盐胁迫对巴西盾柱木幼苗生长的影响

利用不同渗透势的NaCl、CaCl2、KCl、Na2SO4溶液对巴西盾柱木(Peltophorum dubium)幼苗进行胁迫处理,研究盐胁迫对其幼苗生长状况的影响,结果表明:随着溶液渗透势的增加,对根和茎生长的抑制作用增强;子叶的干物质量在多数情况下是随着溶液浓度的增加而增加;根的长度和干物质量与总长度和总干物质量的比例一般与胁迫程度呈正相关关系,有利于其根系深入到盐胁迫程度较低的土壤深层。根的生物量和长度与非盐逆境相比,其值较低,说明其对盐逆境的生态适应能力较弱;CaCl2对巴西盾柱木幼苗生长胁迫程度最高,其次是Na2SO4和NaCl,KCl胁迫,对幼苗影响较小。巴西盾柱木的自然生长环境Ca2 含量较高,可能是巴西盾柱木不适应盐逆境的主要原因。     

Protected areas and native freshwater bivalves are not in the same place in south-east Brazil

1. Bivalves are important components of freshwater ecosystems; however, they are also one of the most threatened animal groups, especially members of the order Unionida. The main threats to freshwater bivalves are habitat modification and invasive species. Protected areas are a common way to minimize impacts and preserve native species, but they are rarely designated with a focus on freshwater invertebrates.
2. The main goal of this article was to describe the distribution of freshwater bivalves in the state of Rio de Janeiro, and the relationship between these species and bioclimatic areas, land use and protected areas.
3. Five native and two invasive bivalve species have been reported in Rio de Janeiro. They occur mainly in bioclimatic areas related to the Paraíba do Sul River and Campista Lowlands. The few records of bivalves inside protected areas are in areas of sustainable use that offer a lower level of protection, and frequently in sympatry with invasive bivalves.
4. Thus, the established protected areas in Rio de Janeiro are not adequately effective for freshwater bivalve conservation, and some species remain under threat even within them. Freshwater bivalves thus remain largely unprotected in the state.
5. The development of new protected areas and management plans should consider other faunal groups that are usually ignored, such as freshwater bivalves, to achieve more inclusive and effective protection.