نتایج جستجو برای: pine trees

تعداد نتایج: 104582  

2013
Eero Nikinmaa

The effects after 25 years of moose browsing on Scots pine stands in Lahemaa National Park were evaluated, emphasizing economic damage. A re-evaluation in 2001 examined stands that had been evaluated in 1975–1976. Moose damage significantly affected the tree species composition which changed over time as pine dominance increased and the number of mixed stands declined. The smaller proportion of...

2007
L. H. Lott C. D. Nelson G. A. Snow

A set of 21 loblolly pine families produced by crossing trees from east Texas were tested for resistance to fusiform rust disease. The parents of these families were surviving trees in stands that experienced extensive mortality in the 1960s due to southern pine beetle infestation. Seedlings were grown in tubes in a greenhouse and artificially inoculated with C. quercuum from five different sou...

Journal: :Environmental pollution 2007
J Staszak N E Grulke M J Marrett W Prus-Glowacki

Effects of canopy ozone (O(3)) exposure and signatures of genetic structure using isozyme markers associated with O(3) tolerance were analyzed in approximately 20-, approximately 80-, and >200-yr-old ponderosa (Pinus ponderosa Dougl. ex Laws.) and Jeffrey pine (Pinus jeffreyi Grev. & Balf.) in Sequoia National Park, California. For both species, the number of alleles and genotypes per loci was ...

2005
ANDREW J. EDELMAN JOHN L. KOPROWSKI

Abert’s squirrels (Sciurus aberti) are reported to depend on ponderosa pine (Pinus ponderosa) for food and nest sites. Introduced Abert’s squirrels in the Pinaleño Mountains of Arizona, however, occupy mixed-conifer forests that contain almost no ponderosa pine (about 2%). We examined selection of drey sites in this introduced population. Dreys (i.e., spherical nests) were built adjacent to the...

1999
Erkki Annila Bo Långström Martti Varama Risto Hiukka Pekka Niemelä

In 1990–1991, Diprion pini extensively defoliated Scots pine (Pinus sylvestris L.) trees in Lauhanvuori National Park in southwestern Finland. Many trees lost all their foliage, while others had ca. 10 % foliage left after the second year of defoliation. Outside the national park, many nearby stands were also heavily defoliated in 1990, but were sprayed with diflubenzuron (Dimilin®) in 1991. Th...

Journal: :Journal of nematology 1982
J C Adams A L Morehart

Etiological studies to determine the cause of decline and death of Pinus spp. in Delaware were initiated in 1980. The pinewood nematode, Bursaphelenchus xylophilus, was found to be the major canse of mortality in Japanese black pine (Pinus thunbergii). When inoculated into healthy 5-yr-old Japanese black pines, B. xylophilus produced typical decline symptoms observed in the field. The xylophilo...

2016
Guillermo Guada J. Julio Camarero Raúl Sánchez-Salguero Rafael M. Navarro Cerrillo

Mediterranean pine forests display high resilience after extreme climatic events such as severe droughts. However, recent dry spells causing growth decline and triggering forest dieback challenge the capacity of some forests to recover following major disturbances. To describe how resilient the responses of forests to drought can be, we quantified growth dynamics in plantations of two pine spec...

Effect of fire on phyto-sociology of understorey vegetation in chir pine forests of three different silvological characteristics was compared with pure grassland. 15 grasses, 1 sedge, 5 legumes and 21 non-legumes were recorded in the four study sites. Floristic composition gradually increased from June to August and then declined slowly by October in all the plots. Maximum number of species wa...

2006
S. H. Lee H. K. Cho

Since 1988 pine wilt disease has spread over rapidly in Korea. It is not easy to detect the damaged pine trees by pine wilt disease from conventional remote sensing skills. Thus, many possibilities were investigated to detect the damaged pines using various kinds of remote sensing data including high spatial resolution satellite image of 2000/2003 IKONOS and 2005 QuickBird, aerial photos, and d...

2006
V. C. Baldwin

Prediction equations based on 130 sample trees from thinned and unthinned loblolly pine (Pinus taeda L.) plantations in central Louisiana re presented for the green and dry weights of aboveground tree components. Sample trees ranged from 2 to 21 in. dbh, 18 to 94 ft in height and from 9 to 55 yr in age. Significant differences in partial stem weight between trees from thinned and unthinned stan...

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