Treesearch

Herbaceous perennial species may exhibit winter or summer dormancy, or they may be spring ephemerals with dormancy extending from summer through winter. Herbaceous perennials, and spring ephemerals in particular, are most common in strongly seasonal but relatively mesic temperate environments. Warm deserts are typically dominated by shrubs and annuals that are better adapted to withstand or avoid severe summer heat. Astragalus holmgreniorum Barneby (Fabaceae) is a perennial spring ephemeral that has a restricted distribution at the northeastern edge of the Mojave Desert. We explored...

Forest ecosystems in an ecotone and their dynamics to climate change are growing ecological and environmental concerns. Phenology is one of the most critical biological indicators of climate change impacts on forest dynamics. In this study, we estimated and visualized the spatiotemporal patterns of forest phenology from 2001 to 2017 in the Qinling Mountains (QMs) based on the enhanced vegetation index (EVI) from MODerate-resolution Imaging Spectroradiometer (MODIS). We further analyzed this data to reveal the impacts of climate change and topography on the start of the growing season...

Study region: Lower Mississippi River Alluvial Valley (LMRAV) is located in the humid subtropical region of mid-south USA, and Lower Yazoo River Watershed (LYRW) in Mississippi is within the LMRAV. Study focus: Groundwater depletion due to anthropogenic activities is an issue of water resource concern in the LMRAV. Some studies suggested that forest lands reduce water recharge from land surface into aquifers as compared to agricultural lands. However, very few efforts have been devoted to investigating the relationship of water recharge and land use in the LMRAV. This study was designed to...

Release burning is the term used to describe prescribed fire conducted in the mid- to latter stages of the oak (Quercus spp.) regeneration process to promote the dominance of oak reproduction. In this context, the fire exploits differences in resource allocation (roots versus stems) between oak seedlings and those of other hardwoods to free the oaks from excessive competition. Fire seasonality and fire intensity strongly influence release burning outcomes with hot fires conducted in late spring being most beneficial for promoting oak dominance. However, release burning must be used wisely...

Many national forest inventories (NFI) use auxiliary data to increase the precision of estimates. Typically, this is accomplished via stratified estimation techniques that rely on assignment of similar sample plot observations to strata constructed with the goal of lowering the variance of estimates. While early applications of stratification used strata constructed from photointerpretation of aerial photography, current technology makes using wall-to-wall digital map information more appealing due to automated processing capabilities; however, there is generally a reduction in classificati...

Disease-suppression strategies are much more effective when diseases are detected at early stages, long before symptoms and signs develop. Relatively new disease-detection tools, electronic-nose (e-nose) devices, have been used successfully in the veterinary, agricultural and biomedical fields. E-nose instruments utilize multi-sensor arrays capable of detecting gaseous mixtures containing volatile organic compounds (VOCs) within air samples. Unique complex mixtures of VOCs, released by microbial pathogens and associated diseases, may be detected collectively as an aroma signature (derived...

Phytophthora ramorum, a microscopic pathogen belonging to Phylum Oomycota, has been causing sudden oak death in California forests for over 25 years. In the U.S., this pathogen primarily kills Quercus agrifolia (coast live oak) and other oaks in genus Quercus, section Lobatae, as well as Notholithocarpus densiflorus(tanoak); in the UK, Ireland and France, it also killsLarix kaempferi(Japanese larch) and causes stem cankers and/or foliar blight on a variety of native and non-native hosts including Fagus sylvatica(beech), Castanea sativa, (sweet chestnut), Q. falcata(southern red oak) and Q....

Mining companies use the Forestry Reclamation Approach (FRA) when reclaiming mined land with the aim of establishing functional forests as a post-mining land use. Invasive exotic plant species (IES) can interfere with successful reforestation. Thus, reclamation of active mine sites should aim to prevent colonization of IES plants if native forest restoration is the end goal. Once IES become established, they are difficult to eradicate and can potentially delay bond release. Therefore, it is best to manage for IES before they become established. Following the FRA is a good way to accomplish...

The emerald ash borer, Agrilus planipennis, is the most damaging invasive forest insect pest ever to have invaded North America. It is native to Asia and is established in the United States, Canada, European Russia and Ukraine where it threatens native ash across North America and Europe. We evaluated trap designs, colors, and lures for A. planipennis detection at sites with varying infestation levels. Purple or green sticky prism traps and multiple funnel traps hung in the canopy of ash trees and double-decker traps (consisting of two sticky prisms attached to a 3m vertical pole at 3m and...

Advances in topobathymetric LiDARs could enable rapid surveys at sub-meter resolution over entire stream networks. This is the first step to improving our knowledge of riverine systems, both their morphology and role in ecosystems. The Experimental Advanced Airborne Research LiDAR B (EAARL-B) system is one such topobathymetric sensor, capable of mapping both terrestrial and aquatic systems. Whereas the original EAARL was developed to survey littoral areas, the new version, EAARL-B, was also designed for riverine systems but has yet to be tested. Thus, we evaluated the ability of EAARL-B to...