Biodiversity and agriculture Alan Feest SRF Faculty of Engineering

What is biodiversity? What do you think it is?

What is biodiversity? The Convention on Biological Diversity definition is: Biological Diversity means the variability among living organisms from all sources including inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes within species, between species and of ecosystems (genes, species and ecosystems). What is wrong with this definition?

A new definition of biodiversity Biodiversity can be viewed as a quality described by a range of indices representing the functional characteristics of a taxonomic group. I have used the following: Species Richness, Population, Biomass, Rarity or Conservation Importance, Evenness or Dominance or Special Index such as indication of nitrogen pollution.

Measuring biodiversity Requires standardisation of sampling but there are other possibilities

What can we measure? Species richness: The number of species in a unit area/sample. For our example 20 x 4m radius circles = 1,000m2 (0.1 ha) But it could be pit-fall traps or in a stream kick samples. What is weak about this measurement?

What can we measure? Population: the number of individuals in a unit area/sample This should be related to numbers of individuals per species but can be for indeterminate species (mosses for example) limited to occurrence which then over a set of 20 samples would provide a frequency. What is weak about this measurement?

What can we measure? Evenness or dominance: consider the following: two sites both have a 100 individuals of ten species. One site there are 10 individuals of ten species and the other has 91 individuals of 1 species and 1 each of 9 species. How do they differ? We have a variety of possible measurements: Shannon-Wiener, Simpson and Berger-Parker. For the first two the higher the number the more even the populations. The B-P is very easy to compute. What is weak about this measurement?

What can we measure? Biomass: the amount of living material per species and in the total sample. For those taxa that have determinate sizes the population counts can be converted to biomass by simple conversion equations. For example the biomass of a fungus is proportional to the area of the cap (πr2). Since for some taxa there is a great difference in size per individual (>10,000 fold in macrofungi)) this becomes a an important measurement and the data can be used for E/D calculations. It relates to the role of the organism group in a ecosystem. What is weak about this measurement?

What can we measure? Rarity/conservation value: all species are not equal! Generally we put more value on rare species than on common ones but it might also be those that are in decline. I have created a Species Conservation Value Index (SCVI) where the rarity of the species is allocated from records or within sample incidence. Expressed as a mean value per species plus the SD since rare species will not change a mean in a speciose sample but will show in the SD. What is weak about this measurement?

What can we Measure? Special indices: for example probably the greatest threat to UK biodiversity is nitrogen deposition so we can create a nitrogen index. Using this approach I have shown that the decline of butterflies in the Netherlands for example, is the result of the deposition of nitrogen and this is probably the case in the UK .

How good is our sample? Given the incidence of species it is possible to calculate the expected number of species in full/complete sample (theoretical!). Two ways: Non-parametric Chao 1&2 or iterative Monte Carlo sampling: Bootstrap and Jackknife. From this we can show that the 20 sample sampling design generally records in excess of 80% of the species present. Is an 80% sample accurate enough?

What can we measure? The relative balance of these six measurements expresses the BIODIVERSITY QUALITY of the taxon under examination. Changes in the relationship of these indices shows the changes in biodiversity. This can only be done realisitically for species and not for genes or ecosystems!

Results from the chart: Species Richness: 61 Simpson Index: 20.51 (7.7) Density: 4512 SCVI: 12.59+/-16.85 Biomass: 897813 g Chao 1: 62 Chao 2: 70 Bootstrap: 70 Jackknife: 72

How does this relate to your interests? 1. All agriculture affects biodiversity but using these methods you should be able to set biodiversity quality baselines and by resurveying later show improvement or decline. 2. It can provide evidence of best practice through establishing management methods that improve biodiversity of the target organisms. 3. A wide range of organisms can be assessed depending on what might be considered a good indicator for the site. For many sites ground beetles or spiders would be good indicators.

Advantages for non-ecologists 1. YOU do not need to know what things are called (although this thought will terrify ecologists!). 2. It resolves biodiversity to a series of indices which engineers/ bureaucrats/ politicians are happy to encounter since they are familiar with financial spreadsheets! 3. Statistical significance can be attached to differences/similarities of sites over time or between sites. 4. Gives a clearer understanding of biodiversity and what it means. The changing relationship of the indices shows what is happening. 5. It can be built into developments by setting baselines to be tested post development for difference. 6. There is a computer programme that does all the calculations (BQC). 7. There is a stop rule to effort so the “size” of a survey is defined and the resources necessary are reasonably predictable.

Examples of use 1. We have assessed the biodiversity effect of a range of crops (Miscanthus, Oil-seed Rape, Linseed, Willow coppice 2. Have shown that nitrogen pollution affects butterfly populations. Much of this comes from agriculture. 3. Have followed the biodiversity quality of farmland birds for 14 years and indicated the extremely worrying decline despite additional feeding. 4. We are assessing the biodiversity quality of for example the land holdings of water companies. 5. We have assessed the fungi along a pipeline route over 100km of countryside so that the best biodiversity sites can be avoided.