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Forests: Temperate Evergreen and Deciduous

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Temperate forests represent one of the major biomes on Earth. They are most common in eastern North America, western and central Europe, and northeastern Asia, where the climate is defi ned by warm summers, cold winters, and intermediate levels of precipitation. To a lesser extent, they are also present in this same climate in Australia, New Zealand, South America, and South Africa. Temperate forests are dominated by either deciduous or evergreen canopies. In temperate deciduous forests, more commonly found in the Northern Hemisphere, plants drop their leaves in autumn, allowing for high seasonal variation in light availability to the understory. By contrast, in temperate evergreen forests, which are more commonly found in the Southern Hemisphere, plants keep their leaves year round. The temperate forest biome is rich in geologic and anthropocentric history, with much of the land shaped by glacial and human activity. Located in some of the most industrialized places in the world, temperate forests have been instrumental to socioeconomic development in these regions. As a consequence, these forests have been heavily impacted by expanding human populations, which remain the primary continuous threat to the structure and function of these forests.
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Encyclopedia of Natural Resources DOI: 10.1081/E-ENRL-120047447
214 Copyright © 2014 by Taylor & Francis. All rights reserved.
Ecotone—
Fragmentation
Forests: Temperate Evergreen and Deciduous
Lindsay M. Dreiss
John C. Volin
Department of Natural Resources and the Environment, University of Connecticut, Storrs, Connecticut, U.S.A.
Abstract
Temperate forests represent one of the major biomes on Earth. They are most common in eastern North
America, western and central Europe, and northeastern Asia, where the climate is defi ned by warm
summers, cold winters, and intermediate levels of precipitation. To a lesser extent, they are also present
in this same climate in Australia, New Zealand, South America, and South Africa. Temperate forests are
dominated by either deciduous or evergreen canopies. In temperate deciduous forests, more commonly
found in the Northern Hemisphere, plants drop their leaves in autumn, allowing for high seasonal variation
in light availability to the understory. By contrast, in temperate evergreen forests, which are more commonly
found in the Southern Hemisphere, plants keep their leaves year round. The temperate forest biome is
rich in geologic and anthropocentric history, with much of the land shaped by glacial and human activity.
Located in some of the most industrialized places in the world, temperate forests have been instrumental to
socioeconomic development in these regions. As a consequence, these forests have been heavily impacted
by expanding human populations, which remain the primary continuous threat to the structure and function
of these forests.
INTRODUCTION
Temperate forests represent one of the major biomes on
Earth, covering ~14% of Earth’s terrestrial land surface[1]
(Fig. 1). Along with boreal and subtropical/tropical wet
and dry forests, temperate forests are one of the Earth’s
dominant forest types. In comparison to other types, tem-
perate forests are intermediate in latitude, temperature, and
precipitation. By contrast, they generally exhibit much
stronger seasonality, favoring those plant and animal spe-
cies that were able to adapt to short-term climatic variation.
Environmental stresses from seasonal change include
extreme temperatures and variable access to moisture (in
the form of rain and/or snow), light, and nutrients (due to
the deciduous nature of some canopies). As a result, sig-
nifi cant changes in microclimates and growing conditions
throughout the year are common, creating adaptive oppor-
tunities and resulting in unique structure and composition
of ecosystems.[2–4]
Temperate forests are located in some of the most heav-
ily populated and developed regions on Earth, including
much of eastern North America, western and central
Europe, northeastern Asia and, to a lesser extent, Australia,
New Zealand, South America, and South Africa[5–7] (Fig. 1).
Temperate forests are an established part of the history and
culture of these regions and continue to play an important
role in providing ecosystem services to human popula-
tions, including timber products, carbon storage, clean
drinking water, erosion prevention, recreation, tourism,
aesthetics, property value security, and others. On the other
hand, the unsustainable use of such services has led to
negative consequences for temperate forest ecosystems
worldwide.
In this entry, we provide an overview of temperate for-
ests from both an ecological and societal perspective. We
describe the unique characteristics of temperate deciduous
and evergreen forests, the major anthropogenic agents that
have impacted them in the past and some of the emerging
threats they face today.
CLIMATE
Climate is a fundamental factor in defi ning the temperate
forest biome. Generally, a forest is considered temperate
if it is located in a region with hot summers and cold win-
ters. The annual range in temperature can be ±30°C, and
the mean annual temperature is between 3 and 18°C, with
mean midwinter temperature below 8°C and mean mid-
summer temperature about 18°C.[8] In the Northern Hemi-
sphere, the length of the frost-free period ranges from 120
to over 250 days, with growing season and temperature
increasing closer to the equator. As a result of less land
mass in the Southern Hemisphere, the climate is milder
than at similar latitudes in the Northern Hemisphere. Tem-
peratures in the Southern Hemisphere can be cold, but
typically far less than 1% of the hours of the year are
Forests: Temperate Evergreen and Deciduous 215
Ecotone—
Fragmentation
subject to frost, while in the Northern Hemisphere
subfreezing temperatures are typically reached many days
during the winter.[6]
Temperate forests receive even precipitation year round
averaging 750–1500 mm/yr. Snowfall can range from non-
existent in southern regions to extremely heavy in northern
regions. In the Northern Hemisphere, temperate forests are
geographically located between the boreal forest/tundra
and the tropical/subtropical forests while in the Southern
Hemisphere they are found south of the tropical/subtropi-
cal forests up to tree line in some areas (Fig. 1). Corre-
spondingly, the climate, productivity and species diversity
of temperate forests are intermediate in relation to other
biomes.[9]
The seasonal climatic regime in the temperate forest
regions has changed very little in the past 1000–2000 years.
