Editing Pinus pinaster (section)

=== Invasiveness ===

==== Results of invasion ====
''Pinus pinaster'' is a successful [[invasive species]] in South Africa. One of the results of its invasion in South Africa is a decrease in the [[biodiversity]] of the native environment.{{sfnp|Moran|Hoffmann|Donnelly|van Wilgen|2000}} The increase of [[extinction]] rates of the native species is correlated with the introduction of these species to South Africa. Invasive species occupy [[habitats]] of native species often forcing them to extinction or endangerment. For example, invasive species have the potential to decrease the diversity of native plants by 50–86% in the [[Cape Peninsula]] of South Africa.<ref name="Higgins">{{cite journal |last=Higgins |first=S |title=Predicting the Landscape-Scale Distribution of Alien Plants and Their Threat to Plant Diversity |journal=Conservation Biology |year=1999 |volume=13 |issue=2 |pages=303–313 |doi=10.1046/j.1523-1739.1999.013002303.x |bibcode=1999ConBi..13..303H |trans-title=Conservation Biology}}</ref> ''P.&nbsp;pinaster'' is found in shrubland in South Africa; when compared to other [[Biophysical environment|environments]], shrublands have the largest decline of species richness when invaded by an invasive species (Z=–1.33, p<0.001).<ref name="Gaertner">{{cite book |last=Gaertner |first=M |title=Impacts of alien plant invasions on species richness in Mediterranean-type ecosystems: a meta-analysis |year=2009 |edition=33rd |pages=319–338 |trans-title=Progress in Physical Geography}}</ref> Compared to [[graminoids]]; trees, annual [[herbs]], and creepers have a larger effect on decline of [[species richness]] (Z=–3.78; p<0.001).<ref name="Gaertner" /> Lastly, compared to other countries, South Africa had the largest species richness decline when faced with invasive species.<ref name="Gaertner" />  South Africa is not home to many insects and diseases that limit the population of ''P.&nbsp;pinaster'' back in its native habitat.{{sfnp|Moran|Hoffmann|Donnelly|van Wilgen|2000}} Not only is there evidence that alien plant invasions decrease biodiversity, but there is also evidence that the location of ''P.&nbsp;pinaster'' increases its negative effect on the species richness.

In addition, depending on the regions ''P. pinaster'' invades, ''P.&nbsp;pinaster'' has the potential to dramatically alter the quantity of water in the environment. If ''P.&nbsp;pinaster'' invades an area covered with grasses and shrubs, the water level of the streams in this area would lower significantly because ''P. pinaster'' are [[evergreen trees]] that take up considerably more water than grasses and shrubs all year around.<ref name="Carbon">{{cite journal |last=Carbon |first=B.A. |year=1982 |title=Deep drainage and water use of forests and pastures grown on deep sands in a Mediterranean environment |trans-title=Journal of Hydrology |journal=Journal of Hydrology |volume=55 |issue=1 |pages=53–63 |bibcode=1982JHyd...55...53C |doi=10.1016/0022-1694(82)90120-2}}</ref> They deplete [[Surface run off|run-off]] in [[Drainage basin|catchment areas]] and water flow in rivers. This depletes the resources available for other species in the environment. ''P.&nbsp;pinaster'' tends to grow rapidly in [[riparian zones]], which are areas with abundant water where trees and plants grow twice as fast and invade. ''P.&nbsp;pinaster'' takes advantage of the water available and consequently reduces the amount of water in the area available for other species.<ref name="Carbon" /> The fynbos catchments on the [[Western Cape]] of South Africa are a habitat negatively affected by ''P.&nbsp;pinaster''. Twenty-three years after planting the pines, there was a 55% decrease in streamflow in this area.{{sfnp|Moran|Hoffmann|Donnelly|van Wilgen|2000}} Similarly, in [[KwaZulu-Natal]] Drakensberg there was an 82% reduction in streamflow 20 years after introducing ''P. pinaster'' to the area. In the [[Mpumalanga Province]], 6 streams completely dried up 12 years after [[grasslands]] were replaced with pines. To reinforce that, there is a negative effect from the invasive species ''P.&nbsp;pinaster'', these areas of dense ''P.&nbsp;pinaster'' were thinned and the number of trees in the area decreased. As a result, the [[streamflow]] in the fynbos catchments of the Western Cape increased by 44%. The streamflow in the Mpumalanga Province increased by 120%.{{sfnp|Moran|Hoffmann|Donnelly|van Wilgen|2000}}  As a result of ''P.&nbsp;pinaster'' growth, there is often less understory vegetation for livestock grazing. Once again there was a positive effect when some of the pines were removed and agreeable range grasses were planted. The grazing conditions for the sheep of the area were greatly improved when the ''P.&nbsp;pinaster'' plantation was thinned to 300 trees per hectare. The invasion of ''P.&nbsp;pinaster'' leads to the decrease of [[understory]] vegetation and therefore a decrease in [[livestock]].<ref name="Papanastasis">{{cite book |last=Papanastasis |first=V. |title=Effects of thinning, fertilisation and sheep grazing on the understory vegetarion of ''Pinus pinaster'' plantations |year=1995 |pages=181–189 |trans-title=School of Forestry and Natural Environment}}</ref>

