THE PERFORMANCE OF UNDERSTOREY HERBACEOUS PERENNIALS IN LOW MAINTAINED URBAN PARKS

The stylized naturalistic herbaceous perennial planting is the most innovative approach in the urban landscape (Dunnett and Hitchmough, 2007; Oudolf and Kingsbury, 2014; Rainer and West, 2015). The characteristic beautiful prairies and meadows ecosystem (Schmithals and Kuhn, 2017; Hitchmough, 2017), as well as the herbaceous understory vegetation (Martinek, 2004; Hillová, 2010; Schulte, 2017) became the most frequent sources of inspiration for landscape designers around the world. The enrichment of herbaceous layers is an essential part of recreation of urban woodland and urban parks in last decades (Gilbert and Anderson, 2004; Brunet, 2007). Enhancement of attractive field layer species has been possible by natural succession processes (Gilbert and Anderson, 2004; Brunet, 2007; Onaindia et al., 2013) or management interventions (Martinek, 2004; Riedel et al., 2007). Natural colonization was found out to be very poor and slow and should build out from cores of ancient woodland for optimal ground vegetation development. However, many typical forest species are not able to disperse across open fields (Brunet, 2007) and are not able to persist through competitive aggressive ruderal weed species (Francis, 1998; Hill, 2002). Without effective control of these competitive species, any attempts to either encourage or actively introduce other less competitive ground layer species (by sowing or planting) are likely to be unsuccessful (Hill, 2002). The successful herbaceous plant introduction by direct enhancement techniques to increase species diversity and additional correct management may be a long-term benefit in the appearance, use, ecology and provision of wildlife habitat (Woodland, 2005). Mixed planting is the simplest way to establish a multipurpose and dynamic perennial community in low maintained urban parks. The affordable perennial mixes which combine attractiveness with low maintenance were developed under the auspices of the German Federation of Plant Nurseries (BdS) (Riedel et al., 2007; Schulte, 2017). This has become an excellent tool for practitioners who may be possible to ensure quality and functional introduction of semi-shade and shade tolerant herb layers into low maintained urban parks. The aim of this research project was to investigate the performance of diverse herbaceous perennials mixtures in low maintained urban woodland edges. The key research questions were as follows:  What effects does the structure of woody plant species have on the establishment success of understorey planting mixtures?


Introduction
The stylized naturalistic herbaceous perennial planting is the most innovative approach in the urban landscape (Dunnett and Hitchmough, 2007;Oudolf and Kingsbury, 2014;Rainer and West, 2015).The characteristic beautiful prairies and meadows ecosystem (Schmithals and Kuhn, 2017;Hitchmough, 2017), as well as the herbaceous understory vegetation (Martinek, 2004;Hillová, 2010;Schulte, 2017) became the most frequent sources of inspiration for landscape designers around the world.The enrichment of herbaceous layers is an essential part of recreation of urban woodland and urban parks in last decades (Gilbert and Anderson, 2004;Brunet, 2007).Enhancement of attractive field layer species has been possible by natural succession processes (Gilbert and Anderson, 2004;Brunet, 2007;Onaindia et al., 2013) or management interventions (Martinek, 2004;Riedel et al., 2007).Natural colonization was found out to be very poor and slow and should build out from cores of ancient woodland for optimal ground vegetation development.However, many typical forest species are not able to disperse across open fields (Brunet, 2007) and are not able to persist through competitive aggressive ruderal weed species (Francis, 1998;Hill, 2002).Without effective control of these competitive species, any attempts to either encourage or actively introduce other less competitive ground layer species (by sowing or planting) are likely to be unsuccessful (Hill, 2002).The successful herbaceous plant introduction by direct enhancement techniques to increase species diversity and additional correct management may be a long-term benefit in the appearance, use, ecology and provision of wildlife habitat (Woodland, 2005).Mixed planting is the simplest way to establish a multipurpose and dynamic perennial community in low maintained urban parks.The affordable perennial mixes which combine attractiveness with low maintenance were developed under the auspices of the German Federation of Plant Nurseries (BdS) (Riedel et al., 2007;Schulte, 2017).This has become an excellent tool for practitioners who may be possible to ensure quality and functional introduction of semi-shade and shade tolerant herb layers into low maintained urban parks.The aim of this research project was to investigate the performance of diverse herbaceous perennials mixtures in low maintained urban woodland edges.The key research questions were as follows: What effects does the structure of woody plant species have on the establishment success of understorey planting mixtures?
What effects does the structure of woody plant species have on the vitality of understorey planting mixtures?
2 Material and Methods

