Permutation procedures for multi-dimensional applications in wood related research

Summary Two nonparametric statistical techniques are presented which allow the user to evaluate the effect of a treatment on an n-dimensional set of variables associated with forest products. The multi-response permutation procedures (MRPP) are a broad category of permutation techniques based on a variety of distance functions. Earlier work on this subject has demonstrated that when the distance function is selected appropriately, one-dimensional MRPP represent a rational alternative to traditional comparative statistical analysis techniques, such as the Student's t-test (t-test). In the work presented herein, MRPP are broadened to include analyses on the effect of a treatment on data were containing multiple variables which may be correlated. These tests are a MRPP based on Euclidean distance (MRPP-E) and a MRPP motivated by Hotelling's T² test (MRPP-H) which can account for the variance-covariance structure of the data. Four hundred eighteen data points representing the moduli of elasticity (MOE) and rupture (MOR) of eight foot-long (244 cm), nominal 2 × 4 inch² (51 × 102 mm²), No. 2 grade, Douglas-fir, dimension lumber from seven growing regions in the western United States were selected for use in this study. Data were analyzed using one- and two-dimensional, classical, parametric techniques (i.e. t-test and Hotelling's T² test) and the more intuitive and nonparametric MRPP in similar dimensions. The results indicated that the MOE demonstrated some degree of sensitivity to the growth region, while the MOR proved to be insensitive. Also, considerable differences in inference drawn regarding the presence of statistically significant differences between data sets existed as a function of the analytical test method used. The unique structure of the data encountered in this study showed that MRPP-E was insufficiently sensitive to the variance-covariance structure of the data. Visual examination of the data suggested that MRPP-H is more appropriate for the present data than MRPP-E. Received 7 October 1998     

Soil Vampyrellid amoebae that cause small perforations in conidia of Cochliobolus sativus

The parasitic habits of two mycophagous amoebae, members of the Vampyrellidae isolated from soil, were studied under laboratory conditions. The amoeboid organisms resembled Theratromyxa weberi and Vampyrella vorax. Both organisms lysed conidia of Cochliobolus sativus and chlamydospores o Thielaviopsis hasicola within digestive cysts. Perforations 1 μm dia or less were observed in walls of the lysed fungus spores. The mycophagous Theratromyxa sp. and V. vorax were differentiated in laboratory culture chambers on the basis of morphology, encystment, excystment and diameter of perforations produced in walls of conidia of C. sativus. Both organisms differed from a previously-described species of Vampyrella which causes large perforations and annular depressions in spore walls.     

Construction,operation and performance of a modified diatomaceous earth filter for shellfish hatcheries

A commercially available diatomaceous earth filter has been successfully modified for microfiltering sea water used to grow bivalve larvae. The filter consistently removes up to 96% of the suspended matter in the water down to at least 2.3 microns, and reduces the number of heterotrophic bacteria to between 1 and 5 × 10² ml^?1. Growth and development of bivalve larvae in this water is excellent.     

ENVIRONMENTAL ATTITUDES AND CONSUMER PREFERENCE FOR ENVIRONMENTALLY-FRIENDLY BEVERAGE PACKAGING: THE ROLE OF INFORMATION PROVISION AND IDENTITY LABELING IN INFLUENCING CONSUMER BEHAVIOR

This study examined whether urban Chinese consumers with stronger environmental values have higher valuations for plastic beverage bottles that are made of post-consumer recycled material(rPET) or that come in large sizes that use plastic more efficiently. It also assesses the effectiveness of environmental information provision and green identity labeling in increasing consumer willingness to pay for environmentally-friendly packaging. The results suggest that urban Chinese consumers are willin...     

Engineering investigation of design procedures for closed containment marine aquaculture systems

The objective of this paper is to investigate potential design procedures for rigid, closed containment aquaculture systems deployed in the marine environment. In this context, closed containment is a term used to describe a range of aquaculture technologies that attempt to restrict and control interactions between farmed fish and the external aquatic environment, with the goal of minimizing impacts. The containment units are often closely spaced and moored to the seafloor bottom. The geographical area of interest is the Straits of Georgia, British Columbia in Canada.In this study, the design configurations of multiple closed containment systems are investigated. The design procedures include examining: (1) local environmental conditions, (2) drag forces on multiple containment units, (3) wave loading, (4) undamped heave motions, (5) mooring gear components and (6) material stresses on a rigid containment structure. Operational and other design considerations are also discussed. Preliminary findings indicate that wave forces could be substantial. In addition, little is known about how containment units, which are closely spaced, will respond individually or as a farm when subjected to surface waves.     