This is refl ected in the structure and ecosystem dynamics
of the forests.[10] Winter deciduous trees or coniferous
evergreen species that are physiologically dormant during
winter months dominate the majority of the forests. Genera
differ between Northern and Southern hemispheres.
Examples include Acer, Fagus, Tilia, Quercus, Carya,
Populus, Ulnus, Betula, Fraxinus, Magnolia, Cornus,
Robinia, and Juglans in the Northern Hemisphere and
Eucalyptus, Acacia, Quercus, and Nothofagus in the
Southern Hemisphere.
At higher latitudes and altitudes, where temperatures
range from –30 to 20°C annually, temperate forests become
more dominated by coniferous evergreen tree species.
These regions are generally drier, with annual precipitation
from 300 to 900 mm. Seasons are defi ned by cold, long
snowy winters and warm, humid summers with at least
four to six frost-free months.[11] Evergreen temperate for-
ests may also occur in regions with a stronger maritime
climatic infl uence. Precipitation can be very high (typically
700–1000 mm) and snow is uncommon.[12,13] Summer fog
is often an important contributor to moisture uptake, reduc-
ing stresses from evapo-transpiration. In addition, the
growing season is much longer and sometimes continuous
in forests closer to the equator. In the midst of global
climate change, however, a shift is occurring in the location
of ecotone and temperate forest species.
Climate-linked range shifts have been observed in the
northern hardwood–boreal forest ecotone where there has
been a decrease in boreal and an increase in northern hard-
wood basal area.[14] The velocity of temperature change is
projected to be much faster in temperate broadleaf and
mixed forests than in temperate coniferous forests.[15]
Temperature being considered the primary control on
treeline formation and maintenance, global warming is also
facilitating treeline advances to greater altitudes and
latitudes.[16,17] The synergistic effects of warming tempera-
tures and intensifying droughts have also triggered con-
cerns. The sensitivity of tree mortality and range shifts can
result from extreme water stress and lead to other ecologi-
cal consequences including changes in carbon stores and
dynamics, changes in microclimate, and changes in future
production of important habitat and food sources.[18,19]
LAND FORMATION AND HISTORY
On the geological time scale, climate has shaped the land
on which temperate forests now grow. Between 110,000
Fig. 1 Global temperate deciduous and evergreen forest biomes.
216 Forests: Temperate Evergreen and Deciduous
Ecotone—
Fragmentation
and 10,000 years ago, during the Late Pleistocene age, gla-
cial ice sheets left large parts of the Eurasian and North
American continents as treeless, frozen tundra.[20,21] Below
the tundra stretched the temperate forests, and beyond
these, temperate, grassy plains. As the glaciers retreated,
they left behind glacial till and lake-bottom sediments. As
the zones of tundra followed the shrinking glaciers, the
boreal and temperate forests encroached on the tundra belt
until the matrix of ecoregions looked much like it does
today. Since the end of the last ice age, human activity has
become a primary factor in shaping temperate forests.
The three largest temperate forest regions, eastern North
America, western and central Europe, and northeastern
Asia, have played an important role in the development of
human society. In North America, temperate forests were
heavily impacted by the spread of European settlements in
the 1700s. Much of the temperate forest was cleared,
logged, and/or burned to make way for agricultural needs
and human settlements.[22,23] In the 18th century, the temper-
ate forests of Europe were the birthplace of new lines of
scientifi c study and management, becoming what is now
modern forestry.[24,25] These practices were applied in
Europe and North America, where temperate forests pro-
vided the wood for fuel, building materials, and raw mate-
rial in industrial processing during the Industrial Revolution
of the 19th and 20th centuries.[26,27] With the spread and
development of forestry practices, large amounts of tem-
perate forest were logged for the production of timber,
pulp, paper goods, and other forest products. During the
19th and into the 20th century, much of the agricultural land
in the temperate forest range in North America was aban-
doned and the temperate forest grew back, peaking in its
coverage in the mid-twentieth century.[28] Today it is once
again under threat from continuous loss and fragmentation
primarily through human developments.
In Europe, many native temperate deciduous forests
have been extirpated and replaced with planted monocul-
tures, many of which are not representative of the native
vegetation.[29] Most of the remaining European temperate
forests display a simplifi ed structure and composition
resulting from centuries of tree harvesting and forest graz-
ing. In other places, land use change and conversion still
continue to affect forest ecosystems. For example, the tem-
perate forests of Asia, which cover parts of China, Japan,
and Korea, were largely unaffected by glaciation through
the Pleistocene.[30,31] Because of this, Asian temperate for-
ests have higher levels of biodiversity than their counter-
parts in Europe or North America and are home to species
with ancestries that extend much further back in geologic
history. However, more recent heavy logging and fi res have
reduced forested land area and caused species such as the
red-crowned crane (Grus japonensis) and the red panda
(Ailurus fulgens) to be listed as endangered.[32] Collectively,
temperate forests across the globe may have experienced
more severe impacts over broader areas than any other
large forest biome.[33]
STRUCTURE AND COMPOSITION
In contrast to grasslands or desert ecosystems, temperate
forests have a more complex structure composed of different
layers of vegetation. Temperate forest layers typically
include a layer of mosses and lichens on the forest fl oor (and
often on tree trunks and limbs), herbaceous and shrub lay-
ers, a subcanopy of trees, and a taller dominant canopy tree
layer.[34] The complexity of the subcanopy and canopy layers
can vary and often depend on the light requirements of the
dominant tree species. Trees are the dominant life form of
these ecosystems and can be either deciduous or evergreen.
