lessons learnt for harvesting seed in biodiversity mitigation and enhancement schemes in the uk

LESSONS LEARNT FOR HARVESTING SEED IN BIODIVERSITY MITIGATION AND ENHANCEMENT SCHEMES IN

THE UKProfessor R Neil Humphries CSci CBiol BSc MA PhD MBS MIPSS FIQ

Sustainable ReclamationASMR National Meeting, Tupelo, Ms. June 8th-15th, 2012

Objective - to understand more about seed collection from natural sources

Study undertaken in 1992 & 1993 5 coalfield grassland – mire/fen meadow

sites in South Wales, UK, harvested early & late July

All UK Biodiversity Action Plan grasslands (NVC mesotrophic grasslands MG5 & MG8; mires M23, M24 & M25; acid grassland U5)

Emorsgate tractor-drawn suction harvester Seed was air-dried, sieved & bagged

Background

1. Donor site species composition and their flower & seed development stages

2. Species composition of harvested seed

3. Efficacy of suction harvester 4. ‘Harvestability’ of seed

Four Studies Undertaken

Seed Harvesting

MG5 Cynosurus cristatus – Centaurea nigra meadow

M23 Juncus effusus – Juncus acutiflorus – Galium palustre rush pasture

M24 Molinia caerulea – Cirsium dissectum fen meadow

Number of Key-Constant (+ Rare) Species in Harvested Seed

Summary of Results

NVC Absent

Under Representative

Representative

Over Representative

MG5

3 (1) 3 (-) 2 (1) 5 (-)

M23 1 (1) 4 (-) 5 (1) 1 (-)

M24 3 (5) 2 (-) 4 (1) 3 (-)

Need for – Seed-burden surveys Multiple-harvests Adequate donor sites More than one method of collection Good storage and control of pests

Lessons Learnt

Year prior to harvest and harvest year: Determine species composition & field scale

spatial variation, access, and Species flower/seed architecture & seed

ripening/shedding period(s), methods of collection

Determine areal contribution to seed yield (area / grasses & forbs) and number of harvests required (single or multiple)

Change land use to maximise seed yield (remove grazing pressure)

1 – Seed Burden Surveys

Need for multiple harvests because: Different seed yields between years (1992 &

1993) Species ripen at different times within

years:

2 - Multiple Harvests

Site (1992)

NVC June Early July

Late July

Aug Sept

Bryntirion MG5 2 18 13 9 6Glyn-yr-Henllan

M23 2 23 15 6 6Blaenclairch

M24 1 23 9 6 10

Preplanning - Access for harvest method Species composition Control of land use & management

Adequate yield of seed (area) –

3 - Donor Sites

Sowing Rate kg/ha

Grass @10

Forbs @ 5 Rushes & Sedges @ 3

Donor Size ha

8 1.3 2.3

More than one seed collection method available

More than one because of: Weather - dry standing crop Access limitations (steep, patterned & soft

ground) Selective harvest of seed / seed heads

(flower architecture, key species, weevil infestation)

4 - More Than One Method

Seed collected is valuable in terms of effort and limited resource

Reduced viability through infestation by mildews and white-shouldered house moth

If not sown on collection there is need for:

Drying & dry storage Insecticide treatment

5 - Storage & Control of Pests

Study is highly relevant to today’s drive to establish native plant grassland communities

Study provides basis for planning collection and evidence for achievability to planning authorities

Showed need for careful & informed planning, realistic & achievable programme spanning seed ripening times & a number of years, and sufficient donor resource

Conclusions

AcknowledgementsBritish Coal (former national coal company) for their foresight and funding of this study