Soil organic carbon and nitrogen pools drive soil C-CO2 emissions from selected soils in Maritime Antarctica

The ongoing trend of increasing air temperatures will potentially affect soil organic matter (SOM) turnover and soil C-CO2 emissions in terrestrial ecosystems of Maritime Antarctica. The effects of SOM quality on this process remain little explored. We evaluated (i) the quantity and quality of soil organic matter and (ii) the potential of C release through CO2 emissions in lab conditions in different soil types from Maritime Antarctica. Soil samples (0–10 and 10–20 cm) were collected in Keller Peninsula and the vicinity of Arctowski station, to determine the quantity and quality of organic matter and the potential to emit CO2 under different temperature scenarios (2, 5, 8 and 11 °C) in lab. Soil organic matter mineralization is low, especially in soils with low organic C and N contents. Recalcitrant C form is predominant, especially in the passive pool, which is correlated with humic substances. Ornithogenic soils had greater C and N contents (reaching to 43.15 g kg^− 1 and 5.22 g kg^− 1 for total organic carbon and nitrogen, respectively). C and N were more present in the humic acid fraction. Lowest C mineralization was recorded from shallow soils on basaltic/andesites. C mineralization rates at 2 °C were significant lower than at higher temperatures. Ornithogenic soils presented the lowest values of C-CO2 mineralized by g of C. On the other hand, shallow soils on basaltic/andesites were the most sensitive sites to emit C-CO2 by g of C. With permafrost degradation, soils on basaltic/andesites and sulfates are expected to release more C-CO2 than ornithogenic soils. With greater clay contents, more protection was afforded to soil organic matter, with lower microbial activity and mineralization. The trend of soil temperature increases will favor C-CO2 emissions, especially in the reduced pool of C stored and protected on permafrost, or in occasional Histosols

As Leguminosae arbóreas das florestas estacionais do Parque Estadual do Itacolomi, Minas Gerais, Brasil

Este estudo consiste do tratamento taxonômico das Leguminosae arbóreas das florestas estacionais do Parque Estadual do Itacolomi (PEI). As coletas de material botânico ocorreram mensalmente, entre setembro de 2004 e novembro de 2005, ao longo de oito trilhas distribuídas em áreas de florestas estacionais submontana, montana e altimontana. O levantamento resultou em 39 táxons reunidos em 22 gêneros e distribuídos entre as três subfamílias: Caesalpinioideae (9 espécies), Mimosoideae (17) e Papilionoideae (13). Os gêneros mais representativos foram Inga (8 espécies), Machaerium (4), Senna e Dalbergia (3, cada), Abarema, Anadenanthera e Tachigali (2, cada). Bauhinia, Cassia, Copaifera, Melanoxylon, Calliandra, Mimosa, Piptadenia, Pseudopiptadenia, Stryphnodendron, Andira, Bowdichia, Ormosia, Platypodium, Pterocarpus e Swartzia apresentaram uma espécie cada. Ormosia friburgensis e Tachigali friburgensis são registradas pela primeira vez para o estado de Minas Gerais. São fornecidos chave de identificação, descrições, ilustrações, dados fenológicos, comentários taxonômicos e preferência por habitats de cada táxon no PEI.This study presents the taxonomic treatment of woody Leguminosae in seasonal forests of Itacolomi State Park (PEI). Botanical material was collected monthly, from September 2004 to November 2005, along eight trails in submontane, montane and upper montane seasonal forests. Woody Leguminosae were represented by 39 taxa in 22 genera distributed among the three subfamilies: Cesalpinioideae (9 species), Mimosoideae (17), and Papilionoideae (13). The most representative genera were Inga (8 species), followed by Machaerium (4), Senna and Dalbergia (3 each), Abarema, Anadenanthera, and Tachigali (2 each). Bauhinia, Cassia, Copaifera, Melanoxylon, Calliandra, Mimosa, Piptadenia, Pseudopiptadenia, Stryphnodendron, Andira, Bowdichia, Ormosia, Platypodium, Pterocarpus, and Swartzia were represented by one species each. Ormosia friburgensis and Tachigali friburgensis are reported for the first time in Minas Gerais state. Analytical key, descriptions, illustrations, data on phenology, and comments on taxonomy and preferred habitat in PEI are provided for all taxa