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J. A. Dar et al.
biomass to the soil by converting into charcoal that is decay-resistant and can stay
for about 3000–12,000 years in the soil (DeLuca and Aplet 2008; Milakovsky et al.
2012).
Boreal forest biome are experiencing greater rates of global warming than any
other forest on Earth (Gauthier et al. 2015; Astrup et al. 2018). It has been expected
that the environmental conditions in the warming world would significantly alter
the photosynthetic and respiration processes, thereby affecting the carbon balance
of boreal forests (Milakovsky et al. 2012). The type of vegetation in boreal forests
strongly influences the respiration process by determining the quality of litter produced (Harden et al. 2000; Milakovsky et al. 2012). A rise in soil temperatures due
to global warming is expected to increase the rates of decomposition and respiration,
although it is also possible that these processes proceed in slower rates, owing to
shifts in the microbial communities, caused by soil warming (Allison and Treseder
2008; Milakovsky et al. 2012). Fire also alters the soil characteristics by causing
changes in soil temperature and soil moisture, by reducing or removing the insulating lichen and moss layers, etc. Fire also contributes to carbon sequestration by
contributing huge amounts of charcoal to the soil carbon pool (Milakovsky et al.
2012). However, increase in temperatures as a consequence of global warming could
lead to increases in thaw depth in those areas covered by permafrost, thus accelerating
microbial decomposition and releasing large amounts of two important greenhouse
gases, viz. carbon and methane (Leigh 2009) that had been accrued for several centuries. Higher temperatures would facilitate the widespread occurrence of fires with
increased frequency and severity across the boreal forest biome (Stocks 2004; Lorenz
and Lal 2010).
Increase in atmospheric carbon dioxide concentrations generally stimulates plant
growth and carbon accumulation by carbon fertilization and this is often seen as a
means of offsetting the carbon losses caused due to wildfires (Balshi et al. 2007;
Milakovsky et al. 2012). A mild drought affects only the respiration process, while
a severe drought impedes both photosynthesis and respiration (Barr et al. 2007;
Milakovsky et al. 2012). Any change in water balance would affect carbon uptake
more severely in high latitude ecosystems than high temperatures (Lorenz and Lal
2010). If the climate change causes warm temperatures in early spring, forest productivity would increase enhancing the biomass and carbon stocks (Chen et al. 1999).
However, if temperatures increase at the fag end of the growing season, moisture
stress could be an important problem, where the increase in growth would be outdone
by increase in respiration and may/may not be coupled with decrease in photosynthesis (Lindroth et al. 1998; Milakovsky et al. 2012). Therefore, whether precipitation
increases or decreases along, with the rise in temperature, there would be strong influences on the carbon flux (Pastor and Post 1988; Milakovsky et al. 2012). Furthermore,
it has been predicted that future warming would surpass the optimum photosynthetic
temperatures of several boreal tree species (Way and Sage 2008; Lorenz and Lal
2010). Drought affected regions are more susceptible to pest and insect outbreaks,
which would enhance the rates of tree mortality and thereby release of the stored
carbon (Frey et al. 2004). Apart from wildfires and drought stress, boreal forests are
J. A. Dar et al.
biomass to the soil by converting into charcoal that is decay-resistant and can stay
for about 3000–12,000 years in the soil (DeLuca and Aplet 2008; Milakovsky et al.
2012).
Boreal forest biome are experiencing greater rates of global warming than any
other forest on Earth (Gauthier et al. 2015; Astrup et al. 2018). It has been expected
that the environmental conditions in the warming world would significantly alter
the photosynthetic and respiration processes, thereby affecting the carbon balance
of boreal forests (Milakovsky et al. 2012). The type of vegetation in boreal forests
strongly influences the respiration process by determining the quality of litter produced (Harden et al. 2000; Milakovsky et al. 2012). A rise in soil temperatures due
to global warming is expected to increase the rates of decomposition and respiration,
although it is also possible that these processes proceed in slower rates, owing to
shifts in the microbial communities, caused by soil warming (Allison and Treseder
2008; Milakovsky et al. 2012). Fire also alters the soil characteristics by causing
changes in soil temperature and soil moisture, by reducing or removing the insulating lichen and moss layers, etc. Fire also contributes to carbon sequestration by
contributing huge amounts of charcoal to the soil carbon pool (Milakovsky et al.
2012). However, increase in temperatures as a consequence of global warming could
lead to increases in thaw depth in those areas covered by permafrost, thus accelerating
microbial decomposition and releasing large amounts of two important greenhouse
gases, viz. carbon and methane (Leigh 2009) that had been accrued for several centuries. Higher temperatures would facilitate the widespread occurrence of fires with
increased frequency and severity across the boreal forest biome (Stocks 2004; Lorenz
and Lal 2010).
Increase in atmospheric carbon dioxide concentrations generally stimulates plant
growth and carbon accumulation by carbon fertilization and this is often seen as a
means of offsetting the carbon losses caused due to wildfires (Balshi et al. 2007;
Milakovsky et al. 2012). A mild drought affects only the respiration process, while
a severe drought impedes both photosynthesis and respiration (Barr et al. 2007;
Milakovsky et al. 2012). Any change in water balance would affect carbon uptake
more severely in high latitude ecosystems than high temperatures (Lorenz and Lal
2010). If the climate change causes warm temperatures in early spring, forest productivity would increase enhancing the biomass and carbon stocks (Chen et al. 1999).
However, if temperatures increase at the fag end of the growing season, moisture
stress could be an important problem, where the increase in growth would be outdone
by increase in respiration and may/may not be coupled with decrease in photosynthesis (Lindroth et al. 1998; Milakovsky et al. 2012). Therefore, whether precipitation
increases or decreases along, with the rise in temperature, there would be strong influences on the carbon flux (Pastor and Post 1988; Milakovsky et al. 2012). Furthermore,
it has been predicted that future warming would surpass the optimum photosynthetic
temperatures of several boreal tree species (Way and Sage 2008; Lorenz and Lal
2010). Drought affected regions are more susceptible to pest and insect outbreaks,
which would enhance the rates of tree mortality and thereby release of the stored
carbon (Frey et al. 2004). Apart from wildfires and drought stress, boreal forests are