Written evidence submitted by Professor Alistair Griffiths (INS0042)

 

The Royal Horticultural Society Director of Science and Collections and Research and Development Chair of the Environmental Horticulture Roundtable Group.

 

  1. How important are urban spaces in helping to reverse insect/ decline?

 

Evidence is that they are vital (especially cultivated spaces – gardens/ allotments) in many aspects on invertebrate diversity and may possibly provide a reservoir for close by rural / farmed environment. These cultivated landscapes and their native and non-native biodiversity are critically important as refuges to help pollinators and invertebrates thrive and in connecting people with nature. However, these cultivated landscapes with circa 400,000 different types of plants are not recognised or measured as being valuable biodiversity for the UK.

 

Domestic gardens cover 720, 000 hectares, with 25% - 30% of urban areas consisting of gardens and 49% of the UKs population actively garden and have associated biodiversity in their gardens. It is therefore essential to explore, especially with regards to climate change and climate resilience, adaptation and mitigation how gardens and the nation’s gardeners and cultivated landscapes could help us and biodiversity to thrive.

 

As with other land use areas there is a lack of baseline data for gardens, this may be worse as gardens have traditionally been perceived as biodiversity deserts and the biodiversity they support unrecorded. A misconception - that cultivated garden plants are no good for biodiversity – A number of studies/surveys provide the evidence that this is untrue. I highlight a few of these below.

 

 

Known benefits of Gardens for invertebrate biodiversity (evidence based)

 

 

Reference: https://www.amazon.co.uk/Wildlife-Garden-Thirty-year-Jennifer-Owen/dp/1907057129

 

 

 

 

 

 

 

 

Reference: Sheffield BUGS Project https://impact.ref.ac.uk/casestudies/CaseStudy.aspx?Id=11853

 

 

Reference: https://www.rhs.org.uk/science/conservation-biodiversity/plants-for-bugs

 

              Reference:               https://resjournals.onlinelibrary.wiley.com/doi/10.1111/icad.12645

 

 

 

 

 

Report here: https://www.greatdixter.co.uk/Handlers/Download.ashx?IDMF=3a85fbff-022c-441a-8c03-52b999019bf2

 

 

Report here: Comparative semi-stratified invertebrate diversity study of the Agroforestry Research Trust Forest Garden and Schumacher Nativ

 

Evidence on Pollinator support is even stronger:

 

 

References:

 

Fetridge et al 2008  Annals of the Entomological Society of America, 101:1067–1077 https://academic.oup.com/aesa/article-abstract/101/6/1067/2758518?redirectedFrom=fulltext

 

Osborne et al 2008 Journal of Applied Ecology, 45:784–792 https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2664.2007.01359.x

 

Samnegard, et al. 2011. Biological Conservation 144: 2602–2606. https://www.sciencedirect.com/science/article/abs/pii/S0006320711002618

 

 

Reference: Baldock et al. 2015 Where is the UK’s pollinator biodiversity? The importance of urban areas for flower visiting insects Proc. R. Soc. B 282: 20142849. https://royalsocietypublishing.org/doi/10.1098/rspb.2014.2849 The authors conclude “Urban areas are growing, and improving their value for pollinators should be part of any national strategy to conserve and restore pollinators.” Further work found that residential garden and allotments are pollinator ‘hotspots’ due to area covered and both abundance and diversity of pollinators supported. Again urban planning should be used to support pollinators

 

Reference Baldock et al 2019 Nature ecology and evolution https://doi.org/10.1038/s41559-018-0769-y

 

 

 

References:

 

Tew  et al 2022 J Appl Ecol. 2022 59:801–811.  https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2664.14094?ref=inkcap-journal

 

Tew et.al. 2021 Journal of Ecology. 2021; 00:1–11. https://www.pure.ed.ac.uk/ws/portalfiles/portal/199778162/1365_2745.13598.pdf

 

  1. What are your thoughts on Biodiversity metric 4.0 and how can this be improved?

 

-          Biodiversity net gain (BNG) strategy is to develop land and contribute to the recovery of nature. It is making sure the habitat for wildlife is in a better state than it was before development. This applies from November 2023 for large developments and small sites from April 2024.

