Effects of Land Base Change on Habitat Suitability

The graph below shows the distribution of bird species' responses to each type of land base change in the Al-Pac FMA area between 2010 and 2023. Examples of how different species respond to overall land base changes include:

• Between 2010 and 2023 in the Al-Pac FMA area, changes in bird habitat suitability due to natural disturbances—such as wildfire (-11% to +26%) and the aging of naturally disturbed stands (-13% to +19%)—were greater than those caused by all human disturbances combined (-9% to 4%). The Brown Creeper saw the largest increase in habitat suitability with the aging of naturally disturbed stands (+19%), as it relies on the standing dead trees common in older forests to forage for insects, spiders, and larvae found beneath their peeling bark. The Golden-crowned Kinglet showed the greatest decline in habitat suitability from wildfire (-11%), as it depends on the dense foliage of mature conifers for both foraging and nesting cover.
• Between 2010 and 2023, more bird species showed decreases (59%) than increases (41%) in habitat suitability associated with new forestry, with changes ranging from –10% to +8%. The largest declines were observed for old-forest specialists such as the Black-throated Green Warbler (–10%) and Bay-breasted Warbler (–6%). In contrast, early-seral species like the Alder Flycatcher (+8%) and Clay-colored Sparrow (+5%) increased in suitability, benefiting from shrubby habitats created after disturbance. The aging of older harvest areas partially offset these effects, narrowing the net forestry-related change to between –9% and +4%.
• When examining the effects of new human footprint (excluding forestry), changes in bird habitat suitability were generally small (ranging from –1% to +1%). However, more bird species showed decreases (83%) than increases (17%) in suitability—compared with wildfire (64% decrease) and the natural aging of disturbed stands (54% decrease).
• There were nine species with more than 5% net loss of habitat due to combined land base changes between 2010 and 2023. The majority of these species, including the Yellow-bellied Flycatcher (-14%) and Ovenbird (-10%), are primarily associated with young to mid-aged forest habitats and lose habitat as forest stands mature.  
• There were seven species with at least a 5% increase in habitat suitability overall. This included species that rely on recent fires for habitat, such as the Black-backed Woodpecker (+19%), as well as species that prefer habitats created after fire and forestry that can provide dense cover for nesting, such as the Mourning Warbler (+7%).
   

The graph below shows the distribution of mammal species' responses to each type of land base change in the Al-Pac FMA area between 2010 and 2023. Examples of how different species respond to overall land base changes include:

• In the Al-Pac FMA area, change in mammal species’ habitat suitability was small for all types of land base changes combined, ranging from -2% to +3%. 
• Most large mammals detected with wildlife cameras are habitat generalists that can use a wide range of habitats and/or are more responsive to changes in the availability of forage or of prey.

The graph below shows the distribution of soil mite species' responses to each type of land base change in the Al-Pac FMA area between 2010 and 2023. Examples of how different species respond to overall land base changes include:

• When all land base changes are combined, habitat suitability declined across the Al-Pac FMA area for 69% of soil mite species between 2010 and 2023 ranging from a 37% loss of habitat to a 16% gain.
• Habitat suitability declined for 64% of soil mite species (ranging from -6% to +8%) as a result of new forestry activities between 2010 and 2023. Aging of previously harvested forest areas led to improved habitat conditions for 57% (-5% to +3%) of species—partially offsetting these losses. However, the overall net effect of forestry was still negative, with habitat suitability declining for 62% (-7% to +5%) of species. Forest harvest can decrease the availability and diversity of leaf litter, which reduces the availability and composition of food for soil mites^[3].
• The range of habitat suitability changes due to fire (-14% to +28%) as well as the aging of naturally disturbed stands (-23% to +30%)—indicates that some mite species respond more strongly to natural changes than to human footprint. 
• Habitat suitability dropped by at least 10% for ten species due to combined changes on the land base. For example, Peloribates sp. 3 DEW (-15%) and Neoribates sp. 2 DEW (-15%), which are associated with young to mid-aged forests (20–60 years), declined as natural stands aged.
• The species with the largest gains in habitat had stronger responses to natural land base changes than to changes due to forestry or other human footprint. Scutozetes lanceolatus (+10%) and Eupelops septentrionalis (+10%) responded most strongly to fire, while Epidamaeus sp. 1 DEW (+16%) responded most strongly to native aging.

