Substrate impacts on Hyacinthoides non-scripta growth Dr Samantha Langdon (rECOrd Bluebell BAP project officer) 1 Contents Acknowledgements 3 1.0 Introduction 4 2.0 Methods 6 3.0 Results 7 4.0 Discussion 9 5.0 References 11 2 Acknowledgments Sincere thanks are due to staff in the Department of Biological Sciences at the University of Chester for allowing us to use their laboratory equipment for calculating the final dry mass of the leaves. Thanks are also due to staff at Victoria Park in Widnes, Halton, for provision of plant pots. Compost was also provided free of charge by Halton Borough Council, for which we are very grateful. 3 1.0 Introduction Habitat restoration is increasingly imperative in modern environments, as human- induced habitat damage has caused threats to biodiversity as well as to individual species. Restoration and creation of new habitats is often required if habitats become lost and fragmented and is seen as a key consideration within applied ecological research (Ormerod, 2003). In urbanised areas, habitat loss and fragmentation can be particularly marked due to loss through development, leaving remaining patches spatially isolated (Vandergast, Bohonak, Weissman & Fisher, 2007). This is also the case in rural areas, where agricultural practices can also leave significant gaps between patches (Rickman & Connor, 2003). Fragmentation can impact negatively on genetic diversity, due to decreased interconnectivity between species populations (Honnay & Jaquemyn, 2006; Jump & Peñuelas, 2006; Vandergast et al., 2007). Therefore, the creation of habitat ‘corridors’, whereby habitat is either created or restored in gaps between existent populations, is often deemed a successful method for establishing species gene flow. For example, this has shown to be effective for transfer of pollen between habitat fragments (Townsend & Levey, 2005). Hyacinthoides non-scripta , the native British bluebell, is a species thought to be threatened by loss of habitat and subsequent fragmentation in the UK (Plantlife, 2004), which may in turn lead to genetic impoverishment in the future. Promisingly, H. non-scripta is a plant that will grow under a variety of different conditions and reproduces clonally, making it a potentially good candidate for successful restoration measures, as defined by Pywell et al. (2003). Numerous high profile schemes have attempted to raise awareness of its status and the need for its conservation (for example, the Bluebells for Britain survey by Plantlife in 2003, and the Natural History Museum’s online bluebell survey in 2007); however, whilst recording distribution is essential, schemes that actively encourage habitat management and creation are vital for the long-term conservation of this species. In the Borough of Halton, active steps have been taken by the Borough Council to create new H. non-scripta populations, which will help to reverse the effects of fragmentation in what is essentially a highly urbanised area. This has been achieved through the implementation of their H. non-scripta local Biodiversity Action Plan (LBAP) and has involved planting of bulbs and seeds across the borough. However, 4 varying levels of success have been witnessed between different site types (Langdon, 2007), which may be due to a variety of factors, such as substrate type, light availability, temperature gradients and human disturbance through trampling. In Halton sites, two methods were utilised for H. non-scripta bulb planting: planting directly into the existent soil and into compost produced from local green waste collected by the council from Halton residents. The compost method was used on sites where a heavy, clay substrate was present, specifically on ex-landfill sites. Other sites had sandy as well as loam substrates, providing a variety of different soil types across the borough. In the field, the compost proved to be very successful, at least in the short-term (Langdon, 2007). However, more data is required on the use of this substrate for H. non-scripta planting before it can be recommended more widely. The substrate type may therefore be an important factor when predicting the likely success of H. non-scripta bulb planting schemes. Therefore, this study examined whether the substrate type had an impact on initial H. non-scripta growth following planting. Three substrates were tested (clay topsoil, compost and sand) in a controlled experiment, designed to detect differences in growth performance of newly planted H. non-scripta bulbs. Growth within the first year of planting was examined, as future growth of bulbs may be influenced by plant size in this period. The amount of leaf material produced may be important for the future survival of introduced bulbs, as nutrients are collected back from the leaves when flowering is complete (Blackman & Rutter, 1954). If leaves are damaged or stunted, fewer nutrients will be available for storage and subsequent growth. This information may prove not only useful to future H. non-scripta management in Halton but in other UK areas where active bluebell conservation is underway. 