Temperate forests undergo different stages in ecosystem
succession, allowing for the coexistence of plant species
with different life history strategies. These adaptations are
often linked to specifi c growing conditions associated with
different stages of forest growth. As a result, gradual transi-
tions in plant community composition and forest structure
change over time.[35,36] A classic example of succession in
northeastern temperate forests in North America is when
pioneer tree/shrub species such as birch (Betula spp.) and
poplar (Populus spp.), which are fast growing and require
high light availability, are often the fi rst to establish follow-
ing a disturbance. As trees grow and the canopy begins to
close, conditions become more favorable for more long-
lived, shade-tolerant species such as maple (Acer spp.), oak
(Quercus spp.), beech (Fagus spp.), and hemlock (Tsuga
spp.). These later-successional trees become dominant or
codominant and eventually out-compete early successional
species, reaching heights of 35–40 m.[37] This process takes
place over hundreds of years and can be reset at any time
by a disturbance of natural or human origin. Indeed, within
a relatively large and healthy naturally occurring forest
area, all of these successional stages are present at once.
Disturbance regimes, which refer to the type, intensity,
and frequency of disturbances in a particular region, have a
substantial impact on the composition and age structure of
vegetation.[38–40] In temperate forests, eolic events such as
hurricanes, tornadoes, and thunderstorm downbursts are a
major contributor to forest dynamics. Fire was once also an
important natural regulator, but with land use changes and
suppression of fi re by humans, many temperate forests
have become increasingly dominated by late successional
species.[41] Other natural disturbances include pest/disease
outbreaks, fl ood or drought, and snow and landslides.
Temperate Deciduous Forest
The temperate deciduous forest canopy is composed mostly
of broadleaved angiosperm tree species with the inclusion of
some coniferous tree species. Temperate deciduous broad-
leaved forests are often defi ned by the associations of spe-
cies. Association names are most useful for distinguishing
broad differences in forest type and are often representative
of variation in soils, topography, and climate. For example,
in eastern North America, some common associations are
Forests: Temperate Evergreen and Deciduous 217
Ecotone—
Fragmentation
heating/cooling). However, with the onset of global climate
change, recent studies recognize that temperature plays a
more important role in many phenological events.[48,49]
Plant hormonal signals to leaves cause chlorophyll, the
compound that absorbs light for photosynthesis and makes
the leaves look green, to degrade. Some nutrients from
the leaves are partially recovered and moved (i.e.,
retranslocated) to stem and trunk tissues before the leaves
fall off.[50–53] Buds are formed and go into dormancy until
the following spring, when the accumulation of degree
days over a temperature threshold triggers leaf growth.
Canopy tree species differ in their timing of bud break and
leaf expansion, with the development of the forest canopy
taking place over a period of a month or more.[54] Once
intact canopies are in full leaf fl ush and the growing season
is underway, typically only 1–5% of sunlight reaches the
forest fl oor.[55–57] Therefore, the portion of the year when
canopy trees are leafl ess creates a unique opportunity of
increased light availability for understory vegetation.
With the beginning of the warm season, herbaceous
plants, shrubs and small trees begin growth before the can-
opy does. Because maximum incident solar radiation fl ux
and zenith angle of the sun are larger in the spring months,
there is greater transmission of light and a greater likeli-
hood for understory plants to reach photosynthetic capacity
before canopy leaf fl ushing.[58,59] In an evolutionary adapta-
tion designed to maximize the amount of light received,
some plants, known as spring ephemerals, complete most
of their annual growth cycle in the few weeks between
snowmelt and the closure of the tree canopy. Other more
shade-tolerant species begin or continue to grow after can-
opy closure.[60]
Animal life
Many animals in temperate deciduous forests are mast-
eaters (nuts and acorns) or omnivores. Herbivores (e.g.,
deer, hare, and rodents) perform important tasks in the eco-
system, such as aiding in plant seed dispersal, but may
cause stress when their populations are overly abundant.
Small rodents, such as squirrels and chipmunks (Tamias
spp.), and some birds, such as blue jays (Cyanocitta cris-
tata), cache large seeds/nuts in the autumn for sustenance
in the winter.[61] Seeds that animals fail to recover may
grow in their buried location. Omnivores include raccoon,
opossum, skunk, fox, and black bear in North America and
badger, mink, and marten in Europe. Asian forest fauna
also include primates such as macaques. In temperate for-
ests around the world, humans have drastically reduced the
populations of many large carnivores such as wolves in
North America and Europe and tigers in Asia, and now
smaller carnivores such as coyote (Canis latrans) and lynx
(Lynx spp.) fulfi ll part of this niche.[62,63]
Some animals have adapted unique behaviors to better
suit them for the varied seasons. For example, some
Oak–Hickory and Beech–Maple.[42] The temperate decidu-
ous broadleaved forest that extends across East Asia (from
30° to 60°N) displays the greatest diversity of vegetation.
The greater diversity in Asian temperate deciduous forests is
likely the result of being less severely glaciated during the last
ice age. This was largely a result of the more connected land-
mass, which allowed temperate forests to retreat from the
advancing glaciers. For instance, in North America, the Flor-
ida peninsula and Gulf of Mexico coastal region was the
southern limit for temperate forest refuge, while in Europe
the east to west mountain range of the Alps limited southern
migration. Other locations of deciduous broadleaved forests
include areas around the eastern Black Sea, mountainous
regions in Iran and Caspian Sea, and a narrow strip of South
America including southern Chile and Argentina.[34,43–45]
The composition of deciduous temperate forest depends
on latitude. In North America, birches (Betula spp.), aspen
(Populus spp.), and maples (Acer spp.) are common, along
with needle-leaved conifers such as pines (Pinus spp.).
