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A land manager's guide to conserving habitat for forest birds in ...

A land manager's guide to conserving habitat for forest birds in ...

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Photo: Doug Tozer This method has several limitations that can negatively affect the health of the stand over time. This method fails to control the number of trees (basal area), balance of species, or the quality of the trees that remain. Often many of the smaller trees that remain are slower growing, genetically inferior trees, or less desirable species. After repeated cuts, stands harvested using diameterlimit will have compromised health, diversity, and productivity as the best individuals are often removed each harvest, leaving successively poorer growing and poorer quality trees for regeneration. Stands tend to reestablish poorly, have a simplified stand structure, and provide only marginal wildlife habitat. Despite being widely recognized as a poor forestry practice, most municipal tree conservation by-laws approve diameter-limit cutting as the minimum standard. Selective Cutting or High Grading Unlike the selection system, selective cutting can be grouped with high-grading as a form of harvesting that is not recognized as a silvicultural system and is not considered good forestry. Generally speaking this form of cutting involves the removal of the best trees or tree species leaving poor quality stands with trees of the poorest genetics to remain as breeding stock for future stands. Unscrupulous operators may portray this as a light form of harvesting; sometimes only a few trees are removed, however the long term impact of repeated high-grading cannot be underestimated. Today’s land managers should no longer use this obsolete practice. Managing Conifer Plantations Conifer species (evergreens) such as white pine, hemlock, and white cedar are important components of southern Ontario woodlands. In many cases these species are present in smaller numbers than they would have been historically. Unlike most hardwood species, many conifers tend to grow in pure stands. Currently, conifer plantations provide this small, but important biodiversity element to the southern Ontario’s landscape. Plantations serve a variety of values. They operate as nurse crops for hardwoods, accelerate or encourage forest succession, rehabilitate and stabilize the soil, shorten the time frame for economic return of forest products, act as a windbreak, or serve as a financial investment. Plantations may add diversity to a landscape, link degraded or fragmented forest patches, stabilize eroded areas, and protect waterways. Although conifer plantations tend to provide limited food for wildlife, they have tremendous value for a variety of species as a source of protection from the elements and from predators. A number of bird species rely on forests that contain conifers including: Pine Warbler, Yellow-rumped Warbler, Blackthroated Green Warbler, Pine Siskin, Red-breasted Nuthatch, and Northern Goshawk. Plantations often serve as a good first step to restoring blowsands and marginal farmlands into forest. By nature conifers are typically the first species to colonize areas that are devastated by fire or other major disturbances, and through the natural processes of succession eventually evolve into a mixed hardwood forest. Considerable effort over the past 100 years has gone into restoring forest cover to some of the most disturbed, eroded, fragile, and otherwise unproductive lands through the planting of conifers. These were chosen due to their ability to tolerate the harsh, open conditions of the often dry and infertile blowing sandy areas (called blowsands). Adapted to these early successional conditions, conifers make an obvious first choice for modern restoration efforts. However, techniques have been developed for establishing more diverse mixes of trees, shrubs, and other plants where conditions and management resources warrant this approach. Like many natural early successional forests, conifer plantations often begin as a single species (monoculture) established at high density spacing. The land quickly becomes closed in by a canopy of trees, with some grasses, forbs, and shrubs. Once the closed canopy condition is established (5–10 years) the forest floor becomes an open, unvegetated, low diversity monoculture. The trees continue to grow rapidly until 10–25 years of age when competition (for Red pine plantation — Photo: Ken Elliott 44 Forest Harvesting

Conifer plantation — Photo: Ken Elliott light, water, space, and nutrients) between the planted trees starts to mature conifers trees over the long term will retain another rare reduce their growth. It is at this point that managers should consider habitat element that was once more common in the southern Ontario thinning to maintain the growth, quality, and health of the remaining woodland landscape. As with other silviculture systems, efforts within trees. This also adds the disturbance necessary to establish the conifer plantations should be aimed at promoting the retention of regeneration of a diversity of deciduous species that are better suited snags, cavity trees, and other old growth attributes while minimizing to the later stages of succession, when a more humid and less harsh the creation of edge habitat. forest microclimate exists. If left unmanaged, growth will slow, and eventually trees begin to weaken and die due to a lack of resources. As trees weaken, they are more susceptible to insects and disease. Without thinning, wildlife diversity within the plantation monoculture will remain low or slow to develop. The value of the planted trees can often be lost and the progression of succession in the understorey may end up being decades behind. By continuing to thin these plantations on an 8–15 year cycle you can maintain good growth of the canopy trees while providing continuous sunlight to the understorey and forest floor. This gives colonizing hardwoods the room and sunlight they need to grow, and disturbs the soil surface to encourage germinations of seeds. As such, plantations will benefit from adjacent natural hardwood seed sources. Typically under these conditions a dense diverse tree seedling layer develops. Where seed is in shorter supply or restoration of hardwood species is more urgent, you may need to consider planting native seeds or seedlings suited to the site, in the canopy gaps. Through a series of successive thinnings, the structural elements such as downed wood, canopy gaps, and diverse vegetation layers develop. Over time, these managed plantations become difficult to distinguish from the surrounding, naturally established woodlands. When establishing and managing new conifer plantations, land managers may consider modifications to conventional designs that may advance the process of succession. Planting blocks, multiple rows, or even individual suitable native hardwood trees within strategic locations will allow mature deciduous species to occur on the site earlier than they would naturally, and these trees will provide a seed source for the plantation as a whole. Row configuration and spacing can be varied to create more natural conditions. The choice of thinning prescription should consider spacing of residual trees, the amount of light reaching the forest floor, ground disturbance, and variable gap sizes to accommodate different species. Keeping individuals and groups of large Colonizing hardwoods — Photo: Ken Elliott Forest Harvesting 45

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