Task 4

Working in the field

I attended a teaching session in the field on 09 October 2023 led by Dr Matthew Bulbert (Senior Lecturer in Conservation Ecology) and Dr Andrew Lack (Senior Lecturer in Environmental Biology). This visit was to Aston Rowant National Nature Reserve, where we were based on a south west facing slope of chalk grassland, just to the north west of Cowleaze Wood.

This session covered:

• Identification of plants down to the lowest taxonomic level (ideally to species) by using a quadrat to define the sampling area.

• Identification of invertebrates by using a sweep net and pooter to collect the samples.

Working in the field

Quadrat thrown into position for sampling. Not truly random but acceptable for this exercise

Sweep net used for 30 seconds whilst walking through vegetation to sample invertebrates.

Pooter used to extract samples from sweep net and deposit into plastic tube for identification.

Provide evidence of the plants that you managed to identify and the features by which they were identified. If you made a mistake, where was the mistake made?

By following the family key (Streeter, D et al., 2016), looking at the characters, the species keys or the table created as part of Task 2 the following plants were identified:

Crataegus monogyna (Hawthorn)

• Leaves compound, alternate

• Shrub, stem with prickles

Family = Rosaceae

• Thorny

• Lobes longer than broad

Plantaginaceae (Plantain)

• Leaves in basal rosette

• Leaves with parallel veins

Family = Plantaginaceae

Clinopodium vulgare (Wild Basil)

• Leaves opposite

Family = Lamiaceae

• Flowers in whorls, without stalks

Galium album (Hedge Bedstraw)

• Leaves in whorls >= 4

Family = Rubiaceae

Note: At this point Dr Lack talked through the vegetative key (Poland and Clement, 2020), as getting further was proving difficult

• Whorls of small leaves, vein in the middle

• Prickles on leaf edges pointing forward

• Smooth stem

Fragaria vesca (Wild Strawberry)

• For this one I was unsure where to start, although it did look familiar. Dr Lack provided the identification that it was wild strawberry by sight.

  Family = Rosaceae

  • Hairy stem

  • Leaves Ternate (divided into 3 leaflets)

  • Apical tooth (tooth at apex) as long or as long as neighbours

Rosa canina (Dog-rose)

• I saw the hooked prickles and thought that it looked 'rose-like'. However, when looking at the family key I saw that the leaves in Rosaceae were alternate. I mistakenly thought the leaves were opposite - not realising that the leaves were compound and I was actually looking at leaflets that were opposite.

  Family = Rosaceae

  • Strongly hooked prickles

  • Leaflets, glabrous (smooth or glossy)

Thymus pulegioides (Large Thyme)

• Unsure of this, my initial thought was possibly in the Geraniaceae family as it looked to have elongated ovary.

  Dr Lack highlighted some characters for identification.

  Family = Lamiaceae

  • Leaves opposite

  • Stems 4-angled

  • Long hairs on angles (i.e. edges/corners of stem)

Invertebrate sampling

The sampling of invertebrates produced specimens from: Aranae, Coleoptera, Gastropoda and Himeptra.

Aranea

Count = 10

Coleoptera

Count = 1

Coleoptera

Count = 5

Gastropoda

Count = 1

Himeptera

Count = 2

1 aphid, 1 hopper. Both are Homoptera.

When sampling plants and animals what considerations do you need to take into account?

For both plants and animals it is important to define the sampling units e.g. squares in a grid and sampling frame e.g. the list of all squares (Sutherland 2006).

It must be possible to replicate sampling. Information recording location, date/time, methods must be complete.

Plants:

Determine sampling method based on: small, medium, large; and whether organisms are common or rare (Wheater, Cook and Bell, 2020).

For this case we used quadrat sampling, so the size of the quadrat (based on diversity of organisms) and the placement of the quadrat (randomly or systematically) are of importance. As part of this exercise we attempted to quantify the cover of the plant species within the quadrat by estimating the proportion of the quadrat occupied by each species. We estimated the Hawthorn to cover approx 25% but did not finish our analysis. There are a number of scales that could be used to estimate cover, such as the Braun-Blanquet and Domin scales, as there can be problems estimating cover (Sutherland, 2006, pp190-191).

Animals:

The methods used need to be standardised (Wheater, Cook and Bell, 2020), aiming to reduce bias. For example, in this case we were using sweep nets so we could attempt to standardise by setting a time for sampling e.g. 30 seconds, or number of sweeps. The results will be 'noisy' as there will be variations in how different people complete the sampling but the aim is to reduce this variability as much as possible.

The type of animal to be sample will determine to a large extend the method of sampling i.e. for ground based invertebrates a sweep net would be inappropriate but a pit-fall trap may be better suited.

In this exercise using a sweep net to sample invertebrates, we found a number of arachnids were sampled. If we were requiring these samples to be studied in detail then it would be a good idea to separate them into different sampling tubes (so other organisms were not captured in any webs), or to use formaldehyde to preserve the specimens.

In the two areas that you sampled for plants what was the difference? And why was there a difference?

Due to time constraints each group of students only sampled in one area. At the top of the slope or further down-slope. The plants that I sampled were towards the top of the slope.

In terms of difference in plant composition between near the top of the slope and the bottom of the slope, the upper part had more woody vegetation e.g. Crataegus monogyna (Hawthorn), presumably as this is nearer where the larger established trees are. Additionally there was more Daucus carota ssp. carota (Wild Carrot) and Thymus pulegioides (Large Thyme) towards the top of the slope. Campanula rotundifolia (Harebells) were only found lower down the slope.

We later learned that the upper part of the slope had been ploughed in the past, albeit only for a short while but it appears that this may have been enough to influence the plant assemblage present.

In the two areas that the invertebrates were sampled what was the difference? If any? And why was there a difference?

Due to time constraints each group of students only sampled in one area. At the top of the slope or further down-slope. The invertebrates that I sampled were towards the top of the slope.

There were more permanent ant-hills lower down the slope, perhaps this was related to the historical ploughing or it could be that it is closer to the footpath so there is more disturbance at the top of the slope. Other factors such as soil composition and climactic conditions could be a factor e.g. perhaps the upper part is more windswept.

Was there any other learnings that you wish to comment on above and beyond the questions mentioned above?

As part of this session I also learned that chalk (calcium carbonate) is alkaline and that typically alkaline soils are more diverse than acidic ones (in terms of plant species).

Additionally, that hoppers can not only walk forwards and sideways but also backwards which is an unusual trait.

References

Sutherland, W. J. (2006) Ecological census techniques : a handbook. 2nd edition. Cambridge, UK: Cambridge University Press.

Wheater, C. P., Cook, P. A. and Bell, J. R. (2020) Practical field ecology. 2nd edition. Hoboken, NJ: Wiley-Blackwell.

Poland, J. and Clement, E. J. (2020) The vegetative key to the British flora : a new approach to naming British & Irish vascular plants based on vegetative characters. Second edition. Southampton [England]: John Poland.

Streeter, D., Hart-Davies, C., Hardcastle, A., Cole, F. and Harper, L. (2016) Collins wild flower guide. Revised and updated 2nd edition. London: William Collins.