Coniferous species tend to decline in abundance further
south, but they remain in localized areas that exhibit drier,
more nutrient-poor conditions and higher altitudes.
In Europe, forests at higher elevations are composed
mainly of conifers (Picea spp. and Abies spp.) and Fagus
spp., as well as larch (Larix decidua).
In central temperate deciduous forests, broadleaved
deciduous species in Europe include oaks (Quercus spp.),
European beech (Fagus sylvatica), and hornbeam (Carpinus
betulus) [with Fraxinus spp. and Castanea spp. often just as
common as Carpinus]. Common trees in North America
include sugar maple (Acer saccharum), American beech
(Fagus grandifolia), basswoods (Tilia spp.), oaks, and hick-
ories (Carya spp.). In Asia, Japanese beech (Fagus crenata),
oaks, maples, ashes (Fraxinus spp.) and basswoods are most
common. At lower latitudes, broadleaved deciduous species
are joined by broadleaved evergreen angiosperm trees, such
as oaks, beeches (Northofagus spp.), eucalyptus ( Eucalyptus
spp.), and pines (Podocarpus spp.).
Plant life
Deciduous leaves are the most distinctive feature of tem-
perate deciduous broadleaved forests. Autumn changes in
leaf color and senescence have become very important to
these regions both economically and ecologically. “Leaf-
peeping” tourists travel to deciduous forest destinations to
view displays of reds, oranges, and yellows and invest in
local markets.[46,47] The dropping of leaves in the fall is also
a phenological event or recurring biological cycle that
changes the seasonal microhabitat, creating unique under-
story conditions for other plants and animals.
The onset of plant phenophases such as spring leaf fl ush
and autumn leaf senescence are controlled by two major
environmental signals: photoperiod (relative length of
days/nights) and total degree days (relative measure of
218 Forests: Temperate Evergreen and Deciduous
Ecotone—
Fragmentation
Plant life
While broadleaved trees in the Northern Hemisphere are
exposed to variable environmental stress, broadleaved trees
in the Southern Hemisphere are under weaker seasonal
forces. Because of milder climates and less extreme vari-
ability in the Southern Hemisphere, it is more advanta-
geous for trees to expose leaves all year round in order to
maximize photosynthesis and carbon gain.[66,67] Temperate
broadleaved evergreen tree leaves are generally thick with
smooth margins as opposed to deciduous leaves, which by
comparison are generally thin and lobed. These differences
are in part due to higher levels of rainfall and humidity.
Southern Hemisphere species maintain a waxy outer layer
on leaves to repel water. In these mild temperate evergreen
forests, species compositions are mainly from the fami-
lies of Lauraceae, Fagaceae, Theaceae, Magnoliaceae,
and Hamamelidaceae, all of which have a relatively low
resistance to cold and freezing temperatures.[68,69] In the
Southern Hemisphere, the very dry-adapted forests of
Australia are also found. Fire disturbance in this dry region
has allowed for the domination of Eucalyptus spp. which
have thick bark for fi re-resistance.[70,71]
Also relatively common in many temperate evergreen
forests are narrow-leaved evergreen trees. These species
produce their seeds in compact structures called cones,
which allow for greater protection of reproductive material
from predation as well as some unique adaptations to envi-
ronmental conditions.[72] Some evergreen conifers have
at, triangular scale-like leaves, such as found in the
Cupressaceae and some Podocarpaceae, while many ever-
green trees also produce needle-like leaves, which increase
the leaf area for photosynthesis and are thicker and smaller
to avoid desiccation.[73,74] Rates of area- or massed-based
leaf photosynthesis in temperate needle-liked evergreen
trees are typically much lower than for leaves of temperate
deciduous tree species, except when amortized over the life
of the leaf.[75] Temperate deciduous trees only keep their
leaves for one growing season, while temperate evergreen
forests keep their leaves for much longer.
The moist temperate coniferous forests dominated by
tree species such as giant sequoias (Sequoiadendron gigan-
teum), coastal redwoods (Sequoia sempervirens), Douglas
rs (Pseudotsuga menziesii), and kauris (Agathis australis)
sustain the highest levels of biomass in any terrestrial eco-
system.[76] These forests are rare and known for a rich vari-
ety of plant and animal species. Typically, two or more tree
layers of large broadleaved, dome-shaped evergreen angio-
sperms are present. These forests, which grow in moist
regions, are also known for higher abundance and diversity
of epiphytes and vines.
In maritime climates, fog can provide a signifi cant
amount of the annual water available to vegetation.[77]
Forming over adjacent oceans and water bodies, the moist
air travels with both humidity and nutrients that can be
mammals store fat and hibernate or go into torpor during
the cold months. Some birds take shelter in the trees by
becoming cavity-nesters, while others are migratory and
avoid the cold winters by fl ying to more southerly climes.
Soils and nutrients
Temperate deciduous forest soils show variation with lati-
tude and altitude, as well as with moisture. At the northern
or higher extent of the range, where there is a greater pres-
ence of needle-leaf evergreen tree species, soils tend to be
relatively acidic and nutrient poor. By contrast, soils are
strongly leached and less productive in the southern or
lower ranges. Temperate deciduous forest soils, however,
tend to be deep and fertile and do not freeze year-round.
Brown forest soils (alfi sols, in the American soil taxon-
omy) develop under the nutrient-demanding broadleaf
trees whose leaves bind the major nutrient bases.[64,65] This
causes leaf litter to be less acidic and provide a rich humus
layer. Along with the favorable summer growing season,
this is one of the reasons why this biome has historically
been popular for agricultural use.
