How to use native plants in your pond
It should be obvious why you need to use native plants in a wildlife friendly pond or garden. But I'll lay it out for you here in case you're under any doubt.
Exotic species offer very little in the way of benefit to native insects, other than a nectar source for adult insects. No butterfly or moth species are adapted to using exotic plants as food for their larvae. ie caterpillars.
Native plants act in several ways to improve a pond.
The roots will help stabilise the shore edge of a pond. They will also act as natural filtration by absorbing nutrients from the water. This reduces build up of excess nutrients which can pollute the water or build up as toxins and poison wildlife.
Oxygenate the water as they release oxygen from their roots and stems in tiny streams of bubbles.
Provide foraging and shelter for small invertebrates and amphibians.
Did you know that frog and toad tadpoles start out as herbivores before becoming insectivores. They will eat the jelly of the spawn first, then move on to algae, dead plant matter and leaves of pond plants.
This is one of my own ponds in early summer showing the wide variety of plants growing in and around the water.
A wildlife pond, whether it be a naturally occurring pond in the countryside or a lined pond created in a garden, should not have plastic baskets filled with plants in it.
I strongly recommend planting young pond plants into a substrate on the pond bottom.
You don't need special pond soil bought from a garden centre.
In my experience, over many years of creating ponds, not only in gardens but for conservation charities, I have never brought in pond soil or compost.
In several ponds I've only used course grit or gravel to act as an anchoring substrate for plug plants.
The roots will establish in this and as the pond matures, enough plant matter and waste from pond animals will act as a source of nutrients, which the plants roots can absorb and filter out.
Pond plants fall into several categories
Deep water. Those which root into the bottom of the pond. Some will send up leaves and flowers to the surface.
Oxygenators. Rooting into the bottom of the pond, often growing in large clumps.
Surface cover/free floating. Seasonal plants emerging to the surface during warmer weather to spread across the surface.
Emergent. Growing in the deeper water around the margins and sending up leaves and stems above the water level.
Marginal. Growing with their feet in the damp edges of the pond. Most will tolerate being submerged for long periods.
Each type of plant plays an important part in the ecology of the pond. Like the layers of foliage in a forest they offer cover to one another. Provide forage for the animal life. Act as food for some invertebrates as well as the aforementioned early stages in a tadpoles life. Provide egg laying opportunities for various invertebrates. Not just within the pond but above the water as well. And emergent and marginal plants allow the larvae stage of dragon and damselflies to crawl from their aquatic home into the open air. From here they will transform and emerge as adults.