Group of cone-bearing seed plants
Conifers
are a group of
cone-bearing
seed plants
, a subset of
gymnosperms
. Scientifically, they make up the
division
Pinophyta
(
), also known as
Coniferophyta
(
) or
Coniferae
. The division contains a single extant
class
,
Pinopsida
. All
extant
conifers are
perennial
woody plants
with
secondary growth
.
[a]
The great majority are
trees
, though a few are
shrubs
. Examples include
cedars
,
Douglas-firs
,
cypresses
,
firs
,
junipers
,
kauri
,
larches
,
pines
,
hemlocks
,
redwoods
,
spruces
, and
yews
.
[1]
As of 2002, Pinophyta contained seven families, 60 to 65 genera, and more than 600 living species.
Although the total number of species is relatively small, conifers are
ecologically
important. They are the dominant plants over large areas of land, most notably the
taiga
of the
Northern Hemisphere
, but also in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While
tropical rainforests
have more
biodiversity
and turnover, the immense conifer forests of the world represent the largest terrestrial
carbon sink
. Conifers are of great economic value for
softwood
lumber
and
paper
production.
Names and taxonomy
[
edit
]
Conifer
is a Latin word, a compound of
conus
(cone) and
ferre
(to bear), meaning "the one that bears (a) cone(s)".
The division name Pinophyta conforms to the rules of the
International Code of Nomenclature for algae, fungi, and plants
(ICN), which state (Article 16.1) that the names of higher
taxa
in plants (above the rank of family) are either formed from the name of an included family (usually the most common and/or representative), in this case
Pinaceae
(the
pine
family), or are descriptive. A descriptive name in widespread use for the conifers (at whatever rank is chosen) is
Coniferae
(Art 16 Ex 2).
According to the ICN, it is possible to use a name formed by replacing the termination
-aceae
in the name of an included family, in this case preferably
Pinaceae
, by the appropriate termination, in the case of this division
-ophyta
. Alternatively, "
descriptive botanical names
" may also be used at any
rank
above family. Both are allowed.
This means that if conifers are considered a division, they may be called Pinophyta or Coniferae. As a class, they may be called Pinopsida or Coniferae. As an order they may be called Pinales or Coniferae or
Coniferales
.
Conifers are the largest and economically most important component group of gymnosperms, but nevertheless they comprise only one of the four groups. The division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa. Subdivision of the living conifers into two or more orders has been proposed from time to time. The most commonly seen in the past was a split into two orders,
Taxales
(Taxaceae only) and
Pinales
(the rest), but recent research into
DNA sequences
suggests that this interpretation leaves the Pinales without Taxales as
paraphyletic
, and the latter order is no longer considered distinct. A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, and Cupressales containing the remaining families (including Taxaceae), but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse
morphology
.
There were seven families of conifers
c.
2011
,
[3]
with 65?70 genera and over 600 living species (
c.
2002
).
[4]
: 205
[5]
[
needs update
]
The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the
Cephalotaxaceae
may be better included within the Taxaceae, and some authors additionally recognize
Phyllocladaceae
as distinct from Podocarpaceae (in which it is included here). The family
Taxodiaceae
is here included in the family Cupressaceae, but was widely recognized in the past and can still be found in many field guides. A new classification and linear sequence based on molecular data can be found in an article by Christenhusz et al.
[6]
The conifers are an ancient group, with a
fossil
record extending back about 300 million years to the
Paleozoic
in the late
Carboniferous
period; even many of the modern genera are recognizable from fossils 60?120 million years old. Other classes and orders, now long extinct, also occur as fossils, particularly from the late Paleozoic and
Mesozoic
eras. Fossil conifers included many diverse forms, the most dramatically distinct from modern conifers being some
herbaceous
conifers with no woody stems.
[7]
Major fossil orders of conifers or conifer-like plants include the
Cordaitales
,
Vojnovskyales
,
Voltziales
and perhaps also the
Czekanowskiales
(possibly more closely related to the
Ginkgophyta
).
Multiple studies also indicate that the
Gnetophyta
belong within the conifers despite their distinct appearances, either placing them as a
sister group
to
Pinales
(the 'gnepine' hypothesis) or as being more derived than Pinales but sister to the rest of the group. Most recent studies favor the 'gnepine' hypothesis.
[8]
[9]
[10]
Phylogeny
[
edit
]
The earliest conifers appear in the fossil record during the Late
Carboniferous
(
Pennsylvanian
), over 300 million years ago. Conifers are thought to be most closely related to the
Cordaitales
,
a group of extinct Carboniferous-Permian trees and clambering plants whose reproductive structures had some similarities to those of conifers. The most primitive conifers belong to the paraphyletic assemblage of "
walchian conifers
", which were small trees, and probably originated in dry upland habitats. The range of conifers expanded during the Early
Permian
(
Cisuralian
) to lowlands due to increasing aridity. Walchian conifers were gradually replaced by more advanced
voltzialean
or "transition" conifers.
