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“An important first step is making dog owners aware of this fertilization effect.”Getty Images
This story was originally published in the Guardian and is reproduced here as part of the Climate Desk collaboration.
Urine and feces from dogsAccording to a new study, they are being deposited in nature reserve in such large quantities that it is likely that it will be damaging wildlife.
The analysis revealed that footpaths can result in ground fertilization with nitrogen and phosphorus at levels that could be considered illegal on farmland.
The scientists arrived at their conclusions after counting the number of dogs in four nature reserves near Ghent over 18 months. Belgium. They stated that the situation would be comparable across Europe, home to approximately 87million dogs.
The research found that dogs are fed at their homes and then excrete nutrients when they go on walks. That leaves them with an average of 4.5kg of nitrogen per acre and 2kg of phosphorus per year. This is the same level of pollution that is known to be transported through the atmosphere from industry, agriculture, and traffic fumes. It ranges from 2 to 10 kilograms of nitrogen. The impact of dog urine and feces is also significant.
Many dog walkers think that leaving their pet’s excretions in nature will not do any harm. Overfertilization is a bad idea because most ecosystems have low nutrient levels. Hogweed and nettlesTo drive out others and the wildlife dependent on them.
“We were surprised by how high the nutrient inputs from dogs could be,” said Prof Pieter De Frenne of Ghent University, who led the research. “Atmospheric nitrogen inputs from agriculture, industry and traffic rightfully receive a lot of policy attention, but dogs are entirely neglected in this respect.”
Researchers determined the illegal levels for nitrogen and phosphorus in situations when dogs must be kept on leads. They can only wander 2 meters along a path. “Those levels are quite staggering, as our study concerned nature reserves,” he said. “Of course, there are a lot of beneficial effects [to walks in nature], both physically and psychologically, for owners and their dogs but the drawback is bringing in significant amounts of nutrients.”
De Frenne stated that the levels of dog ownership are very similar in many western European countries, so there is no reason why the situation in Ghent would be any different. British charity Plantlife warns against nitrogen pollution is “one of the greatest threats to our wild plants, lichens, and fungi, yet little is being done to tackle it.”
The Research, published in the journal Ecological Solutions and Evidence, he counted more that 1,600 dogs in 500 nature reserve visits. They did this at all times of the day and on all seven days of the week. This data was combined with the dogs’ excretion levels of nitrogen, phosphorus and other nutrients to estimate the total nutrients that were deposited.
Scientists had kept track of whether the dogs were walking on leads. This allowed them to calculate that 51 kg/acre/year of nitrogen was lost by paths, and 1.6 kg/acre/year was lost to the rest of nature reserves. If all the dogs were kept on leads, the amount of nitrogen would have risen to about 71kg/acre/year via paths, with a similar increase in phosphorus.
It was easy to remove all the phosphorus from dog feces, but not all the nitrogen. Dog urine contains a lot of phosphorus and significant nitrogen. “Urine is, of course, difficult to take away,” said De Frenne. Research has shown that even after dogs are banned, high levels of nutrients can persist for up to three years.
“An important first step is making dog owners aware of this fertilization effect,” De Frenne said. “I think many people will just pick up the feces.” But the urine would remain and he said managers of nature reserves with sensitive ecosystems could consider banning dogs, which already happens in some places to protect birds and other wildlife.
Rob Stoneman, director for landscape recovery at The Wildlife Trusts, UK, said: “Nature reserves are special places for nature conservation, where wildlife and fragile habitats are protected. Although poo is part of nature, dog poo can cause damage to the ecology of fragile habitats. Wherever you walk your dog, it is important to pick up, bag and bin poo, to ensure the continued protection of these wild areas for us all to enjoy.”
De Frenne stated that the next steps in the research could include soil analysis to verify the estimates made in the current investigation and extension of the analysis to pet cats.
