Treesearch

Plant invasion typically occurs within a landscape‐scale framework of abiotic and biotic conditions, often resulting in emergent feedbacks among environment, ecosystem functions, and the dominance of invasive species. Understanding the mechanisms underlying successful invasions is an important component of conservation and management efforts, but this has been poorly investigated in a spatially explicit manner. Knowing where and why invasion patterns change throughout the landscape enables managers to use context‐specific controls on the spread of invasive species. Using high‐resolution...

This study used tree data from field plots in urban areas to describe forest structure in urban areas throughout California. The plot data were used with numerical models to calculate several ecosystem services produced by trees. A series of transfer functions were calculated to scale-up results from the plots to the landscape using urban tree canopy (UTC) mapped at 1-m resolution for each combination of 6 land use classes and climate zones. California's UTC covered 15% of the urban area and contained 173.2 million trees, five per city resident. UTC per capita was lowest among U.S. states...

This special issue of Forest Phytophthoras serves as part of the proceedings from the Sixth Sudden Oak Death Science Symposium held June 21 -23, 2016 at Fort Mason Center in San Francisco, CA, USA. The symposium marked almost 16 years to the day that David Rizzo (UC Davis) and Matteo Garbelotto (UC Berkeley) identified the cause of sudden oak death to be a previously unknown Phytophthora species, later named Phytophthora ramorum. Many of the approximately 200 participants at the conference have dedicated the past 15 years, a large portion of their life’s work, to protect U.S. forests from...

Forests at risk to diseases caused by invasive Phytophthora pathogens can be grouped into two broad classes: those already invaded by the focal pathogen where disease has emerged or those at significant risk of invasion and subsequent emergence of disease. This dichotomy represents distinct management scenarios – treating after or before disease emerges – with a set of epidemiological, ecological, and practical management characteristics that determine optimal actions and associated costs. Here we present the initial outcomes from two management experiments aimed at restoring forest...

The Hawaiian Islands are among the most isolated and recently inhabited places on Earth. Discovered by Polynesian voyagers some 1000 years ago, people arrived to find unique wildlife and plants arrayed across a remarkable range of ecosystems. Polynesian settlers relied on traditional methods to cultivate canoe crops across the wide range of climate and soils. Early Hawaiian societies adapted to regular climate variations, including periods of extreme drought. Today, as drought events become more severe, contemporary communities must also learn to adapt.

Gross primary production (GPP) is the Earth’s largest carbon flux into the terrestrial biosphere and plays a critical role in regulating atmospheric chemistry and global climate. The Moderate Resolution Imaging Spectrometer (MODIS)-MOD17 data product is a widely used remote sensing-based model that provides global estimates of spatiotemporal trends in GPP. When the MOD17 algorithm is applied to regional scale heterogeneous landscapes, input data from coarse resolution land cover and climate products may increase uncertainty in GPP estimates, especially in high productivity tropical...

Measuring progress toward sustainability goals is a multifaceted task. International, regional, and national organizations and agencies seek to promote resilience and capacity for adaptation at local levels. However, their measurement systems may be poorly aligned with local contexts, cultures, and needs. Understanding how to build effective, culturally grounded measurement systems is a fundamental step toward supporting adaptive management and resilience in the face of environmental, social, and economic change. To identify patterns and inform future efforts, we review seven case studies...

Valley oak (Quercus lobata) is a majestic, endemic California native oak, found throughout California's foothills, valleys and flood plains. It is threatened because: Contracted range due to housing and agriculture. Low recruitment in existing stands as a function of land use and increased stress on existing trees and recruitment due to recent and projected climate change. Valley oak substantially shapes ecosystem functions and biodiversity where it occurs through above ground (e.g., provides shelter with cavities, and food with acorns) and below ground (e.g., soil stability and productivit...

Restoration of western dry forests in the USA often focuses on reducing fuel loads. In the range of the spotted owl, these treatments may reduce canopy cover and tree density, which could reduce preferred habitat conditions for the owl and other sensitive species. In particular, high canopy cover (≥70%) has been widely reported to be an important feature of spotted owl habitat, but averages of stand-level forest cover do not provide important information on foliage height and gap structure. To provide better quantification of canopy structure, we used airborne LiDAR imagery to identify...

The aim of this workshop breakout group session was to review significant gaps within each of three major themes (In-situ Conservation, Ex-situ Conservation, and Restoration of Species and Ecosystems) and to identify actionable solutions to move genetic conservation efforts forward. In order to identify solutions and action items for the tree conservation community, participants were asked to consider the session goals throughout the proceedings, provide examples of gaps in the field, and suggest actions to overcome roadblocks. To maximize participant feedback, a number of easel pads were...