Impacts of landscape treatments on plant species richness within road corridors and adjacent ecosystems - Rosalyn Thompson
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This study examined the impacts of different landscape treatments on plant species richness within road corridors and adjacent ecosystems. It found that road verges had higher species richness than adjacent fields. Species richness was higher on soil slopes treated with the new post-guideline approach compared to the pre-guideline approach. On rock slopes, species richness did not differ significantly between the pre-guideline planted approach and the post-guideline natural recolonization approach. The soil seed bank contributed additional plant species, particularly on naturally recolonized slopes. Lower soil fertility was associated with higher species richness, suggesting the new landscape treatments help prevent establishment of invasive species.
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Impacts of landscape treatments on plant species richness within road corridors and adjacent ecosystems - Rosalyn Thompson
- 1. Impacts of Landscape Treatments on Plant Species Richness within Road Corridors and Adjacent Ecosystems Rosalyn Thompson University College Cork SIMBIOSYS FINAL CONFERENCE Dublin: 28th June 2012.
- 2. Road Verges: 3 Research Areas 1. Species richness: (a) Road Verge vs. Adjacent Land. (b) Pre-guidelines vs. Post-guidelines 2. Contribution of Soil Seed Bank 3. Nutrient status of Soil in Road Schemes Preliminary Conclusions
- 3. Research in Context - Background • 2006 NRA Produced Guidelines • Landscaping of Verge area: Move away from a high input/ horticultural approach to one following an Ecological Landscape Design approach. • Opportunity in 2009 to study Pre- and Post- guidelines sites.
- 4. Research in Context - How slopes were landscaped Traditionally, this involved: • finishing engineering aspects • covering with topsoil image: Lego • treating with herbicide Glenealy Landscaping • applying fertilizer • planting…. Ecowitch A.C.E.S.
- 5. New Approach • Use subsoil (soil slopes) or NO soil (rock/scree) • Avoid herbicides and fertilizer • Create Open Habitat Mosaics (OHM) incorporating native species of local provenance: Soil Slopes. Allow Natural Recolonisation (NR): Rock/scree Slopes. Soil Slope (OHM) Rock/scree Slope (NR)
- 6. Species Richness: Road Verge vs. Adjacent Land Use Road Verges Rock/Scree Slope Soil Slope Wider verge Adjacent Fields Margin Centre-improved grassland Centre-tillage
- 7. Reference Points along Transect 310km Transect west-east Semi-natural grassland Improved grassland
- 8. 1. Species Richness: All Road Sites 18 16 14 Mean no. of Species 12 10 8 6 4 2 0 KM west from Wexford Road Verge Field Margin Field Centre
- 9. Species Richness on Road Verges: Soil Slopes – All Species – Comparison of Treatments Mean species richness in semi-natural Including grasslands all species Treatments are different (P< 0.05)
- 10. Species Richness on Road Verges: Soil Slopes (II) - Comparison of Treatments Mean species Native richness in species semi-natural only grasslands Post Treatments are different to Both Pre treatments (P< 0.05)
- 11. Species Richness Road Verges Rock/scree (native species) Early Summer only Early & Late Summer Treatments are not sig. different (P > 0.05)
- 12. 2. Below-ground plant community: the contribution of the Soil Seed Bank 2010: Soil collected spring following plant survey. Outdoor germination 2 seasons
- 13. Species recorded Rock face Glebe Co. Kerry (NR): 2009: Quadrats (Q); 2010: Soil Seed Bank Trial (SSB) Species Q SSB Species Q SSB Species Q SSB Aegopodium Geranium Epilobium podagria. robertianum. parviflorum Angelica Lythrum Hypericum sylvestris salicaria humifusum Athyrium filix Rubus Juncus effusus lemina fruticosa Elytrigia Teucrium Plantago major repens scorodonia Hedera Poa pratensis Ulex europaeus Juncus Scirpus conglomeratus Cardamine setaceus flexuosa Lonicera Carex pendula Veronica periclymenum persica Rubus idaeus Epilobium Viola riviniana ciliatum Species Richness: Q = 8; Both = 5; SSB = 11; TOT = 24
- 14. 3. Soil Fertility Subsoil Topsoil Grasslands with higher numbers of native plant species require LOW soil fertility.
- 16. Preliminary Conclusions • Higher mean species richness in Road Verge than either Margin or Centre of the adjacent field. • Seed bank data important – particularly to NR. • Topsoil nutrient status should be determined: (low nutrient status may costs/effort involved in its alternative disposal/incorporation) • If POST-GUIDELINES treatments are producing results ≥ PRE-G then POST is to be adopted as the more sustainable approach.
