Modeling Forest Owner Harvesting Behaviour and Future Intentions in Tasmania

Our ability to design public policies that effectively promote the efficient use of privately owned forest resources is underpinned by an understanding of the way in which forest production and investment decisions are made, and of how forest owners respond to changes in social, economic, and institutional conditions. A model of non-industrial private forest owners (NIPF) past harvesting behaviour and future harvesting intentions using a logit approach is presented. A Tobit model, which investigates harvesting intensity, is also developed. The responses to a survey of 386 NIPF owners in Tasmania are used to construct the data set consisting of socio-economic characteristics of NIPF owners, their forest ownership objectives, and property characteristics. The current study is innovative in that the role of NIPF owner objectives and attitudes is assessed in three econometric models exploring past harvesting behaviour, harvesting intensity, and future harvesting intentions. A series of observations can be made from comparing the results of the three models. For example, higher pulp prices are unlikely to affect NIPF owners harvesting intentions but are likely to increase harvesting intensity. The financial characteristics of the NIPF owner contribute most to predicting future harvesting intentions, with financial security being a disincentive to future harvesting. Landowner objectives and attitudes are important in explaining past harvesting activities and future intentions but do not significantly affect harvesting intensity. Furthermore, there are significant differences between different types of landowners in terms of the incentives that are likely to make them change their mind about participating in native forest harvesting.     

Asymmetric scattering of polarized electrons by organized organic films of chiral molecules

Electron transmission experiments demonstrate a large asymmetry in the scattering probability of polarized electrons by thin organized films of chiral molecules. This large asymmetry results from the interaction of the electron's wavefunction with many scatterers (molecules) in the organized monolayer structure and represents a manifestation of quantum interference on the scale of supramolecular lengths.     

Efficacy of a vacuum benthos sampler for collecting demersal fish eggs from gravel substratum

Abstract— We used two densities of eggs (low=900 eggs/m²; high=5100 eggs/m²) in laboratory experiments to estimate the recovery efficiency of the Brown benthos sampler for collecting fish eggs from gravel substrate and to determine if differences (e. g., 5-fold) in egg density in the substratum could be detected with the sampler. The mean egg recovery efficiency of the sampler in the low and high density treatments was 30% (SE=8.7) and 35% (SE=3.8), respectively. The difference between the treatment means was not significant. Therefore, data from the two treatments were pooled and used to estimate the recovery efficiency of the sampler (32.7%, SE=4.4). However, we were able to detect a 5× difference in the number of eggs collected with the sampler between the two treatments. Our estimate of the recovery efficiency of the sampler for collecting fish eggs was less than those reported for the sampler's efficiency for collecting benthic macroinvertebrates. The low recovery efficiency of the sampler for collecting fish eggs does not lessen the utility of the device. Rather, ecologists planning to use the sampler must estimate the recovery efficiency of target fauna, especially if density estimates are to be calculated, because recovery efficiency probably is less than 100%.     

Hazards to wildlife from the use of DDT in orchards

An investigation into the poisoning of birds with 1,1,1-trichloro-2, 2-di (4-chlorophenyl) ethane (DDT) on a fruit farm in South-East England is described. Pesticide levels in wild birds were sufficient to be held responsible for deaths. It is suggested that levels in samples of soil, earthworms, sludge, eggs, etc. did not indicate the source of the poisoning. Examination of caged birds following exposure to normal spraying indicated little hazard from this type of operation. Some discussion of the assessment of levels of intoxication is included.     

The time factor in egg formation for hens exposed to ahemeral light-dark cycles

Three hundred and two White Leghorn pullets were killed at intervals 5 min to 7 h following oviposition. The reproductive tract was then examined and, from the position of the yolk, estimates were made of the mean time spent by the ovum in different parts of the oviduct. Half the birds examined had been kept under 24‐h cycles (14 h light : 10 h dark) and half under 27‐h cycles (14 h light : 13 h dark). Mean intervals from oviposition to ovulation were 24 min and 36 min for birds under 24‐h and 27‐h cycles respectively. The difference between these values can be associated with the different rates of lay of birds under the two treatments. Mean times spent in the upper oviduct and the shell gland were estimated as 5·15 h and 19·76 h for the 24‐h cycles and 5·41 h and 20–70 h for the 27‐h cycles. The increase in albumen weight which has been reported to follow from the use of 27‐h cycles can thus be associated with extra time spent in the magnum. The reported increase in shell weight of 10% is more than would be expected from a 5% increase in time spent in the shell gland.