Quantitative permeability imaging of plant tissues

A method for mapping tissue permeability based on time-dependent diffusion measurements is presented. A pulsed field gradient sequence to measure the diffusion encoding time dependence of the diffusion coefficients based on the detection of stimulated spin echoes to enable long diffusion times is combined with a turbo spin echo sequence for fast NMR imaging (MRI). A fitting function is suggested to describe the time dependence of the apparent diffusion constant in porous (bio-)materials, even if the time range of the apparent diffusion coefficient is limited due to relaxation of the magnetization. The method is demonstrated by characterizing anisotropic cell dimensions and permeability on a subpixel level of different tissues of a carrot (Daucus carota) taproot in the radial and axial directions

Seedling Establishment and Survival on Restored Campsites in Subalpine Forest

This study experimented with common restoration techniques (scarification, soil amendments, mulch, and seeding) on six closed wilderness campsites in subalpine forests in Oregon. Effectiveness in encouraging seedling establishment, growth, and survival was assessed every year for the first 7 years following treatment. Closure and restoration of the campsites increased the density of plants established from seed. Despite an original density of virtually zero, mean density of perennial plants was 55 plants/m2 7 years after closure. All the treatments, with the exception of the biodegradable mulch mat, increased plant density. Seven years after treatment, seeding had increased plant density 5-fold, whereas scarification and soil amendments (organic matter, compost, and soil inoculum) had each increased density 3-fold. The organic and compost amendments also had the positive benefit of increasing growth rates and shortening the time-to-reproductive maturity. Results suggest that restoration of the herbaceous cover on these campsites can occur rapidly using the techniques employed. All but one of the species we seeded established in substantial quantities and survived at densities exceeding their density in the naturally sparse herbaceous cover on these sites. Thirty-six perennial species volunteered on these sites. The remaining challenge is reestablishment of the shrub species that comprise much of the ground cover in these forests. These species seldom establish from seed