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We analyzed critical life-history variables for two rare fire-dependent annual Geranium species in southern Sweden, which are today threatened because of effective fire suppression. At recently burned sites with abundant recruitment, seedlings occurred only where the humus layer had been completely removed by smoldering fire. Emergence depths ranged 1-6 cm in the mineral soil. Soil sampling at four sites revealed that in unburned soil Geranium seeds were located only in the mineral soil. Surprisingly, residual seeds were still present where fire had burned away the humus layer. An experiment showed that both species deposit seeds relatively evenly within a radius of 5-6 m, through ballistic dispersal. Repeated sampling in the field over a 2-year period after seed dispersal at one site indicated a low rate of seed depletion, corroborated by an indoor incubation of seeds. Our results show that successful management of these species depend on deep-burning prescribed fire, which can only result after severe drought. On the other hand, the seed bank is extremely long-lived, as viable seeds were present at a site last burned 200 years ago. This well-protected seed bank will likely buffer against both ill-timed fires and occasional failure in the recruiting seedling populations. [ABSTRACT FROM AUTHOR]

We describe an approach to form stimuli-responsive pressure-sensitive adhesive (PSA) films that are activated by thermal energy. This approach is used to form films that do not adhere on contact to any non-adhesive substrates. However, upon activation using heat as a stimulus, the films change irreversibly into PSA coatings. In order to develop this system, a PSA polymer emulsion stabilized by a novel low-molecular-weight polymeric stabilizer was synthesized. This emulsion was dried at ambient conditions to form films with a well-defined morphology with the PSA encapsulated by a protective matrix of polymeric stabilizer. This morphology is not thermodynamically stable and is disrupted when the temperature is elevated above the glass transition temperature of the protective polymeric stabilizer. Thermodynamically-driven rearrangement of the phases leads to the PSA migrating to and occupying the air–film interface. The impact of the amount and composition of the stabilizer in the PSA emulsion on emulsion stability, latency and stimulus response was explored. Supporting data for the proposed mechanism include TEM micrographs of the film morphology. [ABSTRACT FROM AUTHOR]