consumption of fossil fuels on a large scale in the era of industrialisation, the range of
the carbon dioxide cycle is expanding. It had been estimated that forest trees hoard
about 90% of all carbon fixed by the plant as plant biomass. After some research, the
relationship between forest phenology and the response towards the continued rise in
atmospheric CO 2 concentration is still ambiguous.
Plant phenophases are governed by the atmospheric CO 2 seasonal cycle on the
Earth as it affects the net ecosystem exchange (NEE) of CO 2 between the Earth
biosphere and the atmosphere. Some research has shown that the increasing concentration of CO 2 in the Northern Hemisphere has witnessed more green cover,
considered to cause increasing CO 2 assimilation by plants over a longer growing
season in response to global warming. Elevated CO 2 concentration has elongated the
growing season of plant phenology by advancing the spring season and delaying leaf
senescence. Remote sensing studies using the NDVI have supported this statement
by observing increased NDVI values, which indicate geographically significant
increases in the photosynthesis process (Myneni et al. 1997; Tucker et al. 2001).
In the Boreal forest, which accounts for 13% of the carbon stored in the biomass and
43% of the carbon stored in soil, increased carbon assimilation and earlier leaf
emergence have been shown, which notably increased ecosystem photosynthesis
but had less effect on respiration (Black et al. 2000). Moderate increase in this gas
leads to promotion of growth and productivity in plants having a C3 photosynthetic
pathway, whereas negligible effects are seen in plants with a C4 pathway. In their
study, Ahrends et al. revealed the association between forest phenology and gross
primary productivity (GPP); they observed there is significant correlation between
camera-based phenology and GPP and remarkable reliance of CO 2 exchange phenomenon during the growing stage of the tree species, mainly during spring season.
As the respiration process is more likely to become acclimatised, compared to
photosynthesis, therefore increase in carbon availability in the forest leads to more
growth at increased temperatures by abating carbon loss then by assimilating carbon
(Way and Oren 2010).
However, a large increase in CO 2 concentration leads to global rise in temperature, which in turn can increase respiration rate, increase plant life duration, accelerate nutrient mineralisation in soil, and increase the rate of evapotranspiration, thus
affecting the phenology of plants. Such devices as open top chambers, free air
carbon dioxide enrichment (FACE), and greenhouses are used more in recent
research as controlled environment solutions to understand the impact of global
climate change on plant growth and productivity.
Temperature
Temperature, which controls most of the enzymatic reactions in plant processes, also
is crucial in governing the phenology of plants. In 1735, a pioneer phenologist, Rene
Antoine Ferchault Reaumur, foremost confirmed the relationship between temperature and phenology by testing the relationship between phenology and the
190
P. Tiwari et al.
the carbon dioxide cycle is expanding. It had been estimated that forest trees hoard
about 90% of all carbon fixed by the plant as plant biomass. After some research, the
relationship between forest phenology and the response towards the continued rise in
atmospheric CO 2 concentration is still ambiguous.
Plant phenophases are governed by the atmospheric CO 2 seasonal cycle on the
Earth as it affects the net ecosystem exchange (NEE) of CO 2 between the Earth
biosphere and the atmosphere. Some research has shown that the increasing concentration of CO 2 in the Northern Hemisphere has witnessed more green cover,
considered to cause increasing CO 2 assimilation by plants over a longer growing
season in response to global warming. Elevated CO 2 concentration has elongated the
growing season of plant phenology by advancing the spring season and delaying leaf
senescence. Remote sensing studies using the NDVI have supported this statement
by observing increased NDVI values, which indicate geographically significant
increases in the photosynthesis process (Myneni et al. 1997; Tucker et al. 2001).
In the Boreal forest, which accounts for 13% of the carbon stored in the biomass and
43% of the carbon stored in soil, increased carbon assimilation and earlier leaf
emergence have been shown, which notably increased ecosystem photosynthesis
but had less effect on respiration (Black et al. 2000). Moderate increase in this gas
leads to promotion of growth and productivity in plants having a C3 photosynthetic
pathway, whereas negligible effects are seen in plants with a C4 pathway. In their
study, Ahrends et al. revealed the association between forest phenology and gross
primary productivity (GPP); they observed there is significant correlation between
camera-based phenology and GPP and remarkable reliance of CO 2 exchange phenomenon during the growing stage of the tree species, mainly during spring season.
As the respiration process is more likely to become acclimatised, compared to
photosynthesis, therefore increase in carbon availability in the forest leads to more
growth at increased temperatures by abating carbon loss then by assimilating carbon
(Way and Oren 2010).
However, a large increase in CO 2 concentration leads to global rise in temperature, which in turn can increase respiration rate, increase plant life duration, accelerate nutrient mineralisation in soil, and increase the rate of evapotranspiration, thus
affecting the phenology of plants. Such devices as open top chambers, free air
carbon dioxide enrichment (FACE), and greenhouses are used more in recent
research as controlled environment solutions to understand the impact of global
climate change on plant growth and productivity.
Temperature
Temperature, which controls most of the enzymatic reactions in plant processes, also
is crucial in governing the phenology of plants. In 1735, a pioneer phenologist, Rene
Antoine Ferchault Reaumur, foremost confirmed the relationship between temperature and phenology by testing the relationship between phenology and the
190
P. Tiwari et al.