Effects of temperature on survival and growth of juvenile spinefoot rabbitfish (Siganus rivulatus)

Interest in culturing marbled spinefoot rabbitfish Siganus rivulatus is increasing in countries on the Eastern Mediterranean, Red Sea and Arabian Gulf. However, information on environmental tolerances and requirements for optimal growth are scarce. In the present work, the temperature requirements for spinefoot rabbitfish were investigated in two experiments. In the first experiment, juvenile rabbitfish were distributed into eight 180 L square tanks at 12 fish per tank. The temperature in four tanks was reduced at a rate of 1 °C day^?1 and in four tanks was increased by 1 °C day^?1 until the fish stopped feeding. Minimum and maximum temperatures for feeding were recorded. In the second experiment, the fish were placed in four temperature treatments (17, 22, 27, 32 °C) at four replicates per treatment for 8 weeks. Survival and growth were evaluated. Fish stopped feeding at 14 and 36 °C. Their maximum growth rate was at 27 °C, and survival was 100% in all treatments. The relationship between specific growth rate and temperature was parabolic, described by the equation: SGR=?0.0014 (T³)+0.0798 (T²)?1.3089 (T)+6.7342. The results show that S. rivulatus is a eurythermal fish whose optimal temperature for growth is circa 27 °C.     

A multi-scale analysis of western spruce budworm outbreak dynamics

Context

Forest insect outbreaks are influenced by ecological processes operating at multiple spatial scales, including host-insect interactions within stands and across landscapes that are modified by regional-scale variations in climate. These drivers of outbreak dynamics are not well understood for the western spruce budworm, a defoliator that is native to forests of western North America.

Objectives

Our aim was to assess how processes across multiple spatial scales drive western spruce budworm outbreak dynamics. Our objective was to assess the relative importance and influence of a set of factors covering the stand, landscape, and regional scales for explaining spatiotemporal outbreak patterns in British Columbia, Canada.

Methods

We used generalized linear mixed effect models within a multi-model interference framework to relate annual budworm infestation mapped from Landsat time series (1996–2012) to sets of stand-, landscape-, and regional-scale factors derived from forest inventory data, GIS analyses, and climate models.

Results

Outbreak patterns were explained well by our model (R ² = 93%). The most important predictors of infestation probability were the proximity to infestations in the previous year, landscape-scale host abundance, and dry autumn conditions. While stand characteristics were overall less important predictors, we did find infestations were more likely amongst pure Douglas-fir stands with low site indices and high crown closure.

Conclusions

Our findings add to growing empirical evidence that insect outbreak dynamics are driven by multi-scaled processes. Forest management planning to mitigate the impacts of budworm outbreaks should thus consider landscape- and regional-scale factors in addition to stand-scale factors.

     

Legacy effects of past land use on current biodiversity in a low-intensity farming landscape in Transylvania (Romania)

Context

Ecological impacts of past land use can persist for centuries. While present-day land use is relatively easy to quantify, characterizing historical land uses and their legacies on biodiversity remains challenging. Southern Transylvania in Romania is a biodiversity-rich area which has undergone major political and socio-economic changes, from the Austro-Hungarian Empire to two World Wars, communist dictatorship, capitalist democracy, and EU accession—all leading to widespread land-use changes.

Objectives

We investigated whether present-day community composition of birds, plants, and butterflies was associated with historical land use.

Methods

We surveyed birds, plants, and butterflies at 150 sites and classified those sites as forest, arable land, or managed grassland for six epochs using historical maps from the 1870s, 1930s, and 1970s, satellite imagery from 1985 to 2000, and field visits in 2012. Sites were labelled permanent if they had the same land use at all epochs and non-permanent otherwise. We used clustering and PERMANOVA based on community similarity to test for associations between community composition and land-use history.

Results

We found significant differences (p = 0.030) in bird communities between permanent and non-permanent forest sites, and permanent and non-permanent grassland sites (p = 0.051). No significant associations were found among plants or butterflies and land-use history.

Conclusions

Bird communities were associated with historical land use, though plants and butterflies were not. Historical land-use change in our study area was likely not sufficiently intense to cross relevant ecological thresholds that would lead to legacy effects in present-day plant and butterfly communities.