[11]
Conifers were largely unaffected by the
Permian?Triassic extinction event
,
[12]
and were dominant land plants of the
Mesozoic
era. Modern groups of conifers emerged from the Voltziales during the Late Permian through
Jurassic
.
[13]
Conifers underwent a major decline in the
Late Cretaceous
corresponding to the explosive
adaptive radiation
of
flowering plants
.
[14]
Description
[
edit
]
All living conifers are woody plants, and most are trees, the majority having a monopodial growth form (a single, straight trunk with side branches) with strong
apical dominance
. Many conifers have distinctly scented
resin
, secreted to protect the tree against
insect
infestation and
fungal
infection of wounds. Fossilized resin hardens into
amber
, which has been commercially exploited historically (for example, in New Zealand's 19th-century
kauri gum
industry).
The size of mature conifers varies from less than one metre to over 100 metres in height.
[15]
The world's tallest, thickest, largest, and oldest living trees are all conifers. The tallest is a
coast redwood
(
Sequoia sempervirens
), with a height of 115.55 metres (although one mountain ash,
Eucalyptus regnans
, allegedly grew to a height of 140 metres,
[16]
the tallest living
angiosperms
are significantly smaller at around 100 metres.
[17]
[18]
) The thickest (that is, the
tree with the greatest trunk diameter
) is a
Montezuma cypress
(
Taxodium mucronatum
), 11.42 metres in diameter. The largest tree by three-dimensional volume is a giant sequoia (
Sequoiadendron giganteum
), with a volume 1486.9 cubic metres.
[19]
The smallest is the
pygmy pine
(
Lepidothamnus laxifolius
) of New Zealand, which is seldom taller than 30 cm when mature.
[20]
The oldest non-clonal living tree is a Great Basin bristlecone pine (
Pinus longaeva
), 4,700 years old.
[21]
Foliage
[
edit
]
Since most conifers are evergreens,
[1]
the
leaves
of many conifers are long, thin and have a needle-like appearance, but others, including most of the
Cupressaceae
and some of the
Podocarpaceae
, have flat, triangular scale-like leaves. Some, notably
Agathis
in Araucariaceae and
Nageia
in Podocarpaceae, have broad, flat strap-shaped leaves. Others such as
Araucaria columnaris
have leaves that are awl-shaped. In the majority of conifers, the leaves are arranged spirally, the exceptions being most of Cupressaceae and one genus in Podocarpaceae, where they are arranged in decussate opposite pairs or whorls of 3 (?4).
In many species with spirally arranged leaves, such as
Abies grandis
(pictured), the leaf bases are twisted to present the leaves in a very flat plane for maximum light capture. Leaf size varies from 2 mm in many scale-leaved species, up to 400 mm long in the needles of some pines (e.g. Apache pine,
Pinus engelmannii
). The
stomata
are in lines or patches on the leaves and can be closed when it is very dry or cold. The leaves are often dark green in colour, which may help absorb a maximum of energy from weak sunshine at high
latitudes
or under forest canopy shade.
Conifers from hotter areas with high sunlight levels (e.g. Turkish pine
Pinus brutia
) often have yellower-green leaves, while others (e.g.
blue spruce
,
Picea pungens
) may develop blue or silvery leaves to reflect
ultraviolet
light. In the great majority of genera the leaves are
evergreen
, usually remaining on the plant for several (2?40) years before falling, but five genera (
Larix
,
Pseudolarix
,
Glyptostrobus
,
Metasequoia
and
Taxodium
) are
deciduous
, shedding their leaves in autumn.
[1]
The seedlings of many conifers, including most of the Cupressaceae, and
Pinus
in Pinaceae, have a distinct juvenile foliage period where the leaves are different, often markedly so, from the typical adult leaves.
Tree ring structure
[
edit
]
Tree rings
are records of the
influence
of
environmental
conditions, their anatomical characteristics record growth rate changes produced by these changing conditions. The microscopic
structure
of conifer wood consists of two types of
cells
:
parenchyma
, which have an oval or polyhedral shape with approximately identical dimensions in three directions, and strongly elongated tracheids.
Tracheids
make up more than 90% of timber volume. The tracheids of earlywood formed at the beginning of a
growing season
have large radial sizes and smaller, thinner
cell walls
. Then, the first tracheids of the transition zone are formed, where the radial size of cells and the thickness of their cell walls changes considerably. Finally, latewood tracheids are formed, with small radial sizes and greater cell wall thickness. This is the basic pattern of the internal cell structure of conifer tree rings.
