Identification and characterization of two new Gymnosporangium species causing rust on Juniperus rigida in China.

A serious Juniperus rigida rust disease was found in Gansu Province, China. The disease incidence is approximately 80-90%. We also found rust disease on both Cotoneaster multiflorus and Sorbus in the same location. Two novel Gymnosporangium species were identified from the infected plants. Based on morphological observations and phylogenetic analyses, we describe the two new taxa as G. gansuense and G. granulatosporum. We also determined their life cycles. Moreover, this study documented a novel aeciospore surface structure with two different surface types on one aeciospore. We describe it here as "granular."

Diverging shrub and tree growth from the Polar to the Mediterranean biomes across the European continent.

Climate warming is expected to enhance productivity and growth of woody plants, particularly in temperature-limited environments at the northernmost or uppermost limits of their distribution. However, this warming is spatially uneven and temporally variable, and the rise in temperatures differently affects biomes and growth forms. Here, applying a dendroecological approach with generalized additive mixed models, we analysed how the growth of shrubby junipers and coexisting trees (larch and pine species) responds to rising temperatures along a 5000-km latitudinal range including sites from the Polar, Alpine to the Mediterranean biomes. We hypothesize that, being more coupled to ground microclimate, junipers will be less influenced by atmospheric conditions and will less respond to the post-1950 climate warming than coexisting standing trees. Unexpectedly, shrub and tree growth forms revealed divergent growth trends in all the three biomes, with juniper performing better than trees at Mediterranean than at Polar and Alpine sites. The post-1980s decline of tree growth in Mediterranean sites might be induced by drought stress amplified by climate warming and did not affect junipers. We conclude that different but coexisting long-living growth forms can respond differently to the same climate factor and that, even in temperature-limited area, other drivers like the duration of snow cover might locally play a fundamental role on woody plants growth across Europe.