Field margins are a crucial aspect of agricultural landscapes which occur in different forms next to all agricultural fields (Marshall 1988; Moonen and Marshall 2001). These margins can provide a series of extremely important functions within the landscape which can be divided according to (de Snoo 1995; Udo de Haes 1995) into agronomy and animal husbandry function by defining land ownership, providing stock fencing and shelter, providing windbreak for crops, enhancing pollination and providing wood and wild game (Marshall et al. 2002; Marshall and Moonen 2002a; Marshall 1993, 1995; Zuria and Gates 2006), environmental role by controlling the transport of pesticides, herbicides and nutrients; reducing erosion and runoff (Balzan and Moonen 2014; Bianchi et al. 2006; Crowder et al. 2010; D’Acunto et al. 2014; Haycock et al. 1992; Powell et al. 2004), conservation role by providing species refugia and complementing biodiversity by providing habitat, feeding and breeding locations (Altieri 1999; De Cauwer et al. 2006; Leidner and Kidwell 2000; Ma et al. 2013; Musters et al. 2009; Pfiffner and Luka 2000; Vickery et al. 2009) and recreational and cultural or historical interests by providing field access, and areas for walking, driving, hunting; promote tourism via aesthetics, maintain culture and heritage (Marshall and Moonen 2002a; Pollard et al. 1974; Zuria and Gates 2006).
Currently, there are a lot of studies have been done in Europe on the importance of the field margins to the agro-ecosystems; which varies between studies done on the vegetation of the field margins (Bassa et al. 2012a; Kleijn and Snoeijing 1997; Moonen and Marshall 2001; Tarmi et al. 2009; Tarmi et al. 2011), birds (Vickery et al. 2009), insects (Fuentes-Montemayor et al. 2011; Ó hUallacháin et al. 2013; Olson and Wäckers 2007) and how the field margins biodiversity can react with the landscape (Bassa et al. 2011; Marshall 2009; Poggio et al. 2010) or on the importance of the field margin itself within the ecosystem (Marshall et al. 2002; Marshall 1995; Marshall and Moonen 2002b); even so, we found that there are few studies about this important piece of the ecosystem have been done in South Korea (Kang et al. 2013; Martin et al. 2013).
In South Korea, at the time that they are trying to improve and expand the agriculture best management practices, organic farming and the green growth, there are no laws controlling the field margin’s management schemes, width or length within the agroecosystems which can help improving this remarkable segment of the ecosystem.
Grasping how plant species growing on the field margins respond to different management schemes and how the individual species and the species richness of field margins can be conserved and reestablished will help enriching their functions and roles within the agroecosystem. Currently, it became well known that the field margin plant species are affected by the surrounding landscape (Marshall et al. 2006) and the management practices (Jobin et al. 1997).
In the current study, we examined the plant species richness and the presence of individual plant species growing at the field margins in relation to the different management activities and the surrounding landscape elements in agricultural landscapes of South Korea. To achieve our goal, we addressed three particular questions:
- Are the natural field margins associated to higher species richness than the managed ones?
- Are the landscape elements and the field margin’s topographic features important for increasing the species richness, if so, which is the most appropriate and at which scale?
- Are the field margin’s management activities and the surrounding landscape elements important for the species distribution, if so, which is the most appropriate and to which species?
Effect of field margin management, topographic features and landscape context on the species richness:
The management of the field margin, landscape context and topographic features explained the variations in the species richness of the field margins in the argroecosystems. According to (de Snoo 1999; Hansson and Fogelfors 2000; Maron and Jefferies 2001; Tarmi et al. 2011), applying cutting activities and/or herbicides to the field margins tend to increase species diversity. Some other studies like (Cordeau et al. 2012; Gove et al. 2007; Jobin et al. 1997; José-María et al. 2013; Kleijn and Snoeijing 1997) showed that using herbicides and/or cutting tend to reduce the species richness; while in (Bassa et al. 2012b; Kang et al. 2013; Marshall and Nowakowski 1996) they stated that there is no effect of cutting nor herbicide’s application on the species diversity and species richness. The current study proved that the natural field margins had higher species richness in compare to the managed ones (Figure 4), during our research, we sampled 300 plots covering the entire study area which gave us the opportunity to analyze the effect of the different management activates in details. On the other hand, the applications of cutting and herbicides to the field margins in South Korea are totally unlike than these in Europe, as the farmers apply the management activities regularly for almost the whole season without allowing the vegetation reestablishment, this suggested our idea that due to the uncontrolled management practices, it was too hard for the species to be replaced, and the remaining species cannot spread (Jobin et al. 1997).