[22]
Reproduction
[
edit
]
Most conifers are
monoecious
, but some are
subdioecious
or
dioecious
; all are
wind-pollinated
. Conifer seeds develop inside a protective cone called a
strobilus
. The cones take from four months to three years to reach maturity, and vary in size from
2 to 600 millimetres (
1
⁄
8
to
23
+
5
⁄
8
in) long.
In
Pinaceae
,
Araucariaceae
,
Sciadopityaceae
and most
Cupressaceae
, the cones are
woody
, and when mature the scales usually spread open allowing the seeds to fall out and be dispersed by the
wind
. In some (e.g.
firs
and
cedars
), the cones disintegrate to release the seeds, and in others (e.g. the
pines
that produce
pine nuts
) the nut-like seeds are dispersed by
birds
(mainly
nutcrackers
, and
jays
), which break up the specially adapted softer cones. Ripe cones may remain on the plant for a varied amount of time before falling to the ground; in some fire-adapted pines, the seeds may be stored in closed cones for up to 60?80 years, being released only when a fire kills the parent tree.
In the families
Podocarpaceae
,
Cephalotaxaceae
,
Taxaceae
, and one
Cupressaceae
genus (
Juniperus
), the scales are soft, fleshy, sweet, and brightly colored, and are eaten by fruit-eating birds, which then pass the seeds in their droppings. These fleshy scales are (except in
Juniperus
) known as
arils
. In some of these conifers (e.g. most Podocarpaceae), the cone consists of several fused scales, while in others (e.g. Taxaceae), the cone is reduced to just one seed scale or (e.g. Cephalotaxaceae) the several scales of a cone develop into individual arils, giving the appearance of a cluster of berries.
The male cones have structures called
microsporangia
that produce yellowish pollen through meiosis. Pollen is released and carried by the wind to female cones. Pollen grains from living pinophyte species produce pollen tubes, much like those of angiosperms. The
gymnosperm
male gametophytes (pollen grains) are carried by wind to a female cone and are drawn into a tiny opening on the ovule called the
micropyle
. It is within the ovule that pollen-germination occurs. From here, a pollen tube seeks out the female gametophyte, which contains archegonia each with an egg, and if successful, fertilization occurs. The resulting
zygote
develops into an
embryo
, which along with the female gametophyte (nutritional material for the growing embryo) and its surrounding integument, becomes a
seed
. Eventually, the seed may fall to the ground and, if conditions permit, grow into a new plant.
In
forestry
, the terminology of
flowering plants
has commonly though inaccurately been applied to cone-bearing trees as well. The male cone and unfertilized female cone are called
male flower
and
female flower
, respectively. After fertilization, the female cone is termed
fruit
, which undergoes
ripening
(maturation).
It was found recently that the
pollen
of conifers transfers the
mitochondrial
organelles
to the
embryo
,
[
citation needed
]
a sort of
meiotic
drive that perhaps explains why
Pinus
and other conifers are so productive, and perhaps also has bearing on observed sex-ratio bias.
[
citation needed
]
-
Pinaceae: unopened female cones of
subalpine fir
(
Abies lasiocarpa
)
-
Taxaceae: the fleshy aril that surrounds each seed in the
European yew
(
Taxus baccata
) is a highly modified seed cone scale
-
Pinaceae: pollen cone of a
Japanese larch
(
Larix kaempferi
)
Life cycle
[
edit
]
Conifers are
heterosporous
, generating two different types of spores: male
microspores
and female
megaspores
. These spores develop on separate male and female
sporophylls
on separate male and female cones. In the male cones, microspores are produced from microsporocytes by
meiosis
. The microspores develop into pollen grains, which contain the male gametophytes. Large amounts of pollen are released and carried by the wind. Some pollen grains will land on a female cone for pollination. The generative cell in the pollen grain divides into two
haploid
sperm cells by
mitosis
leading to the development of the pollen tube. At fertilization, one of the sperm cells unites its haploid nucleus with the haploid nucleus of an egg cell. The female cone develops two ovules, each of which contains haploid megaspores. A megasporocyte is divided by meiosis in each ovule. Each winged pollen grain is a four celled male
gametophyte
. Three of the four cells break down leaving only a single surviving cell which will develop into a female
multicellular
gametophyte. The female gametophytes grow to produce two or more
archegonia
, each of which contains an egg. Upon fertilization, the
diploid
egg will give rise to the embryo, and a seed is produced. The female cone then opens, releasing the seeds which grow to a young
seedling
.
- To fertilize the ovum, the male cone releases
pollen
that is carried in the wind to the female cone. This is
pollination
. (Male and female cones usually occur on the same plant.)
