emergence, leaf fall, plant responses to environmental changes, and changes in the
greening of the biosphere can be easily observed (Myneni et al. 1997). Different
plant types differ greatly with varying environmental factors. For boreal and temperate vegetation, temperature and photoperiod factors mainly govern leaf phonology, whereas in tropical and subtropical vegetation precipitation has the most
influence besides temperature and photoperiod. Earth climate changes caused by
global warming lead to variation in leaf phenology. Impact on leaf phenology also
varies with type of species found in a region. Some species have the capacity to adapt
in a changing environment without any distinguishable change in leaf phenology
whereas others indicate the climate change of a region by showing alterations in their
leaf phenology. Modelling is now important in assessing the impact of climate
change on leaf phenology and the productivity of terrestrial ecosystems.
Shifting of vegetation towards higher northern latitudes is a result of global
heating of land surfaces. Many researchers note the northern pole is getting greener
each year. Average lengthening of the growing season by about 11 days from
increased global temperature has been detected in tree species in Europe from the
beginning of the 1960s to the end of the twentieth century, related to the earlier onset
of leaf buds and delayed leaf senescence (Menzel and Fabian 1999). A study on four
woody plant species showed that the effect of temperature on leaf set was stronger at
lower latitudes or altitude as well as in more continental climates, although the date
of leaf colouring did not show a continuous pattern. In the same study, significant
warming across China during the study period showed lengthening of the growing
period of leaves: leaf emergence was advanced by 5.44 days from 1960 to 2009 and
the leaf colouring date was delayed by 4.56 days during the same time (Dai et al.
2014).
Changes in the occurrence and timing of leaf phenophases may either accelerate
or slow rates of climate change depending upon the vegetation at a particular
geographical location. Leaf phenology, which regulates albedo, transpiration,
exchange of molecules between vegetation and the atmosphere, and cloud formation, when faced with change in turn will impact the climate system. It is found that
tropical forests lower the rate of global warming through evaporative cooling,
whereas boreal forests, which have low albedo, will show positive climate forcing.
The evaporative effect of temperate forests is still unclear as there is less information
(Bonan 2008).
Impact on Reproductive Phenology Caused by Climate Change
Increase average temperature of the Earth is changing flowering phenophases in
different species. Flowering in plants primarily depends upon temperature and
precipitation, which is disturbed by climate change which in return affects flowering
phenology. Many studies indicate that flowering dates are being advanced in
flowering species. A study in Japan on the cherry tree found that flowering times
in and around Osaka and other cities in Japan, with average temperature rise in
8 Forest Phenology as an Indicator of Climate Change: Impact and Mitigation. . .
195
greening of the biosphere can be easily observed (Myneni et al. 1997). Different
plant types differ greatly with varying environmental factors. For boreal and temperate vegetation, temperature and photoperiod factors mainly govern leaf phonology, whereas in tropical and subtropical vegetation precipitation has the most
influence besides temperature and photoperiod. Earth climate changes caused by
global warming lead to variation in leaf phenology. Impact on leaf phenology also
varies with type of species found in a region. Some species have the capacity to adapt
in a changing environment without any distinguishable change in leaf phenology
whereas others indicate the climate change of a region by showing alterations in their
leaf phenology. Modelling is now important in assessing the impact of climate
change on leaf phenology and the productivity of terrestrial ecosystems.
Shifting of vegetation towards higher northern latitudes is a result of global
heating of land surfaces. Many researchers note the northern pole is getting greener
each year. Average lengthening of the growing season by about 11 days from
increased global temperature has been detected in tree species in Europe from the
beginning of the 1960s to the end of the twentieth century, related to the earlier onset
of leaf buds and delayed leaf senescence (Menzel and Fabian 1999). A study on four
woody plant species showed that the effect of temperature on leaf set was stronger at
lower latitudes or altitude as well as in more continental climates, although the date
of leaf colouring did not show a continuous pattern. In the same study, significant
warming across China during the study period showed lengthening of the growing
period of leaves: leaf emergence was advanced by 5.44 days from 1960 to 2009 and
the leaf colouring date was delayed by 4.56 days during the same time (Dai et al.
2014).
Changes in the occurrence and timing of leaf phenophases may either accelerate
or slow rates of climate change depending upon the vegetation at a particular
geographical location. Leaf phenology, which regulates albedo, transpiration,
exchange of molecules between vegetation and the atmosphere, and cloud formation, when faced with change in turn will impact the climate system. It is found that
tropical forests lower the rate of global warming through evaporative cooling,
whereas boreal forests, which have low albedo, will show positive climate forcing.
The evaporative effect of temperate forests is still unclear as there is less information
(Bonan 2008).
Impact on Reproductive Phenology Caused by Climate Change
Increase average temperature of the Earth is changing flowering phenophases in
different species. Flowering in plants primarily depends upon temperature and
precipitation, which is disturbed by climate change which in return affects flowering
phenology. Many studies indicate that flowering dates are being advanced in
flowering species. A study in Japan on the cherry tree found that flowering times
in and around Osaka and other cities in Japan, with average temperature rise in
8 Forest Phenology as an Indicator of Climate Change: Impact and Mitigation. . .
195