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Wild flower seed origin and grassland restoration

The Importance of Wildflower Seed Origin in the Restoration of Diverse Grassland

Institute of Grassland and Environmental Research 01/09/1997
 
A.T. Jones
Biodiversity Group, Institute of Grassland and Environmental Research,
Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB

Introduction
Methods for grassland restoration
Redefining our objectives

Introduction

 
With the huge losses of wildflower grassland since the 50s, there has recently been a focus on methods for their restoration. Many of the approaches involved in meadow creation have in essence been inherited from agriculture as have the targets i.e. visually appealing crops of wildflowers established to a given recipe and flowering in the first year. These well-intentioned methodologies have attempted to create new conservation areas but there has often been complete ignorance of the need to consider genetic variation in wildflower species. Furthermore, certain seed companies had offered seed-mixtures containing non-native, imported seed and also seed from crop grown wildflowers without sufficient regulation and hence populations of non-British varieties of native wildflowers and even completely non-native species have become established.
 
More and more evidence is being uncovered that our native wildflower species are genetically highly variable with these differences linked to soil type, climate, geographical location and history of habitat. In considering the importance of our meadows at a global level, we have no endemic higher plant flora, nearly all our higher plant species being shared with continental Europe, however, the evolution of and the combinations of species that have developed under our hyper-oceanic climate are unique. It is precisely the protection and enhancement of this very richness in genetic diversity that should be the main target of future restoration and conservation efforts. 
 

Methods for grassland restoration
 
There are parallels in grassland restoration with the restoration of works of art. Where damage has occurred to a painting, then the recreation of an original detail is based strictly on the tints and pattern surrounding those damaged areas. Similarly, where diverse grasslands have been lost through agricultural intensification then we should base restoration on the surviving genetic resources of the surrounding areas.
 
Given that financial resources will always be limiting, such techniques relying on donor sources of biodiversity in the vicinity of a new restoration sites, may be economically more viable rather than bringing in new material from completely different districts in a laissez faire fashion. Already in ESAs, which are being extended to the general countryside in the form of the countryside stewardship scheme, there is scope for farmers who conserve wildflowers to receive income from the harvesting of wildflower seed. This seed can be used in grassland restoration programmes concerning other farmers within the same district, once factors such as soil type and ecological factors are matched. This approach would be much cheaper than buying in expensive and inappropriate commercial wildflower seed mixtures. Within ESA areas there could be donors and recipients of diversity, funded by the ESA grants towards conserving biodiversity that are currently in place.
 

Redefining our objectives

 
Very often in grassland restoration, conservation resources are directed towards the creation of artificial combinations of species and the quest for diversity to the nth level. Such a. target, alone, is a misguided one and I believe objectives should be directed at the finer detail of ecological and genetic structure and relationships with other biota. Two common and to some extent mutually exclusive reasons are often voiced for writing off the importance of the conservation of genetic diversity in the general countryside:
 
1. 'Nothing worth saving', i.e. any patterns of genetic variation in grassland have been lost through a history of agricultural and industrial damage or past widespread movement of plant material.
2. 'The environmental sieve', i.e. whatever mistakes we make in habitat restoration, for instance, in introducing alien plant material, selection forces will automatically weed them out and the natives will reassert themselves.
 
To the 1st point, a system of nature reserves argues that there is much that has survived and also wildflower species have managed to move to 'new habitats, e.g. railway cuttings and road verges. From a casual glance through publications of the Botanical Society of the British Isles and old floras, it can be seen that many very old populations of certain species survive despite agricultural intensification.
 
To the 2nd point, this is simply not the case and in many native vegetation types around the world the main threat is of the spread of exotic, introduced aliens. With sufficient resources, it would be quite easy to obliterate natural patterns of genetic variation in populations of many wildflower species by widespread, indiscriminate sowing of inappropriate wildflower seed mixtures.
 
At the intraspecific level it can be a relatively easy task to introduce non-native strains of a particular species to an non-native area. Recent research at Aberystwyth (Jones and Hayes unpublished) has shown that in some cases non-native material can even outperform native material in a grassland situation.
 
Table 1.
Flowering frequency score for alien and native genotypes of wildflower species introduced into an extensive sward:
  
 
  Plantago lanceolata Prunella vulgaris Centaurea nigra

native  0.260  0.084  0.018

alien 0.362  0.137  0.144

s.e.d      0.0225**


If we cannot within ESAs, manage and restore our own remaining grasslands to sufficiently rigorous standards, then why should we expect those in other countries, responsible for much richer floras, to adequately conserve their indigenous habitats.

 


Page last modified on Tuesday 19 of June, 2012 16:49:23 BST