Temperate Evergreen Forest
Temperate broadleaved evergreen forests occur at the
warm, moist end of the latitudinal gradient of temperate
forests and are characterized by long, hot, humid growing
seasons, and relatively milder winters. Precipitation is high
(1000–1750 mm) and the forest is dominated by broad-
leaved evergreen angiosperms. These forests occur in east-
ern Asia, coastal regions of New Zealand and Australia,
western coastal regions of North America and parts of Chile,
South Africa, and warmer European regions.[34, 43–45] There
are several forest variants that occur in regions of maritime
and dry-season climates. Maritime broadleaved forests are
dominated by tall, broadleaved evergreen angiosperms and
narrow- to broadleaved conifers and exhibit very high pre-
cipitation (2000–3000 mm). Maritime needle-leaved forests
occur only in a narrow band along the coastline of North
America from California to Alaska and throughout coastal
southern Europe and are known for needle- and scale-leaved
evergreen conifers such as giant sequoias in North America
or angiosperms such as evergreen oaks in Europe. Dry-
season broad-sclerophyll forests occur in areas with periodic
drought, exhibiting more of a Mediterranean climate, with
hot dry summer and cool wet winters.
Needle-leaved conifers can be interspersed within
deciduous canopies or occur in patches. They tend to grow
at higher altitudes near treeline or in drier regions. Condi-
tions can be highly seasonal, with severe winters and warm,
humid summers. Conifer tree species include fi r (Abies
spp.), spruce (Picea spp.), pine (Pinus spp.), cedar (Thuja
spp.), hemlock (Tsuga spp.), and larch (Larix decidua)
among others.
Forests: Temperate Evergreen and Deciduous 219
Ecotone—
Fragmentation
temperature and metabolism without eating, drinking, def-
ecating, or urinating.[92] In austral regions, temperate ever-
green forests are also home to many endemic species such
as Leadbeater’s possum (Gymnobelideus leadbeaten),
Parma wallaby (Marcopus parma) and Albert’s lyrebird
(Menura alberti).
Soil and nutrients
Soils of temperate evergreen forests are well leached and
low in productivity. Ultisols represent older, unglaciated
soils that have been weathered to a much greater degree
than those of temperate deciduous forests. Ultisols are gen-
erally less fertile than most temperate deciduous forest
soils and were further degraded under plantation and sub-
sistence agriculture in both the colonial and postcolonial
periods.[65,93]
THREATS
Threats to the temperate forest biome stem from direct
or indirect human activity. Historically, farming has been
one of the main reasons for deforestation in temperate
biomes. Today, an increasing number of roads, residential
and other developments have left forests highly frag-
mented, raising concerns over the healthy functioning of
these ecosystems.[94] Many of the plant species living in
temperate forests are well-adapted and function optimally
in soils with fairly low nutrient availability. However, more
impervious surfaces as well as modern agricultural and
industrial practices can alter nutrient availability and con-
tribute to a decline in forest health. Atmospheric deposition
of nitrogen, acid deposition and fertilizer applications are
changing the rate of input of nutrients along with the growth
and dynamics of temperate forest communities.[95–97] This
also leads to alterations in soil properties, nutrient cycling
and microbial community composition as well as nutrient
imbalances in plants and increases in forest mortality.
These nutrient imbalances in plants make them more vul-
nerable to other outside stressors such as diseases and
introduced invasive species.[98–100]
Human activities are also altering global climate, a
foundation for the characterization and distribution of tem-
perate forests. For deciduous canopies, observational evi-
dence has linked global climate change to differences in the
timing of spring leaf growth and autumn leaf drop. Warm
springs cause leaves to grow earlier, sometimes by up to
one month (http://www.usanpn.org), lengthening the dura-
tion of the growing season in some temperate forests.[101–103]
Climate variation may also result in a shift in fl owering
periods, potentially causing disruption in timing with pol-
linators/dispersers. In Japan, cherry blossom (Prunus
serrulata) trees are blooming earlier than they did histori-
cally, causing concerns regarding the traditional festivals
and tourism that surround the annual event.[104] Evidence of
intercepted by plants, reducing water stress caused by
transpiration. Some studies suggest that some leaf shapes
have evolved for more effi cient collection of fog drip.
It has also been hypothesized that fog in dry summer
months is essential in supporting the sustained growth of
large trees such as the redwoods of California.[78,79]
Temperate coniferous forests at higher altitudes often
have narrow tree morphologies which allow heavy snow to
slough off branches before breaking them.[72,73] These for-
ests are dense, with trees growing close together to mini-
mize wind damage; wind minimization is important
because conifers often have very shallow root systems due
to higher allocation of nutrients in the top layers of soil.[80,81]
Evergreen trees in higher, drier areas allocate carbon to
thick bark for greater protection from low-heat summer
res. Some conifers have adapted to take advantage of fi re
events, producing serotinous cones in which seeds are
maintained in a dormant state until a fi re occurs, opening
the cones and releasing the seeds for germination.[82,83]
Because the canopy of these temperate forests is ever-
green, the vegetation in the understory experiences low light
availability. Understory plants have adapted to maximize
their light/energy capture as well as their photosynthetic
capacity under such conditions. Shaded plants tend to allocate
more growth to leaves, displaying larger, thinner leaves
which take up more horizontal area for light capture.[75,84]
Physiologically, shade leaves saturate at lower light levels
and have lower light compensation points, which allows
them to maintain positive rates of net photosynthesis at low
light levels. Understory plants also adapt to respond quickly
to environmental changes in order to make use of sunfl ecks
or brief, unpredictable periods of high sunlight usually lasting
only seconds.[85–87] Instantaneous adjustments in photosyn-
thetic rates allow plants to be effi cient with the limited light
they receive to put toward carbon gain.