- The pollen fertilizes the female gamete (located in the female cone). Fertilization in some species does not occur until 15 months after pollination.
[23]
- A fertilized female gamete (called a
zygote
) develops into an
embryo
.
- A
seed
develops which contains the embryo. The seed also contains the integument cells surrounding the embryo. This is an evolutionary characteristic of the
Spermatophyta
.
- Mature seed drops out of cone onto the ground.
- Seed germinates and seedling grows into a mature plant.
- When the plant is mature, it produces cones and the cycle continues.
Female reproductive cycles
[
edit
]
Conifer reproduction is synchronous with seasonal changes in temperate zones. Reproductive development slows to a halt during each winter season and then resumes each spring. The male
strobilus
development is completed in a single year. Conifers are classified by three reproductive cycles that refer to the completion of female strobilus development from initiation to seed maturation. All three types of reproductive cycle have a long gap between
pollination
and
fertilization
.
One year reproductive cycle
: The genera include
Abies
,
Picea
,
Cedrus
,
Pseudotsuga
,
Tsuga
,
Keteleeria
(
Pinaceae
)
and
Cupressus
,
Thuja
,
Cryptomeria
,
Cunninghamia
and
Sequoia
(
Cupressaceae
)
. Female strobili are initiated in late summer or fall of a year, then they overwinter. Female strobili emerge followed by pollination in the following spring. Fertilization takes place in summer of the following year, only 3?4 months after pollination. Cones mature and seeds are then shed by the end of that same year. Pollination and fertilization occur in a single growing season.
[24]
Two-year reproductive cycle
: The genera includes
Widdringtonia
,
Sequoiadendron
(
Cupressaceae
) and most species of
Pinus
. Female
strobilus
initials are formed in late summer or fall then overwinter. Female strobili emerge and receive pollen in the first year spring and become conelets. The conelet goes through another winter rest and, in the spring of the second year
archegonia
form in the conelet. Fertilization of the archegonia occurs by early summer of the second year, so the pollination-fertilization interval exceeds a year. After fertilization, the conelet is considered an immature cone. Maturation occurs by autumn of the second year, at which time seeds are shed. In summary, the one-year and the two-year cycles differ mainly in the duration of the pollination-fertilization interval.
[24]
Three-year reproductive cycle
: Three of the conifer species are
pine
species (
Pinus pinea
,
Pinus leiophylla
,
Pinus torreyana
) which have pollination and fertilization events separated by a two-year interval. Female strobili initiated during late summer or autumn of a year, then overwinter until the following spring. Female
strobili
emerge then pollination occurs in spring of the second year then the pollinated strobili become conelets in the same year (i.e. the second year). The female
gametophytes
in the conelet develop so slowly that the
megaspore
does not go through free-nuclear divisions until autumn of the third year. The conelet then overwinters again in the free-nuclear female gametophyte stage. Fertilization takes place by early summer of the fourth year and seeds mature in the cones by autumn of the fourth year.
[24]
Tree development
[
edit
]
The growth and form of a forest tree are the result of activity in the primary and secondary
meristems
, influenced by the distribution of photosynthate from its needles and the hormonal gradients controlled by the apical meristems.
[25]
External factors also influence growth and form.
Fraser recorded the development of a single white spruce tree from 1926 to 1961. Apical growth of the stem was slow from 1926 through 1936 when the tree was competing with
herbs
and
shrubs
and probably shaded by larger trees. Lateral branches began to show reduced growth and some were no longer in evidence on the 36-year-old tree. Apical growth totaling about 340 m, 370 m, 420 m, 450 m, 500 m, 600 m, and 600 m was made by the tree in the years 1955 through 1961, respectively. The total number of needles of all ages present on the 36-year-old tree in 1961 was 5.25 million weighing 14.25 kg. In 1961, needles as old as 13 years remained on the tree. The ash weight of needles increased progressively with age from about 4% in first-year needles in 1961 to about 8% in needles 10 years old. In discussing the data obtained from the one 11 m tall white spruce, Fraser et al. (1964)
[25]
speculated that if the photosynthate used in making apical growth in 1961 was manufactured the previous year, then the 4 million needles that were produced up to 1960 manufactured food for about 600,000 mm of apical growth or 730 g dry weight, over 12 million mm
3
of wood for the 1961 annual ring, plus 1 million new needles, in addition to new tissue in branches, bark, and roots in 1960. Added to this would be the photosynthate to produce energy to sustain respiration over this period, an amount estimated to be about 10% of the total annual photosynthate production of a young healthy tree. On this basis, one needle produced food for about 0.19 mg dry weight of apical growth, 3 mm
3
wood, one-quarter of a new needle, plus an unknown amount of branch wood, bark and roots.
