Treesearch

We investigated the effects of seasonal changes in soil moisture and temperature on the morphological growth traits of fine roots (< 2mm in diameter) and vascular cambium activity of stems and coarse roots in a mature Quercus ilex L. stand in the South of Italy. Fine roots were sampled by a soil core method, and cambium tissues were carefully collected by hammer and chisel. Mean annual fine root mass and length were 115 gm-2 (live 45 gm-2; dead 70 gm-2) and 471mm-2 (live 244mm-2, dead 227mm-2), respectively. Mean diameter size of fine root necromass was higher than for fine root biomass....

Securing desirable forest regeneration outcomes is an essential component of sustainable forest management. When natural reproduction is preferred over planting, achieving desirable outcomes may be the principal challenge for forest managers, as reports of struggles and even failures are common across many regions and forest ecosystems. Informing managers and policymakers of the prospects of regeneration success before practices and policies are implemented promotes long-term sustainability because rehabilitating undesirable regeneration outcomes is often lengthy, expensive, and uncertain....

Estimating nitrogen (N) deposition to terrestrial ecosystems is complicated by the multiple forms and routes of N loading from the atmosphere.We used the integrated total nitrogen input (ITNI) method, which is based on the principle of isotope dilution within a plant-liquid-sand system, to quantify N inputs to coastal sage scrub ecosystems in Riverside, California. Using the ITNI method, we measured atmospheric N deposition of 29.3 kg N ha−1 yr−1 over a range of aboveground plant biomass of 228 to 424 g m−2. From 85 to 96% of the atmospheric N inputs were taken up by plants in the ITNI...

The Asian long-horned beetle (ALB), a Cerambycidae, is an urban tree pest native to East Asia accidentally introduced to other continents via solid wood packing material. It was first detected in Europe in 2001, and since then infestations have been found in ten European countries. Using a 485-bp-long fragment of the mitochondrial barcode gene (COI), we studied the genetic diversity and structure of ALB populations in both native and invaded ranges, with a specific focus on Europe. Three main haplotypes were found across the native and invaded distribution of ALB. The native area in Asia...

We use a Nash bargaining framework to examine scope for bargaining in invasive species problemswhere spread depends on the employment of costly controls.Municipalities bargain over a transfer payment that slows spread but requires an infested municipality to forgo nonmarket benefits from the host species. We find that when the uninfestedmunicipality has a relative bargaining power advantage, bargaining may attain the first-best solution. However, in many cases a short-term bargaining agreement is unlikely to succeed, which suggests a role for higher levels of government to facilitate...

A critical aspect of urban green infrastructure management hinges on the treatment of native and invasive species. Invasive species are widely seen as a major threat, yet the context-specific values people have for some of these species pose challenges for their management. Here, we offer a case study of the 9/11 survivor tree, a Callery pear (Pyrus calleryana Decne.) that survived the terrorist attack on September 11, 2001 at the World Trade Center in New York City and has since become a symbol of resilience. That individual tree and its progeny are beloved and they are also characterized...

Biosecurity surveillance has been highlighted as a key activity to discover non-native species at the initial stage of invasion. It provides an opportunity for rapidly initiating eradication measures and implementing responses to prevent spread and permanent establishment, reducing costs and damage. In importing countries, three types of biosecurity activities can be carried out: border surveillance targets the arrival stage of a non-native species at points-of-entry for commodities; postborder surveillance and containment target the establishment stage, but post-border surveillance is...

International trade and movement of people are largely responsible for increasing numbers of non-native insect introductions to new environments. For forest insects, trade in live plants and transport of wood packaging material (WPM) are considered the most important pathways facilitating long-distance invasions. These two pathways as well as trade in firewood, logs, and processed wood are commonly associated with insect infestations, while "hitchhiking" insects can be moved on cargo, in the conveyances used for transport (e.g., containers, ships), or associated with international movement...

Understanding the structure and function of urban landscapes requires integrating social and ecological research. Here, we integrate parallel social and ecological assessments of natural areas within New York City. We examined social data (from a rapid assessment of park use and meaning, collected at a park zone level) alongside ecological data (froma plot-based assessment of forest structure and diversity). In-depth interviews with researchers and managers (n = 11) involved with the social and ecological assessments revealed commonly-held values considered critical for integration,...

Annual screenings of forage grasses and legumes for shade tolerance were conducted from 1996 to 2001 in the outdoor Shade Tolerance Screening Laboratory at the Horticulture and Agroforestry Research Center, University of Missouri. Forty-three forages were grown under non-shade (100% of full sunlight), moderate shade (45%), and dense shade (20%) without competition for water and nutrients. Annual forage yield (g pot-1) was equal to or higher under moderate shade for all 43 forages and under dense shade for 31 forages than the non-shade control. Relative distance plasticity index (RDPI), a...