Jump to content

Conifer

From Wikipedia, the free encyclopedia
(Redirected fromConiferous tree)
For other uses, seeConifer (disambiguation).

Conifer
Temporal range:307–0MaCarboniferous–Present
Large coniferforestcomposed ofAbies albaatVosges,EasternFrance
Scientific classificationEdit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Gymnospermae
Division: Pinophyta
Class: Pinopsida
Subclasses, orders, and families
Synonyms
  • Coniferophyta
  • Coniferae
  • Pinophytina

Conifersare a group ofcone-bearingseed plants,a subset ofgymnosperms.Scientifically, they make up thedivisionPinophyta(⫽pɪˈnɒfɪtə,ˈpaɪnoʊfaɪtə⫽), also known asConiferophyta(⫽ˌkɒnɪfəˈrɒfɪtə,-oʊfaɪtə⫽) orConiferae.The division contains a single extantclass,Pinopsida.Allextantconifers areperennialwoody plantswithsecondary growth.[a]The great majority aretrees,though a few areshrubs.Examples includecedars,Douglas-firs,cypresses,firs,junipers,kauri,larches,pines,hemlocks,redwoods,spruces,andyews.[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 areecologicallyimportant. They are the dominant plants over large areas of land, most notably thetaigaof theNorthern 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. Whiletropical rainforestshave morebiodiversityand turnover, the immense conifer forests of the world represent the largest terrestrialcarbon sink.Conifers are of great economic value forsoftwoodlumberandpaperproduction.

Names and taxonomy[edit]

A coniferous forest pictured in the coat of arms of theKainuu regioninFinland

Coniferis a Latin word, a compound ofconus(cone) andferre(to bear), meaning "the one that bears (a) cone(s)".

The division name Pinophyta conforms to the rules of theInternational Code of Nomenclature for algae, fungi, and plants(ICN), which state (Article 16.1) that the names of highertaxain 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 casePinaceae(thepinefamily), or are descriptive. A descriptive name in widespread use for the conifers (at whatever rank is chosen) isConiferae(Art 16 Ex 2).

According to the ICN, it is possible to use a name formed by replacing the termination-aceaein the name of an included family, in this case preferablyPinaceae,by the appropriate termination, in the case of this division-ophyta.Alternatively, "descriptive botanical names"may also be used at anyrankabove 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 orConiferales.

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) andPinales(the rest), but recent research intoDNA sequencessuggests that this interpretation leaves the Pinales without Taxales asparaphyletic,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 diversemorphology.

Phylogeny of the Pinophyta based oncladisticanalysis ofmolecular data.[2]

There were seven families of conifersc. 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, theCephalotaxaceaemay be better included within the Taxaceae, and some authors additionally recognizePhyllocladaceaeas distinct from Podocarpaceae (in which it is included here). The familyTaxodiaceaeis 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 afossilrecord extending back about 300 million years to thePaleozoicin the lateCarboniferousperiod; 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 andMesozoiceras. Fossil conifers included many diverse forms, the most dramatically distinct from modern conifers being someherbaceousconifers with no woody stems.[7]Major fossil orders of conifers or conifer-like plants include theCordaitales,Vojnovskyales,Voltzialesand perhaps also theCzekanowskiales(possibly more closely related to theGinkgophyta).

Multiple studies also indicate that theGnetophytabelong within the conifers despite their distinct appearances, either placing them as asister grouptoPinales(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]

The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow.

Phylogeny[edit]

The earliest conifers appear in the fossil record during the LateCarboniferous(Pennsylvanian), over 300 million years ago. Conifers are thought to be most closely related to theCordaitales,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 EarlyPermian(Cisuralian) to lowlands due to increasing aridity. Walchian conifers were gradually replaced by more advancedvoltzialeanor "transition" conifers.[11]Conifers were largely unaffected by thePermian–Triassic extinction event,[12]and were dominant land plants of theMesozoicera. Modern groups of conifers emerged from the Voltziales during the Late Permian throughJurassic.[13]Conifers underwent a major decline in theLate Cretaceouscorresponding to the explosiveadaptive radiationofflowering plants.[14]

Description[edit]

Tāne Mahuta,the biggestkauri(Agathis australis) tree alive, in theWaipoua Forestof the Northland Region ofNew Zealand.

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 strongapical dominance.Many conifers have distinctly scentedresin,secreted to protect the tree againstinsectinfestation andfungalinfection of wounds. Fossilized resin hardens intoamber,which has been commercially exploited historically (for example, in New Zealand's 19th-centurykauri gumindustry).