- 17. Acknowledgements • SIMBIOSYS project (2007-B-CD-1-S1) is part of the Science, Technology, Research & Innovation for the Environment (STRIVE) Programme 2007 – 2013, funded by the Irish Government under the National Development Plan 2007-2013 and administered by the Environmental Protection Agency
- 18. With thanks to…. • Dr Pádraig Whelan (UCC), Professor Mark Emmerson (QUB) - Supervisors • Lisa Dolan (UCC) – Research Assistant • Dr Nova Sharkey (TCD) – Research Assistant • Máiread Kiely (UCC) Senior Technical Officer Plant Science • Paul Green (Botanical Society of the British Isles) • Steven Darby MSci (Chemistry) • Louise Russell, Jovanna Arndt, Dearbhail McKenna, Simon Mills – Field Assistants • Mary Hamilton, Aisling O’Shea, Eimear Egan – Greenhouse Assistants • Dr Sonia Monteiro, Aisling O’Shea – Lab Assistants • All our landowners • Kerry, Cork, Waterford and Wexford City and County Councils
- 19. Soil Nutrients & Mean Species Richness (Season A). Soil slopes: pre- and post-guidelines (i) 25 [P] mg/kg 20 Total Kjeldahl Nitrogen (g N/Kg dry wt) MEAN s.r 15 10 5 0 R11-pre R12-post R13-pre R21-post R14-pre R6-post R20-pre R27-post R16-pre R25-post R17-pre R28-post R19-pre R7-post Road Verge Sites (pre-guidelines = planted; post-guidelines = open habitat mosaic) east to west [P] min. fertility [N] min. fertility Dixie & Bisgrove (1996).
- 20. Soil Nutrients & Mean Species Richness (Season A). Soil slopes: pre- and post-guidelines (ii) 25 [P] mg/kg [N] g/kg 20 MEAN s.r 15 10 5 0 R12-post R0-pre R21-post R1-pre R6-post R23-pre R27-post R4-pre R25-post R9-pre R28-post R5-pre R7-post R8-pre Road Verge Sites (pre-guidelines = standard grass seed mix; post-guidelines = open habitat mosaic) east to west [P] min. fertility [N] min. fertility Dixie & Bisgrove (1996).
- 22. Pre-guideline planting… • Incorporated non-native species which are out of context or have an urbanizing effect Fagus sylvatica Purpurea Cotoneaster horizontalis Copper Beech Wall or Rock Cotoneaster • …some of which are now invasive
- 23. Community Stability Sorenson β-Diversity Score for each site Using Sørensen Pair Treatment Score 7 PL 0.29 similarity index 3 NR 0.33 8 NR 0.38 8 PL 0.39 2c 6 NR 0.4 β= 6 PL 0.5 4 PL 0.5 S1 + S2 4 NR 0.55 5 PL 0.57 7 NR 0.57 3 PL 0.59 0 = dissimilar 5 NR 0.63 1 = identical 2 PL 0.63 2 NR 0.67 1 PL 0.7 1 NR 0.7
- 24. Data Collection: Above-ground plant community 2009: above-ground plant communities surveyed Two 2m x 2m quadrats (adjacent to carabid pitfall traps)
- 25. Plant Communities & Invasion Resistance Above-ground plant communities: • 93 species of higher plants and ferns PL 34 35 21 NR • 87 “Native” 4 Non-native (2 undetermined) Below-ground plant communities • 17 additional species PL 4 2 11 NR 4 = Non-native
- 26. Study Design • Study area N25/N22 primary route • 310km east to west transect • 8 pairs of rock/scree sites • Each pair: 1 x pre- and 1 x post-guidelines • Similar in age, aspect and geographical location
- 27. Invasion Resistance • Above-ground: Non-native Species = 4 Acer Aegopodium Cotoneaster sp. Crocosmia x pseudoplatanus podagraria Cotoneaster Crocosmiiflora Sycamore Ground elder Montbretia • Potential threats • Rate of invasion: PL = 0.125m-1 NR = 0.5m-1
- 28. Potential benefits of the Natural Recolonization (NR) approach… Reduced environmental impacts Lower fertility → prevents establishment of (alien) invasive species. No importation of soils / plants / pests Reduced management of a hazardous area including vegetation Reduced financial costs
- 29. All Verges: Pre-guidelines vs. Post-g. Treatment: = Pre = Post
- 30. Species Richness on Road Verges: Soil Slopes (II) - Comparison of Treatments Native species Pre-Guidelines only Post-guidelines Treatments are different (P> 0.05)
- 31. Species Richness on Road Verges: Rock/Scree Slopes - PRE-POST (PLANTED – NATURAL RECOLONISATION) 18 16 14 Mean Species Richness Mean species richness 12 12 10 Planted NR 8 Species richness 10 6 4 8 2 0 pair 1 pair 2 pair 3 pair 4 pair 5 pair 6 pair 7 pair 8 1 2 3 4 5 6 7 8 6 Sites Sites by pairs a.Planted b.NR PL NR Treatment Treatment Sites grouped by treatment: Sites arranged by pairs PL planted NR natural recolonisation PL NR
Notes de l'éditeur
- Within the Road Transport research there are several areas of research, which in addition to those here include Invasion Resistance by Alien (or non-native) species. This research is on going.However, NOW I will present some preliminary results to the following 3 Questions: 1. How species-rich are the road verges in comparison to the adjacent field? Is there any difference to those communities which were created prior to the 2006 guidelines to those which followed the new guidelines.2. What is happening in the below-ground plant community? It is one thing to survey the plants you can see, but do you gain any further insight by studying the soil seed bank>3. What is the nutrient status of the soil which inevitably gets moved around when roads get built?
