State of the Greater Fundy Ecosystem

GREATER FUNDY ECOSYSTEM RESEARCH PROJECT

UNB Faculty of Forestry and Environmental Management

State of the Greater Fundy Ecosystem

Forestry and its Impacts on Biodiversity
in the Greater Fundy Ecosystem

Bill Freedman
Department of Biology
Dalhousie University, Halifax, N.S.
B3H 4J1

INTRODUCTION

Forestry activities associated with harvesting and management can affect biodiversity in many ways (Freedman et al., 1994, 1996). The most immediate effects are related to the disturbance of existing habitats within affected stands. This typically happens, for example, when forests are clear-cut, or when regenerating stands are subject to silvicultural thins or herbicide treatments.

Intense, stand-level disturbances of the types associated with forestry practices cause great changes in the suitability of habitats for indigenous plants and animals that are present prior to the disruption. At the same time, however, opportunities are created for early-successional species, most of which are also typically indigenous to the region.

In addition, intensive forest management results in the development of stand types that are substantially different from those initially present on the site. A longer-term change of this kind is referred to as an ecological conversion. For example, intensive management in the lands surrounding Fundy National Park are converting the natural, mixed-species forests indigenous to the region into tree plantations. Because the mature plantations are dominated by tree-sized plants, they are considered forest ecosystems. However, they are anthropogenic forests with a relatively simple structure, being strongly dominated by even-aged, similar-sized cohorts of particular species of conifers. This is in marked contrast to the much more heterogenous character of the natural forests that have been replaced. Many indigenous species cannot breed in the plantations because of their simple habitat attributes, and their paucity of critical habitat elements such as snags, cavity trees, and coarse woody debris.

A young spruce plantation along Shepody Road (Photo: A. Skibicki)

Bunchberry is commonly found in stands of mature forest in the GFE (Photo: M. Burzynski)

Other influences of forestry result in disturbances and stressors that are important at the larger scale of landscape.For instance, the construction of a network of logging roads within a management area will allow hunters much easier access to Black Bear and White-tailed Deer and increase the access of anglers to Trout. If not regulated, the increased rates of exploitation of these game species can lead to local depletions of their populations. Recreation involving all-terrain vehicles can also be enhanced by the presence of logging roads, and these disturbances are important stressors of some species and communities.

Extensive conversions of natural forests into plantations also has landscape-level effects on biodiversity values. As forestry progressively changes the landscape into a mosaic dominated by plantations of various age, the residual areas of natural forest become increasingly isolated. The remaining "islands" of natural forest may suffer losses of their ecological integrity if they are too small to sustain viable populations of some indigenous species, or viable areas of certain indignous communities (such as old-growth forest). Small, stand-level fragments such as woodlots are at most risk from insularization, but this process is also a challenge for certain biodiversity values of protected areas as large as Fundy National Park.

In this chapter we will discuss some of the specific effects of disturbances and conversions associated with forestry practices on selected elements of indigenous biodiversity in the GFE.

EFFECTS ON VEGETATION

Any severe disturbance of a forest results in large changes in the dominant species and sizes of plants that occur on the site. One obvious change is that tree-sized plants no longer dominate the site after clear-cutting. The associated environmental changes result in great increases in opportunities for the numerous species of ruderal plants that are adapted to taking advantage of the relatively uncompetitive conditions that occur after any severe disturbances of forests. These opportunistic plants dominate the initial stages of succession, later becoming reduced in abundance or even eliminated from the community as succession proceeds and tree-sized plants re-establish their dominance.

A recent clearcut in the GFE's Intensive Study Area (Photo: A. Skibicki)

Many early-successional species have benefitted greatly from disturbances and habitat changes associated with forestry in the Greater Fundy Ecosystem (see Veinotte et al., and Roberts and Methven, this volume). These are mostly indigenous plants, and include the Fireweed, Flat-topped White Aster, Hay-scented Fern, Red Raspberry, Rough Goldenrod, Swamp Thistle, Woolly Bulrush, and numerous other species. These same species are also abundant after natural disturbances in the GFE, such as those associated with Spruce Budworm and wildfire.

Unlike ruderal plants, some other species are tolerant of environmental stresses that occur beneath a closed forest canopy. Examples of such plants are the Bunchberry, Red Trillium, Shield Fern, Feather-mosses (such as Pleurozium schreberi and Hylocomium splendens), and certain lichens, such as Lungwort. Some of these species are intolerant of the competitive conditions that occur after clear-cutting, and they decrease in abundance after the disturbance. Eventually, these plants regenerate or re-colonize the disturbed site, assuming that conditions suitable for their presence re-develop, as normally occurs during natural regeneration. However, this is not the case in mature plantations in the GFE, because their dense forest canopy does not allow much of an understorey vegetation to occur. For this reason, the plant community of mature plantations is depauperate in species composition and diversity.

Lungwort (Photo: A. Skibicki)

EFFECTS ON BIRDS

Many indigenous species of birds utilize the habitats of mature forests for breeding, migrating, or wintering. Numerous other species, however, require early-successional habitats for these purposes, including those created through such forestry practices as clear-cutting.