Although lots of studies showed that the field margin width has a positive effect on the species richness (Bassa et al. 2012a; Kang et al. 2013; Ma et al. 2002; Tarmi et al. 2009) our study showed that there is a negative relationship between the field margin width and the species richness (Table 2), that is because we sampled our vegetation data in 3 plots/site where these plots added to the middle of the field margin regardless the width of the field margin itself.
Recent research has taken into account the effect of the landscape context (Sosnoskie et al. 2007; Weibull et al. 2003), landscape heterogeneity (Bassa et al. 2011; Bassa et al. 2012a) and landscape complexity (1″Aavik et al. 2008) on the species richness (Bassa et al. 2012a; Weibull et al. 2003), species diversity (Sosnoskie et al. 2007) and species composition (Aavik et al. 2008; Bassa et al. 2011) within the field margins.
The current research agreed with the above mentioned ones, as we found that the plant species richness in field margins was positively affected by landscape context “% of non crop” at different buffer sizes around the sites (Table 2), we found that by increasing the percentage of the non crop areas, especially at 300m and 400m buffers around the sites, the species richness increased, due to the increasing in the landscape heterogeneity and complexity.
Species response to management and landscape context:
Within the studied that have been done to test the species responses to the environmental variable, we found that there are rare studies that have been done on the effect of the landscape context and management on individual plant species. Some of these studies tested the individual species response to the grazing and management intensities (Dorrough et al. 2007; Dorrough et al. 2012; Dorrough et al. 2011; Dorrough and Moxham 2012; Zimmer et al. 2010a; Zimmer et al. 2010b), while some others tested the plant responses to landscape scales, context and grazing and management (Dorrough et al. 2007; Dorrough et al. 2012). Other studies reported the importance of the landscape context and landscape structure to the response of certain species (Kattwinkel et al. 2009; With and Crist 1995).
In agreement with the previously mentioned studies our study showed the importance of the field margin management “natural or managed” activities and the percentage of the landscape context around the study sites on the distribution of individual species within the study area. We found that the annual grass species with a maximum height of 50cm like Cyperus microiria, Persicaria longiseta, Setaria viridis, Setaria sp were related in their distribution but not restricted to the managed field margins because these species are fast growing in compare to the perennial ones (Figure 6 and Appendix A). While the perennial herbaceous and woody species with a height of more than 100cm like Phragmites japonica, Zizania latifolia, Artemisis spwere in their distribution to the natural field margins as these species get the ability to grow with little disturbance and without any cutting or herbicide applications (Figure 6 and Appendix A).
The same trend has been found in the effect of the non crop percentage on the species distribution, as the perennial species like Phragmites japonica, Eupatorium japonicum, Hypericum sp tend to occupy the field margins which has low non crop percentage, these species characterized by its herbaceous nature and height of more than 100cm (Figure 7 and Appendix A). But species like Bidens frondosa, Persicaria nepalensis, Persicaria thunbergii, Conyza canadensis were found to prefer the field margins with high non crop percentage, these species are annual growing species, weedy nature and with short height ~ 50cm (Figure 7 and Appendix A).
According to the results we have got from the effect of field margins’ management and the landscape context on species distribution and the species richness, we can say that the annual species are responsible for increasing the species richness in the field margin, as they are fast growing even under the cutting and herbicide application activities.
In conclusion, our study proved that in areas like South Korea, new laws and strategies should be developed to control the management schemes within the field margins in the Korean agriculture landscapes. These management schemes will help in conserving the biodiversity by providing the suitable habitats for flora and fauna and consequently, will affect the soil quality and stability which will help in controlling the soil erosion happens during the monsoon time in South Korea. The annual species favor but not restricted to the managed field margins while the perennial species prefer the natural ones. The increasing of the species richness is the responsibility of the annual species as they can grow easily in both the natural and managed field margins. Further long-term research should be done on how we can link the ecosystem services provided by the landscape and the plant diversity within the field margins due to its valuable benefit to the whole ecosystem.
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