- So you may have heard about these guidelines this morning from Padraig…………Produced in 2006 cover many aspects on the creation and landscaping of the road corridor – including the landscaping of the road verge where there has been a move away from a high input approach in terms of TIME / MATERIALS / (MONEY!), to a low-input one which would better reflect the wider landscape.In 2009 the opportunity arose to study road landscaping treatments of a similar age – some of which had followed the old practices, others which had adhered to the new guidelines.
- PLANTING: Garden favourites – Many of them Non-native …..which may look lovely in an urban setting, but have the effect of urbanising the countryside and furthermore some of which have now been found to be highly invasive once they have escaped their original confines.
- The new approach includes the use of subsoil – as this normally has a lower nutrient level than farmland which has had various applications of fertilizers over the years – some of which can persist for years, especially if there is no crop (including grass) to use it to grow. Fertilizers can also be avoided as you are not trying to establish garden plants. Herbicides are another chemical introduction which is costly and potentially hazardous which can be omitted. TWO of the POST-GUIDELINES treatments which are now being adopted are: OHM on soils slopes (and also wider verges) and Natural Recol on Rock or scree slopes.
- So, how did we do this? Basically we took 3 types of engineered road verge…….. I surveyed the plants whilst you can see Erin augering a hole for her pitfall traps and Lisa putting down a sand bed for mammal tracks…One of the unique elements in the design of this project was, not only its large scale, but the fact that we investigated the adjacent field as well the road verge. In that adjacent field we took the MARGIN and then we went in to the CENTRE of the filed.
- Here you can see the East-West transect (all 310km of it) which follows the N25/N22 corridor. IN ADDITION we have 20 Non-roaded Reference Points along the transect: 10 for Semi-natural grassland; 10 for Improved Grassland.
- Looking at ALL Road sites east to west: In general, The pink line is above the yellow and blue lines, meaning that OVERALL the road verges have a higher mean species richness than either the centre of the field (which is what you would expect, as these tend to be highly managed) and the MARGIN of the field.
- BUT focussing on the ROAD VERGES< HOW DO the post-guidelines sites stack up against the pre-guidelines sites? If we look at species richness as a whole, then you can see that the post-guidelines sites have a higher species richness that the pre-guidelines ones.THE Dotted line that you can see represents the average species richness found in the semi-natural grassland sites – the mean of the reference sites along the east-west transect. So the mean of the post-guidelines sites is matching that in terms of species numbers.
- However, arguably, looking at species richness alone is a bit of a blunt instrument, as what we are interested in are the NATIVE SPECIES which will act as resources for many of our beneficial insects which pollinate our crops or consume agricultural pests, in addition to being our natural cultural heritage.So having stripped out the aliens (non-native species), the statistical model was re-run….and we got the same result i.e. the post-guideline sites were significantly different to, not only the pre-guidelines overall, but BOTh types of treatments. There was no significant difference between the 2 pre-guidelines sites.
- Before the non-native species were removed, the species richness – particularly on the Planted treatments……The lower species richness on the Natural Recol is understandable as plants are ONLY arriving from the surrounding area – the envt can be harsh, there is little soil and there can be high exposure to the elements.However, EVENTUALLY, these communities should develop in to ones which reflect the wider landscape.