Nas comunidades vegetais, as plantas podem interagir de maneira positiva, negativa ou neutra. Essa á uma característica muito importante para garantir a sobrevivência, além de fornecer informações para construção de conhecimento e produtos a serem utilizados no controle específico de algumas plantas daninhas. O objetivo do trabalho foi realizar revisão bibliográfica sobre os efeitos da alelopatia em comunidades vegetais, podendo ser observado tanto nas competições intraespecífica quanto na interespecífica. Com base nos resultados da literatura é provável que os compostos alelopáticos possam alterar componentes do ecossistema que, por sua vez, conduzem processos e interações, as quais modificam a composição e dinâmica das comunidades vegetais. No entanto, uma grande lacuna na pesquisa da alelopatia recai sobre a inexistência de metodologias a serem aplicadas em campo que demonstrem o papel desses compostos no desenvolvimento interespecífico e ao longo da comunidade. Desse modo, faz-se necessário que os estudos levem em consideração quais as fontes de variação entre as espécies, os tipos de impactos causados nas espécies associadas e, principalmente, os seus efeitos em nível de comunidade.
Direct seeding is a promising and low-cost restoration technique. To avoid wasting seeds, the selection of species with high field performance in their establishment can increase efficiency. We aimed to identify groups of forest species with the ability for direct seeding in a seasonal forest, investigate taxonomic similarity effects on species behavior regarding seeds’ and seedlings’ early functional traits, and classify species based on their probability of success by direct seeding. A planting system of 38 seasonal forest species was implemented at a density of 250,000 seeds ha−1. The emergence was monitored over 720 days, and all individuals were identified, tagged, counted, and measured for height (H) and diameter at collar height (DCH). We evaluated early traits of seed vigor (field seed emergence), seedling performance, probability of success, and species autoecology. Species’ ability for direct seeding was more related to the level of species phylogeny than to their family. Pioneer and non-pioneer species demonstrated similar abilities for direct seeding associated with field emergence, seedling abundance, and persistence. Field seed emergence traits influenced species’ ability for direct seeding more than seedling survival or growth. Species’ ability for direct seeding was related to early seed vigor traits expressed by field seed emergence and was independent of their density.
A pandemia SARS-Cov-2 estabeleceu a necessidade de adoção de medidas restritivas para conter a disseminação do vírus. Em 2021, devido ao elevado número de casos de COVID-19 no município de Araraquara, Brasil, e após o esgotamento das vagas hospitalares em 2021, foi anunciado um bloqueio. Analisamos o efeito do distanciamento social dessa cidade, utilizando dados fornecidos pela prefeitura municipal ao longo de um período total de 90 dias. Usamos esses dados em uma tabela de vida, uma importante ferramenta que avalia o impacto de doenças na dinâmica populacional de uma espécie. Os resultados indicaram uma taxa básica de mortalidade de 0,0138 no período analisado e uma redução considerável no número de casos infectados e óbitos por COVID-19 após 24 dias de isolamento. Nossos resultados mostraram a eficácia do distanciamento social em conter a propagação da doença, com redução de 80% no número de óbitos, bem como a utilidade da tábua de vida como ferramenta útil para análise de dados.
In Brazil, most degraded areas are occupied by exotic and invasive species, which require alternatives for their management. We evaluated the allelopathic effects of Waltheria indica in the laboratory from aqueous extracts of leaves and roots on the germination of the species Lactuca sativa L. (lettuce), Urochloa brizantha (Hochst. ex A.Rich.) RDWebster (brachiaria) and Handroanthus chrysotrichus (Mart. ex DC.) Mattos (yellow Ipe). We collected adult one-year-old Waltheria indica shrubs in ecological restoration areas by direct seeding. We used two treatments with aqueous extracts of leaves and roots and a control without extract, with ten repetitions of 10 seeds per treatment, totaling 600 seeds per test species. Germination and use of tetrazolium assays to evaluate the potential respiratory activity of the roots were used. The aqueous extract of W.indica leaves affected the number of germinated seeds of all test species, while the aqueous extract of roots affected only L. sativa and H. chrysotrichus. There were no significant differences between treatments (leaf and root extracts) in species germination. The aqueous extracts of Waltheria indica leaves and roots affected germination and cellular respiration of the studied species, mainly in Lactuca sativa. The identification of W. indica allelopathic compounds may be an initial step so that in the future new bioherbicides are produced from extracts of this species, or even that its seeds can be sown together with non-sensitive native species, aiming for control of exotic species in ecological restoration projects.
We evaluated band planting (BP) to assess its efficiency in the early restoring of ecological processes using a multi-criteria protocol known as Framework for the Evaluation of Natural Resource Management Systems Incorporating Sustainability Indicators (MESMIS) to obtain the ecological functionality consolidation index (EFCI). We sampled a 4.3 ha-1 plantation, aged 3 years, with BP, 1.5-m space between bands, 2-m space between seedlings, and a 3.5-m band of natural regeneration, ten areas with conventional planting (CP), aged 5 years, in the coverage and diversity models, and ten areas restored by natural regeneration (NR), aged 4 years. Sampling was carried out in 36 10 m x 10 m blocks, totaling 144 plots, 15 blocks for BP, 11 blocks for CP, and 10 blocks for NR. Species richness was similar between the areas; however, there was a significant difference between BP and the other areas (CP and NR) by the Dunn’s test (p < 0.05). The NR area had the highest diversity (H' = 3.03; J' = 0.76), followed by BP (H' = 2.56; J' = 0.62), and CP (H' = 2.0; J' = 0.48), whereas the BP area (4.348 ind.ha-1) had the highest density. The BP had the highest EFCI for diversity (0.100), control, and management (0.067) compared to NR, for diversity (0.022), and similar to CP in soil protection and nutrient cycling (0.047). BP was efficient in recovering early ecological processes under conditions similar to fragments in the initial stage of succession.
Pre-emergent herbicides can contribute to the control of weed competition in direct seeding restoration, however it is necessary to evaluate their effects on seeds of native tropical forest species. The aim of the study was to assess the potential impact of the herbicide indaziflam on the germination of 17 forest species. For this, a dosage of 180 mL of the product in 200L of water was compared to the control without herbicide. The degree of sensitivity of each species was calculated by a ratio between the percentage of germination with herbicide (GH) and the control without herbicide (GC) classifying them as: extremely sensitive (ES= (GH/GC) <0.25), sensitive (S=0.25< (GH/GC) <0.50), low sensitivity (LS=0.50< (GH/GC) <0.75), indifferent (I=0.75< (GH/GC) <1.0) and potentiated (P= (GH/GC) >1). The herbicide promoted a significant reduction in mean germination in 35% (n=6) of the species and 59% (n = 10) were sensitive or extremely sensitive to indaziflam, and only three did not germinate. On the other hand, 29.4% (n=5) showed low sensitivity or indifference to the herbicide, while seed germination was slightly increased by indaziflam to 11.7% (n=2). Pre-emergent indaziflam can be recommended in direct seeding restoration, as only 17.6% (n=3) of the species were inhibited by pre-emergent. However, the effect of indaziflam varies by species and requires further studies to support large-scale use in direct seeding.
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