 

With the goal of making sure the habitat for wildlife is in a better state than it was before the development and the evidence shared above about the importance of gardens for biodiversity we feel that focus of the calculator tool is heavily focussed on native plants rather than focussing on the value of both native and non-native plants. We feel this is a missed opportunity, for biodiversity net gain on a development site, especially with regards to the essential role of cultivated landscapes for biodiversity and to aid with climate adaptation and resilience.

 

For example:

 

  1. Onsite Habitat baselining and creation: When you select Habitat = Urban then = Vegetated Garden then this is automatically scored on Distinctiveness as a low score (when we know from the above evidence that this is not the case). In addition, the Condition assessment is defaulted as Not/Applicable also giving a low score. The RHS would like to work with the developer of this tool to provide evidence that better defines distinctiveness of these cultivated landscapes and to create a scoring for the distinctiveness of this habitat. These cultivated landscapes will become even more important for both biodiversity and climate resilience in the future.

 

  1. Onsite Hedge baselining and creation: When you select Hedgerow type and then select Non-Native and Ornamental Hedgerow – Distinctiveness is scored as very low and the condition is defaulted as being poor. The RHS would like to work with the developer of this tool to incorporate both native and non-native values with regards to these cultivated landscapes   

 

e.g. In 2010 the Open Air Laboratories (OPAL) citizen science survey. Results from 2891 surveys were analysed. This research highlighted that urban hedges as important habitats for wildlife for example. The percentage of the 24 recorded invertebrate group found that urban hedges in this study was higher for Ant, Bee, Butterfly, Centipede, Earwig, Lacewing, Shieldbug, Slug, Wasp, and Woodlouse than for rural hedges. In addition, urban was very similar to rural hedges for Hoverfly, Ladybird and Snail. Further work also needs to be done in this area.

 

Reference: Gosling, Laura et al. “Differences Between Urban and Rural Hedges in England Revealed by a Citizen Science Project.” BMC ecology 16 Suppl 1.Suppl 1 (2016): 15–15. Web. https://bmcecol.biomedcentral.com/articles/10.1186/s12898-016-0064-1

 

 

  1. Garden Trees and Ecosystem Services: Where private gardens are created, any tree planting within the created garden should not be included within post-development sheets of the metric. The habitat type ‘Urban – Vegetated garden’ should be used. This does not encourage developers to plant trees in gardens, which provide multiple benefits for biodiversity and other benefits. If recorded as ‘Urban –Vegetated garden’ this will be scored as low.

 

  1. Condition and creation Assessment states: The process of assigning habitat condition, to be undertaken by a competent person. How many of the assessors have had proper training in this metric? How many of these assessors have the right expertise in both ecology and horticultural plants. We think there is an opportunity and a need for biodiversity net-gain to train environmental horticulturists and have these work alongside ecologists who have had training and evidence shared about the biodiversity benefits of both native and non-native plants and habitats and their mixtures to be a competent person in filling the condition baseline and assessments.

 

  1. The RHS have contacted DEFRA four times about working collaboratively with them with regards to garden plant biodiversity, both native and non-native and the Biodiversity net Gain 4.0 calculator tool. However, we have had no reply. We believe this is a positive opportunity for wildlife, developers, government and those that live in new developments. In particularly, as gardens provide multiple ecosystem services, including physical, mental and social health benefits – clearly demonstrated during the COVID-19 outbreak.  

 

  1. What are the drivers of insect loss in urban spaces nationally including urban and peri-urban areas?

 

There is a lack of evidence and we don’t know if there is insect loss in urban areas. We don’t have long-term data i.e. decades of insects and their abundance across the board in urban spaces and funding to do this is urgently needed. However, it is likely that the drivers of insect loss highlighted in Dicks paper in 2020 are contributing with the top five drivers being Land management; Land cover and configuration; Pesticide use; Climate Change and Pest and Pathogens.

 

Reference: Dicks et al., (2020). A global assessment of drivers and risks associated with pollinator decline. 10.21203/rs.3.rs-90439/v1. https://assets.researchsquare.com/files/rs-90439/v1/d6bee961-1c1e-4751-ae1c-3e3bc173ac0a.pdf?c=1637596089

 

In addition in urban areas there are additional drivers which we don’t know the true impact of. These include paving over front gardens, garden grabbing, use of plastic plants, including artificial grass, increased abundance of the domesticated honeybee, new developments with small non-connected gardens, a lack of gardens and poor planting not using both native and non-native in new developments. Also removal of green space on building developments linked to value engineering or cost savings.