Studies in the GFE have shown that natural, mixed-species forests sustain breeding populations of many species, including Ruffed Grouse, Downy and Hairy Woodpecker, Yellow-bellied Flycatcher, Black-capped and Boreal Chickadee, Red-breasted Nuthatch, Golden-crowned and Ruby-crowned Kinglet, Olive-backed and Hermit Thrush, Solitary and Red-eyed Vireo, Purple Finch, and various warblers, including Nashville, Northern Parula, Magnolia, Black-throated Blue, Yellow-rumped, Black-throated Green, Blackburnian, Bay-breasted, American Redstart, and Ovenbird (see Johnson and Freedman, Sabine, Parker and Hache, and Parker and Doucette, this volume).

In contrast, the early successional habitats of plantations younger than about 15 years support populations of other indigenous species, such as Common Snipe, Common Nighthawk, Alder Flycatcher, Palm Warbler, Mourning Warbler, Common Yellowthroat, Song Sparrow, Lincoln's Sparrow, White-throated Sparrow, and Northern Junco. The species richness and diversity of birds in the young plantations are somewhat less than in the natural forests, but the total avian populations are of comparable size.

Some breeding species utilize the plantations as they mature into simple-structured conifer forests, notably Yellow-bellied Flycatcher, Golden-crowned and Ruby-crowned Kinglet, Olive-backed and Hermit Thrush, American Robin, White-throated Sparrow, Northern Junco, and several warblers, including Nashville, Magnolia, Yellow-rumped, Black-throated Green, Blackburnian, and Bay-breasted. Other species of forest birds do not, however, utilize the maturing plantations for breeding purposes. These include species of Woodpeckers, Chickadees, Nuthatches, Brown Creeper, and other birds that require deadwood as critical habitat elements. These species suffer because cavity trees, snags, and coarse woody debris are absent or uncommon in plantation habitats (Fleming and Freedman, this volume; Freedman et al., 1996). As plantations progressively dominate the landscape of the GFE, protected areas such as Fundy National Park may become the only large-sized refugia for these and other species that require cavities and deadwood as critical elements of their habitat.

EFFECTS ON MAMMALS

"Small mammals" in the GFE include various species of mice, voles, and shrews. Research conducted elsewhere in the Maritime Provinces has shown that most species in this group are quite tolerant of habitat changes associated with forestry, and that they occur through most of post-clearcutting secondary succession (Swan et al., 1984; Parker, 1989; Parker, this volume).

As long as there is sufficient refuge cover available, lagomorphs, such as Snowshoe Hare, can benefit from the presence of clear-cuts and young plantations (Parker, 1984, 1986). This species largely feeds on low-growing shrubs and herbs that are abundant in these habitats. Similarly, White-tailed Deer often benefit from the large quantities of nutritious and abundant browse that are available on clear-cuts and young plantations (Freedman, 1995).

In contrast, some other species of mammals can suffer as a result of habitat losses associated with forestry. American Marten and Fisher, for example, are smaller carnivores that have declined in abundance over much of their range because of the effects of over-trapping coupled with habitat losses through forestry. These species appear to require mature, conifer-dominated forests as a necessary component of their range, including habitat elements of older-growth forests, such as abundant woody debris (Buskirk, 1992; Freedman et al., 1996). The extensive development of intensively managed plantations in the GFE has likely degraded the habitat available for these species (see Bourgeois, this volume).

Black Bear is another species at potential risk in the GFE. Black Bears utilize coarse woody debris as a substrate in which to forage for invertebrates, and as a microhabitat for winter denning (Freedman et al., 1996). Because plantations are severely deficient in large-dimension woody debris, the extensive development of these forests in the GFE can decrease the denning habitat available for Black Bears. This species is also subject to considerable hunting pressure in the GFE, a circumstance that is partly owing to the far-reaching network of logging roads, which makes this species readily accessible to hunters (Forbes et al., this volume).

EFFECTS ON AMPHIBIANS

Because soils and bedrock are quite permeable over much of the GFE, standing water in the form of lakes, ponds, and pools is not very abundant. This constrains the abundance of some species of amphibians, because standing water is a critical habitat needed by most amphibian species for breeding.

The construction of forestry roads requires large quantities of mineral aggregates, which generally obtained locally from borrow pits that later fill with water. In addition, forestry roads have ditches on either side to channel meltwater and stormflows into streams. These anthropogenic ponds and ditches provide breeding habitat that is utilized by several species of amphibians in the GFE, including American Toad, Blue-spotted Salamander, Green Frog, Pickerel Frog, Spring Peeper, Wood Frog, and Yellow-spotted Salamander (Waldick et al., this volume). Unfortunately, because most ditches and borrow pits are rather shallow and occur in exposed locations, they often dry out in the summer, before most amphibian larvae have had enough time to complete metamorphosis. This situation creates a “sink” that attracts the population but does not result in successful breeding.