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 acoast 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 livingangiospermsare significantly smaller at around 100 metres.[17][18]) The thickest (that is, thetree with the greatest trunk diameter) is aMontezuma 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 thepygmy 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]

Pinaceae:needle-like leaves and vegetative buds of Coast Douglas fir (Pseudotsuga menziesiivar.menziesii)
Araucariaceae:awl-like leaves of Cook pine (Araucaria columnaris)
InAbies grandis(grand fir), and many other species with spirally arranged leaves, leaf bases are twisted to flatten their arrangement and maximize light capture.
Cupressaceae:scale leaves ofLawson's cypress(Chamaecyparis lawsoniana); scale in mm

Since most conifers are evergreens,[1]theleavesof many conifers are long, thin and have a needle-like appearance, but others, including most of theCupressaceaeand some of thePodocarpaceae,have flat, triangular scale-like leaves. Some, notablyAgathisin Araucariaceae andNageiain Podocarpaceae, have broad, flat strap-shaped leaves. Others such asAraucaria columnarishave 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 asAbies 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). Thestomataare 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 highlatitudesor under forest canopy shade.

Conifers from hotter areas with high sunlight levels (e.g. Turkish pinePinus brutia) often have yellower-green leaves, while others (e.g.blue spruce,Picea pungens) may develop blue or silvery leaves to reflectultravioletlight. In the great majority of genera the leaves areevergreen,usually remaining on the plant for several (2–40) years before falling, but five genera (Larix,Pseudolarix,Glyptostrobus,MetasequoiaandTaxodium) aredeciduous,shedding their leaves in autumn.[1]The seedlings of many conifers, including most of the Cupressaceae, andPinusin Pinaceae, have a distinct juvenile foliage period where the leaves are different, often markedly so, from the typical adult leaves.

Tree ring structure[edit]

A thin transverse section showing the internal structure of conifer wood

Tree ringsare records of theinfluenceofenvironmentalconditions, their anatomical characteristics record growth rate changes produced by these changing conditions. The microscopicstructureof conifer wood consists of two types ofcells:parenchyma,which have an oval or polyhedral shape with approximately identical dimensions in three directions, and strongly elongated tracheids.Tracheidsmake up more than 90% of timber volume. The tracheids of earlywood formed at the beginning of agrowing seasonhave large radial sizes and smaller, thinnercell 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]

Main article:Conifer cone

Most conifers aremonoecious,but some aresubdioeciousordioecious;all arewind-pollinated.Conifer seeds develop inside a protective cone called astrobilus.The cones take from four months to three years to reach maturity, and vary in size from2 to 600 millimetres (1⁄8to23+5⁄8in) long.

InPinaceae,Araucariaceae,Sciadopityaceaeand mostCupressaceae,the cones arewoody,and when mature the scales usually spread open allowing the seeds to fall out and be dispersed by thewind.In some (e.g.firsandcedars), the cones disintegrate to release the seeds, and in others (e.g. thepinesthat producepine nuts) the nut-like seeds are dispersed bybirds(mainlynutcrackers,andjays), 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 familiesPodocarpaceae,Cephalotaxaceae,Taxaceae,and oneCupressaceaegenus (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 inJuniperus) known asarils.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 calledmicrosporangiathat 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. Thegymnospermmale gametophytes (pollen grains) are carried by wind to a female cone and are drawn into a tiny opening on the ovule called themicropyle.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 resultingzygotedevelops into anembryo,which along with the female gametophyte (nutritional material for the growing embryo) and its surrounding integument, becomes aseed.Eventually, the seed may fall to the ground and, if conditions permit, grow into a new plant.

Inforestry,the terminology offlowering plantshas commonly though inaccurately been applied to cone-bearing trees as well. The male cone and unfertilized female cone are calledmale flowerandfemale flower,respectively. After fertilization, the female cone is termedfruit,which undergoesripening(maturation).