Animal life
The fauna of the temperate evergreen forest is similar to
that of the deciduous forest ecosystems, with many smaller
mammals, large ungulates and a few larger omnivorous
mammals contributing to biological interactions. Many of
these species, mostly birds and small rodents, have adapted
skills to compensate for the scarcity of food in these nutri-
ent poor systems. The red squirrel (Sciurus vulgaris)
removes cone scales to reach the nutrient rich seeds of the
coniferous trees.[88,89] They often hoard these seeds, many
of which they do not recover, resulting in seed dispersal.
In dry forests at higher latitudes, large ungulates such as
moose (Alces alces) browse nutritious spring vegetation
and wetland foliage in warmer seasons and on young
tree shoots when the ground is frozen and covered with
snow.[90,91] Some fauna in the coniferous evergreen forests
located at higher latitudes have also adapted to the cold,
snowy winters. For example, bears (Ursus spp.) are able to
go into long periods of dormancy, maintaining both body
220 Forests: Temperate Evergreen and Deciduous
Ecotone—
Fragmentation
sustainable use of these resources and proper protection
and management of temperate forests will be important in
ensuring the health and productivity of the biome.
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... The relative popularity of Autumn among continents increases with the continent's proportion of deciduous trees (rs = 0.850, p = 0.015, Table S9). Specifically, North America has a much higher proportion of red-coloured deciduous species than does Europe (Renner & Zohner, 2020), and temperate Australia and New Zealand have relatively few deciduous trees (Dreiss & Volin, 2014). The exceptionally bright reds of North American leaves may reflect relatively high concentrations of anthocyanins and xanthophylls, which provide protection against relatively high autumnal UV radiation in North America compared with Europe (Renner & Zohner, 2020). ...
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Parents often weigh social, familial, and cultural considerations when choosing their baby's name, but the name they choose could potentially be influenced by their physical or biotic environments. Here we examine whether the popularity of month and season names of girls covary geographically with environmental variables. In the continental USA, April, May, and June (Autumn, Summer) are the most common month (season) names: April predominates in southern states (early springs), whereas June predominates in northern states (later springs). Whether April's popularity has increased with recent climate warming is ambiguous. Autumn is most popular in northern states, where autumn foliage is notably colourful, and in eastern states having high coverage of deciduous foliage. On a continental scale, Autumn was most popular in English-speaking countries with intense colouration of autumn foliage. These analyses are descriptive but indicate that climate and vegetation sometimes influence parental choice of their baby's name.
... This study describes the temperature sensitivity (Q 10 ) of dark CO 2 fixation rates and compares it to that of net soil respiration rates across soil profiles of deciduous and coniferous forests, the two temperate forests based on vegetation (Dreiss and Volin, 2014;Adams et al., 2019). Soils of two acidic forest plots from the Hummelshain forest, Germany, dominated by beech (deciduous) and spruce (coniferous) tree species were incubated under two temperature conditions (4 and 14 • C). ...
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Globally, soil temperature to 1 m depth is predicted to be up to 4 ∘C warmer by the end of this century, with pronounced effects expected in temperate forest regions. Increased soil temperatures will potentially increase the release of carbon dioxide (CO2) from temperate forest soils, resulting in important positive feedback on climate change. Dark CO2 fixation by microbes can recycle some of the released soil CO2, and CO2 fixation rates are reported to increase under higher temperatures. However, research on the influence of temperature on dark CO2 fixation rates, particularly in comparison to the temperature sensitivity of respiration in soils of temperate forest regions, is missing. To determine the temperature sensitivity (Q10) of dark CO2 fixation and respiration rates, we investigated soil profiles to 1 m depth from beech (deciduous) and spruce (coniferous) forest plots of the Hummelshain forest, Germany. We used 13C-CO2 labelling and incubations of soils at 4 and 14 ∘C to determine CO2 fixation and net soil respiration rates and derived the Q10 values for both processes with depth. The average Q10 for dark CO2 fixation rates normalized to soil dry weight was 2.07 for beech and spruce profiles, and this was lower than the measured average Q10 of net soil respiration rates with ∼2.98. Assuming these Q10 values, we extrapolated that net soil respiration might increase 1.16 times more than CO2 fixation under a projected 4 ∘C warming. In the beech soil, a proportionally larger fraction of the label CO2 was fixed into soil organic carbon than into microbial biomass compared to the spruce soil. This suggests a primarily higher rate of microbial residue formation (i.e. turnover as necromass or release of extracellular products). Despite a similar abundance of the total bacterial community in the beech and spruce soils, the beech soil also had a lower abundance of autotrophs, implying a higher proportion of heterotrophs when compared to the spruce soil; hence this might partly explain the higher rate of microbial residue formation in the beech soil. Furthermore, higher temperatures in general lead to higher microbial residues formed in both soils. Our findings suggest that in temperate forest soils, CO2 fixation might be less responsive to future warming than net soil respiration and could likely recycle less CO2 respired from temperate forest soils in the future than it does now.
... when the dry periods become longer and longer, plants become lower and lower''. This may elucidate the dominance of suffruticose chamaephytes, in this study, which can survive dry periods by death of only the upper parts of the shoot and dwarf phanerophytes (nano-phanerophytes). Nanism (dwarf growth) is a direct response to drought(Raunkiaer 1937).Dreiss and Volin (2014) emphasized that dropping of plant leaves (deciduous leaves) is another phenological event that occurs as a response to drought, while plants that bear leaves all the year seasons (evergreen plants) are drought tolerant. The difference in the reproductive phenology between evergreen and deciduous species in the present study ...
