In the dry Swiss Rhone Valley, Scots pine forests have experienced increased mortality in recent years. It has commonly been assumed that drought events and bark beetles fostered the decline, however, whether bark beetle outbreaks increased in recent years and whether they can be linked to drought stress or increasing temperature has never been studied. In our study, we correlated time series o...

Using historical General Land Office record as a reference, this study employed a landscape-scale disturbance and succession model to estimate the future cumulative effects of six alternative management plans on the tree species composition for various physiographic settings for the Mark Twain National Forest in Missouri. The results indicate that over a 200-year horizon, the relative abundance...

Whitebark pine is an important component of high elevation ecosystems in the western United States and Canada. Many wildlife species, including grizzly and black bears, squirrels, and birds, forage on the large, wingless seed. Whitebark pine relies heavily upon the Clark's nutcracker for seed dispersal and regeneration. Due to fire exclusion, white pine blister rust, and the mountain pine beetl...

The distribution of extractives, lignin, and carbohydrates in radiata pine and their variation with tree age are reviewed. Extractives, their nature, and amount depend on the heartwood content of the tree, and thus upon wood age. Lignin decreases in the pith-to-bark sequence; pentosans content decreases over the first 10-15 growth rings from the pith, after which it is approximately constant. C...

Extensive mortality of whitebark pine, beginning in the early to mid-2000s, occurred in the Greater Yellowstone Ecosystem (GYE) of the western USA, primarily from mountain pine beetle but also from other threats such as white pine blister rust. The climatic drivers of this recent mortality and the potential for future whitebark pine mortality from mountain pine beetle are not well understood, y...

Plant cuticles are covered by epicuticular waxes with considerable ultrastructural and chemical diversity and have great systematic significance. Pinus elderica is a rare pine found naturally only in desert environment southeast of Tbilisi (Georgia). This tree have been probably introduced to Iran about 800 years ago and gradually altered in both shape and size in Nashtifan-Khaf, and changed in...

Loblolly pine (Pinus taeda L.) is the most important commercial tree species in the southeastern United States. Since the 1950s, there have been reports of loblolly pines showing reduced growth and increased mortality, particularly in central Alabama and western Georgia, United States; the phenomenon is termed as southern pine decline (SPD). Recently, the role of rhizophagous (root-feeding) ins...

Phenology has been defined as the study of the timing of recurring biological events, the causes of their timing with regard to abiotic and biotic forces and the interrelation among phases of the same or different event (Reichle 1973, Leith 1974). The role of phenology in forest ecosystems has been discussed for several decades. Today, understanding how tree phenology is quantitatively related ...

A survival model for shortleaf pine (Pinus echinata Mill.) trees growing in uneven-aged stands was developed using data from permanently established plots maintained by an industrial forestry company in western Arkansas. Parameters were fitted to a logistic regression model with a Bernoulli dependent variable in which ‘1” represented individual tree survival and “0” represented individual tree ...

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...