 

  1. What are your thoughts on Banning Insecticides: The pros and cons of banning insecticides with relation to helping improve biodiversity?

 

A You Gov survey commissioned by the RHS (representative of UK gardeners) in 2022 shows that the majority 62% do not use chemicals for pest control in their gardens and when we asked respondents to indicate whether they had bought a product that killed bugs, 89% said no. This indicates a reasonable level of public support for banning sales of insecticides to the general public. 

However, there are circumstances within gardens and cultivated landscapes where their use may be required, e.g. to prevent spread of invasive species in landscapes of high biodiversity value, so there would need to be exemptions for specific instances of use such as these, by those licensed to apply them.

 

  1. Aesthetics and desire for low maintenance over biodiversity - Persuading people to not use astroturf or changing use of horticultural plants or planning how important are these changes?

 

-          Plants for Pollinators

-          Choice of right plants, right places, right purposes

-          Environmental Horticulture, whereby include an element of ecological planting

-          Different people with different needs so provide solutions

-          Education about the impacts of choice

 

  1. Do you have any policy change recommendations?

 

-          To recognise gardens and cultivated spaces as biodiversity hot spots of high value if in good condition and protect them as green spaces. Incorporate bothe distinctiveness and condition into biodiversity planning (4.0/ Biodiversity Net Gain). The RHS is happy to work with government on this.

 

-          For a competent person to use Biodiversity Net gain metric 4.0 they should obtain full training and a certificate. Part of this training should incorporate the evidence base on the value of non-native plants as well as native plants. To include a horticulturists as well as an ecologist in undertaking the survey work.

 

-          Defra to reverse their decision to no longer have a Horticulture strategy. Not having this strategy misses out on supporting the 720,000 hectares of habitat of which nearly 1 in 2 of the nation actively manage and of which between 25 -30% is in urban areas and is critical for biodiversity net gain, climate resilience and human health. Page 19 of the ‘Unlocking green growth: A plan from the ornamental horticulture and landscaping industry’. Key findings from the ‘Growing a Green Economy report by Oxford Economics and Foresight Factory –states there are significant opportunities and benefits for the UK Government and the general public across several policy domains, which will provide economic growth. With the immediate government support of this Unlocking Green Growth plan the total GDP footprint of our sector can grow to £41.8 billion in 2030, compared to £28.8 billion in 2019. This comes with a projected £8.7 billion UK tax revenues in 2030, up from £6.3 billion in 2019. The number of jobs across the country supported by the industry can also increase from 674,000 in 2019 to 763,000 in 2030.

 

-          Policy and implementation of policing, with stronger legislation on stopping habitat destruction of gardens and cultivated landscapes, in particularly with regards to land use change, and paving over of front gardens.

 

-          Ensuring that all new developments include green space/gardens and that this is not taken out as part of Value Engineering or cost savings.

 

-          Policy that defines Green Infrastructure and Green Skills to include both native and non-native plants – Currently this is dominated by solar panels, energy – this needs to include cultivated plants.

 

  1. What is the impact of light pollution and what could be done to mitigate this/incorporate in planning?

 

-          This is covered off in other written evidence who are more qualified to answer this than me.

 

  1. Specifics on how important native and non-native plants linked to Climate change? How the impact of climate change as many insects are moving north what about cultivated plants and wild seed mixes?

 

-          In 2019 research focused on 520 major cities with regards to impacts of climate change. Bastin et al., stated that by 2050, London could feel as hot as Barcelona, I can confirm that on the 11th June this year London, temperature wise was actually hotter than Barcelona, indicating a speedier climate change shift than we expected. How will our landscapes and insects deal with this?

 

-          In addition the World Economic Forum Global Risks Perception Survey 2022-2023 published in January 2023 Global risks ranks that in 10 years from now the number 1. Risk is Failure to mitigate climate change 2. Failure of climate change adaptation 3. Natural disasters and extreme weather events 4. Biodiversity loss and ecosystem collapse 5. Large-scale involuntary migration 6. Natural resource crises. Last year the number 1 risk was climate action failure. There is a real urgency to act now.