It is sporadically naturalizing in Oakland and San Leandro in northern California.

==== Ecological interactions ====
[[Image:Pinus pinaster JPG2.jpg|thumb|right|Bark of ''P. pinaster''.|upright=1.11]]
''Pinus pinaster'' is particularly successful in regions with fynbos vegetation because it is adapted to high-intensity fires, thus allowing it to outcompete other species that are not as well adapted to high-intensity fires. In areas of fire-prone shrubland, the cones of ''P.&nbsp;pinaster'' will release seeds when in a relatively high-temperature environment for [[germination]] as a recovery mechanism. This adaptation increases the competitive ability of ''P.&nbsp;pinaster'' amongst other species in the fire-prone shrubland.<ref name="Richardson" />  In a 3-year observational study done in [[Spain|Northwestern Spain]], ''P.&nbsp;pinaster'' showed a naturally high [[Regeneration (biology)|regeneration]] rate.<ref name="Calvo">{{cite journal |last=Calvo |first=L |title=Post-fire natural regeneration of a ''Pinus pinaster'' forest in NW Spain |journal=Plant Ecology |year=2008 |volume=197 |issue=1 |pages=81–90 |doi=10.1007/s11258-007-9362-1 |bibcode=2008PlEco.197...81C |hdl=10612/3917 |trans-title=Plant Ecology|hdl-access=free }}</ref> Observations showed a mean of 25.25 seedlings per square metre within the first year and then slowly decreased the next two years due to [[intraspecific competition]].<ref name="Calvo" />  So not only does ''P.&nbsp;pinaster'' compete with other species, they also compete within their own species as well. When the height of ''P.&nbsp;pinaster'' increased there was a negative correlation with the number of ''P.&nbsp;pinaster'' [[seedlings]], results showed a decrease in ''P.&nbsp;pinaster'' seedlings (r=–0.41, p<0.05).<ref name="Calvo" />

Several other characteristics contribute to their success in the regions they have invaded, including their ability to grow rapidly and to produce small seeds with large [[Conifer cone|wings]]. Their ability to grow quickly with short juvenile periods allows them to [[Competition (biology)|outcompete]] many native species while their small seeds aids in their dispersal. The small seeds with large wings are beneficial for wind dispersal, which is the key to reaching new areas in regions with fynbos vegetation.<ref name="Richardson" /> [[Vertebrate]] seed dispersers are not commonly found in mountain fynbos vegetation; therefore those species that require the aid of vertebrate dispersal would be at a disadvantage in such an environment. For this reason, the small seed, low seed wing loading, and high winds found in mountainous regions all combine to provide a favorable situation for the dispersal of ''P.&nbsp;pinaster'' seeds.<ref name="Richardson" />  Without this efficient dispersal strategy, ''P.&nbsp;pinaster'' would not have been able to reach and invade areas, such as South Africa, that are suitable for its growth. Its dispersal ability is one of the key factors that have allowed ''P. pinaster'' to become such a successful invasive species.<ref name="Richardson" />

