RESUMO
In ecological restoration, one of the main challenges is to develop new methods, techniques, and incentives that both favour and reduce maintenance costs in restoration projects. Besides, post-planting maintenance is often neglected hampering seedling survival over time owing to alien grasses, which compete strongly with native plants for resources. To solve these issues, recently, an innovative technology called Nucleário has been developed in Brazil. Aiming to hinder alien competition filters, the Nucleário also attempts to condition a better microenvironment, reducing drought stress through the water storage tank, decreasing temperatures, which facilitates the survival and growth of seedlings in areas under restoration. Another method used to decrease alien grasses, which is inexpensive, is seedling crowning using cardboard lowing maintenance needs in restored areas. Cardboard has similar functions to Nucleário, such as protecting soil against loss of water and nutrients and reducing competition with invasive exotic grasses. Therefore, comparing them also with traditional manual weeding (i.e., clean-weeded crown by hoe), we aimed to verify which technique is most cost-efficient for seedling crown maintenance of Dipteryx alata Vog., which is an indigenous tree species with high economic value owing to its nuts. We tested three techniques in areas under restoration in the Cerrado, in the Environmental Protection Area "Córrego Guariroba" located in Campo Grande, Mato Grosso do Sul, Brazil. We monitored seedlings submitted to the three methods in the wet and the dry periods for biotic (competition with exotic grasses, herbivory, and growth) and abiotic (moisture and soil temperature) indicators. We observed that the Nucleário was the treatment that maintained the highest soil moisture, resulting in a larger canopy area. However, these effects do not reflect increases in the survival rate, diameter, and height of the seedlings. None of the treatments was effective in reducing herbivory. Nucleário was the most effective treatment in reducing the competition of seedlings with invasive grasses. Cardboard presented an implementation value 21.5 times lower than Nucleário and 1.2 times than manual crowning. Given the high purchase price, the Nucleário's cost-benefit ratio was very high compared to the crowning of cardboard and the manual weeding, which discourages us from recommending it for this species with high survival rates. Its project can be revised to decrease herbivory rates, as well as its efficiency tested in the short and long term in different ecosystems and species, particularly species susceptible to water stress.