Experimental site
The investigation of naturalistic herbaceous planting was carried out in the experimental part of the

Experimental design
In May 2008, the total of 15 treatment main plots of 10 m 2 (4 × 2.5 m) in split-plot design of experiment was set up.Five plots were allocated at woodland edge dominated by Acer platanoides (A), another five plots were allocated at woodland edge dominated by Acer platanoides and Prunus domestica (AP), and remaining five plots were allocated at woodland edge dominated by Tilia cordata and Tilia platyphila (TT).Every main plot was then planted by 5 diverse planting mixtures, based on diverse number of plant genera (the mix of 3, 5, 7, 10, 13 species).The experimental mixtures consisted of dominant perennials, companion perennials as well as ground covering perennials.Altogether, 1,050 plants had been planted (Table 1).The ratio between the quantities of species plants in mixture was set up according to their sociability (Hansen and Stahl, 1993).The distribution of perennials was made randomly (Kircher et al., 2017), in planting density 7 species per m 2 .The plants were obtained from perennial nursery Victoria, Čab Slovakia, in traditional 9 cm containers.

Measurements of plant performance
The

Data analysis
Statistical analyses of experimental data were performed using the Statistica Advanced, Version: 12.0, License Number: 135-949-814.The analysis of variance (ANOVA) was performed to estimate statistically significant difference in vitality between their mean values at a confidence level of 95% (p-value <0.05).The multiple range test of the least significant difference test (LSD test) was used to analyse the existence of homogenous samples.

Table 1
The composition of understorey planting mixture The initial clearing of the experimental site had an equable effect on the establishment success of understorey mixture under different forest stand structures.The abundance of a newly established understorey planting mixture in the whole experiment has been between 87.3-87.8%(Table 2).The persistent effect on the establishment success of the understorey mixture has not been affected by the type of the forest stand, but it has been affected by the initial vegetation clearing (Baeten and Verheyen, 2017).Matteuccia struthioptris, Primula veris ´Cabrilo´ and Lysimachia cletroides were significantly more abundant compared to Ligularia przewalskii.The 9-yr-long-time observation showed more divergent changes in the percentage abundance of field layer related to difference in dominant tree species.The total population size in the woodland edge (TT) persists almost unchanged compared with the remaining woodland edges (A, AP) that were increased by abundance of field layer (Table 3).Regardless of these differences, there were recorded: a) initially decline and then full mortality at Ligularia przewalskii, b) the initial persistent establish effect and then full mortality at Matteuccia struthiopteris and Heuchera micrantha ´Palace Purple´, c) progressive decline at Helleborus argutifolius, d) long-term (9-yr-long) stable effect at Lysimachia cletroides, Alchemilla mollis ´Auslese´ and Geranium macrorrhizum ´Spersard´, e) enormous expanding of Aruncus dioicus and Primula veris ´Cabrilo´.

Taxonomic diversity Assortment The count of taxa Total
The most expanding taxa had different adaptive strategies (Grime et al., 2014): C-strategist Aruncus dioicus (Pierce et al., 2012) and S/CSR-strategist Primula veris (Grime et al., 2014).The remaining taxa showed divergent changes related to differences in dominant tree species (  (Kircher et al., 2010) coupled with maintenance of species-richness.Godefroid and Vanderborght (2011) emphasized that successful plant reintroduction needs a global centralized database for rapid and effective broadcasting of information in a standardized and accessible form.