In addition to being an efficient disperser, ''P.&nbsp;pinaster'' is known to produce [[Resins|oleoresins]], such as oily [[terpenes]] or [[fatty acids]], which can inhibit other species within the community from growing.<ref name="Santalla">{{cite journal |last=Calvo |first=L |title=Regeneration after wildfire in communities dominated by ''Pinus pinaster'', an obligate seeder, and in others dominated by ''Quercus pyrenaica'', typical resprouter |journal=Forest Ecology and Management |year=2003 |volume=184 |issue=1 |pages=209–223 |doi=10.1016/S0378-1127(03)00207-X |bibcode=2003ForEM.184..209C |trans-title=Forest Ecology and Management}}</ref> These resins are produced as a defense mechanism against [[insect]] predators, such as the large [[pine weevil]]. According to an experiment done in [[Spain]], the [[resin canal]] density was twice as high in the ''P.&nbsp;pinaster'' seedlings attacked by the weevils compared to the unattacked seedlings. Since ''P.&nbsp;pinaster'' has the ability to regulate their production of defense mechanisms, it can protect itself from predatory in an energy-efficient manner. The resins make the ''P.&nbsp;pinaster'' less vulnerable to damage from insects, but they are only produced in high concentrations when ''P.&nbsp;pinaster'' is under attack. In other words, ''P.&nbsp;pinaster'' does not waste energy producing resins in safe conditions, so the conserved energy can be used for growth or reproduction. These characteristics enhance the ability of ''P.&nbsp;pinaster'' survive and flourish in the areas it invades.<ref name="Krebs">{{cite book |last=Krebs |first=C |title=Ecology |year=2009 |trans-title=Pearson}}</ref> Both the traits of ''P.&nbsp;pinaster'' and the habitat in South Africa are conducive to the success of ''P. pinaster'' in this region of the world.

==== Options for biological control ====
[[Insects]] and [[mites]] that feed on the seeds and cones of ''P.&nbsp;pinaster'' can be effective [[biological control]] options. An insect or mite that acts as an ideal biological control should have a high [[Total fertility rate|reproductive rate]] and be [[Host (biology)|host-specific]], meaning that it preys specifically on ''P.&nbsp;pinaster''. The [[Biological life cycle|life cycle]] of the predator should also match that of its specific host. Two key characteristics the predator should also exhibit are [[Self-limiting (biology)|self-limitation]] and the ability to survive in the presence of a declining prey population.<ref name="Krebs" />  Seed feeding insects are an effective control because they have high reproductive rates and target the seeds without diminishing the positive effect of the plant on the environment. Controlling the spread of ''P.&nbsp;pinaster'' seeds in the region is the key to limiting the growth and spread of this species because ''P. pinaster'' has the ability to produce a large number of seeds that are capable of dispersing very efficiently.{{sfnp|Moran|Hoffmann|Donnelly|van Wilgen|2000}}  One possible option is Trisetacus, an [[Eriophyidae|eriophyid]] mite. The main advantage to using this mite to control the population of ''P.&nbsp;Pinaster'' is its specificity to ''P. pinaster''; it can effectively control the population of ''P.&nbsp;pinaster'' by destroying the growing conelets in ''P.&nbsp;pinaster'' while limiting its impact to only this species. Another possible option is [[Pissodes|''Pissodes validirostris'']], a cone-feeding weevil that lays eggs in developing cones. When the [[larvae]] hatch, they feed on the growing seed tissue, preventing ''P.&nbsp;pinaster'' seeds from forming and dispersing. Although the adults feed on the trees as well, they do not do any damage to the seeds and only feed on the shoots of the tree, so they do not appear to negatively impact the growth of the trees. Different forms of ''P.&nbsp;validirostris'' have diverged to become host-specific to different pine trees. The type of ''P.&nbsp;validirostris'' that originated from [[Portugal]] appears to have specialized to ''P.&nbsp;pinaster''; therefore, this insect may be used in the future to control the spread of ''P.&nbsp;pinaster'' in South Africa.<ref name="Hoffmann">{{cite book |last=Hoffmann |first=J |title=Prospects for the biological control of invasive ''Pinus'' species (''Pinaceae'') in South Africa |year=2011 |pages=393–401 |trans-title=African Entomology}}</ref> The uncertainties regarding the host-specificity of different types of ''P.&nbsp;validirostris'', however, require more research to be completed before the introduction of the weevils into South Africa. An introduction of a species that is not host-specific to ''P.&nbsp;pinaster'' can lead to detrimental effects on both the environment and [[Industry (economics)|industries]] that are dependent on certain tree species. Two other biological control possibilities include the [[pyralid]] moth species [[Dioryctria|''Dioryctria mendasella'']] and ''D.&nbsp;mitatella'', but these species attack the vegetative [[Tissue (biology)|tissue]] instead of just the seeds of ''P.&nbsp;pinaster'', harming the plant itself.{{sfnp|Moran|Hoffmann|Donnelly|van Wilgen|2000}}  As of now, the eriophyid mite and cone-feeding weevil seem to hold the most potential to controlling the spread of ''P.&nbsp;pinaster'' in the regions it has invaded because they destroy the reproductive structures of the target invasive species.