5 2.0 Methods The experiment was started on the 30 th of November 2006. H. non-scripta bulbs were sourced from Shipton Bulbs (www.bluebellbulbs.co.uk). Ninety bulbs were randomly allocated to the different substrates (clay topsoil, compost and sand), with 30 in each condition. The topsoil was collected from an ex-landfill site used in the Halton bluebell BAP project for planting (Hale Road Woodland, SJ485849), whereas compost and sand was provided by Halton Borough Council. Bulbs were weighed individually (to one decimal place, due to equipment limitations) prior to planting and were randomly allocated to numbered pots. They were planted into standard 150mm (6 inch) plant pots to a depth of 100mm and watered until saturated. No further watering was carried out during the experiment. Pots were arranged in a fully randomised block design, with 6 experimental blocks each containing 15 pots (five pots from each substrate condition). These were placed outside and were left under natural conditions for the duration of the experiment (Figure 2.1). Figure 2.1 Experimental setup, showing H. non-scripta bulbs planted into three different substrates in a randomised block design. Bulbs were checked frequently from March 2007 for germination. The first bulbs germinated on the 14 th of March. Bulbs were then checked at roughly two-week intervals to note which bulbs had germinated. This continued until the 8 th of June, whereupon the above-ground biomass was harvested, dried at 80 °C for 48 hours and weighed (following Mackay & Neal, 1993). Notes were made as to which bulbs had flowered, but the flowers were not included in the above-ground biomass measurements. Flowers were separated from the leaves prior to the drying 6 treatment; there were too few flowers to consider their biomass separately in addition to the leaves. The data were then analysed using SPSS Version 14 to look for differences between bulbs grown in the different substrate conditions. First, the measurements taken from each bulb before the experiment started were analyzed for differences by one-way ANOVA, to check for differences that may cause impacts later. Differences in means were determined using the test of Least Significant Difference (LSD). Secondly, final biomass means were tested by 2-way mixed-between subjects ANOVA, again using LSD to locate differences between treatment and block means. 3.0 Results In total, 64 bulbs germinated by the end of the experimental period. The first bulbs to germinate were those grown in the topsoil, which started to germinate approximately a month before bulbs in the other two substrates (Figure 3.1). Bulbs planted in sand appeared to do less well than those in other substrates as they were slower to germinate. The substrate which yielded the most germinated bulbs was the clay topsoil with 80% of bulbs planted in it germinating. Those planted in compost had a germination rate of 73%, followed by sand with a rate of 67%. 30 25 20 Topsoil 15 Compost Sand 10 5 No. of bulbs germinated bulbs of No. 0 104 117 137 152 166 173 190 Days after planting Figure 3.1 Germination timescale of H. non-scripta bulbs planted into three different substrates. Despite attempting to randomly allocate bulbs to conditions, the initial mass of the bulbs did vary significantly between conditions ( F = 4.238, P = 0.018). Those bulbs 7 planted into sand were significantly higher in mass than those planted in clay topsoil and compost (Mean values: sand = 5.1g; compost = 3.9g; topsoil = 4.2g). However, the final mean above-ground biomass of the bluebell plants was also significantly different between conditions ( F = 8.304, P = 0.001). There was no effect of block ( F = 0.592, P = 0.706) and there was no interaction effect ( F = 0.846, P = 0.588), showing that results were not confounded by other environmental factors. The LSD test revealed that those grown in compost produced significantly more above-ground biomass than those grown in clay topsoil or sand (Figure 3.2). There was, however, no significant difference between those grown in sand or topsoil. 0.200 * 0.150 0.100 0.050 Mean dry mass (g) mass dry Mean 0.000 Sand Topsoil Compost Substrate Figure 3.2 Difference in mean above-ground biomass of H. non-scripta plants grown in three different substrates. Bars represent standard error. * indicates substrate where above- ground biomass mean is significantly different to other substrates. It appears, therefore, that the initial size of the bulbs did not influence the overall result as there appeared to be no relationship between the initial mass and the final dry mass of the leaves. Although flowers were not taken into consideration in dry mass calculations, it was noted which plants produced flowers. Of the bulbs that flowered (n = 13 out of 90), 69% of these (n = 9) were planted in compost.