Distrubance Effects on Boreal Forest Structure
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disturbance flooding fire insect outbreaks timber harvest
___ bark is least resistant to dire, __ ___ bark is most resistant
birch jack pine
Explain non-serotinous vs serotinous seeds
Non-serotinous= not fire resistant seeds (they’re open) Serotinous= fire resistant (closed, and open with fire) older trees can make these
most disturbances lead back to ___ ___ dominance because most things favor its ___
black spruce recovery
ground fire vs crowing fire:
ground fire= burns shrubs etc, not the trees crowning fire= burns the entire tree
the fire cycling is increasing in ___
frequency
relay succession=
the sequential replacement of species (plant & animal) in an ecosystem recovering from a disturbance
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Intolerant= - jack pine - red pine - aspen Tolerant - spruce - balsam fir - cedar
Why isn’t legacy soil recovering?
deciduous trees dominate early on in succession, and they store C in surface positive feedback of fires= fire frequency is increasing, legacy carbon doesn’t have a chance to replenish
high severity burns have lower initial ___ but increase over time biomass of deciduous ____ over time in high severity burns, but low severity burns have ___ deciduous over time
biomass increase declining
2 fire intensity determinants:
• biomass accumulation (load) –> depends on time since last fire and ecosystem producivity • water budget
2 fire intensity determinants:
• biomass accumulation (load) –> depends on time since last fire and ecosystem productivity • water budget
___ trees are most susceptible to insect outbreaks
stressed/ unhealthy
___ ___ is one of the most damaging insects in the eastern boreal forest
spruce budworm
spruce budworms eat ___ ___ and ___ ___, and their ___ stage is the most damaging
balsam fir (prefers) white spruce larval
Insect outbreaks have 4 stages:
• Release- no more natural control • Peak- exponential increase • Decline- sharp decline • Post-decline- continuing slow decline (goal is to keep this)
spruce budworm outbreaks have increased recently, due to ___ use, ____ practices, ___ suppression, and ___ variation
pesticide use (kills their predators) logging fire climate
after a high-severity burn, deciduous trees will dominate, and they store 5x more carbon than black spruce after 100 years. Why?
higher nitrogen use ecosystem efficiency rapid transfer from soils in deciduous stands
feedback of C and fires is ___ because of the emergence of ___ tree stands, which ___ more carbon
negative! deciduous store