Treesearch
Displaying 13,361 - 13,370 of 65,196 Publications- Many forest ecosystems with a large pine component in the western United States have experienced environmental stress associated with climate change and increased competition with forest densification in the absence of fire. Information on how changes in climate and competition affect carbon allocation to tree growth and defense is needed to anticipate changes to tree vigor and, ultimately, stand structure. This study retrospectively examined the influence of annual climate and competition measures on the growth and defense of 113 large sugar pines (Pinus lambertiana) in a mixed-conifer...AuthorsAndrew Slack, Jeffrey Kane, Eric E. Knapp, Rosemary SherriffKeywordsSourceForests. 8(7): 244Year2017
- Forests around the world are experiencing increasingly severe droughts and elevated competitive intensity due to increased tree density. However, the influence of interactions between drought and competition on forest growth remains poorly understood. Using a unique dataset of stand-scale dendrochronology sampled from 6405 trees, we quantified how annual growth of entire tree populations responds to drought and competition in eight, long-term (multi-decadal), experiments with replicated levels of density (e.g., competitive intensity) arrayed across a broad climatic and compositional...AuthorsLaura S. Kenefic, Christel C. Kern, Louis Iverson, Kelly E. Gleason, John B. Bradford, Alessandra Bottero, Anthony W. D'Amato, Shawn Fraver, Brian J. J. Palik, Michael A. BattagliaKeywordsSourceEcosphereYear2017
- Theory predicts that higher biodiversity in the tropics is maintained by specialized interactions among plants and their natural enemies that result in conspecific negative density dependence (CNDD). By using more than 3000 species and nearly 2.4 million trees across 24 forest plots worldwide, we show that global patterns in tree species diversity reflect not only stronger CNDD at tropical versus temperate latitudes but also a latitudinal shift in the relationship between CNDD and species abundance. CNDD was stronger for rare species at tropical versus temperate latitudes, potentially...AuthorsJoseph A. LaManna, Scott A. Mangan, Alfonso Alonso, Norman A. Bourg, Warren Y. Brockelman, Sarayudh Bunyavejchewin, Li-Wan Chang, Jyh-Min Chiang, George B. Chuyong, Keith Clay, Richard Condit, Susan Cordell, Stuart J. Davies, Tucker J. Furniss, Christian P. Giardina, I. A. U. Nimal Gunatilleke, C. V. Savitri Gunatilleke, Fangliang He, Robert W. Howe, Stephen P. Hubbell, Chang-Fu Hsieh, Faith M. Inman-Narahari, David Janík, Daniel J. Johnson, David Kenfack, Lisa Korte, Kamil Král, Andrew J. Larson, James A. Lutz, Sean M. McMahon, William J. McShea, Hervé R. Memiaghe, Anuttara Nathalang, Vojtech Novotny, Perry S. Ong, David A. Orwig, Rebecca Ostertag, Geoffrey G. Parker, Richard P. Phillips, Lawren Sack, I-Fang Sun, J. Sebastián Tello, Duncan W. Thomas, Benjamin L. Turner, Dilys M. Vela Díaz, Tomáš Vrška, George D. Weiblen, Amy Wolf, Sandra Yap, Jonathan A. MyersKeywordsSourceScienceYear2017
- Mountain pine beetle (Dendroctonus ponderosae Hopkins) (MPB), can cause extensive ponderosa pine (Pinus ponderosa Dougl. ex Laws.) mortality in the Black Hills of South Dakota and Wyoming, USA. Lower tree densities have been associated with reduced MPB-caused tree mortality, but few studies have reported on large-scale thinning and most data come from small plots that may not be representative of a large area. We quantified MPB-caused tree mortality in 21 pairs of commercially thinned and unthinned stands across the Black Hills. Both pre- and postoutbreak, unthinned stands had higher...AuthorsJose Negron, Kurt K. Allen, Angie Ambourn, Blaine Cook, Kenneth MarchandSourceForest Science. doi: http://dx.doi.org/10.5849/FS-2016-061.Year2017
