Background and aims The addition of biochar to soil may offer a chance to mitigate climate change by increasing soil carbon stocks, improving soil fertility and enhancing plant growth. The impacts of biochar in cold environments with limited microbial activity are still poorly known. Methods In order to understand to what extent different types and application rates of biochar affect carbon (C) and nitrogen (N) fluxes in boreal forests, we conducted a field experiment where two different spruce biochars (pyrolysis temperatures 500°C and 650°C) were applied at the rate of 0, 5 and 10 t ha-1 to Pinus sylvestris forests in Finland. Results During the second summer after treatment, soil CO2 effluxes showed no clear response to biochar addition. Only in June, the 10 t ha-1 biochar (650°C) plots had significantly higher CO2 effluxes compared to the control plots. The pyrolysis temperature of biochar did not affect soil CO2 effluxes. Soil pH increased in the plots receiving 10 t ha-1 biochar additions. Biochar treatments had no significant effect on soil microbial biomass and biological N fixation. Nitrogen mineralization rates in the organic layer tended to increase with the amount of biochar, but no statistically significant effect was detected. Conclusions The results suggest that wood biochar amendment rates of 5-10 t ha-1 to boreal forest soil do not cause large or long-term changes in soil CO2 effluxes or reduction in native soil C stocks. Furthermore, the results imply that biochar does not adversely affect soil microbial biomass or key N cycling processes in boreal xeric forests, at least within this time frame. Thus, it seems that biochar is a promising tool to mitigate climate change and sequester additional C in boreal forest soils.

This study aimed to analyze the physical properties of the seeds of Moquiniastrum polymorphum when processed by mini-SAS, X-ray and seed blower systems. The seeds were purchased from Seeds Caiçara, located in Penápolis-SP. After purchase, the seed lot was characterized by standard tests. In the X-ray test the seeds were classified according to their internal morphology as filled, unfilled or malformed. The seed blower was set at six opening settings, resulting in light and heavy fractions. The evaluations were performed by weighing the seeds that remained in the blower (heavy fraction) and by the amount of filled seeds indicated by the X-ray test. The germination tests were composed of four replicates of 50 seeds. The mini-SAS was used for external evaluation. It was concluded that the combined use of the seed blower and the X-ray test was efficient for the evaluation and determination of the physical quality of the seeds of M. polymorphum. The seed blower at opening settings 5 resulted in the best lot quality. The external parameters were not able to qualitatively evaluate the seeds of M. polymorphum.

Resumo: A matocompetição é um dos fatores mais importantes quando se trata de alterações do grau de interferência em plantios florestais, tendo em vista aspectos técnicos como diferentes espécies, sua distribuição e densidade, fatores que embasam as medidas de controle. Objetivou-se, com este estudo, avaliar a influência da matocompetição de capim-braquiária (Urochloa brizantha) no crescimento inicial de espécies florestais em plantio misto. A pesquisa foi realizada em uma área de 1,13 hectares localizada no Instituto Federal de Educação, Ciência e Tecnologia do Espírito Santo (IFES), câmpus de Alegre, ES, e as espécies florestais implantadas foram Cariniana legalis, Joannesia princeps, Pterigota brasiliensis e Toona ciliata. Foram analisados o índice de sobrevivência e as características morfológicas altura total, diâmetro do colo e diâmetro da copa aos 11 e 22 meses após plantio. Os tratos culturais da matocompetição foram controlados até 11 meses de plantio e cessados nos meses seguintes. Com base na análise dos dados, concluiu-se que as espécies implantadas apresentaram crescimento inicial positivo aos 11 meses após plantio com o capim-braquiária controlado, e apenas a Toona ciliata e Joannesia princeps apresentaram crescimento aos 22 meses após plantio sem controle desse capim, sendo estas as que resultaram nos maiores crescimentos das características morfológicas e na sobrevivência em campo.