The Stangrove Pond Survey - 2006

Stangrove Pond Slide Show

Ongoing Management

The value of the pond, as a wildlife haven, has been greatly reduced since my last association with it in the early nineties, underlining the need for constant 'ongoing' assessment and management. One great disadvantage that it faces is its isolation from other suitable habitat, this, however, has always been the case and, to a degree, must simply be accepted as a fact of life unless there is some action to likewise improve the surrounding area, southern shaw, and other less intensely managed parts at the west end of the park. This could easily be accomplished, given the will to do so. A factor which softens this aspect of isolation somewhat is the discovery of at least one substantial population of both great crested and common newts, in ponds, in a garden, in Crouch House Road, close by the park (there may well be several others in the vicinity), and numerous substantial ponds lying close at hand to the west. Such outlying havens can obviously act as sources of repopulation for Stangrove Park Pond, not only in the case of amphibians but for all aquatic species that are able to make the journey.

This also underlines the need to educate and encourage the parks neighbours to garden in a wildlife friendly manner for they clearly form an extremely valuable part of this ecosystem.

The objective of any management plan, in regard to wildlife conservation, is to maintain the optimum habitat for a particularly rare species or to encourage as many species as possible (biodiversity is the current trendy buzz-word) to flourish. In this situation we are trying to stop the natural succession between a bare bottomed expanse of water and an oak woodland, at the most advantageous point, and to hold it there for as long as possible by employing the correct measure of sensitive husbandry. DEFRA and English Nature (Natural England as of October 6th 2006) should be consulted regarding licenses or permissions required before any work commences, making them aware that great crested newts are present.

The main basic reasons for the current state of affairs are light exclusion and enrichment (rotting leaves being one major source, although this afflicts most ponds to some degree and limited enrichment [mesotrophy] is beneficial in promoting the growth of aquatic plants). The most obvious cause of both (I regard duckweed and algae as secondary problems) is excessively large trees growing in the direct proximity. As can be seen from the photograph, the overall impression, when viewed from a distance, is not of a pond but, rather, a copse of trees.

The two mature oaks and one horse chestnut growing at the south-west corner and, to a lesser extent, the horse chestnut on the north-west corner (these are responsible for leaf input in autumn, rather than shading and both horse chestnuts spawn a profusion of seedlings every year) and the trees on the island (these, in particular, have become excessively large and cause problems both with shading and leaf input in autumn) are the worst culprits, together with those growing along the south-eastern quadrant of the bank in line with the passage of the summer sun. I know that the complete removal of the shore-based specimens would probably cause a riot and would, in any case, be too extreme in that moderate cover along the southern bank is desirable. We must therefore compromise to a degree, but anything that could be done to reduce their scale would help. Those on the island should be the first priority and, if at all possible, cut back to coppice stools and some of the logs produced then stacked in piles (on the island would be great as they would be protected from interference) to produce refugea and hibernation sites for the native amphibians. The regrowth from the stumps should then be cut back on a two to three year rotation. Other trees around the perimeter, such as the many willows, are less damaging as their leaves rot and dissipate more rapidly. Their foliage is also not quite so dense and excludes less light, but these too need to be reduced substantially in height and maintained at a more reasonable level. At present the problem of shrouding begins around the middle of May, as everything comes into leaf, although there is some mitigation as the sun rises higher in the sky throughout early summer.

The problem of excessive duck food, mainly bread, enriching and polluting the water, must be sensitively addressed, and, being a man of small courage, I leave it to Edenbridge Town Council as to how the problem is resolved with the local population. The bulk of the input breaks up quickly on contact with the water and is not consumed by the ducks. The well-meaning public are poisoning the pond and encouraging numbers of resident mallard, which the ecology could not otherwise support. These overgraze the flora and prevent the establishment of aquatic plants. They also forage ashore in the early mornings, during summer, and must take a huge toll of both aquatic and terrestrial invertebrates.

Bramble has got a little out of hand, most notably at the western end, although a case could be made for reducing the height slightly but leaving this section mainly intact as it supports a large colony of house sparrows which have suffered a marked decline nationally over the previous decade or so. This area could also be utilised in siting some log piles or concrete slabs, tucked beneath the canopy of bramble, again to serve as refugea/hibernacula for amphibians. The thorny nature of the bramble would also help to discourage disturbance or vandalism. Elsewhere it should be confined to a few low growing ?pillows? and not allowed to dominate the bankside flora to any great a degree. This may not be easy and will require the root system to be removed, or cautious treatment with a systemic weed-killer such as glyphosate, which should be painted onto the leaves, or cut stump ends, early in the season, when growth is vigorous. It should not sprayed.