It was found recently that thepollenof conifers transfers themitochondrialorganellesto theembryo,[citation needed]a sort ofmeioticdrive that perhaps explains whyPinusand 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)
    Pinaceae: unopened female cones ofsubalpine fir(Abies lasiocarpa)
  • Taxaceae: the fleshy aril that surrounds each seed in the European yew (Taxus baccata) is a highly modified seed cone scale
    Taxaceae: the fleshy aril that surrounds each seed in theEuropean yew(Taxus baccata) is a highly modified seed cone scale
  • Pinaceae: pollen cone of a Japanese larch (Larix kaempferi)
    Pinaceae: pollen cone of aJapanese larch(Larix kaempferi)

Life cycle[edit]

Conifers areheterosporous,generating two different types of spores: malemicrosporesand femalemegaspores.These spores develop on separate male and femalesporophyllson separate male and female cones. In the male cones, microspores are produced from microsporocytes bymeiosis.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 twohaploidsperm cells bymitosisleading 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 malegametophyte.Three of the four cells break down leaving only a single surviving cell which will develop into a femalemulticellulargametophyte. The female gametophytes grow to produce two or morearchegonia,each of which contains an egg. Upon fertilization, thediploidegg will give rise to the embryo, and a seed is produced. The female cone then opens, releasing the seeds which grow to a youngseedling.

  1. To fertilize the ovum, the male cone releasespollenthat is carried in the wind to the female cone. This ispollination.(Male and female cones usually occur on the same plant.)
  2. The pollen fertilizes the female gamete (located in the female cone). Fertilization in some species does not occur until 15 months after pollination.[23]
  3. A fertilized female gamete (called azygote) develops into anembryo.
  4. Aseeddevelops which contains the embryo. The seed also contains the integument cells surrounding the embryo. This is an evolutionary characteristic of theSpermatophyta.
  5. Mature seed drops out of cone onto the ground.
  6. Seed germinates and seedling grows into a mature plant.
  7. 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 malestrobilusdevelopment 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 betweenpollinationandfertilization.

One year reproductive cycle:The genera includeAbies,Picea,Cedrus,Pseudotsuga,Tsuga,Keteleeria(Pinaceae)andCupressus,Thuja,Cryptomeria,CunninghamiaandSequoia(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 includesWiddringtonia,Sequoiadendron(Cupressaceae) and most species ofPinus.Femalestrobilusinitials 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 yeararchegoniaform 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 arepinespecies (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. Femalestrobiliemerge 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 femalegametophytesin the conelet develop so slowly that themegasporedoes 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 secondarymeristems,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 withherbsandshrubsand 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 mm3of 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 mm3wood, 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 tocache32,000 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 of2–3 cm (3⁄4–1+1⁄4in) under conditions which favorgermination.[27]

Distribution and habitat[edit]

Conifers are the dominant plants over large areas of land, most notably thetaigaof theNorthern Hemisphere,[1]but also in similar cool climates in mountains further south.

Ecology[edit]

As an invasive species[edit]

Main article:Wilding conifer
A Monterey pine forest inSydney,Australia

A number of conifers originally introduced for forestry have becomeinvasive speciesin parts ofNew Zealand,including radiata pine (Pinus radiata), lodgepole pine (P. contorta),Douglas fir(Pseudotsuga mensiezii) and European larch (Larix decidua).[28]

In parts ofSouth Africa,maritime pine (Pinus pinaster), patula pine (P. patula) and radiata pine have been declared invasive species.[29]Thesewilding conifersare a serious environmental issue causing problems for pastoral farming and forconservation.[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 familyCerambycidaefeed on the wood ofspruce,fir,andhemlock(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 thewhitespotted 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 tinylarvaetunnel 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,pupatein 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]

See also:Silviculture
Globosa,acultivarofPinus sylvestris,a northern European species, in the North AmericanRed Butte Garden

Conifers – notablyAbies(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]

Coniferscan absorb nitrogenin either theammonium(NH4+) ornitrate(NO3−) 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 fosterarginineandamidesand lead to a large increase of freeguanidinecompounds, 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. Manynurserymanagers were long reluctant to apply nitrogenousfertilizerslate 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” toNorway spruceand 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, includingnitrogen,phosphorus,potassium,calcium,magnesium,andsulfur,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]

Thesoftwoodderived from conifers is of great economic value, providing about 45% of the world's annual lumber production. Other uses of the timber include theproduction of paper[41]and plastic from chemically treated wood pulp. Some conifers also provide foods such aspine nutsandjuniper berries,the latter used to flavorgin.