The impact of the forest stand structure on vitality of understorey planting mixtures
Vitality values of understorey planting mixtures changed significantly according to the forest stand structure and age stage of the planting mixture (Figure 1).The striking differences could be detected between the vitality values of the newly established understorey planting mixtures (one year after planting) and fully matured and developed mixtures (9 years after planting).The newly established field layer in the woodland edge (A) attained higher values of vitality (3.13) and then during the maturity stage their values decreased (2.72).
On the other side, the newly established field layer       2004).Maturation of different understorey planting mixtures in the woodland edge (A) led to a stabilization of vitality values at about 2.57-3.1 (no significant statistical differences) (Figure 2a).The vitality values of the lowest and the highest taxonomic diversity mixtures were also significantly lower in the woodland edge (AP) (Figure 2b), and similarly the maturation of different understorey planting mixtures in the woodland edge (AP) led to a stabilization of vitality values at about 2.29-2.7 (no significant statistical differences).But surprisingly, we noticed a significantly increased vitality level in the woodland edge (TT) in 3 different possibilities (3-, 7-, and 13-different taxa in mixtures) (Figure 2c). Figure 3 confirms stabilisation effect of maturation understorey planting mixtures in different woodland edges, if two years of observation are compared.
The mixtures did not show statistically significant differences in vitality values, except low taxonomic diversity mixtures (3-different taxa in woodland edge (A) and 5-different taxa in woodland edge (TT)).In our study, we used 5 variances of taxonomic diversity, but species-richness in plant community varied from a lowland woodland (may support more than 100 herbaceous species in the field layer, including forbs, grasses, sedges, rushes and ferns), in contrast to the site characterized by dense shade, southern beechwoods (may only have 10 to 15 species in the field layer) (Woodland, 2005).Woodland herbaceous species should be introduced into a new area as a part of well balanced and robust mixtures, both ecologically and visually, 15-20 woodland species with a range of flowering times, colours, heights and structures and growth forms (Woodland, 2005;Kircher et al., 2012).

Conclusion
The 9-yr-long-time observation of understorey mixture under different forest stand structures has showed more divergent changes in herb layer establishment success and plant vitality, which can influence setting innovative approaches of the herbaceous perennials planting design.Based on these results we can state the following: the total population size of field layer in the first year of establishment has not been affected by the type of a forest stand, the total population size in woodland edge was dominated by Tilia cordata and Tilia platyphila (TT) persists almost unchanged compared with remaining woodland edges dominated by Acer platanoides (A), or Acer platanoides and domestica (AP), There is the need to state that the worst field layer according to the evaluated parameters (abundance, ground cover, vitality) was observed in the woodland edge dominated by Tilia cordata and Tilia platyphila (TT).These results appeal to future research aims based on a) complex herb and tree assortment and b) establishment, maintenance and restoration approaches.The complex view on understorey vegetation may develop the process of guidelining specific parts of herbaceous perennial planting design -low maintained understorey planting design.

IN
. -Rožeková, M. | The Performance of Understorey Herbaceous Perennials in Low Maintained Urban Parks Plants in Urban areas and landscaPe | 2018 | pp.35-44 Hillová, D. -Rožeková, M. | The Performance of Understorey Herbaceous Perennials in Low Maintained Urban Parks Plants in Urban areas and landscaPe | 2018 | pp.35-44PLANTS IN URBAN AREAS AND LANDSCAPETable 2The percentage abundance of herbaceous forbs taxa in different woodland edge, one year afterplanting(2008) . -Rožeková, M. | The Performance of Understorey Herbaceous Perennials in Low Maintained Urban Parks Plants in Urban areas and landscaPe | 2018 | pp.35-44 IN URBAN AREAS AND LANDSCAPE Table 3 The percentage abundance of herbaceous forbs taxa in different woodland edge, 9 years after planting (2017) .-Rožeková, M. | The Performance of Understorey Herbaceous Perennials in Low Maintained Urban Parks Plants in Urban areas and landscaPe | 2018 | pp.35-44 PLANTS IN URBAN AREAS AND LANDSCAPE

Figure 1 :Figure 2 :
Figure 1: The average vitality values of understorey planting mixtures in different types of woodland edges

Figure 3 IN
Figure 3The average vitality values of understorey planting mixtures in different types of woodland edge and age stage of planting mixture

Table 4
The ground cover of compositions understorey planting mixtures in different types of woodland edges