The Three P’s: Ponds, Plants, and Pollinators

There are a lot of things that get overlooked in life. Often, it is something that is so common, so much a part of our lives, that we neglect to pay attention to the importance this item or task can have. One thing that fits into this category has been the humble pond. This small body of freshwater has been so prevalent in our landscape for so long that we thought we knew everything ponds had to offer.

Perfect Pond (W17) (2)

One of the Manor Farm ponds. The pond is very open to direct sunlight and has an abundance of herbaceous and aquatic plant life.

How wrong we were! Scientific research over the last 20+ years has slowly unravelled what we thought was a simplistic, isolated system that offered little value. Now, ecologists are starting to understand that ponds are complex systems that are integrated into a much larger freshwater network. If you want to be surprised, just consider that a pond may often have much more life in it and utilising its services at any one time than a considerably larger lake just a few miles down the road. Furthermore, ponds in an agricultural setting, or farmland ponds, are an important component of a pond network that can massively increase local biodiversity when considered to be healthy.

We now know that farmland ponds can be incredibly rich sources of plant and animal life, especially with the work that has been done thus far with the Norfolk Ponds Project. This is important to know, especially when taken in context that many farmland ponds within the UK are now struggling under immense pressures, both man-made and environmental. In the past, farmland ponds were managed after their creation to keep woody vegetation such as trees and shrubs from restricting access to cattle/sheep, and often to allow fish stocks to be kept in the ponds for angling. This management allowed for plenty of light to come in and encourage aquatic plants to grow, and also the use of the pond by many animal species such as insects, amphibians, fish, birds, and even mammals. Since the end of the second world war, the practice of cutting back woody vegetation has slowly been abandoned and the farmland ponds have been undergoing a natural succession toward wooded wetland. In many instances, ponds were also deliberately filled in to provide more arable land.

Research has shown that this pond state results in much lower biodiversity. Aquatic plants cannot grow where light is largely unavailable and many animals no longer reside there or utilise the site. Most farmland ponds throughout the UK are in this degraded state, resulting in a landscape-scale decrease in biodiversity. However, ongoing research at University College London, in conjunction with the Norfolk Ponds Project, has shown that ponds in an “overgrown” state can be brought back, or “restored”, to a more open and species-rich body of water.

In order to understand the impacts that an overgrown pond has on certain biological elements of a pond and the role that management may play in helping to mitigate those impacts, a new set of studies is underway. My PhD project is part of this new research. I am particularly interested in plants and pollinators, so my project will focus on understanding how shade impacts aquatic plant community structure as well as how it impacts pollinating insects that would typically use flowering vegetation in and around the pond. I am excited to see what answers this project provides to my question of how shade impacts these two communities.

As a fairly new PhD student, I am still trying to get my research design off the ground. Part of my design revolves around which ponds to use. The research done at UCL has used the Manor Farm ponds near Melton Constable, Norfolk as its muse. These ponds have been managed over the years by Richard Waddingham, so that ponds do not reach this overgrown state. Some of the ponds I will use in my research will be ponds located on Manor Farm. I will compare these managed ponds with ponds that are overgrown and with ponds that are recently “restored”.

I recently met up with my colleague, Jonathan Lewis, who is also just about to embark on his PhD fieldwork this year. We went to Manor Farm to look at the ponds to help us determine which of the ponds we would use for our respective projects. It was remarkable to see the ponds in the bright sunshine of an otherwise cold February in Norfolk. As you can see from some of the pictures I took, the Manor Farm ponds are largely open, with plenty of direct sunlight reaching the pond surface and below. Even though a thin layer of ice covered most ponds, the water was quite clear, so much so that you could make out the aquatic plants that were submerged below the surface of the water. See if you can make out the plants in these photos:

 

W1 (2)

Bulrush enjoying a sunny day at a Manor Farm pond.

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One of the Manor Farm ponds. The pond is very open to direct sunlight and has an abundance of herbaceous and aquatic plant life.

A few days later in the same week, I went up to Lancashire near Burscough to meet Helen Greaves, a PhD colleague who has done some great work with ponds and the Norfolk Ponds Project thus far. We set out to explore the agricultural landscape to find ponds and categorise those ponds that were overgrown or needed management. The comparison between the ponds we found in Lancashire with the ponds I saw at Manor Farm just a few days earlier could not have been more dramatic!

The farmland ponds we discovered in southern Lancashire were typically overgrown with woody vegetation around the shores. Often this vegetation was very thick in spots, so much so that you could not even see the water. The water was on average not very clear, and unlike the Manor Farm ponds, the presence of submerged aquatic plants could not be detected. Many of the Lancashire ponds exhibited late stage aquatic plants such as bulrush, rushes, or iris that emerged out of the pond, but on the whole aquatic plants were nowhere near as plentiful as the Manor Farm ponds. The contrast between the ponds at Manor Farm and Lancashire definitely seemed to point toward negative impacts on aquatic plant communities.

Over the coming months this year, I will begin monitoring ponds in Norfolk, including some on Manor Farm. I will observe aquatic vegetation at overgrown ponds and at managed ponds. I will sample pollinating insects such as bumblebees, butterflies, and moths. With my collected data, I can then compare how shade impacts aquatic plant community structure and what types of pollinating insects use the site and how frequently they visit. I can also determine if restoration or management of ponds (so that they have little shade) impacts both the plant and animal communities in positive ways. The information that can be gleaned from this project will definitely help us to answer how shade impacts plant and animal communities at ponds and what that means for landscape-scale biodiversity as well as conservation techniques. I am excited to get underway and I look forward to sharing what I find with you as the project progresses.

Tannersmith Pond (SD 51160 15594) (1)

A small pond in rural Lancashire. This pond was about 55% shaded by surrounding trees and shrubs.

Hedge Pond (Near Rock & River) (SD 49995 16220)

This Lancashire pond was severely overgrown with woody vegetation of alder, oak, and willow. Only one-quarter of the pond surface was visible.

Secret Salt Pit Pond (SD 50989 15501) (1)

This pond in Lancashire was about 55% shaded and had thick willow and alder growth completely covering one-third of the pond surface.

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