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Topic: What pond classification system to use?

I would like to know what is the best classification system to use for small ponds?

I have been visiting some local ponds in my area to get an idea of the different types and the species that are found in them.  I would really like to be able to group similar ponds together, so that I can compare whats in them better.  I can't find any pond classification system in books or on the web that lets me do this.

I'm using a Fieldnotes database to store the pond descriptions in.  The Freshwater Habitats section has classification systems for lakes, rivers and streams by The Joint Nature Conservation Council so something similar to these would be ideal.  I emailed Green Man Software who said that they don't know a classification system like this for ponds.

I thought that a lot of people would need to use this sort of information in wildlife recording.  How are different types of ponds usually compared?  Are there some other ways, or do people use a different approach (just by size or something)?  At the moment I've been measuring a lot of the pond data including size, origin, connectivity and some of the water chemistry according to the data boxes in Fieldnotes.

Thanks in advance for any help.

Grant

2 (edited by simon 28-11-2013 20:32:19)

Re: What pond classification system to use?

Hi Grant,

The Pond Conservation Trust (called the Freshwater Habitats Trust now, but there's a link from the PCT website) offers - or did until recently - a very detailed worksheet for assessing ponds:

    ' A guide to the methods of the National Pond Survey', by J. Biggs

It used to cost the princely sum of

Re: What pond classification system to use?

Hi,
I've also just started using FieldNotes to add some site information to my wildlife data.  I'm *very* interested in learning how to identify different types of ponds because most of the places where I look out for wildlife are at least near one pond, and I've aslo helped with ponddipping a couple of times and I'd really like to find out more!
I haven't seen this sort of information anywhere else.   I know Pond Conservations website but can you please tell me are there any other web-sites that focus on ponds?

Re: What pond classification system to use?

Hi,

I've had a dig through my notes to provide some background to the problem.  As was mentioned before, I don't know of any formal classification scheme for ponds in the UK.  Presumably this is because, historically and economically, larger waterbodies (lakes, rivers and streams) are more important and have received most attention. 

The latest classification scheme for standing waters (ie. lakes, reservoirs, gravel pits, pools, etc) is described in 'Vegetation communities of British lakes, a revised classification' (Duigan, C. et. al., 2006) [see: http://jncc.defra.gov.uk/page-3703], which extends the original 'Botanical Classification for Standing waters in the UK...' by M Palmer (1992).  The classification scheme is based on a large dataset with a range of waterbody sizes, but employs a lower size cutoff of around 0.01 hectares (ie. 100m2).  This includes large ponds but leaves many smaller permanent and temporary ponds, ditches, etc. undescribed.  At the lower end of the size spectrum the classification scheme is also rather heavily biased by the large number of small waterbodies sampled in Scotland, making it unreliable for general application to ponds.

Similarly a number of classification schemes have been developed for rivers and streams.  The latest scheme for assessing conservation value is described in 'Vegetation communities of British rivers, a revised classification' (Holmes, N.T.) [see: http://jncc.defra.gov.uk/page-2619].  Several alternatives exist; for example the Environment Agency uses the European Water Framework Directive (WFD) to assess the quality of the water environment.

A formal classification scheme specifically describing smaller ponds (ie. standing or very slow-moving water bodies < 0.01h in size) is notable mainly by its absence.  Given the importance of ponds to local wildlife, and the obvious advantages to species/habitat surveying, it is curious that it has been ignored for so long.  When developing FieldNotes' Freshwater habitat descriptor (which currently uses JNCC Lakes and Rivers/Streams classification schemes) I spent some time trying to identify a comparable scheme for ponds.  The main candidates were:

-     Pond Action (since Pond Conservation Trust and now the Freshwater Habitats Trust) carried out a National Pond survey in the nineties, and (I believe) did some preliminary work on developing a classification scheme, presumably based on the collected data.  As far as I know the scheme was never published and I have not managed to chase up any details

Re: What pond classification system to use?

Hi Simon.  Thanks for all the information you posted.  I can see some sense now (a bit!!).

I've been out visiting some of 'my' ponds again over the past couple of weeks.  (Lots of amphibians and everything is very advanced for time of year).  I also asked some friends (who know about such things!!!) about trying the National Vegetation Classification system on ponds, so Ill see what happens...

6 (edited by simon 14-04-2014 22:26:47)

Re: What pond classification system to use?

Over the last month or so I've been trying to look at local ponds from an NVC perspective, to get an idea of how useful this classification system would be for categorising pond types (see above thread).  These are some initial thoughts, focussing on specific types of ponds that I've noticed that seem to fall outside the NVC Aquatic Communities classification scheme.

