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Background Nutrient cycling in tropical forests has a large importance for primary productivity, and decomposition of litterfall is a major process influencing nutrient balance in forest soils. Although large-scale factors strongly influence decomposition patterns, small-scale factors can have major influences, especially in old-growth forests that have high structural complexity and strong plant-soil correlations. Here we evaluated the effects of forest structure and soil properties on decomposition rates and stabilization of soil organic matter using the Tea Bag Index (TBI) in an old-growth riparian forest in southeastern Brazil. These data sets were described separately using Principal Components Analysis (PCA). The main axes for each analysis, together with soil physical properties (clay content and soil moisture), were used to construct structural equations models that evaluated the different parameters of the TBI, decomposition rates and stabilization factor. The best model was selected using Akaike’s criterion. Results Forest structure and soil physical and chemical properties presented large variation among plots within the studied forest. Clay content was strongly correlated with soil moisture and the first PCA axis of soil chemical properties, and model selection indicated that clay content was a better predictor than this axis. Decomposition rates presented a large variation among tea bags (0.009 and 0.098 g·g− 1·d− 1) and were positively related with forest structure, as characterized by higher basal area, tree density and larger trees. The stabilization factor varied between 0.211–0.426 and was related to forest stratification and soil clay content. Conclusions The old-growth forest studied presented high heterogeneity in both forest structure and soil properties at small spatial scales, that influenced decomposition processes and probably contributed to small-scale variation in nutrient cycling. Decomposition rates were only influenced by forest structure, whereas the stabilization factor was influenced by both forest structure and soil properties. Heterogeneity in ecological processes can contribute to the resilience of old-growth forests, highlighting the importance of restoration strategies that consider the spatial variation of ecosystem processes.

Made available in DSpace on 2021-06-25T12:24:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-07-01 Pressing time and temperatures are factors that can influence positively briquettes durability characteristics. This work aimed to analyze physical-mechanical characteristics of sugarcane straw briquettes, produced with different pressing times and two briquetting temperatures, 26 degrees C and 100 degrees C. The characterization of the biomass was made through the tests of proximate analysis and higher heating value (HHV). It was used particles smaller than 1.70 mm and moisture content of 11.5%. Four types of briquettes/treatments were prepared with 15 replicates: A (control, 26 degrees C, 30 s), B (100 degrees C, 30 s), C (100 degrees C, 150 s), D (100 degrees C, 300 s). A hydraulic press was used to briquetting and a muffle was used to heating the cylindrical mold. The longitudinal expansion was measured 1, 2, 4, 6, 24, 48 and 72 hours after briquetting. Briquette resistance was performed by compression and friability test. The results were 80.87 % for volatiles, 5.41 % for ash content, 13.72 % for fixed carbon and 18360 J.g(-1) for HHV (in natura). The results showed that the use of temperature and the highest pressing time applied in briquetting increase the compressive strength, durability and density of the briquettes. Treatment D showed the greater resistance, apparent density and durability rating, which was 1.246 MPa, 0.979 g/cm(3), 84.41 %, respectively. Univ Fed Sao Carlos, Dept Ciencias Ambientais, Campus Sorocaba, BR-18052780 Sorocaba, SP, Brazil Univ Estadual Paulista, Dept Engn Mecan, Campus Guratingueta, BR-12516410 Guaratingueta, SP, Brazil Univ Estadual Paulista, Dept Engn Mecan, Campus Guratingueta, BR-12516410 Guaratingueta, SP, Brazil

Riparian forests suffered from forest fragmentation, which in turn promote the change in the pattern of seed dispersion and modification of soil seed bank. The aim of this study is to indicate the main species that make up the seed bank of a stretch of riparian forest of the Mogi Guaçu River continued to a fragment of semidecidual forest, located in the Air Force Base of Pirassununga. It was delimited ten plots of 10 x 10 m. Four soil samples was collected by plot with a 25 x 25 cm template. Samples were packed in greenhouse for seed germination and monitored every 15 days for six months. Altogether, 494 individuals from 19 families were sampled, distributed in 30 genera and 40 morphospecies. Diversity and distribution of species in the fragment is homogeneous and can be used as source of propagules for forest restoration. RESUMO Florestas ripárias sofrem com a fragmentação florestal, que promove mudanças no padrão de dispersão de sementes e modificação do banco de sementes. O objetivo do presente estudo é indicar as principais espécies que compõem o banco de semntes de um trecho de floresta ripária do Rio Mogi Guaçu River contínuo a um fragmento de floresta estacional, localizada na Guarnição da Aeronáutica de Pirassununga. Foram delimitadas dez parcelas de 10 x 10 m. Quatro amostras de solo foram coletadas através de um molde de 25 x 25 cm. Amostras foram mantidas em estufa para germinação de sementes e monitoradas a cada 15 dias por seis meses. Ao todo, 494 indivíduos pertencentes a 19 famílias foram amostrados, distribuídos em 30 gêneros e 40 morfoespécies. A diversidade e a distribuição das espécies no fragmento é homogênea, podendo ser usado como uma fonte de propágulos para restauração florestal.

Although the normative instruments of urban planning include the environmental impact assessment, there is a loosening of these laws due to public and private interests that have purposes contrary to environmental policies. In the municipality of Ribeirão Preto, coffee and sugarcane monocultures have contributed to the fragmentation of native vegetation, reducing it to 6% of the municipal area (4,200 ha). The Ecological Station of Ribeirão Preto (ESRP) is the larger native remnant (155 ha) and suffers pressures for being located in the urban environment. This work investigated the urban pressure in the Buffer Zone (BZ) and its relation to the changes in the Master Plan (MP) and complementary laws. The land cover maps (2010 and 2017) were also analyzed in order to quantify the conversion of native forests to anthropic uses, showing an intense urban expansion in the BZ over the period analyzed. On the other hand, municipal urban environmental legislation has evolved seeing that the previous MP (dated from 1995) approached the environment in a very specific way, which was modified in the 2018 law, which attempts to integrate the urban zoning to the buffer zone in order to make land use compatible with the ESRP Management Plan.