All of these species rely on food resources from a large diversity of non-coniferous plants in early seral stages May use seedling and sapling conifers for cover or food, but that is probably not the main resource that attracts these species to early seral habitats
Why do early, shrub-dominated stages of forest succession typically support high animal diversity than other stages? Elements/legacies of old-forest remain; combined with flush of productivity from newly available resources (light) 2 important influences on wildlife
Even species that are normally associated with closed canopy forests use early seral forests if the appropriate habitat elements are available
Few species are associated with early seral forests because they primarily use seedling/sapling conifers. Here are 2 examples that specialize on coniferous foliage. But red tree vole and red crossbills use older conifer forests
On the other hand, many species that are thought of as conifer forest associates actually depend on non-coniferous plants to meet some of their needs, at least some of the time Spruce Grouse: Feeds on berries and foliage of shrubs and forbs in conifer dominated forests east of Cascade Mts.; Vaccinium especially important in summer; feeds exclusively on conifer needles in winter; adequate ground cover and shrubs may be important influence on nest success.
Early stages of succession in managed forests do not necessarily provide the same resources as natural, post-disturbance forests.
Residual trees and snags are a critical component of early seral habitat for many species; the presence of many species depends on the availability of these legacy structures. In particular, Woodpeckers love disturbance: it creates food for their prey: ants and beetles Species such as (NOFL, LEWO, BBWO) specialize in open, post-disturbance habitats; create habitat for secondary cavity nesters
Abundance of several woodpecker species increases after stand-replacing fires in dry east side forests: Hairy and black-backed woodpeckers, LEWO, NOFL, bluebirds. Removal of standing deadwood through salvage logging has negative effects on many of these species
The combination of dead and dying trees in open habitats creates habitat that is uniquely suitable for Aerial insectivores (many are cavity nesters); swallows, puma, wifl, bats, webl, atfl
Reptiles in early seral habitats: open for sunning; lots of prey
Dead wood created by disturbances provides refugia for species with low mobility, such as amphibians Large dead wood important in providing cover in otherwise exposed habitat; allows persistence of populations Dead wood in combination with dense cover and abundant seed production from pioneer species in a high-light environment creates suitable habitat for many granivores; e.g., mice, voles, sparrows, finches...
Many species that rely directly on vegetation and mast for food are associated with early successional vegetation in forest gaps or regenerating stands. The light-rich environment of gaps results in greater production of flowers and fruits than the shaded matrix (Harrington et al., 2002). Vegetation in early seral stages tends to be fast growing and reproducing; i.e., lots of foliage, seeds, and fruits produced. Direct source of food for herbivores, granivores, pollinators, omnivores…
Non-coniferous vegetation not only supports species that directly consume it, but also higher level consumers. 90% of the diet of northern spotted owls is composed of small mammals that are associated with non-coniferous vegetation, including wood rats and other rodents (Forsman et al., 1984; Table 1). Glenn et al. (2004) suggested that the presence of broad-leaved habitats in young forests may allow spotted owls to survive in landscapes with less late-seral forest than typically characterizes suitable habitat because of the positive influence on prey abundance. Early seral habitats provides the foundation for food webs that contribute to diversity at multiple trophic levels
Other species that breed in older forests may use early seral habitat during the non-breeding season Studies from eastern hardwood forests have shown that early seral stages are important habitat for some bird species during the post-breeding season. Fledglings find cover and food Some species fatten up on bountiful fruit before migration Several species strongly associated with mature forest are among those that are abundant in early seral during the post-breeding season To my knowledge, post-breeding habitat use has not been well-studied for many PNW species
Early seral stages also offer an abundance and diversity of arthropods for insectivores and small carnivores Several species of shrew are associated with herbaceous, shrubby, and deciduous habitats; Insects can periodically be abundant on conifers, e.g. during outbreaks, but a diversity of herbs, shrubs, and hardwood trees ensures a diverse and stable resource for insectivores.
Early seral habitats are primary breeding habitat for some species. Probable reasons: abundant food and cover; forage primarily on deciduous shrubs and trees MGWA and OCWA are common in early successional forests, but not in closed canopy mid-seral and old forests. Other shrub-associated species may be present throughout all stages of forest development as long as suitable habitat is present. Several species of neotropical migrant birds that rely on early seral or shrubby habitats have been experiencing population declines.
Fontaine et al. 2008: “Broad-leaved hardwoods and shrubs appear to play a major role in structuring avian communities in the Klamath-Siskiyou region. In light of these results, extended periods of early seral broadleaf dominance and short-interval high-severity fires may be important to the conservation of avian biodiversity.”