 

References:  Bastin JF, Clark E, Elliott T, Hart S, van den Hoogen J, et al. (2019).                             Understanding climate change from a global analysis of city analogues.                             PLOS               ONE 14(10): e0224120.                                                                                     https://doi.org/10.1371/journal.pone.0224120

 

              The World Economic Forum Global Risks Perception Survey 2022-2023               published in January 2023             

              https://www.weforum.org/reports/global-risks-report-2023/ 

 

The positive news is that there is a greater number of different types of garden plant diversity used directly by humans in the UK and globally than any other plant types. The different types of food plants used globally is 50,000 (FAO), medicinal plants is 33,500 (RBG Kew). The RHS 2022 Plant Finder lists 69,000 different types of UK cultivated plants (RHS) and the RHS believes that UK gardens contain circa. 400,000 different types of garden plants.  In comparison the UKs native flora consists of 1,500 different types of plant. So why is it that people use these cultivated plants?  Results of an RHS commissioned You Gov Survey of the UK population in December 2022 revealed that 73% say gardening has a positive impact on their mental health, 74% a positive impact on their physical health and 42% a positive impact on their social health. COVID-19. Industry would like to thank Government, for recognising during COVID-19 lockdown that cultivated plant biodiversity is as essential as food and medicine for human health, a human right. In keeping Garden Centres open in England during lockdown gardening and cultivated plants was one of the Nations saviours with regards to improved mental, physical and social health (gardening and meeting friends and families in gardens and cultivated landscapes in cities) during the COVID-19 Pandemic. Essential that everyone should have space to grow.

 

-          Therefore in a rapidly changing climate these cultivated genetic resources and cultivated landscapes are going to become even more essential for tackling climate and biodiversity resilience and benefitting human health. There is 700,000 hectares of domestic garden in the UK and almost half - 49% of the UK citizens actively garden. 25-50% of urban environments consists of cultivated landscapes.

 

  1. What can be done to connect urban greenspaces and the importance of small scale areas?

 

-          Not to underestimate gardens, they are already connected urban green scapes  – Use planning to protect front and back gardens, street trees, urban green spaces. Have more connected thinking between landowners. More greening – including cultivated plants in all developments, commercial, public and private.

 

-          The RHS is working in collaboration with the Natural History Museum (NHM) with the Department for Education as part of the National Education Nature Park. The National Education Nature Park is a project that will drive and increase engagement with nature for all children and young people in school grounds. It will encourage the whole of the education estate to work with them to improve the biodiversity of their grounds. From creating pollinator-friendly habitats where biodiversity can thrive, to digging ponds, the concept will showcase how the education estate will create an environment that supports climate resilience. The Nature Park will also provide opportunities for young people to take part in community science, and in biodiversity monitoring and data analysis - learning important/key skills for the future.

 

-          Supporting initiatives like Pollinating London Together (PLT) created with a specific mission: to enhance green spaces in central London where all the natural pollinators can thrive, and their habitats can be enjoyed by everyone, starting in the City of London. The longer-term vision is to create a template for change and action through leadership that can be implemented in urban environments across the UK. In 2022 a baseline survey of pollinators. A total of 1,827 pollinators were observed across all 26 surveyed sites and all survey dates. This included 23 species of bee, 2 species of wasps, and 2 species of butterflies. The pollinator plants were both native and non-native with the most visited plant out of all of them being non-native Eurybia divaricata (white wood aster). The Pollinating London Together is a great initiative and should be further supported to deliver its mission and vision.

 

-          The Natural Capitol Urban report in 2019: Provisioning services: Community gardens and allotments enable food production in the urban area, although on a small scale. This food production requires insects. Ordnance Survey estimated the area of community gardens and allotments within Great Britain’s urban habitat area at 7,925 hectares in 2019, and an estimated 316,998 allotment plots within Great Britain’s urban areas. The estimated total production of food, from community gardens and allotments, is 154,000 thousand kilogrammes a year.Using data from capital growth 2016 (PDF, 4.45MB), the estimated value of allotment output was £294 million.

References: https://www.ons.gov.uk/economy/environmentalaccounts/bulletins/uknaturalcapital/urbanaccounts

 

12 July 2023