The order of priority of photosynthate distribution is probably: first to apical growth and new needle formation, then to buds for the next year's growth, with the cambium in the older parts of the branches receiving sustenance last. In the white spruce studied by Fraser et al. (1964),
[25]
the needles constituted 17.5% of the over-day weight. Undoubtedly, the proportions change with time.
Seed-dispersal mechanism
[
edit
]
Wind and animal dispersals are two major mechanisms involved in the dispersal of conifer seeds. Wind-born seed dispersal involves two processes, namely; local neighborhood dispersal and long-distance dispersal. Long-distance dispersal distances range from 11.9?33.7 kilometres (7.4?20.9 mi) from the source.
[26]
Birds of the crow family,
Corvidae
, are the primary distributor of the conifer seeds. These birds are known to
cache
32,000 pine seeds and transport the seeds as far as 12?22 km (7.5?13.7 mi) from the source. The birds store the seeds in the soil at depths of
2?3 cm (
3
⁄
4
?
1
+
1
⁄
4
in) under conditions which favor
germination
.
[27]
Distribution and habitat
[
edit
]
Conifers are the dominant plants over large areas of land, most notably the
taiga
of the
Northern Hemisphere
,
[1]
but also in similar cool climates in mountains further south.
Ecology
[
edit
]
As an invasive species
[
edit
]
A number of conifers originally introduced for forestry have become
invasive species
in parts of
New Zealand
, including radiata pine (
Pinus radiata
), lodgepole pine (
P. contorta
),
Douglas fir
(
Pseudotsuga mensiezii
) and European larch (
Larix decidua
).
[28]
In parts of
South Africa
, maritime pine (
Pinus pinaster
), patula pine (
P. patula
) and radiata pine have been declared invasive species.
[29]
These
wilding conifers
are a serious environmental issue causing problems for pastoral farming and for
conservation
.
[28]
Radiata pine was introduced to Australia in the 1870s. It is "the dominant tree species in the Australian plantation estate"
[30]
? so much so that many Australians are concerned by the resulting loss of native wildlife habitat. The species is widely regarded as an environmental weed across southeastern and southwestern Australia
[31]
and the removal of individual plants beyond plantations is encouraged.
[32]
Predators
[
edit
]
At least 20 species of roundheaded borers of the family
Cerambycidae
feed on the wood of
spruce
,
fir
, and
hemlock
(Rose and Lindquist 1985).
[33]
Borers rarely bore tunnels in living trees, although when populations are high, adult beetles feed on tender twig bark, and may damage young living trees. One of the most common and widely distributed borer species in North America is the
whitespotted sawyer
(
Monochamus scutellatus
). Adults are found in summer on newly fallen or recently felled trees chewing tiny slits in the bark in which they lay eggs. The eggs hatch in about two weeks and the tiny
larvae
tunnel to the wood and score its surface with their feeding channels. With the onset of cooler weather, they bore into the wood, making oval entrance holes and tunnelling deeply. Feeding continues the following summer when larvae occasionally return to the surface of the wood and extend the feeding channels generally in a U-shaped configuration. During this time, small piles of frass extruded by the larvae accumulate under logs. Early in the spring of the second year following egg-laying, the larvae, about 30 mm long,
pupate
in the tunnel enlargement just below the wood surface. The resulting adults chew their way out in early summer, leaving round exit holes, so completing the usual 2-year life cycle.
Cultivation
[
edit
]
Conifers ? notably
Abies
(fir),
Cedrus
,
Chamaecyparis lawsoniana
(Lawson's cypress),
Cupressus
(cypress),
juniper
,
Picea
(spruce),
Pinus
(pine),
Taxus
(yew),
Thuja
(cedar) ? have been the subject of selection for ornamental purposes. Plants with unusual growth habits, sizes, and colours are propagated and planted in parks and gardens throughout the world.
[34]
Conditions for growth
[
edit
]
Conifers
can absorb nitrogen
in either the
ammonium
(NH
4
+
) or
nitrate
(NO
3
?
) form, but the forms are not physiologically equivalent. Form of nitrogen affected both the total amount and relative composition of the soluble nitrogen in white spruce tissues (Durzan and Steward).
[35]
Ammonium nitrogen was shown to foster
arginine
and
amides
and lead to a large increase of free
guanidine
compounds, whereas in leaves nourished by nitrate as the sole source of nitrogen guanidine compounds were less prominent. Durzan and Steward noted that their results, drawn from determinations made in late summer, did not rule out the occurrence of different interim responses at other times of the year. Ammonium nitrogen produced significantly heavier (dry weight) seedlings with a higher nitrogen content after 5 weeks
[36]
than did the same amount of nitrate nitrogen. Swan
[37]
found the same effect in 105-day-old white spruce.
