients, salts, and organic matter may cause the appearance of specifc weed species (Garnier et al. 2004; Salama et al. 2017). Some research work has shown a correlation between variation of soil nutrients and plant composition (Shaltout et al. 2014; Angiolini et al. 2017). For example, when soil nitrogen and organic matter reduces, bushes are replaced with grasses (Reynolds et al. 1999; Suding et al. 2008).