Treesearch

Climate change is driving the emergence of novel tree diseases at the global scale, requiring new approaches for the formal confirmation of the pathogenicity of novel pathogens on novel hosts. At the same time, predictive models need to account for the possible effect of environmental changes and of abiotic stressors on disease severity for all diseases. By wound-inoculating Botryosphaeria dothidea on potted California coast live oaks and Cryptostroma corticale on potted silver maples, simultaneously in well-watered and in water-deprived conditions, I show that drought conditions increase...

We investigated the riverscape genetic structure of Klamath smallscale suckers (Catostomus rimiculus) in the Smith River, California, a population believed to have been introduced and founded by approximately six individuals within the last 100 years. Analyzing 15 microsatellites from larval samples across the species’ entire known Smith River range, we discerned: (1) increased genetic diversity downstream, (2) increased within-site differentiation upstream, and (3) isolation by river distance. These introduced suckers displayed a genetic profile expected for native species in river...

Release from interspecific competition can lead to niche shifts and have positive fitness consequences. I studied two closely related and ecologically similar Empidonaxspecies that breed across an elevational gradient in the southern Sierra Nevada, California: Dusky Flycatcher (Empidonax oberholseri) and Hammond’s flycatcher (E. hammondii). The two species coexisted at low and moderate elevations but only Dusky Flycatchers occurred in high elevation forests. Where they co-occurred, Dusky Flycatchers nested primarily in shrubs but at high elevations they nested primarily in trees and snags....

Falcataria falcata, until recently known as Falcataria moluccanaand commonly known as albizia, is a large, fast-growing tree native to the Malaysian peninsula, Indonesia, Papua New Guinea, and Solomon Islands. It has been introduced to, and become naturalized in, continental Africa, Asia, and many Caribbean and Pacific Islands. F. falcatais an early successional pioneer species that typically establishes via purposeful plantings. It readily spreads and outcompetes other tree species as a function of its symbiotic nitrogen-fixing capacity, copious long-lived seedbanks, and rapid growth...

Accurate representation of the location and amount of burned areas is vital to the understanding of patterns and impacts of fires. Some extant burned area maps appear to have high commission errors, which lead to an overrepresentation of burned area. The primary research objective of this study was to assess whether region-specific training data used for machine learning routines improve accuracy of burned area products for western San Diego County. We used training data derived from fine-scale aerial orthoimagery to create and compare three training sets, each with a different Landsat...

In forest ecosystems, the interplay among plant-driven processes and anthropogenic activities profoundly influences water balance dynamics. Hydraulic redistribution is one plant-driven process that can provide a large proportion of a plant's daily water. However, critical gaps exist in our knowledge of hydraulic redistribution including how forest management processes, like thinning, and site-specific factors like basal area and hillslope position, may affect it. To address these gaps, we used hourly volumetric water content measurements from 2016 to 2021 from four sub-watersheds in a...

Mangroves can increase their elevation relative to tidal flooding through biogeomorphic feedbacks but can submerge if rates of sea-level rise are too great. There is an urgent need to understand the vulnerability of mangroves to sea-level rise so local communities and resource managers can implement and prioritize actions. The need is especially pressing for small islands, which have been identified as an area of concern by the IPCC. We developed a generalizable modeling framework for tidal wetlands (WARMER-3) that accounts for species interactions and the belowground processes that...

1. Tropical forest understories tend to be light-limited. The red-to-far-red ratio (R:FR) is a useful and reliable index of light quality and its spatial variability can influence competition between native and non-native seedlings. While per cent light transmittance has been quantified in some Hawaiian lowland wet forests (HLWF), no information exists on how the spatial distribution of understorey light varies in relation to species invasion, or if patterns of seedling regeneration and light are linked. 2. We measured the R:FR of light in the understorey to assess light quality in three...

Southeast Asian (SEA) mangroves are globally recognized as blue carbon hotspots. Methodologies that measure mangrove soil carbon stock (SCS) are either accurate but costly (i.e., elemental analyzers), or economical but less accurate (i.e., loss-on-ignition [LOI]). Most SEA countries estimate SCS by measuring soil organic matter (OM) through the LOI method then converting it into organic carbon (OC) using a conventional conversion equation (%Corg = 0.415 * % LOI + 2.89, R2 = 0.59, n = 78) developed from Palau mangroves. The local site conditions in Palau does not reflect the wide range of...

Climate change is motivating a reassessment of how seeds are selected for reforestation, as rapid environmental change can lead to local maladaptation in trees. Genetic association studies and past seed source climate both have the potential to help identify appropriate planting stock, but these techniques have not been compared and tested as part of an operational planting program. In this study, we combined an analysis of single nucleotide polymorphisms (SNPs) associated with environmental gradients in sugar pine (Pinus lambertiana) with an analysis of post-fire seedling survival and...