Thesis
The present study aims at: 1- preparing a list of the trees and shrubs (of height ≥ 50 cm) in the Egyptian flora, 2- determining the species which are considered alien, 3- determining if there are endemic or near-endemic species among them, 4- checklist analysis in terms of taxonomic diversity, geographical distribution, life forms, flowering times, sex forms, dispersal types, rarity forms, goods and services, threats and physical defense, 5- evaluation of their IUCN Red List Categories, 6- determining the distribution of the threatened taxa in Egypt on a grid map and 7- determining the in situ and ex situ conservation actions taken towards these plants in Egypt. Twenty one field visits were conducted to many locations all over Egypt from winter 2017 to winter 2019 for collecting trees and shrubs. From each location, plant and seed specimens were collected from different habitats. In the present study, 228 taxa belonged to 126 genera and 45 families were recorded, including 2 endemics (Rosa arabica and Origanum syriacum subsp. sinaicum) and 5 near-endemics. They inhabit 10 natural and 4 anthropogenic habitats. Phanerophytes (120 plants) are the most represented life form, followed by chamaephytes (100 plants); while bisexuals are the most represented sex form. Sarcochores (74 taxa) are the most represented dispersal type, followed by ballochores (40 taxa). April (151 taxa) and March (149 taxa) have the maximum flowering plants. SNN (Small geographic range - narrow habitat - non abundant plants) are the most represented rarity form (180 plants). Deserts are the most rich regions with trees and shrubs (127 taxa). North African-Indian Desert chorotype has most occurence of trees and shrubs (165 taxa), followed by Sudanese Park Steppe (104 taxa). Medicinal plants (154 taxa) were the most offered good, while salinity tolerance (105 taxa) was the most represented service. Over-collecting and over-cutting are the most effective threats. Plants with spiny organs (e. g. spiny stipules, leaves, branches, inflorescences and fruits or woody branches with spine-like terminates) are the most represented (64 taxa). Three taxa are evaluated as extinct, another 3 are extinct in the wild, while 101 taxa are threatened with extinction (25 taxa are critically endangered, 52 taxa are endangered and 24 taxa are vulnerable). In addition, some 125 species are under conservation (87 taxa are under in situ conservation in the protected areas, 34 taxa are included in botanic gardens, while 118 taxa are kept in the herbaria as dry specimens and 10 taxa in gene banks as seed samples).
... Humid temperate forests occur at intermediate latitudes and are characterized by a cold winter and a warm and rainy growing season during spring and summer (Dreiss & Volin, 2014). Freeze-thaw cycles (FTC) of xylem sap occur frequently in this type of forests and may be a main factor limiting tree growth, as xylem embolism induced by FTC poses a serious threat for the hydraulic integrity of trees (Sperry et al., 1994;Tyree & Sperry, 1989). ...
Article
In humid temperate forests, the occurrence of frequent freeze–thaw cycles (FTC) is a main factor limiting tree growth, as xylem embolism induced by FTC poses a serious threat to the hydraulic integrity of trees. A high resilience to hydraulic dysfunction involves the enhancement of embolism resistance and/or extra non‐structural carbohydrate (NSC) inputs for restoration of an impaired hydraulic system. However, potentially negative implications of such NSC allocation on tree growth have not yet been explored. At a temperate forest site of northeast China, we studied xylem hydraulics and NSC contents in relation to winter embolism resilience in 15 sympatric broadleaf tree species belonging to three genera with relatively high species richness, but having distinct strategies in maintaining hydraulic integrity over the winter, that is, Acer species that generate positive stem and root pressures contributing to winter embolism refilling, Betula species that only generate root pressure and Populus species that do not generate positive pressure. Acer and Betula species had higher soluble sugar contents in the dormant season and indeed had higher hydraulic resilience to FTC‐induced embolism but slower stem growth. Populus species had higher NSC contents during the growing season and their faster stem growth was also consistent with higher hydraulic efficiency and leaf photosynthetic rate. The positive correlation between tree trunk radial growth rate and hydraulic conductivity suggests that xylem water transport efficiency can be a fundamental basis for tree productivity due to a significant hydraulic‐photosynthetic coordination. The negative correlation between soluble sugar concentration in the dormant season and stem growth rate indicates that metabolic carbon costs for enhancing hydraulic resilience may compromise tree growth during the growing season. Comparisons among Acer, Betula and Populus and the correlation analyses based on phylogenetic independent contrasts strongly support the existence of a trade‐off between hydraulic resilience against FTC‐induced embolism and growth rate among sympatric tree species under humid temperate climate conditions. This trade‐off has likely contributed to the sorting of temperate tree species and genera to different niches along environmental gradients with respect to freezing stress and interspecific competition. A free Plain Language Summary can be found within the Supporting Information of this article. A free Plain Language Summary can be found within the Supporting Information of this article.
... Since phenological development might vary according to the presence/absence of canopy cover and the time when canopy changes Augspurger, 2008), data derived from phenological studies may also depend on the forest type. While in temperate deciduous forests (mainly broadleaves) there is greater seasonal variation in light availability in the understorey, evergreen forests (mainly conifers) maintain quite steady-state light environments (Dreiss and Volin, 2014). ...