Unvegetated reservoirs.
Probably the most difficult problem I've come across is generating an NVC 'score' for ponds which do not have any aquatic vegetation species at all(!)  Some of my favourite ponds are small concrete reservoirs that farmers have built (presumably to provide local water storage for crops / animals).  In many cases they seem to attract more wildlife than similarly-sized natural ponds - I'm guessing that one reason is because they are often built in areas which have few natural ponds or streams, so draw wildlife from a large radius.  They're alive with dragonflies in the summer, and I can find amphibians in or around many almost all the year round (maybe partially because they have difficulty getting out!).  In many cases these artificial ponds don't support any higher plants - however this is where their similarities end.  Some (at one end of the spectrum) contain clear water with little life except mosquito larvae, whilst many others (at the opposite end of the spectrum) are thickly coated with a floating layer of green algae - from a few inches to a foot or so thick - and support an amazing density and diversity of species (in particular snails, immature newts, caddisfly, stonefly and dragonfly larvae).  There are also a number between these two extremes.  As far as I can guess much of the variation arises from differences in inflows to the ponds (nutrient enrichment, etc), although I'm sure that things like depth, accessibility and a host of other factors are also relevant.

Small pools in dense woodlands.
By these I mean ponds where the bottom is covered by a layer of leaves for much of the year - I'm guessing that food-chains in these ponds are fuelled predominantly by decomposition processes.  I know several examples that support very healthy newt populations.  Again the ponds are very sparsely vegetated, either because of the dense shade or moveable substrate, and don't look as if they would fit into an NVC-based classification system easily.  However I'm reserving judgement on these until later in the season (incase there is a brief window of growth).

Elongated, ditch-like ponds.
Highly linear ponds (which in many cases link to adjacent waterbodies) also present difficulties, because the majority of plants (apart from rushes) line the sides.  The boundary between pond-related and adjacent vegetation is indistinct, and highly dependent on water level.  If you follow the pond/ditch for a while it is often bordered by completely different vegetation, which further complicates matters.

Temporary pools.
I haven't had time to look at short-lived pools in any detail.  However many of the sites that I check for frogspawn early in the year are shallow temporary pools on heathland, where the heath vegetation (mainly grasses) persist throughout the life of the pond.  Where temporary pools are relatively short-lived, or where the vegetation community is resistant to submergence, it seems likely that such pools will have little effect on vegetation and as a result would fall outside the aquatic NVC classification.  Temporary pools are used in preference by some species - notably frogs / natterjack toads, but also many invertebrates - as they offer a number of advantages in addition to local availability (rapid warming; predator avoidance; etc).

Ponds with perturbed vegetation communities.
Another problem worth noting is the increasingly common trend of introducing exotic plant species into natural ponds, either deliberately and accidentally.  Several of my local ponds have been deliberately 'improved', in one particular case transforming a sparsely vegetated, acidic heathland pond with a dense covering of water-lilies.  Using an NVC-based system this would be recognised as a completely different pond type; however it is arguable how much the aquatic community has changed, as the location is fairly remote and rate of colonisation by (for example) new invertebrate species likely to be low.  Canadian pondweed offends in a similar way (although more often accidentally).

In summary, I'd say that my initial reaction is that the NVC classification system is (at best) likely to be useful for categorising a subset of ponds which exhibit 'classical' vegetation types, but of limited use in classifying the full range of pond types encountered in the UK.  Part of the difficulty in adopting a purely plant-based classification scheme arises from the 'island' nature of discrete ponds, where colonisation by species (particularly plants) is a chance event.  In particular, ponds in which plants have difficulty establishing, or where atypical (artificially introduced) species dominate will always fall outside such a scheme.

The ditch classification system proposed by JNCC extends the scope slightly; however even from my limited exploration it is clear that a number of additional pond types exist outside these classification schemes.

Simon Skidmore
Green Man Software Ltd

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Re: What pond classification system to use?

Those are some BIG gaps - I could fit  a bus through there!!!

Seriously tho what your saying is that learning the NVC System isn

Re: What pond classification system to use?

Yes - I still find it odd that there doesn't seem to be a standard classification system.

Its difficult to understand how freshwater conservation groups decide which ponds must be conserved at all costs (and which might be easily replaced) without defining different types.  Or simply which ponds need managing or restoring, as many progress through a series of stages to dryish land (pond succession).

The Freshwater Habitats Trust (http://www.freshwaterhabitats.org.uk/) currently have a 'Million Ponds' project.  I don't know what criteria they use to recognise / classify different pond types, but it must be an important consideration for maximising pond diversity.

The FreshwaterLife website (http://new.freshwaterlife.org/) also provides a hub for relevant information, although oddly enough their habitats page does not list ponds as such.  However the website contains a wealth of scientific information and resources, so someone may be able to point you at relevant pages.

It may be worth asking them directly?

Simon Skidmore
Green Man Software Ltd