The general short-term effect of nitrogen fertilization on coniferous seedlings is to stimulate shoot growth more so than root growth (Armson and Carman 1961).
[38]
Over a longer period, root growth is also stimulated. Many
nursery
managers were long reluctant to apply nitrogenous
fertilizers
late in the growing season, for fear of increased danger of frost damage to succulent tissues. A presentation at the North American Forest Tree Nursery Soils Workshop at Syracuse in 1980 provided strong contrary evidence: Bob Eastman, President of the Western Maine Forest Nursery Co. stated that for 15 years he has been successful in avoiding winter “burn” to
Norway spruce
and white spruce in his nursery operation by fertilizing with 50?80 lb/ac (56?90 kg/ha) nitrogen in September, whereas previously winter burn had been experienced annually, often severely. Eastman also stated that the overwintering storage capacity of stock thus treated was much improved (Eastman 1980).
[39]
The concentrations of nutrients in plant tissues depend on many factors, including growing conditions. Interpretation of concentrations determined by analysis is easy only when a nutrient occurs in excessively low or occasionally excessively high concentration. Values are influenced by environmental factors and interactions among the 16 nutrient elements known to be essential to plants, 13 of which are obtained from the soil, including
nitrogen
,
phosphorus
,
potassium
,
calcium
,
magnesium
, and
sulfur
, all used in relatively large amounts.
[40]
Nutrient concentrations in conifers also vary with season, age, and kind of tissue sampled, and analytical technique. The ranges of concentrations occurring in well-grown plants provide a useful guide by which to assess the adequacy of particular nutrients, and the ratios among the major nutrients are helpful guides to nutritional imbalances.
Economic importance
[
edit
]
The
softwood
derived from conifers is of great economic value, providing about 45% of the world's annual lumber production. Other uses of the timber include the
production of paper
[41]
and plastic from chemically treated wood pulp. Some conifers also provide foods such as
pine nuts
and
juniper berries
, the latter used to flavor
gin
.
References
[
edit
]
- ^
a
b
c
d
Campbell, Reece, "Phylum Coniferophyta".
Biology
. 7th ed. 2005. Print. p. 595.
- ^
Derived from papers by A. Farjon and C. J. Quinn & R. A. Price in the Proceedings of the Fourth International Conifer Conference,
Acta Horticulturae
615 (2003)
- ^
"Pinidae (conifers) description ? The Gymnosperm Database"
. Archived from
the original
on 20 February 2016.
- ^
Judd, W.S; Campbell, C.S.; Kellogg, E.A.; Stevens, P.F.; Donoghue, M.J. (2002).
Plant systematics, a phylogenetic approach
(2nd ed.). Sunderland, Massachusetts: Sinauer Associates.
ISBN
0-87893-403-0
.
- ^
Lott, John N. A; Liu, Jessica C; Pennell, Kelly A; Lesage, Aude; West, M Marcia (2002). "Iron-rich particles and globoids in embryos of seeds from phyla Coniferophyta, Cycadophyta, Gnetophyta, and Ginkgophyta: characteristics of early seed plants".
Canadian Journal of Botany
.
80
(9): 954?961.
doi
:
10.1139/b02-083
.
- ^
Christenhusz, MJM; Reveal, J; Farjon, A; Gardner, MF; Mill, RR; Chase, MW (2011). "A new classification and linear sequence of extant gymnosperms".
Phytotaxa
.
19
: 55?70.
doi
:
10.11646/phytotaxa.19.1.3
.
- ^
Rothwell, G.W; Grauvogel-Stamm, Lea; Mapes, Gene (February 2000).
"An herbaceous fossil conifer: Gymnospermous ruderals in the evolution of Mesozoic vegetation"
.
Palaeogeography, Palaeoclimatology, Palaeoecology
.
- ^
Stull, Gregory W.; Qu, Xiao-Jian; Parins-Fukuchi, Caroline; Yang, Ying-Ying; Yang, Jun-Bo; Yang, Zhi-Yun; Hu, Yi; Ma, Hong; Soltis, Pamela S.; Soltis, Douglas E.; Li, De-Zhu (August 2021).
"Gene duplications and phylogenomic conflict underlie major pulses of phenotypic evolution in gymnosperms"
.
Nature Plants
.
7
(8): 1015?1025.
doi
:
10.1038/s41477-021-00964-4
.
ISSN
2055-0278
.
PMID
34282286
.
S2CID
236141481
.
Archived
from the original on 10 January 2022
. Retrieved
10 January
2022
.
- ^
Ran, Jin-Hua; Shen, Ting-Ting; Wang, Ming-Ming; Wang, Xiao-Quan (2018).
