Planting Riparian Buffers Safe for Horses
Riparian buffers are streamside plantings of trees and shrubs that are important for protecting our local streams by absorbing upland pollution, shading and cooling the water, providing habitat for wildlife, and reducing erosion. If you are considering planting a riparian buffer next to a horse pasture, it is important to make sure that those trees and shrubs won’t be harmful to the horses. While trees provide many benefits to streams, rivers, ponds, and other bodies of water, certain species are toxic to horses and should be avoided. Falling branches and buffer maintenance can also be a concern.
Toxic Trees and Shrubs
The following tree and shrub species are native to PA, often used in streamside, riparian buffer plantings, and also happen to be toxic to horses:
- Black, pin, and choke cherry are highly toxic to horses and other livestock. The leaves, twigs, bark, and seeds contain cyanide that can cause anxiety, breathing problems (suffocation), staggering, convulsions, collapse, and even death. The risk is greatest when animals consume wilted leaves.
- Red maples are extremely toxic to horses and ponies. Closely related species, silver and sugar maples, can also be toxic. Wilted or dried leaves (i.e., a branch comes down during a storm or autumn leaves on the ground) contain gallic acid and other toxins that destroy red blood cells, leading to breathing difficulties, jaundice, dark brown urine, and death. Consumption of 1.5-3 pounds of wilted red maple leaves causes toxicity. Green leaves are not toxic, but bark is.
- Box elder seeds and seedlings can cause the equine muscle disease Seasonal Pasture Myopathy, which is 75-90% fatal. The seeds and seedlings contain the toxin hypoglycin A, which interferes with fat metabolism and causes the breakdown of respiratory and muscle cells. The symptoms include tremors, weakness, stiffness, dark urine, rapid breathing, and death – usually within 48 hours. Male box elders, which don't produce seeds, are safe to plant.
- Black locust leaves, seeds, bark, and wood (fence posts) are moderately to highly toxic to all livestock species and cause severe gastritis, colic, and depression.
- Shavings from the black walnut tree are known to cause laminitis in horses that stand on them. In a pasture setting, the trees rarely cause problems, but they should not be the first choice for planting around horses. Walnuts and their hulls on the ground may become moldy and be toxic if consumed. Sawdust from the wood is of particular concern, so be cautious when removing these trees or cutting up fallen branches with a chainsaw in proximity to your pasture.
- Oaks are moderately toxic to horses, cattle, sheep, and pigs. Young leaves and green acorns are the most toxic and cause poor appetite, weight loss, diarrhea, increased drinking, increased urination, kidney failure, edema, and death.
- Elderberry and serviceberry contain cyanogenic glycosides throughout the plant that can be toxic to horses during times of drought. Symptoms include cardiac abnormalities, gastrointestinal upset, diarrhea, coma and death.
- Winterberry, American persimmon, American plum, crab apple, Kentucky coffee tree and buckeye or horse chestnut can also be toxic to horses and should be avoided.
Safer Choices
This takes some commonly used species off the table when creating your planting plan, but there are still plenty of other trees and shrubs that pose less of a threat to the horses on site, including: alders, basswood, black gum, buttonbush, dogwoods, hackberry, hazelnut, hickories, honey locust (thorns can cause puncture wounds so plan planting locations accordingly), hornbeam, ninebark, paw paw, poplars, quaking aspen, red bud, river birch, spicebush, sweetbay magnolia, sweet gum, sycamore, viburnums, and willows.
Other Concerns
Besides concerns about the toxicity of trees and shrubs planted near horse pastures, there are several other factors to consider when planning a riparian buffer near horses.
- Plant shorter plants closer to the fence or increase the distance between the fence and the closest trees to avoid branches falling and breaking the fence once the trees are mature.
- Install gates or ensure there is appropriate access to the riparian buffer to allow for maintenance.
- Maintain a mowed buffer between the fence and your newly planted forest. This minimizes tick populations near the horses.
- Plan for maintenance of the riparian buffer. Some of the weeds and invasive species that plague riparian tree plantings are also toxic to horses.