All of these species also require terrestrial habitats during the adult phases of their life history. Unfortunately, plantation habitats do not provide very good terrestrial habitat for these amphibians (or for fully terrestrial species, such as Red-backed Salamander). This is because the ground surface of young plantations is relatively dry and hot on sunny days, and there are insufficient amounts of moist leaf litter and coarse woody debris to provide refuge habitat for terrestrial amphibians (Adams et al., this volume; Waldick et al., this volume).

FRESHWATER

Studies of stream habitats in the GFE have shown that they can be severely degraded by certain forestry practices, particularly clear-cutting without leaving riparian buffers (O'Brien and Freedman, this volume). This practice results in damages caused by the occurrence of excessively warm water during the summer, siltation of materials eroded from the watershed and streambanks, and the blocking of stream channels with woody debris. In addition, there is still a considerable legacy of aquatic damages caused by historical logging practices in the GFE, particularly the use of streams and rivers for driving logs to the Bay of Fundy during the springtime (Cooper and Clay, this volume). This practice caused severe scouring of the beds and banks of streams and rivers, and dams constructed to store water for this purpose blocked spawning runs of anadromous fish and also caused large changes in hydrology. Other aquatic damages have been caused by the use of streams as skidding trails, and the construction of poorly designed logging roads. The most important damages associated with roads were caused by not installing enough adequately sized culverts at stream crossings, a factor that resulted in erosion and down-stream damages.

These habitat changes associated with forestry have severely degraded the suitability of streams and rivers in the GFE to support populations of Brook Trout and Atlantic Salmon, as well as other aquatic species indigenous to the region. Fortunately, studies in the GFE and elsewhere have demonstrated that most of these aquatic damages can be avoided or greatly reduced if care is taken when constructing roads and culverts and while skidding logs, and by leaving riparian buffers of uncut forest beside all water courses (O'Brien and Freedman, this volume). The efficacy of riparian buffers in avoiding damages to aquatic habitats is well understood, and the DNRE has suggested quite specific guidelines for this practice.

FOREST COMMUNITIES

The Greater Fundy Ecosystem supports a number of distinctive kinds of natural forest, some of which occur relatively extensively on the landscape, while others are uncommon or rare. Some types, such as stands dominated by Eastern White Cedar, and old-growth forests of all kinds, have become much reduced in the GFE and are now endangered elements of indigenous biodiversity.

Old-growth forests are late-successional ecosystems, with particular biological and ecological attributes that distinguish them from younger stages in forest succession (Freedman, 1995; Freedman et al., 1996). Old-growth forests have an uneven-aged population structure, including numerous old trees and a complex physical structure that includes multiple layers in the canopy, big trees, and many snags and dead logs lying on the forest floor. Particular stands of old-growth forest cannot generally be preserved, because they are always subject to the effects of unpredictable, catastrophic disturbances, or to the more pervasive influences of environmental change (for example, in climate). Consequently, if old-growth forests are to remain a feature of the landscape, it is necessary to ensure that large protected areas exist that can sustain the longer-term ecological dynamics that allow this kind of ecosystem to develop. Fundy National Park is the only substantial protected area in the GFE and the Fundy Model Forest, but it is not yet known whether it is large enough to sustain old-growth forest dynamics over the longer term.

Some regional examples of natural forest are not represented in Fundy National Park, for example, stands dominated by Eastern White Cedar. Forests of this character will, therefore, have to be protected outside of the Park, and this will require establishing additional protected areas in the GFE. A gap analysis has been conducted in the GFE as a component of a larger study in the Fundy Model Forest (Loo and MacDougall, see Chapter 2). It is critical that representative areas of all indigenous types of forest and other communities, as identified in the gap analysis, become protected as soon as possible. Otherwise, these elements of indigenous biodiversity will surely disappear from the landscape of the Greater Fundy Ecosystem and the Fundy Model Forest.

SYNOPSIS

If industrial forestry is to be conducted on a landscape in an ecologically sustainable fashion, all of the following criteria must be met: (1) the productivity of the primary resource (i.e., the commercial forest) must be maintained, so that economic commodities and livelihoods can be sustained over the longer term; (2) the productivity of secondary economic resources must also be maintained, including hunted deer, hare, upland gamebirds, and sportfish, and non-consumptive recreational opportunities; and (3) all elements of indigenous biodiversity must be maintained, in at least minimum sustainable populations (for species) and at least minimum sustainable areas (for ecosystems, such as old-growth forest).

Forest management plans for the GFE and Fundy Model Forest are largely accommodating the needs of elements (1) and (2), but some aspects relevant to indigenous biodiversity are at risk. Further damages can be avoided, and existing degradation can be substantially repaired, by implementing the guidelines for forest management that have been proposed by the GFE Research Group (Woodley and Forbes, see Chapter 7). Particular attention should be paid to rapidly completing a network of protected areas, modifying site-management plans to accommodate critical habitat needs of certain species, and taking measures to protect aquatic habitats.

It must, however, be recognized that the guidelines proposed by the GFE Research Group are preliminary, because they are based on an incomplete understanding of ecological processes in the GFE. Consequently, it will be necessary to monitor the efficacy of these guidelines in achieving ecological sustainability in the conduct of forestry and other economic activities on the landscape of the Greater Fundy Ecosystem and Fundy Model Forest.

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