Once the enrichment and light exclusion problems have been addressed and overcome, the pond could do with having the build up of rubbish and rotting leaves removed. This would be most easily achieved by using a long reach digger, or similar. Ideally working on one half of the pond in one year and the other the next, however, if sufficient manual labour is available it might prove a little more sensitive to do things by hand. This would reduce the level of detritus but would not eradicate it to the same extent that mechanical means would achieve and may prove sufficient to improve the situation, without massive disturbance and, given the poor state of the aquatic flora, I fancy that the whole area could be covered in one autumn using rakes and drag lines with little overall detriment.

Water levels, generally (given that we have experienced a protracted dry spell throughout the past two years or so), have held up well since the last major work and I feel that any talk of serious dredging in the immediate future is, possibly, premature (see note in 'Conclusion'). It is, however, in the nature of ponds that further such works will eventually become necessary and I thought that I should include my ideas in this report for future reference. Remember that I may be wrong about the ponds origins, and that a cautious approach should be employed in case the pond is of lined construction, especially if considering any increase in depth.

Any future dredging/reprofiling should be carried out over at least two years (no more than half the pond in any one year (see note in 'Conclusions'), to produce a shallow margin, as is currently the case anyway. Extending out to around ten feet from the bank, then shelving gently to around four feet to prevent invasive regeneration of bur-reed and reedmace. An easier option may be to scrape out a gently graded dish shape. Shallow at the edges (a very shallow margin extending to around four to six feet from the bank in order to produce a marshy border [hydrosere] would be perfect) grading down to around four feet in the middle. It might also be an idea to include a few deeper hollows of about eight to ten feet, although this may prove to be unrealistic on such a limited expanse of water. The benefit of these deeper parts would be to increase the overall volume of water relative to surface area and assist in stabilising water temperature in times of extreme heat or cold, it would also help to buffer any input of pollutants. In any case the provision of good variety of depths with a shallow shoreline should be the main objective.

It must be remembered that any such work, although beneficial in the long term, will inevitably have a negative short-term effect on the ponds value as a habitat. No matter how sensitively it is carried out. Even clearing out rubbish and leaf litter will badly set back any aquatic flora albeit temporarily, and this may push any species with a low viability, such as great crested newts, into extinction at this site, although, as we have seen, there is potential for repopulation. Like a doctor prescribing drugs for the overall well-being of a patient we must consider any side effects and be very sure of our evaluation of the situation before deciding if, and when, to proceed. When complete it would be worth importing a few buckets of silt from one or two good, well established, local ponds to boost the diversity of the smaller flora and fauna.

Once the current problems are resolved, or following future structural works, it will be time to focus attention on the more sensitive pursuit of replanting. That is not to say that it is not worthwhile trying just a few aquatic specimens to see how things go prior to completion, as if they survive they may well spread rapidly. There is, of course, no need to be so cautious about restocking with marginals/emergents and the earlier that a reliable source is identified the better. Many commercial suppliers exist. Try Beaver Water Plant & Fish Farm Ltd, Beaver Farm, Eastbourne Road, Newchapel, Tel: 01342 833144 or 834413. Or the local wildlife trusts may be willing to help with some thinnings from reserves, etc, as indeed might local pond/lake owners (Hever Castle has masses of flowering rush and the head gardener is a close friend). One word of caution on suppliers of any supposedly native plants:


Marginals (plants growing from the damp bankside) serve several purposes beneficial to the well being of the pond. First as launching platforms, for emergent insects such as dragonflies. They may in some cases also double as water purifiers and help to buffer any input of pollutants. Some provide species specific egg laying sites. While others are more generally acceptable (great crested newts are particularly fond of using the soft leaves of water forget-me-not to wrap their eggs in) and finally many are also pleasing to the eye, adding a splash of colour and attracting flying insects to feed on their nectaries. A list of potential species (some already present) could include any of the following:

  • Creeping Buttercup
  • Creeping Jenny
  • Greater Willowherb
  • Marsh Marigold
  • Meadowsweet
  • Purple Loosestrife
  • Ragged Robin
  • Redshank
  • Soft Rush
  • Yellow Flag Iris
  • Water Forget-me-not
  • Bogbean

Beyond the marginals lie the emergents, with their feet dabbling in the shallows or a little further out. Some such as Amphibious Water Bistort have two distinct forms dependent upon whether they are growing terrestrially or in an aquatic situation. These might include:

  • Amphibious Water Bistort
  • Arrowhead
  • Branched Bur-reed
  • Brooklime
  • Flowering Rush
  • Water Plantain

Finally the oxygenating plants, those almost completely immersed in the open water, may be added. These are very easy to plant. Either being content to float freely, in some cases. Or requiring just a weight in the form of a stone or some other inert and fairly heavy object to be attached in order to carry them to the bottom, where they will root themselves, given that they are not disturbed or eaten by the resident duck population.

Steer clear of canadian pondweed and consider:

  • Curled Pondweed
  • Common Water Crowfoot (may need more careful planting initially)

These soft leafed plants are suited to the spawning requirements of great crested newts and the conditions encountered at Stangrove Park.

  • Spiked Water Milfoil (also worthy of inclusion if it would get a foothold. It will grow in deeper water than other species and tolerates less light)

All the above three species produce attractive flowers, which project above the water surface.

  • Rigid Hornwort (an excellent oxygenator, content to free-float, but its hard leaves are of little use to spawning newts.)

Helpful addresses:

Plantlife International, 14 Rollestone Street, Salisbury, SP1 1DX Tel: 01722 342730

As much of the open bank as possible should be managed as a wildflower meadow, extending as far back from the flat top of the bank as is practicable, and down to the waters edge. Perhaps some more of the bank could be cleared to provide such an aspect, as much of it is very rank and smothered by vigorous, dominant, species such as cow parsley and nettles at present. This will only be worthwhile once the shading and bramble problems are overcome.

There are many suppliers of native plants (a search of The Internet under British Wildflower Suppliers will reveal hundreds) both as seed or grown plants but, as outlined earlier, this is an area where local schools could be involved in growing a good variety of plants and monitoring their progress. I think that plugs, or pot-grown specimens, will have a better chance of establishing themselves than trying to seed the area.

Choice of potential varieties is quite mind-boggling but an obvious selection of favourites could include:

  • Primrose
  • Cowslip
  • Wild Daffodils (Lent Lilies)
  • Milkmaids
  • Foxglove
  • Sorrel
  • Red Campion
  • Agrimony
  • Vetches (various)
  • Red & White Clover
  • Meadow Cranesbill
  • St John's Wort
  • Ox-eye Daisy
  • Common Knapweed

Once established these should be managed as a late meadow and cut in September every year. Ideally by hand, with a scythe or with a motor scythe/reciprocating mower, with the cuttings being left to lie for a few days to shed any remaining seed before being raked up and removed.

The banks could be further enhanced for wildlife by the creation of some additional niches, for shelter or hibernation, not only for the resident amphibians but beneficial for all manner of invertebrates and perhaps even some small mammals. Free standing piles of logs or whatever would doubtless soon be the target for vandalism. But if labour is not too much of a problem a number of paving slabs, or similar, could be set into the bank to provide gaps beneath of around finger thickness, with the front entrance slightly lower than the back to prevent flooding and facilitate good drainage. It has been suggested that the bases for benches around the pond could also accommodate similar features and this too is worthy of consideration. In fact any extra nooks and crannies that may be incorporated into the layout would be worthwhile considering.

With the major works and replanting complete it may be worth considering ways of stopping or slowing the reoccurrence of excessive amounts of leaves getting into the pond. They were still entering the water from the south in considerable quantities as late as the end of February. And, given that radical culling of mature trees is probably a non-starter, I can offer no magical solution other than vigilance in clearing up in autumn or some sort of physical barrier, such as netting or hedging, which seems rather impractical given the scale and location.

Finally, it should be remembered that even without any rare species or higher orders, such as amphibians, the pond, with the correct treatment and ongoing management, still has the potential to become an attractive feature of the park. An excellent facility for education, and a marvellous habitat for an almost infinite number of invertebrates, many of which are airborne and will enthusiastically repopulate the area once conditions are right.