Treesearch

Within the context of global warming and accelerated human activities, the surrounding environments of many terrestrial ecosystems worldwide have become increasingly deteriorated, such that finding suitable methods and effective environmental technology to confront climate change and prevent land degradation is critical to the health and sustainability of the earth. In general, vegetation restoration projects, acknowledged as vital eco-engineering measures for various environmental benefits including carbon sequestration, soil conservation, and erosion control, are widely conducted in...

Several tree wardens have recently reported thefts of burls from pubhc trees, especially in park areas. A burl is a tree growth in which the grain has grown in a deformed manner. It commonly occurs on a tree trunk or branch as a rounded outgrowth filled with small knots.

Abiotic and biotic stressors exert selective pressures on plants, and over evolutionary time lead to the development of specialized adaptations and specific responses to stresses (Safranyik and Carroll 2006, Wallin and Raffa 2002). In this way, the environment in which plants evolve shapes their life cycles, range, growth, reproduction, and defenses. Insects and diseases are particularly potent plant stressors. Insect herbivores exert pressure on plants by feeding on plant parts and using them to reproduce by forming galls and cysts. Some insect species carry mutualistic pathogens on their...

The goals of our studies are to describe the natural variation in the concentration of constitutive heartwood extractives; estimate the genetic parameters related to heartwood characteristics; determine whether there is a genetic connection between constitutive and inducible production of stilbenes; and, together with technical experts, to develop fast and reliable techniques to quantify stilbenes from wood samples and determine whether there are rapid ways to utilize the existing variation in silviculture. We are also collaborating with molecular geneticists to find the markers for pine...

Laurel wilt (LW) is a devastating, emerging disease of native and non-native members of the Lauraceae family in the southeastern United States. Currently, the fungal pathogen (Raffaelea lauricola) and its vector (Xyleborus glabratus) are found in Alabama, Florida, Georgia, Mississippi, and North and South Carolina. The wilt is decimating native stands of redbay (Persea borbonia (L.) Spreng.), and causing significant damage to planted and native sassafras (Sassafras albidum (Nutt.) Nees) and avocado (Persea americana Mill.). Research has addressed significant knowledge gaps that exist for...

During the last decades, European poplar breeders learned the hard way that Melampsora larici-populina (commonly abbreviated as Mlp…) has an impressive adaptive potential (McDonald and Linde 2002). This fungal pathogen defeated all the deployed cultivars carrying qualitative (i.e., complete) resistances inherited from the American eastern black cottonwood Populus deltoides Bartram ex Marsh. in less time than needed to grow a poplar tree

Many temperate and boreal forests are subject to insect epidemics. In the eastern US, over 41 million meters squared of tree basal area are thought to be at risk of gypsy moth defoliation. However, the decadal-to-century scale implications of defoliation events for ecosystem carbon dynamics are not well understood. In this study, the effects of defoliation intensity, periodicity and spatial pattern on the carbon cycle are investigated in a set of idealized model simulations. A mechanistic terrestrial biosphere model, ecosystem demography model 2, is driven with observations from a xeric...

Phosphorus is widely deficient throughout the southern pine region of the United States. Growth responses to P fertilization are generally long-lasting in a wide range of soil types, but little is known about fertilization rates and long-term P cycling and availability. In 1982, exceptionally high P fertilization rates (0, 81, 162, and 324 kg P ha-1) were applied to a loamy Ultisol in central Louisiana, USA. We measured vegetation responses at age 27 years and sequentially extracted soil P to 1 m to elucidate potential P availability into the next rotation. Loblolly pine responded well to...

Eastern filbert blight (EFB) is a devastating fungal disease of European hazelnut, Corylus avellana L., and is considered to be the primary reason hazelnuts have not been developed as a commercial crop in the eastern United States. The pathogen, Anisogramma anomala, is native to a wide area east of the Rocky Mountains, where it is harbored by the wild hazelnut C. americana Marshall. While C. americana is tolerant of the disease, EFB causes stem cankers, dieback, and death of C. avellana, the hazelnut of commerce. The absence of EFB, along with a mild climate, allowed for the development of...

Endophytic fungi are generally considered to be plant mutualists that protect the host plant from pathogens and herbivores. Defensive mutualism appears to hold true particularly for seed-transmitted, alkaloid producing, grass endophytes. However, we propose that the mutualistic nature of plant-endophyte interactions via enhanced plant resistance to pathogens and herbivores should be reconsidered when focusing on woody plants.We compared phenotypic and genetic frequency correlations for two endophytic fungal genera (Fusicladium and Melanconium) and birch rust (Melampsoridium betulinum) with...