Treesearch

The Earth’s climate is warming most rapidly in the high latitudes of the polar and subpolar regions. Winter temperatures, in particular, are increasing.This trend is being observed in Alaska’s Copper River Delta, where scientists Steve Wondzell, Gordon Reeves, and Luca Adelfio conducted a multiyear study on the effects of changing stream temperatures on the incubation duration and emergence times of coho salmon.During their 5-year study, winter conditions shifted from cold and snowy to cool and rainy. Modeling results showed that this would dramatically change the incubation time of coho...

Understanding the contribution of neutral and adaptive evolutionary processes to population differentiation is often necessary for better informed management and conservation of rare species. In this study, we focused on Pinus torreyanaParry (Torrey pine), one of the world's rarest pines, endemic to one island and one mainland population in California. Small population size, low genetic diversity, and susceptibility to abiotic and biotic stresses suggest Torrey pine may benefit from interpopulation genetic rescue to preserve the species' evolutionary potential. We leveraged reduced...

Reintroducing native carnivores risks creating conflict with people and consequently reducing support for coexistence and conservation efforts. Determining the interface between areas of ecological suitability and conflict risk can help enhance success of carnivore restoration, but this is often difficult because accurate data on risks and tolerance are lacking. Gray wolves (Canis lupus), a focus of reintroduction efforts in the US, require tolerance to persist in human-dominated landscapes but also catalyze societal-level conflicts throughout their global range. Via an unprecedented...

Climate change is a crucial factor in increasing wildfire risks, where warmer and drier conditions, increased drought periods and increased lightning strikes have made many areas more susceptible to burning. This special issue focuses on Wildfire and Hydrological Processes,exploring how wildfire has impacted watersheds and water resources. The manuscripts in this collection underscore how wildfire can change the nature of vegetation, characteristics of soils, hydrological flow paths, and residence times of water in the critical zone, and provide new insights toward predictability of...

The magnitude of sediment yield from headwater catchments is controlled by the interactions among hydrology, geomorphology, and soil disturbance. In montane regions like the Sierra Nevada, snow is one of the main factors controlling the timing and magnitude of hydrological fluxes. However, the role of snow on modulating spatial and temporal variation of sediment yield remains unclear. Using 120-site years of sediment yield data from 10 headwater catchments (drainage area 50–475 ha), we examined the sediment yield characteristics across an elevational gradient (1,777–2,381 m elevation) in...

Suspended sediment transport in montane headwaters is important to water quality and nutrient balances. However, predictions of sediment source and transport can be difficult, in part, because of a changing climate and increasing frequencies of disturbances. We used observations from 10 headwater streams in water year (WY; starting on 1st October ending on 30th September) 2007–2009 and 2013–2018 to determine the potential impacts of climate and forest management on suspended sediment delivery. We analysed hysteretic responses of suspended sediment for 76 events in five headwater catchments...

Plants resist herbivores and pathogens by using constitutive (baseline) and inducible (change in defense after an attack) defenses. Inducibility has long been predicted to trade off with constitutive defense, reflecting the economic use of resources. However, empirical evidence for such tradeoffs is variable, and we still lack understanding about when and where defense trade-offs occur. We tested for tradeoffs between constitutive and induced defenses in natural populations of three species of long-lived pines (Pinus balfouriana, P. flexilis, P. longaeva) that differ greatly in constitutive...

Trade-offs between plant defense investment and fitness traits, including growth, are often invoked to explain evolutionary strategies targeted at resisting herbivores. Many Pinus species have specialized herbivores, including the mountain pine beetle (MPB), Dendroctonus ponderosae, and have historically been a focus of defense investigations. We compared defense traits of two high-elevation Pinus species, P. aristata and P. flexilis, that are hosts to MPB and hypothesized to have different growth and defense traits and potential trade-offs. Interspecific differences were assessed by...

The precipitous decline of the keystone species whitebark pine (Pinus albicaulis Engelm.) has resulted in dramatic changes to many high elevation ecosystems in the western U.S. and Canada. To restore these ecosystems, there is a need to establish populations of whitebark pine that will persist in the face of both natural and anthropogenic disturbances (e.g. climate change, white pine blister rust [Cronartium ribicola J.C. Fisher]). The listing of whitebark pine as endangered in Canada and its recent proposed listing as threatened in the U.S. reinforce the urgency of the need to act. This...

All native North American white pines are highly susceptible to white pine blister rust (WPBR) caused by Cronartium ribicola. Understanding genomic diversity and molecular mechanisms underlying genetic resistance to WPBR remains one of the great challenges in improvement of white pines. To compare major gene resistance (MGR) present in two species, southwestern white pine (Pinus strobiformis) Cr3 and limber pine (P. flexilis) Cr4, we performed association analyses of Cr3-controlled resistant traits using single nucleotide polymorphism (SNP) assays designed with Cr4-linked polymorphic...