References[edit]

  1. ^abcdCampbell, Reece, "Phylum Coniferophyta".Biology.7th ed. 2005. Print. p. 595.
  2. ^Derived from papers by A. Farjon and C. J. Quinn & R. A. Price in the Proceedings of the Fourth International Conifer Conference,Acta Horticulturae615 (2003)
  3. ^"Pinidae (conifers) description – The Gymnosperm Database".Archived fromthe originalon 20 February 2016.
  4. ^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.ISBN0-87893-403-0.
  5. ^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.
  6. ^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.
  7. ^Rothwell, G.W; Grauvogel-Stamm, Léa; Mapes, Gene (February 2000)."An herbaceous fossil conifer: Gymnospermous ruderals in the evolution of Mesozoic vegetation".Palaeogeography, Palaeoclimatology, Palaeoecology.
  8. ^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.ISSN2055-0278.PMID34282286.S2CID236141481.Archivedfrom the original on 10 January 2022.Retrieved10 January2022.
  9. ^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.PMC6030518.PMID29925623.
  10. ^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.ISSN1874-933X.S2CID10045023.
  11. ^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.ISSN0960-9822.PMID28898663.
  12. ^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.ISSN2041-1723.PMC6344494.PMID30674875.
  13. ^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.PMID30157290.
  14. ^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.ISSN0027-8424.PMC7682372.PMID33139543.
  15. ^Enright, Neal J; Hill, Robert S (1990).Ecology of the southern conifers.Washington, DC: Smithsonian.
  16. ^"STATE FOREST OF THE WATTS RIVER".Age.22 February 1872.Retrieved6 April2024.
  17. ^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.ISSN2624-893X.
  18. ^"100 metres and growing: Australia's tallest tree leaves all others in the shade".ABC News.11 December 2018.Retrieved6 April2024.
  19. ^Vidakovic, Mirko (1991).Conifers: morphology and variation(in Croatian). Translated by Soljan, Maja. Croatia: Graficki Zavod Hrvatske.
  20. ^Wassilieff, Maggy."Conifers".Te Ara – the Encyclopedia of New Zealand updated 1-Mar-09.Archivedfrom the original on 1 March 2010.Retrieved17 December2012.
  21. ^Dallimore, W; Jackson, AB; Harrison, SG (1967).A handbook of Coniferae and Ginkgoaceae(4th ed.). New York: St. Martin's Press. p. xix.
  22. ^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.OSTI5675533.S2CID150405447.
  23. ^"Gymnosperms".Archived fromthe originalon 27 May 2015.Retrieved11 May2014.
  24. ^abcSingh, H (1978).Embryology of gymnosperms.Berlin: Gebruder Borntraeger.
  25. ^abcFraser, 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.
  26. ^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.PMID16705965.
  27. ^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.S2CID38439470.
  28. ^ab"South Island wilding conifer strategy".Department of Conservation (New Zealand).2001. Archived fromthe originalon 14 August 2011.Retrieved19 April2009.
  29. ^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.Retrieved28 June2016.
  30. ^"Fauna conservation in Australian plantation forests: a review"Archived2017-08-08 at theWayback Machine,May 2007, D.B. Lindenmayer and R.J. Hobbs
  31. ^"Pinus radiata".Weeds of Australia.keyserver.lucidcentral.org. 2016.Archivedfrom the original on 19 June 2017.Retrieved22 August2018.
  32. ^"Blue Mountains City Council – Fact Sheets [Retrieved 1 August 2015]".Archived fromthe originalon 24 June 2015.Retrieved22 August2018.
  33. ^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)
  34. ^Farjon, Aljos (2010).A handbook of the world's conifers.Brill Academic Publishers.ISBN978-9004177185.
  35. ^Durzan, DJ; Steward, FC (1967). "The nitrogen metabolism ofPicea glauca(Moench) Voss andPinus banksianaLamb. as influenced by mineral nutrition ".Can. J. Bot.45(5): 695–710.doi:10.1139/b67-077.
  36. ^McFee, WW; Stone, EL (1968). "Ammonium and nitrate as nitrogen sources forPinus radiataandPicea glauca".Soil Sci. Soc. Amer. Proc.32(6): 879–884.Bibcode:1968SSASJ..32..879M.doi:10.2136/sssaj1968.03615995003200060045x.
  37. ^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.
  38. ^Armson, KA; Carman, RD (1961).Forest tree nursery soil management.Ottawa ON: Ont. Dep. Lands & Forests, Timber Branch.
  39. ^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.
  40. ^Buckman, HO; Brady, NC (1969).The Nature and Properties of Soils(7th ed.). New York: Macmillan.
  41. ^"Coniferous Wood - an overview".ScienceDirect.Retrieved12 March2024.
  1. ^This depends on the placement ofGnetophytes,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[edit]

External links[edit]

Wikimedia Commons has media related toPinophyta.
Wikispecieshas information related toPinophyta.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Conifer&oldid=1228770365"