- We introduce a new representation of coupled solute and water age dynamics at the catchment scale, which shows how the contributions of young runoff waters can be directly referenced to observed water quality patterns. The methodology stems from recent trends in hydrologic transport that acknowledge the dynamic nature of streamflow age and explores the use of water age fractions as an alternative to the mean age. The approach uses a travel time‐based transport model to compute the fractions of streamflow that are younger than some thresholds (e.g., younger than a few weeks) and compares...AuthorsPaolo Benettin, Scott Bailey, Andrea Rinaldo, Gene E. Likens, Kevin J. McGuire, Gianluca BotterKeywordsSourceHydrological ProcessesYear2017
- Emerging evidence shows that interactions between soils and subsurface flow paths contribute to spatial variations in stream water chemistry in headwater catchments. However, few have yet attempted to quantify chemical variations in soils at catchment and hillslope scales. Watershed 3 (WS3) at Hubbard Brook Experimental Forest, New Hampshire, USA, was studied in order to better understand pedogenesis and its relationship to subsurface water dynamics. In WS3, 99 soil profiles were described, sampled by horizon, and assigned to a hydropedologic unit (HPU), a functional classification...AuthorsRebecca R. Bourgault, Donald S. Ross, Scott Bailey, Thomas D. Bullen, Kevin J. McGuire, John P. GannonKeywordsSourceGeodermaYear2017
- Measurements of soil water potential and water table fluctuations suggest that morphologically distinct soils in a headwater catchment at the Hubbard Brook Experimental Forest in New Hampshire formed as a result of variations in saturated and unsaturated hydrologic fluxes in the mineral soil. Previous work showed that each group of these soils had distinct water table fluctuations in response to precipitation; however, observed variations in soil morphology also occurred above the maximum height of observed saturation. Variations in unsaturated fluxes have been hypothesized to explain...AuthorsJohn P. Gannon, Kevin J. McGuire, Scott Bailey, Rebecca R. Bourgault, Donald S. RossKeywordsSourceHydrological ProcessesYear2017
- The Wabanaki Youth in Science (WaYS) program provides mentoring and training opportunities in the life sciences for Native American youth in Maine. This program, which was motivated by a shortage of young natural resource professionals to manage tribal lands, uses a multifaceted approach (i.e., camps, community outreach, and internships with cultural resource and natural resource mentors) to recruit and retain native youth in science fields. A defining characteristic of the program is the integration of knowledge from cultural resource and natural resource mentors. This approach helps...Authorstish carr, Laura S. Kenefic, Darren J. RancoSourceJournal of ForestryYear2017
- Sediment losses as concentrations and yields were measured for a year from 12 segments of a newly constructed (buried) natural gas pipeline on the US Forest Service’s Fernow Experimental Forest in West Virginia. Pipeline segments were separated by waterbars which served as drainage features. Six segments were northwest-facing, and six were southeast-facing. Three segments on each aspect were seeded with warm season native herbaceous species at rates used by the Forest Service (1×). All remaining segments received seeding at three times that rate (3×). Forest Service-established rates of...AuthorsPamela Edwards, Bridget M. Harrison, Karl W.J. Williard, Jon E. SchoonoverKeywordsSourceWater, Air, & Soil PollutionYear2017
- Increased availability of monomeric aluminum ( Al3+) in forest soils is an important adverse effect of acidic deposition that reduces root growth and inhibits nutrient uptake. There is evidence that Al3+ exposure interferes with NO3− uptake. If true for overstory trees, the reduction in stand demand for NO3− could increase NO3− discharge in stream water. These effects may also differ between species that tolerate different levels of soil acidity. To examine these ideas, we measured changes in relative uptake of NO3− and NH4+ by six tree species in situ under increased soil Al3+ using a...AuthorsMark B. Burnham, Jonathan R. Cumming, Mary Beth Adams, William T. PeterjohnKeywordsSourceOecologiaYear2017