Accurate measurement of optical properties of narrow leaves and conifer needles with a typical integrating sphere and spectroradiometer

Accurate information on the optical properties (reflectance and transmittance spectra) of single leaves is important for an ecophysiological understanding of light use by leaves, radiative transfer models and remote sensing of terrestrial ecosystems. In general, leaf optical properties are measured with an integrating sphere and a spectroradiometer. However, this method is usually difficult to use with grass leaves and conifer needles because they are too narrow to cover the sample port of a typical integrating sphere. Although ways to measure the optical properties of narrow leaves have been suggested, they have problems. We propose a new measurement protocol and calculation algorithms. The protocol does not damage sample leaves and is valid for various types of leaves, including green and senescent. We tested our technique with leaves of Aucuba japonica, an evergreen broadleaved shrub, and compared the spectral data of whole leaves and narrow strips of the leaves. The reflectance and transmittance of the strips matched those of the whole leaves, indicating that our technique can accurately estimate the optical properties of narrow leaves. Tests of conifer needles confirmed the applicability.     

Patterns of hybrid formation among cryptic species of bird‐nest fern,Asplenium nidus complex (Aspleniaceae), in West Malesia

In order to clarify patterns of hybrid formation in the Asplenium nidus complex, artificial crossing experiments were performed between individuals of genetically differentiated groups based on the sequence of the rbcL gene, including A. australasicum from New Caledonia, A. setoi from Japan and several cryptic species in the A. nidus complex. No hybrid plants were obtained in crosses between nine of the 16 pairs. Even for pairs that generated hybrids, the frequency of hybrid formation was lower than expected given random mating, or only one group was able to act as the maternal parent, when the genetic distance (Kimura's two parameter) between parental individuals was at least 0.006. Sterile hybrids were produced by three pairs that were distantly related but capable of forming hybrids. Considering the results of the crosses together with the genetic distance between the parental individuals, it seems that the frequency of hybrid formation decreases rapidly with increasing divergence. The frequency of hybrid formation has not been previously examined in homosporous ferns, but it seems that a low frequency of hybrid formation can function as an important mechanism of reproductive isolation between closely related pairs of species in the A. nidus complex in addition to hybrid sterility. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 160 , 42–63.     

Effects of forestry on the thermal habitat of Dolly Varden (<Emphasis Type="Italic">Salvelinus malma</Emphasis>)

Forestry activities in riparian areas are known to affect stream communities considerably. Not only do riparian deforestation resulting from agriculture or urbanization developments affect stream communities but extensive commercial plantation and forestry practices can alter stream environments adjacent to remaining, intact or secondary forests. Because forestry often includes the construction of logging roads through the riparian zone, this can directly degrade stream environments. Twelve streams in the Shiretoko Peninsula, Hokkaido were investigated so as to determine the effects of forestry practices on stream temperature, periphyton biomass, grazer (benthic invertebrates) biomass and Dolly Varden (Salvelinus malma Walbaum) biomass. The greater the proportion of planted area in the catchment, the higher the stream temperature. Stream temperature directly affects periphyton biomass and Dolly Varden biomass negatively. Neither stream temperature nor periphyton biomass predicted grazer biomass, whereas a positive correlation was found between grazer biomass and Dolly Varden biomass that forage on invertebrates. The overall results indicated that Dolly Varden in the Shiretoko streams were negatively affected by forestry practices and the resultant stream temperature increases. Without effective future riparian forest management, the complex effects of both riparian disturbance and ongoing global warming could further reduce Dolly Varden populations in the region.