Treesearch

The existing fire-oak literature is contradictory on whether fire helps or hinders the oak regeneration process. This confusion occurs because the fire-oak studies have been conducted under a wide variety of conditions. In this paper, we review the fire-oak literature by stand age class, season of burn, and number of burns to identify commonalities and trends. Overall, prescribed fire reduces the density of small diameter stems in the midstory, preferentially selects for oak reproduction and against mesophytic hardwood reproduction, equalizes the height growth rates between these two...

We studied the response of tree regeneration to a sequence of several low-intensity prescribed fires followed by canopy gap formation in southern Ohio. Advance reproduction was recorded in 52 gaps (average size = four dead canopy trees) that formed following a white oak decline event, 13 years after fires began and 5 years after the gaps had formed. Of the 52 gaps, 28 were in three burned stands and 24 were in three unburned stands. Unburned gaps were being filled by shade-tolerant saplings and poles. In contrast, shade-tolerant saplings had been greatly reduced in the burned stands and...

Santo Domingo’s Colonial City (Ciudad Colonial in Spanish) was established in 1498 by Christopher Columbus, making it the first European settlement in the New World and the site of the first cathedral, hospital, customs house and university in the Americas. The city was laid out on a grid pattern that became the model for almost all town planners in the New World (UNESCO 2014). It is located along the western bank of the Ozama River and is about one square kilometer in size (see fold-out map).

Delmarva Bays are depressional wetlands that are elliptical in shape with sandy rims, and occur mainly in the central portion of the Delmarva Peninsula within the Mid- Atlantic United States. Situated in a region with abundant agriculture, Delmarva Bays and other wetlands may enhance water quality by reducing nutrient and sediment levels in local waters. A significant portion have been drained and converted from forested wetlands to agriculture. Using LiDAR to locate Bays, we estimate that there are 17,000 Bays on the Delmarva Peninsula, which is an order of magnitude greater than earlier...

Understanding local groundwater hydrology and geochemistry is critical for evaluating the effectiveness of wetlands at mitigating agricultural impacts on surface waters. The effectiveness of depressional wetlands at mitigating nitrate (NO3) transport from fertilized row crops, through groundwater, to local streams was examined in the watershed of the upper Choptank River, a tributary of Chesapeake Bay on the Atlantic Coastal Plain. Hydrologic, geochemical, and water quality data were collected from January of 2008 through December of 2009 from surface waters and networks of piezometers...

Dr. Leopold is correct in that a tree can be planted with only a shovel. However, we all know that if that tree is to survive and thrive in the built environment, it will need much more. Tree growth and longevity depends on so many factors, from management considerations, like proper planting and long-term care and pruning cycles, to environmental factors, like site conditions and species tolerances. If arborists, urban forest managers, and communities are to be successful in stewardship of urban trees, then we need more than a shovel and possibly more than an act of creation from a poet...

Contemporary forest harvesting practices, specifically harvesting woody biomass as a source of bioenergy feedstock, may remove more woody debris from a site than conventional harvesting. Woody debris, particularly smaller diameter woody debris, plays a key role in maintaining ecosystem nutrient stores following disturbance. Understanding nutrient concentrations within woody debris is necessary for assessing the long-term nutrient balance consequences of altered woody debris retention, particularly in forests slated for use as bioenergy feedstocks. Nutrient concentrations in downed woody...

The development and use of critical loads of air pollutant deposition in the U.S. is gaining momentum, and recent research efforts in the U.S. have produced valuable data for calculating critical loads. Critical loads are used to quantify the levels of air pollutants that are expected to impact forest health, soil fertility, aquatic biota condition, and other ecosystem responses. In addition, model refinements for improving critical loads estimates, and maps for illustrating critical loads for acidification and nitrogen saturation and eutrophication resulting from excess nutrient nitrogen,...

Nonnative plant invasions are a management concern, particularly in riparian forests, but little is known about mechanisms through which they influence vertebrate communities. In the American Southwest, native trees such as cottonwood (Populus spp.) are thought to provide better habitat for breeding birds than nonnative plants, which are more tolerant of human-altered conditions. To evaluate effects of riparian forest composition on riparian-nesting birds, we examined nest plant use along two rivers in New Mexico that differed in abundance of nonnative vegetation. Of the nests we observed,...

The Pacific Northwest (PNW) of the conterminous United States is characterized by large variations in climate and topography, and provides an ideal geographic domain for studying interactions between regional climate and vegetation dynamics. We examined vegetation carbon (C) and water dynamics along PNW climate and topographic gradients using a process-based biogeochemical model, BIOME-BGC, the algorithms of which form bases for a fully-prognostic treatment of carbon and nitrogen cycles in Land Community Model (CLM). Simulation experiments were used to (1) analyze spatial and temporal...