Thesis
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The need to develop forest management systems other than clearfelling has resulted in a requirement for improved understanding of the potential of continuous cover forestry (CCF). One suggested method for the conversion of forest stands into CCF systems and for bringing under-performing forests into productivity is thinning in conjunction with underplanting. This study was an attempt to provide information on species suitability for underplanting of two important trees in European forestry: pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.). To determine the morphological, physiological and growth responses of these two species to different light conditions, beech and oak seedlings previously grown at full light for two years were covered by shading nets that provide different shade levels (62%, 51% or 28% of full light) or continued to be exposed to full light. The different shade levels were intended to mimic a range of underplanted conditions and the process of acclimation to shade was studied to provide information on the ecology and adaptation of underplanted seedlings. In addition to the controlled-shade experiment another study to determine the physiological responses of beech natural regeneration to shade was conducted under natural light conditions (from open gaps to closed canopy).Both oak and beech displayed similar acclimation in response to shade for most of the traits investigated. At the plant level, seedling acclimation to shade included higher biomass allocation to above than below-ground parts and greater energy investment on height than diameter growth. At the leaf level, seedlings grown under shade reduced their leaf thickness and photosynthetic rates per unit area and increased their specific leaf area. This increase in specific leaf area seems to be one mechanism that allows seedlings to perform well under shade conditions. Another acclimation to low light conditions was to increase the efficiency of the photosystem II under shade. Photosynthetic rates were higher and leaves were retained for longer in seedlings grown at full light than under shade. Hence, this probably led to a greater growth in the full light than under shade. Despite this greater growth at full light, the results of this study suggest that beech and oak seedlings would be able to acclimate and perform well if underplanted below overstories that reduce the available light to as low as 28% of full light without having any significant adverse effect on the quality of the final crop.
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Along with climate change, another foremost concern that can debilitate our lives and impact humankind as a whole happens to be the spread of Infectious zoonotic diseases. Unfortunately, epidemics arising out of such diseases have been on the rise over time. One of the major causes of the outbreak of these diseases is the degradation of forests due to the loss of biodiversity and the pristine ecosystem. The land use and land cover (LULC) changes within and around the forest due to anthropogenic pressures are disturbing the sustenance and resilient capacity of the ecosystem, resulting in loss of habitat for the animals. This chapter highlights few such concerns like deteriorating man and environment relationship leading to forest degradation; the rising zoonotic disease outbreaks and its relationship with land use and land cover changes; and the role of forest plantation in the degradation of forest ecosystem health. These concerns are further analyzed through a case study of Wayanad district known for its rich evergreen and deciduous forest in the State of Kerala, India. The chapter concludes with the need for recognition of establishing regional priorities with the identification of hot spot areas, where several of the drivers of emerging zoonotic diseases are present, with strengthened afforestation and suitable LULC change policies and surveillance systems.
Book
This striking book provides a handy summary of the ecology of the world's vegetation. The introductory chapters provide a basic back-drop to the subject. The subsequent chapters examine sequentially the form and function of each major biome throughout the world.
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Ecological consequences of shrub encroachment are emerging as a key issue in the study of global change. In mesic grasslands, shrub encroachment can result in a fivefold increase in ecosystem leaf area index (LAI) and a concurrent reduction in understory light and herbaceous diversity. LAI and light attenuation are often higher for shrub thickets than for forest communities in the same region, yet little is known about the contribution of sunflecks in shrub-dominated systems. Our objective was to compare fine-scale spatial and temporal dynamics of understory light in shrub thickets to the light environment in typical forest communities. We used an array of quantum sensors to examine variation in diffuse and direct light and determined the relative contribution of sunflecks during midday in Morella cerifera shrub thickets, a 30-yr-old abandoned Pinus taeda plantation, and a mature, second-growth, deciduous forest. Instantaneous photosynthetic photon flux density (PPFD) was measured at 1-s intervals at five sites in each community during midday. In summer, understory light during midday in shrub thickets was approximately 0.8% of above-canopy light, compared to 1.9% and 5.4% in pine and deciduous forests, respectively. During summer, PPFD was uncorrelated between sensors as close as 0.075 m in shrub thickets compared to 0.175 m and 0.900 m in pine and deciduous forests, respectively, indicating that sunflecks in shrub thickets were generally small compared to sunflecks in the two forests. Sunflecks in shrub thickets were generally short (all <30 s) and relatively low in intensity (<150 micromol photons x m(-2) x s(-1)) and contributed only 5% of understory light during midday. Sunflecks were longer (up to 6 minutes) and more intense (up to 350 micromol photons x m(-2) x s(-1)) in the two forest communities and Contributed 31% and 22% of understory light during midday in pine and deciduous forest, respectively. The combination of high LAI and relatively short-stature of M. cerifera shrub thickets produces a dense canopy that reduces both diffuse light and the occurrence of sunflecks. The lack of sunflecks may limit the number of microsites with a favorable light environment and contribute to the reduction in understory cover and diversity within the shrub thickets.
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Hibernation in the Ursidae has been extensively researched over the past 30 years. This paper reviews findings of that research in the areas of general physiology and energetics; protein, fat, and bone metabolism; metabolic endocrinology; reproductive physiology and lactation; serum chemistry and hematology; and the ureaxreatinine ratio. Bears in hibernation exhibit several characteristics distinct from the deep hibernation of rodents, such as a lesser reduction in body temperature, protein conservation, lack of defecation and urination, and normal bone activity. The physiological constraints of hibernation are coupled to adaptations in reproductive physiology, such as delayed implantation and lactation. I argue that ureaxreatinine is not a reliable indicator of hibernation, although ongoing research is searching for an opioid-like hibernation trigger. Study of hibernation physiology will continue to bear fruit, especially in the areas of evolution, physiology, and medicine.