Spanish black pine populations of the Spanish Central System are unique to peninsular level for being the only ones exclusively developed on siliceous substrates (granitic rocks, gneisses and micaschists) (Genova & Moya, 2012).
As shown by the dendrogram analysis (Figure 2), two main clusters emerged (A and B), corresponding to the segregation of the two main vegetation units compared in this work, where Spanish black pine and Scots pine forests in the Gredos range were separated.
15) clearly separates samples containing Spanish black pine (cluster A1b) from those without (cluster A1a).
It represents orotemperate submediterranean (orosubmediterranean) humid relict Spanish black pine mesoforests growing throughout the central and eastern Gredos Mountains (Figure 1, Table 4).
Cluster B2 represents pure Spanish black pine forests in the lower supramediterranean humid bioclimatic belt of the Gredos range (~900-1450 m asl), southeast oriented on the southern slope and northwest oriented on the northern slope of these mountains.
These communities are mainly located in southeast exposures due to the thermic requirements of Spanish black pine (Figure 1), representing supratemperate submediterranean (suprasubmediterranean) humid relict forests.
Spanish black pine has disappeared from many habitats of the Gredos range, mainly as a result of wildfires, excessive grazing and uncontrolled ploughing (Genova & al.
The worm-like, microscopic nematodes infected the black pines through wounds created by wood-boring insects such as the cerambycid, a long-horned beetle.
Brian Schneeman, an industrious young man working on an Eagle Scout badge, single-handedly raised more than $1,500 and, under the supervision of State Parks staff, purchased and planted 200 trees and shrubs in a five-acre tract previously populated by withered Japanese black pines.
The Japanese black pine (Pinus thunbergiana) also was easily propagated.
As the result of heavy loss of the Japanese black pine in the coastal parks, New York State Parks Commissioner Bernadette Castro in early 1995 ordered a tree replenishment program that uses trees and shrubs native to Long Island.
Although seeds from outside New York are available from commercial sources, DEC nursery director John Solan prefers to use seeds from New York State trees to maintain the genetic strains of the native species and to avoid disastrous events such as the die-off of the Japanese black pine in Long Island.