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- In Mediterranean areas, dry deposition is a major component of the total atmospheric N input to natural habitats, particularly to forest ecosystems. An innovative approach, combining the empirical inferential method (EIM) for surface deposition of NO3- and NH4+ with stomatal uptake of NH3, HNO3 and NO2 derived from the DO3SE (Deposition of Ozone and Stomatal Exchange) model, was used to estimate total dry deposition of inorganic N air pollutants in four holm oak forests under Mediterranean conditions in Spain. The estimated total deposition varied among the sites and matched the geographica...AuthorsHéctor García-Gómez, Sheila Izquieta-Rojano, Laura Aguillaume, Ignacio González-Fernández, Fernando Valiño, David Elustondo, Jesús M. Santamaría, Anna Àvila, Andrzej Bytnerowicz, Victoria Bermejo, Rocío AlonsoSourceEnvironmental Pollution. 243: 427-436Year2018
- Invasions of introduced species have homogenized ecological communities worldwide, leading to losses of native species and the services they provide. Some of these invaders substantially alter nutrient cycling, which changes conditions for all other organisms, but less is known about the potential influence of these species on nitrogen (N) trace gas emissions that affect atmospheric processes. We used a natural experiment to explore whether the establishment of an introduced nitrogen (N) fixing tree (Falcataria moluccana) and recent invasion of an amphibian predator, the Caribbean tree...AuthorsSharon J. Hall, David P. Huber, Flint F. HughesKeywordsSourceEcosphereYear2018
- Ecological restoration is needed to counter global-scale ecosystem degradation, but can conflict with endangered species conservation when restoration impacts habitat quality. In such cases, prioritizing long-vacant patches for restoration is an intuitively appealing strategy for minimizing the effects on endangered species. Metapopulation models grounded in empirical data potentially provide a rigorous framework for developing theoretical “patch vacancy thresholds” (i.e., duration of vacancy required before implementing restoration) and assessing the implications of such criteria for...AuthorsConnor M. Wood, Sheila A. Whitmore, R.J. Gutiérrez, Sarah C. Sawyer, John J. Keane, M. Zachariah. PeerySourceBiological ConservationYear2018
- Rising temperatures and extended periods of drought compromise tree hydraulic and carbohydrate systems, threatening forest health globally. Despite winter's biological significance to many forests, the effects of warmer and dryer winters on tree hydraulic and carbohydrate status have largely been overlooked. Here we report a sharp and previously unknown decline in stem water content of three conifer species during California's anomalous 2015 mid‐winter drought that was followed by dampened spring starch accumulation. Recent precipitation and seasonal vapor pressure deficit (VPD) anomaly,...AuthorsJ. Mason Earles, Jens Stevens, Or Sperling, Jessica Orozco, Malcolm P. North, Maciej A. ZwienieckiKeywordsSourceNew PhytologistYear2018
- Species that breed in stream environments with unpredictable interannual variability in hydrological regimes may exhibit plasticity in the timing of their breeding activities. Breeding phenology should coincide with conditions and habitats that maximize a species' reproductive success. For the lotic-breeding frog Rana boylii, the timing of breeding activities of a population can vary by more than a month among years. To examine the influence of abiotic factors on the variation in the timing of onset and patterns (i.e., peaks and pauses) in breeding activity of R. boylii, we sampled seven...AuthorsClara A. Wheeler, Amy J. Lind, Hartwell H. Welsh, Adam K. CummingsKeywordsSourceJournal of HerpetologyYear2018
- The purposeful use of any silvicultural method, including mechanical methods, managed wildfire, prescribed fire, or a combination of approaches, to intentionally alter the fuel complex in such a way as to modify fire behavior and thereby minimize the potential negative impacts of future wildfires on ecosystem goods and services, cultural resources, and human communities.AuthorsChad M. Hoffman, Brandon M. Collins, Michael A. BattagliaKeywordsSourceIn: Manzello, S. L., ed. Encyclopedia of Wildfires and Wildland-Urban Interface (WUI) Fires. Springer, Cham. doi: 10.1007/978-3-319-51727-8_83-1.Year2018
- Quantifying shrub biomass can assist in natural resource management decision making. Nonlinear mixed effect models (NMEM) were developed to predict total aboveground biomass as well as biomass in leaves, 1-hour, 10-hour, and 100 or more hour fuel classes for seven species of shrubs common to the northeastern California. Using crown area as a predictor, an allometric (power) model was used as a base model. Coefficients varied by species, component, and by a nested combination of these random effects. The results showed that NMEM that used shrub species as random effect performed better than...AuthorsSteve Huff, Krishna P. Poudel, Martin Ritchie, H. TemesgenKeywordsSourceForest Ecology and ManagementYear2018
- Changes to vegetation structure and composition in forests adapted to frequent fire have been well documented. However, little is known about changes to the spatial characteristics of vegetation in these forests. Specifically, patch sizes and detailed information linking vegetation type to specific locations and growing conditions on the landscape are lacking. We used historical and recent aerial imagery to characterize historical vegetation patterns and assess contemporary change from those patterns. We created an orthorectified mosaic of aerial photographs from 1941 covering approximately...AuthorsJamie Lydersen, Brandon M. CollinsKeywordsSourceEcosystemsYear2018
- Chisholm and Fung claim that our method of estimating conspecific negative density dependence (CNDD) in recruitment is systematically biased, and present an alternative method that shows no latitudinal pattern in CNDD. We demonstrate that their approach produces strongly biased estimates of CNDD, explaining why they do not detect a latitudinal pattern. We also address their methodological concerns using an alternative distance-weighted approach, which supports our original findings of a latitudinal gradient in CNDD and a latitudinal shift in the relationship between CNDD and species abundance.AuthorsPerry 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. Myers, Joseph 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, 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 NovotnyKeywordsSourceScience. 360(6391): eaar5245Year2018
- Shifting disturbance regimes can have cascading effects on many ecosystems processes. This is particularly true when the scale of the disturbance no longer matches the regeneration strategy of the dominant vegetation. In the yellow pine and mixed conifer forests of California, over a century of fire exclusion and the warming climate are increasing the incidence and extent of stand‐replacing wildfire; such changes in severity patterns are altering regeneration dynamics by dramatically increasing the distance from live tree seed sources. This has raised concerns about limitations to natural...AuthorsKristen L. Shive, Haiganoush K. Preisler, Kevin R. Welch, Hugh D. Safford, Ramona J. Butz, Kevin L O'Hara, Scott L. StephensKeywordsSourceEcological Applications. 28(6): 1626-1639Year2018