The graph below shows the distribution of vascular plant species' responses to each type of land base change in the Al-Pac FMA area between 2010 and 2023. Examples of how different species respond to overall land base changes include:

• Between 2010 and 2023, vascular plant species exhibited a roughly even balance of positive and negative responses to changes in habitat suitability across the entire land base, with individual species showing shifts ranging from a 38% decrease to a 37% increase.
• The impacts of natural disturbances on vascular plant habitat suitability during this period were mixed. Wildfire reduced suitability for 59% of species, with changes ranging from –31% to +44%, while aging of naturally disturbed stands increased suitability for about half of species (–20% to +21%). Many vascular plants are long-lived, shade-tolerant species associated with older, closed-canopy forests; they typically decline after fire and harvesting but increase as forests mature. For example, Canada Anemone thrives in the moist, well-drained soils of mature and old forests.
• Changes in habitat suitability due to forestry (-6% to +16%) were smaller than those from natural disturbance. Between 2010 and 2023, habitat suitability declined for 60% of vascular plant species affected by forestry. However, many species benefit from the increased sunlight and reduced competition following canopy removal; for example, Alpine Milk Vetch (+16%) thrives in the full sun and open conditions of recently harvested areas.
• Habitat suitability declined by more than 10% for nine species as a result of all land base changes combined between 2010 and 2023. All nine of these species—such as Cow Wheat (-38%), and Blue Columbine (-29%)—had strong negative responses to the net effect of fire and aging. 
• There were 21 species with habitat gains of more than 10% as a result of all land base changes combined. Most of these species prefer early seral habitat and respond negatively to aging of naturally disturbed stands and harvest areas. For example, Hay Sedge (+25%) and Bicknell’s Geranium (+24%) both respond positively to disturbance by fire.

The graph below shows the distribution of moss species' responses to each type of land base change in the Al-Pac FMA area between 2010 and 2023. Examples of how different species respond to overall land base changes include:

• Between 2010 and 2023 in the Al-Pac FMA area, changes in habitat suitability for mosses due to natural factors—including fire (-12% to +25%) and the aging of naturally disturbed stands (-16% to +16%)—were greater than those caused by human disturbances including forestry (-7% to +9%) and from other human footprint (-1% to +4%).
• Across all disturbances, habitat suitability declined for the majority of moss species, with other human footprint having the strongest negative effect (88% of species), followed by forestry (71%) and fire (70%). Most moss species depend on the cool, moist conditions provided by mature and old forests and respond negatively to canopy removal.
• In forestry areas, the drop in habitat suitability from new harvesting between 2010 and 2023 was mostly balanced by forest aging, which improved habitat suitability for 69% of moss species.
• There were six species with more than 10% net loss of habitat due to combined land base changes between 2010 and 2023. All of these species—such as Red Leaf Moss (-25%) and Slender-stemmed Hair Moss (-19%)—had strong negative responses to the net effect of fire and aging.
• There were five species with habitat gains of more than 10% as a result of all land base changes combined. All of these species had a strong positive response to fire.

The graph below shows the distribution of lichen species' responses to each type of land base change in the Al-Pac FMA area between 2010 and 2023. Examples of how different species respond to overall land base changes include:

• Between 2010 and 2023 in the Al-Pac FMA area, changes in lichen habitat suitability driven by natural factors—such as wildfire (–14% to +16%) and the aging of naturally disturbed stands (–13% to +23%)—were greater than those caused by human disturbances, including forestry (–11% to +4%) and other human footprint (–1% to +1%).
• During this period, habitat suitability declined for most lichen species in response to new disturbances: 95% were affected by other human footprint, 92% by wildfire, and 84% by new forestry. Many lichen species depend on mature trees, dead wood, or stable rock surfaces for growth, making them sensitive to both natural and human disturbance.
• Habitat suitability improved for 80% of species as harvested areas aged, helping to offset some of the negative impacts of forestry.
• Eight species experienced more than a 10% net loss of habitat due to combined land base changes, with wildfire being the primary driver. For example, habitat suitability declined for American Starburst (–28%) and Common Clam Lichen (–22%) both favor stable, shaded habitats with mature trees and decaying wood.
• There were three lichen species with at least a 10% increase in habitat due to combined land base changes: Two-toned Tube Lichen (+11%), Salted Shield (+11%), and Peg-leg Soldiers (+11%). All three species had strong positive responses to different types of natural disturbance—forest aging, the net effect of fire and aging, and wildfire, respectively.