We are seeing declines in populations of some shrub-associated species, No direct evidence that these declines are related to changes in the availability and quality of early seral habitat, but a connection does seem plausible. These declines suggest the need for a critical evaluation of the habitat requirements of early-seral and shrub–associated species
Why can’t we just clear cut a forest and instantly have quality early seral habitat that meets the needs of the previously mentioned species
The reason we can’t just clear cut a forest and instantly have quality early seral habitat that meets the needs of the previously mentioned species is that Shrub development takes time for shrubs to become old enough to produce flowers and fruit; C. Harrington: stem diameter positively correlated with number of flowers; large shrubs more likely to flower and produce seed Many intolerant shrub species can exist under closed canopies, but won’t flower and fruit unless sufficient light is available. So if canopy closes too soon, production is lost. Takes time for shrubs to develop thick stems and to be colonized by epiphytes, which add another whole layer of biological complexity to the system
Understory vegetation has not been favored by past and present forest practices aimed at timber production In order to get conifers established quickly, and to ensure their dominance, Managers traditionally have “controlled” shrubs and hardwoods in young forests Shrubs are viewed as competitors for resources that should be going to the crop trees, but for many species of wildlife, non-coniferous vegetation is the essential, defining element of early seral. OFP rules mandate that conifers are reestablished on harvest units to specified densities within a specified time frame
By the time a D-fir stand is 30-40 years old, the conifer canopy makes up the main layer of vegetation, and any understory that survived early control has long been shaded out....
Summary: Focus on conifer establishment has Reduced abundance of flowering, seed-producing vegetation reduced temporal span of early seral habitats = shortened duration of shrub dominance; consequences for migratory species that return to the same breeding location year after year?
By focusing on the rapid establishment and dominance of conifers, the diversity and duration of the shrub stage is reduced Under natural forest development scenario (i.e., without “vegetation control”) early seral habitat would be suitable for OCWA from stand age 5 - > 30 (>25 generations).
Currently: no clearcuts on federal land. Size limit on area of partial harvests. Focus on restoration of late-seral forest structure, but again, focus is on trees. the restoration of old forest structure is a current focus of management on federal and state lands, primarily emphasizing the large-tree component of these forests. This approach is in danger of neglecting both early seral stages dominated by shrubs or deciduous trees, and the non-conifer understory components of mature forests.
Features important in supporting diversity of wildlife could be present throughout all stages of forest development Important to keep legacies, including shrubs, to carry through from one stage to the next.
Key Features Of Early Seral Habitats For Wildlife
Key Features of Early Seral Habitats for Wildlife Joan Hagar USGS-FRESC Matt Lee
Following Natural Disturbance ... <ul><li>Structure </li></ul><ul><ul><li>Legacy trees and snags </li></ul></ul><ul><ul><li>Open (low tree density) </li></ul></ul><ul><ul><li>Large wood </li></ul></ul><ul><li>Composition </li></ul><ul><ul><li>Herbs and Grasses </li></ul></ul><ul><ul><li>Shrubs </li></ul></ul><ul><ul><li>Deciduous hardwoods </li></ul></ul>Bob Altman
Species associated with closed canopy forest also use early seral habitats… IF appropriate habitat elements are available
Species that specialize on conifers Red Tree Vole Hemlock Looper Red Crossbill
Many conifer forest associates rely on diversity of plants Spruce Grouse
Arthropods <ul><li>Insect diversity correlated with plant diversity </li></ul><ul><li>Deciduous species support more insects </li></ul><ul><li>Influence of deciduous litter on soil food webs? </li></ul>
Effects of Conifer-centric Forest Management on Early Seral Habitat <ul><li>Fewer residual structures </li></ul><ul><li>Altered vegetation composition </li></ul><ul><ul><li>Alters patterns of food abundance </li></ul></ul><ul><ul><li>Reduces diversity of food resources </li></ul></ul><ul><ul><li>Alters food webs </li></ul></ul><ul><li>Reduced temporal span </li></ul>
Consequences of reduced temporal span of early seral habitats <ul><li>Limit on shrub size and age </li></ul><ul><li>Shortens duration of shrubby habitat </li></ul><ul><li>Reduced persistence of shrubs into mid-aged forests </li></ul>
Restoration of Late Seral Forest <ul><li>Emphasizes large trees </li></ul><ul><li>Size limit on harvest area on federal lands </li></ul><ul><li>What will understory look like? </li></ul>