"Phylogenomics resolves the deep phylogeny of seed plants and indicates partial convergent or homoplastic evolution between Gnetales and angiosperms"
.
Proceedings of the Royal Society B: Biological Sciences
.
285
(1881): 20181012.
doi
:
10.1098/rspb.2018.1012
.
PMC
6030518
.
PMID
29925623
.
- ^
Farjon, Aljos (26 March 2018).
"The Kew Review: Conifers of the World"
.
Kew Bulletin
.
73
(1): 8.
Bibcode
:
2018KewBu..73....8F
.
doi
:
10.1007/s12225-018-9738-5
.
ISSN
1874-933X
.
S2CID
10045023
.
- ^
Feng, Zhuo (September 2017).
"Late Palaeozoic plants"
.
Current Biology
.
27
(17): R905?R909.
Bibcode
:
2017CBio...27.R905F
.
doi
:
10.1016/j.cub.2017.07.041
.
ISSN
0960-9822
.
PMID
28898663
.
- ^
Nowak, Hendrik; Schneebeli-Hermann, Elke; Kustatscher, Evelyn (23 January 2019).
"No mass extinction for land plants at the Permian?Triassic transition"
.
Nature Communications
.
10
(1): 384.
Bibcode
:
2019NatCo..10..384N
.
doi
:
10.1038/s41467-018-07945-w
.
ISSN
2041-1723
.
PMC
6344494
.
PMID
30674875
.
- ^
Leslie, Andrew B.; Beaulieu, Jeremy; Holman, Garth; Campbell, Christopher S.; Mei, Wenbin; Raubeson, Linda R.; Mathews, Sarah (September 2018).
"An overview of extant conifer evolution from the perspective of the fossil record"
.
American Journal of Botany
.
105
(9): 1531?1544.
doi
:
10.1002/ajb2.1143
.
PMID
30157290
.
- ^
Condamine, Fabien L.; Silvestro, Daniele; Koppelhus, Eva B.; Antonelli, Alexandre (17 November 2020).
"The rise of angiosperms pushed conifers to decline during global cooling"
.
Proceedings of the National Academy of Sciences
.
117
(46): 28867?28875.
Bibcode
:
2020PNAS..11728867C
.
doi
:
10.1073/pnas.2005571117
.
ISSN
0027-8424
.
PMC
7682372
.
PMID
33139543
.
- ^
Enright, Neal J; Hill, Robert S (1990).
Ecology of the southern conifers
. Washington, DC: Smithsonian.
- ^
"STATE FOREST OF THE WATTS RIVER"
.
Age
. 22 February 1872
. Retrieved
6 April
2024
.
- ^
Shenkin, Alexander; Chandler, Chris J.; Boyd, Doreen S.; Jackson, Toby; Disney, Mathias; Majalap, Noreen; Nilus, Reuben; Foody, Giles; bin Jami, Jamiluddin; Reynolds, Glen; Wilkes, Phil; Cutler, Mark E. J.; van der Heijden, Geertje M. F.; Burslem, David F. R. P.; Coomes, David A. (2019).
"The World's Tallest Tropical Tree in Three Dimensions"
.
Frontiers in Forests and Global Change
.
2
: 32.
Bibcode
:
2019FrFGC...2...32S
.
doi
:
10.3389/ffgc.2019.00032
.
hdl
:
2164/12435
.
ISSN
2624-893X
.
- ^
"100 metres and growing: Australia's tallest tree leaves all others in the shade"
.
ABC News
. 11 December 2018
. Retrieved
6 April
2024
.
- ^
Vidakovic, Mirko (1991).
Conifers: morphology and variation
(in Croatian). Translated by Soljan, Maja. Croatia: Graficki Zavod Hrvatske.
- ^
Wassilieff, Maggy.
"Conifers"
. Te Ara ? the Encyclopedia of New Zealand updated 1-Mar-09.
Archived
from the original on 1 March 2010
. Retrieved
17 December
2012
.
- ^
Dallimore, W; Jackson, AB; Harrison, SG (1967).
A handbook of Coniferae and Ginkgoaceae
(4th ed.). New York: St. Martin's Press. p. xix.
- ^
Ledig, F. Thomas; Porterfield, Richard L. (1982). "Tree Improvement in Western Conifers: Economic Aspects".
Journal of Forestry
.
80
(10): 653?657.
doi
:
10.1093/jof/80.10.653
.
OSTI
5675533
.
S2CID
150405447
.
- ^
"Gymnosperms"
. Archived from
the original
on 27 May 2015
. Retrieved
11 May
2014
.
- ^
a
b
c
Singh, H (1978).
Embryology of gymnosperms
. Berlin: Gebruder Borntraeger.
