ENHANCING HEADWATER WETLANDS IN PALMER BROOK
AMÉLIORATION DES TERRES HUMIDES DE HEADWATER À PALMER BROOK
The project “Enhancing Headwater Wetlands in Palmer Brook” was sponsored by the National Wetland Conservation Fund through the Government of Canada, and was completed by the HRAA in the summer and fall of 2017. This project consisted of restoring a 30 meter forested buffer zone around two provincially regulated wetlands in the Palmer Brook tributary that were encroached upon by a gravel extraction site.
In order to reclaim the 1.1 hectare area, the compact soil on site was excavated, regraded, and the area was filled with a 7 cm top/mineral soil layer. A cover crop of white Dutch clover was planted to decrease the risk of invasive species growth, to fix nitrogen into a form that all plants require, and help mattify the soil to prevent erosion during the initial phases of the project. With help from the St. John Scouts, other community volunteers and HRAA staff, a mix of native tree species (tamarack, white pine, red, black, and white spruce) were planted on site. As the vegetative community establishes itself, this buffer zone will improve wetland functions and water quality downstream by helping to filter out sediments, improving the storage of floodwater, and improving nutrient cycling. Native hardwoods are already beginning to re-establish naturally, and the site already looks like a much different place!
The HRAA feels this project was so successful that we have already scoped out sites to undertake future similar projects. It will be rewarding to monitor the growth of our forest and see improvements to water quality for years to come!
Le projet «Amélioration des Terres Humides Dans le Ruisseau Palmer» a été parrainé par le Fonds National de Conservation des Terres Humides par le Gouvernement du Canada et a été complété par l'HRAA à l'été et à l'automne 2017. Ce projet consiste à restaurer une zone tampon boisée de 30 mètres. deux zones humides réglementées par la province dans l'affluent du Ruisseau Palmer qui ont été empiétées par un site d'extraction de gravier. Afin de récupérer la superficie de 1,1 hectare, le sol compact sur le site a été excavé, recréé et la zone a été remplie d'une couche supérieure de 7 cm / sol minéral. Une culture de couverture de trèfle blanc a été plantée pour réduire le risque de croissance des espèces envahissantes, pour fixer l'azote sous une forme dont toutes les plantes ont besoin, et pour aider à maturer le sol pour prévenir l'érosion pendant les phases initiales du projet. Avec l'aide des Scouts de St. John, d'autres bénévoles communautaires et du personnel de l'ARHE, un mélange d'espèces d'arbres indigènes (mélèze laricin, pin blanc, épinette rouge, noire et blanche) a été planté sur place. À mesure que la communauté végétative s'établira, cette zone tampon améliorera les fonctions des milieux humides et la qualité de l'eau en aval en aidant à filtrer les sédiments, en améliorant le stockage des eaux de crue et en améliorant le cycle des éléments nutritifs. Les bois durs indigènes commencent déjà à se rétablir naturellement, et le site ressemble déjà à un endroit très différent! Le HRAA estime que ce projet a connu un tel succès que nous avons déjà établi des sites pour entreprendre de futurs projets similaires. Ce sera gratifiant de surveiller la croissance de notre forêt et de voir des améliorations à la qualité de l'eau pour les années à venir!
HAMMOND RIVER FLOODPLAIN RESTORATION PROJECT
The Hammond River Floodplain Restoration Project has successfully implemented measures to return an 8.3 hectare fallow pasture to a forested floodplain wetland.
A prominent issue affecting water quality in the Hammond River Watershed is damage to riparian zones through agricultural practices. This causes unnatural rates of erosion by removing the large trees, shrubs and other vegetation that naturally stabilize the soil and keep it intact during high energy rainfall and flow events. As river banks erode, they eventually become too steep for trees and shrubs to establish. This exaggerates the problem, leaving the banks vulnerable to further erosion. Heavily eroded banks become unsuitable for the plant and animal species that naturally occupy these riparian areas, thereby lowering bio-diversity in the region.
Agricultural land negatively effects water quality, by reducing the infiltration, attenuation and filtration capacity of the land. This amplifies the effects of flooding and allows pollutants, microbes, and nutrients to enter waterways at an accelerated rate. Water temperature is also impacted by a reduction in forest cover, which can decrease oxygen levels in the water and raise the concentration of contaminants, such as E. coli.
By restoring this hay field, located in the floodplains of the Hammond River, the overall health of the watershed is improved. The inherent ecosystem services that wetlands provide are invaluable to biodiversity, water quality and recreational users of the Hammond River. Wetlands help to filter water, provide nutrients and spawning areas for aquatic life, reduce water temperatures, and protect against the effects of climate change such as flooding and extreme rainfall events. In the long term, this area will grow into a forested floodplain that is located at a vulnerable point for the Hammond River, and its tributary, Palmer Brook.
In 2014-2015, the HRAA staff, in partnership with the Canadian Rivers Institute and Boreal Environmental, designed a 2 year restoration plan and monitoring protocol to evaluate tree establishment and wetland species recruitment. Following the planning phase, the site was searched for rare plants and a bird survey was conducted.
In July 2015, the restoration phase began. Riparian areas surrounding the project were planted with water tolerant willow stakes, to create, reinforce and vegetate a 5 m buffer around the project area. Soon after, the project area was hayed, bush hogged, ploughed and disc harrowed to remove competing species and increase porosity and aeration in the soil. Sediment retention infrastructure (including fencing and hay bales) was placed around the low lying areas of the site to prevent the run off of sediment into the adjacent waterways.
After the land was reshaped, 10 vernal pools were created. Three of these pools were large and 7 of them were small existing depressions that were created by modifying the natural landscape. Vernal pools are important components of wetlands, they provide important habitat for unique plants, insects, and amphibians. Once the earth work was completed the land was seeded with a low lying cover crop. The cover crop is used to retain soil, while fixing nitrogen, and helps to prevent the growth of grass which can easily out-compete seedlings.
In May-June 2016, ~29,000 seedlings, whips, and shrubs were planted with the help of many volunteers. Several wetland tree species including: silver maple, red oak, burr oak, butternut, and American elm were planted in the higher areas while alder, willow, serviceberry, and dogwood were planted in low lying areas. All sediment retention infra-structure was removed from the site and a sign was installed on the property. After three months of growth, tree survival was measured and estimated to be 97%; however, HRAA staff feels this estimate may be over-representative. The first winter will be the most challenging for the plants a more and a more representative evaluation of tree survival will be obtained in 2017.
The HRAA will continue to monitor the progress of the site over time, using the information gained as a guide for future wetland restoration projects. Wetland species recruitment will be estimated in 2017, and again in 2022. Tree survival will be re-evaluated in 2017, using quadrats estblished 2016. The HRAA would like to thank the National Wetland Conservation Fund, for their support on the Hammond River Floodplain Restoration project. This project will help to preserve water quality and biodiversity in the watershed, while serving as a model for years to come for future wetland restoration projects.