Treesearch

Shear modulus (G) of thin wood composite materials is one of several important indicators that characterizes mechanical properties. However, there is not an easy method to obtain this value. This study presents the use of a newly developed cantilever beam free vibration test apparatus to detect in-plane G of thin wood composite materials by measuring the first order free vibration cantilever specimens and its logarithmic decrement of vibration. Six sets of commercially purchased thin wood composite materials having three different fiber types were tested. A significant linear correlation...

The Golden-olive Woodpecker is a generalist species found in a wide range of habitats, being particularly common in coffee plantations within Nicaraguan cloud forests. Observations of an individual feeding at the base of Cecropia leaves revealed it was consuming Mullerian bodies that the Cecropia produces to feed Azteca ants as part of a host-inhabitant mutualistic symbiosis. This record further documents the plasticity of some species as they search for alternative sources of energy.

Carbon sequestration is a major ecosystem service provided by tropical forests. Especially in light of global climate change, understanding the drivers of forest productivity is of critical importance. Although abiotic conditions (e.g., precipitation) are known to influence forest productivity, ecological theory predicts that biodiversity may also have independent effects on productivity. We estimated standing aboveground biomass (AGB) in mature forests of Puerto Rico that span a strong precipitation gradient and 2 general soil types. With these data, we examined the independent and...

Mona Island protects one of the most important remnants of Caribbean dry forests and hosts a high diversity of rare and endangered plant and animal species. Feral ungulates (goats and pigs) were introduced to the island ~500 y ago, and their populations may be threatening the conservation of Mona Island’s native biodiversity. In this study, we used permanent fenced and unfenced plots at 4 different depression-forest sites on Mona Island to assess longterm (10-y) understory vegetation dynamics and the potential responses of this vegetation stratum to ungulate exclusion. Depression forests...

Stocked trout (Salmonidae) in reservoir tailwater systems in the Southern United States have been shown to use tributary streams for spawning and rearing. The lower Mountain Fork of the Little River below Broken Bow Dam is one of two year-round tailwater trout fisheries in Oklahoma, and the only one with evidence of reproduction by stocked rainbow trout (Oncorhynchus mykiss). Whether stocked trout use tributaries in this system for spawning is unknown. Furthermore, aninventory of the resident fish communities in these tributaries is lacking. To address these gaps, we surveyed 10 tributaries...

Does seed dormancy allow disturbance-oriented forest herbs such as Ageratina altissima to persist in heterogeneous natural communities? To document seed longevity and dormancy state, Ageratina seeds were buried in nylon mesh bags in second-growth forest stands in south-eastern Ohio, USA. Bags were recovered at 2-month intervals, and seeds were tested for viability and germinability in the lab. Live seed numbers declined rapidly, with seed banks exhausted in an estimated 33–37 months. Seeds showed a strong dormancy polymorphism, with 71–84% of live seeds germinable between March and July,...

Plant derived cellulose nano-fibers (CNF) are a material with remarkable mechanical properties compared to other natural fibers. However, efforts to produce nano-composites on a large scale using CNF have yet to be investigated. In this study, scalable CNF nano-composites were made from isotropically porous CNF preforms using a freeze drying process. An improvised Liquid Composite Molding (LCM) process was used to make the nano-composites using a high bio-content ‘green’ epoxy resin. Formation of the freeze dried CNF preforms' porous network highly affects the mechanical properties of the...

The complex three-dimensional (3-D) structure of tropical forests generates a diversity of light environments for canopy and understory trees. Understanding diurnal and seasonal changes in light availability is critical for interpreting measurements of net ecosystem exchange and improving ecosystem models. Here, we used the Discrete Anisotropic Radiative Transfer (DART) model to simulate leaf absorption of photosynthetically active radiation (lAPAR) for an Amazon forest. The 3-D model scene was developed from airborne lidar data, and local measurements of leaf reflectance, aerosols, and...

Research on the influence of social network structure over flows of knowledge in support of sustainability governance and action has recently flourished. These studies highlight three challenges to evaluating knowledge-action networks: first, defining boundaries; second, characterizing power distributions; and third, identifying obstacles to knowledge sharing and connectivity. We present concepts from social network analysis (SNA) commonly found to influence knowledge flows. We examine applications of SNA from across the social sciences and use the case of land governance in San Juan,...