- ^
a
b
c
Fraser, DA; Belanger, L; McGuire, D; Zdrazil, Z (1964). "Total growth of the aerial parts of a white spruce tree at Chalk River, Ontario, Canada".
Can. J. Bot
.
42
(2): 159?179.
doi
:
10.1139/b64-017
.
- ^
Williams, CG; LaDeau, SL; Oren, R; Katul, GG (2006). "Modeling seed dispersal distances: implications for transgenic Pinus taeda".
Ecological Applications
.
16
(1): 117?124.
Bibcode
:
2006EcoAp..16..117W
.
doi
:
10.1890/04-1901
.
PMID
16705965
.
- ^
Tomback, D
; Linhart, Y (1990). "The evolution of bird-dispersed pines".
Evolutionary Ecology
.
4
(3): 185?219.
Bibcode
:
1990EvEco...4..185T
.
doi
:
10.1007/BF02214330
.
S2CID
38439470
.
- ^
a
b
"South Island wilding conifer strategy"
.
Department of Conservation (New Zealand)
. 2001. Archived from
the original
on 14 August 2011
. Retrieved
19 April
2009
.
- ^
Moran, V. C.; Hoffmann, J. H.; Donnelly, D.; van Wilgen, B. W.; Zimmermann, H. G. (4?14 July 1999). Spencer, Neal R. (ed.).
Biological Control of Alien, Invasive Pine Trees (Pinus species) in South Africa
(PDF)
.
The X International Symposium on Biological Control of Weeds
. Montana State University, Bozeman, Montana, USA. pp. 941?953.
Archived
(PDF)
from the original on 6 October 2016
. Retrieved
28 June
2016
.
- ^
"Fauna conservation in Australian plantation forests: a review"
Archived
2017-08-08 at the
Wayback Machine
, May 2007, D.B. Lindenmayer and R.J. Hobbs
- ^
"Pinus radiata"
.
Weeds of Australia
. keyserver.lucidcentral.org. 2016.
Archived
from the original on 19 June 2017
. Retrieved
22 August
2018
.
- ^
"Blue Mountains City Council ? Fact Sheets [Retrieved 1 August 2015]"
. Archived from
the original
on 24 June 2015
. Retrieved
22 August
2018
.
- ^
Rose, A.H.; Lindquist, O.H. 1985. Insects of eastern spruces, fir and, hemlock, revised edition. Gov’t Can., Can. For. Serv., Ottawa, For. Tech. Rep. 23. 159 p. (cited in Coates et al. 1994, cited orig ed 1977)
- ^
Farjon, Aljos (2010).
A handbook of the world's conifers
. Brill Academic Publishers.
ISBN
978-9004177185
.
- ^
Durzan, DJ; Steward, FC (1967). "The nitrogen metabolism of
Picea glauca
(Moench) Voss and
Pinus banksiana
Lamb. as influenced by mineral nutrition".
Can. J. Bot
.
45
(5): 695?710.
doi
:
10.1139/b67-077
.
- ^
McFee, WW; Stone, EL (1968). "Ammonium and nitrate as nitrogen sources for
Pinus radiata
and
Picea glauca
".
Soil Sci. Soc. Amer. Proc
.
32
(6): 879?884.
Bibcode
:
1968SSASJ..32..879M
.
doi
:
10.2136/sssaj1968.03615995003200060045x
.
- ^
Swan, HSD (1960). The mineral nutrition of Canadian pulpwood species. 1. The influence of nitrogen, phosphorus, potassium, and magnesium deficiencies on the growth and development of white spruce, black spruce, jack pine, and western hemlock seedlings grown in a controlled environment (Report). Woodlands Res. Index Number 116. Montreal QC: Pulp Paper Res. Instit. Can. Tech. Rep. 168.
- ^
Armson, KA; Carman, RD (1961).
Forest tree nursery soil management
. Ottawa ON: Ont. Dep. Lands & Forests, Timber Branch.
- ^
Eastman, B (28 July ? 1 August 1980). "The Western Maine Forest Nursery Company".
Proc. of the North American Forest Tree Nursery Soils Workshop
. Syracuse, New York: Environment Canada, Canadian Forestry Service, USDA For. Serv. pp. 291?295.
{{
cite conference
}}
: CS1 maint: date and year (
link
)
- ^
Buckman, HO; Brady, NC (1969).
The Nature and Properties of Soils
(7th ed.). New York: Macmillan.
- ^
"Coniferous Wood - an overview"
.
ScienceDirect
. Retrieved
12 March
2024
.
- ^
This depends on the placement of
Gnetophytes
, which have been traditionally excluded from the conifers, though recent molecular evidence suggest gnetophytes are the sister to the Pinaceae. See text for details.
Bibliography
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edit
]
External links
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]
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