Treesearch

Extreme, downslope mountain winds often generate dangerous wildfire conditions. We used the wildfire spread model Fire Area Simulator (FARSITE) to simulate two wildfires influenced by strong wind events in Santa Barbara, CA. High spatial-resolution imagery for fuel maps and hourly wind downscaled to 100 m were used as model inputs, and sensitivity tests were performed to evaluate the effects of ignition timing and location on fire spread. Additionally, burn area rasters from FARSITE simulations were compared to minimum travel time rasters from FlamMap simulations, a wildfire model similar...

Reductions in snow accumulation and melt in headwater basins are increasing the water stress on forest ecosystems across the western US. Forest thinning has the potential to reduce water stress by decreasing sublimation losses from canopy interception; however, it can also increase snowpack exposure to sun and wind. We used the high-resolution (1 m) energy and mass balance Snow Physics and Lidar Mapping (SnowPALM) model to investigate the effect of two virtual forest thinning scenarios on the snowpack of two adjacent watersheds (54 km2total) in the Lake Tahoe Basin, California, where...

Fruits of Miconia calvescens DC. (Melastomataceae) were dissected to study insect frugivory in this plant in its native habitat in Costa Rica. Larvae of an unknown Mompha species (Lepidoptera: Momphidae), Anthonomus monostigma Champion (Coleoptera: Curculionidae), and unidentified Diptera and Hymenoptera were found in M. calvescens fruits. The Mompha species, described here as new as Mompha luteofascia Koster & Badenes-Pérez, was the most abundant insect frugivore in M. calvescens, infesting up to 38.1% of the fruits sampled. Feeding damage by M. luteofascia was positively correlated with...

Gene copy number variation is frequent in plant genomes of various species, but the impact of such gene dosage variation on morphological traits is poorly understood. We used a large population of Populuscarrying genomically characterized insertions and deletions across the genome to systematically assay the effect of gene dosage variation on a suite of leaf morphology traits. A systems genetics approach was used to integrate insertion and deletion locations, leaf morphology phenotypes, gene expression, and transcriptional network data, to provide an overview of how gene dosage influences...

We used Landsat-based measures of annual evapotranspiration (ET) to explore the effects of wildfires on vegetation water use across California’s Sierra Nevada. Wildfires decreased ET relative to unburned and pre-fire controls, in many areas this reduction persisted for at least 15 years. The ET reduction averaged 265 mm yr−1(36% of pre-fire ET) during the first year after fire, and 169 mm yr−1(23%) over the first 15 years after fire. The ET reduction varied with burn severity, pre-fire canopy density, and hydro-topographic environment. In areas burned at low severity the ET reduction in...

The Adaptive Silviculture for Climate Change (ASCC) network tests silvicultural treatments to promote ‘resistance’ or ‘resilience’ to climate change or speed ‘transition’ to new forest types. Based on projected increases in air temperatures and within-season dry periods in southeastern USA, we installed resistance, resilience and transition treatments involving species selection and varied intensities of density reduction, plus an untreated control, in mixed longleaf pine-hardwood woodland in southwest Georgia USA. Within a year of treatment a tropical cyclone, Hurricane Michael, exposed...

This study was conducted to improve estimation of concomitant variables for implementation of a stand density management diagram (SDMD) for ponderosa pine (Pinus ponderosaLaws.) in northern California and Oregon. In traditional SDMD, isolines for variables such as stand volume are presented in such a way that uncertainty with estimation is not available. We developed the new top height and stand volume equations, as well as aboveground biomass and percent canopy cover, for building isolines in the SDMD using high-quality data collected from well-managed even-aged stands. The data were...

The Sudden Oak Death (SOD) Blitzes consist of yearly surveys led by citizen scientists designed to map the distribution of Phytophthora ramorum, cause of the forest disease called SOD, across northern California. During the 2017 Santa Cruz County SOD Blitz, six rare or endangered Arctostaphylos(manzanita) species were found to be possibly symptomatic for the first time. Symptoms included branch cankers and associated canopy mortality, and affected multiple individuals per species. Isolates of P. ramorumwere obtained from each of the six species and, through a 30-day-long inoculation...

The objective of this study was to understand how genetic variation in a riparian species, Populus angustifolia, affects mass and energy exchange between the land and atmosphere across ~1,700 km of latitude of the western United States. To examine the potential for large‐scale land–atmosphere feedbacks in hydrologic processes driven by geographic differences in plant population traits, we use a physical hydrology model, paired field, and greenhouse observations of plant traits, and stable isotope compositions of soil, stem, and leaf water of P. angustifoliapopulations. Populations show...

The spatiotemporal dynamics of plant water sources are hidden and poorly understood. We document water source use of Quercus garryanagrowing in Northern California on a profile of approximately 50 cm of soil underlain by 2–4 m of weathered bedrock (sheared shale mélange) that completely saturates in winter, when the oaks lack leaves, and progressively dries over the summer. We determined oak water sources by combining observations of water stable isotope composition, vadose zone moisture and groundwater dynamics, and metrics of tree water status (potential) and use (sapflow). During the...