Can transplanting seedlings with protection against herbivory be a cost-effective restoration strategy for seasonally flooded environments?

Abstract

Transplantation of naturally regenerating seedlings (hereafter wildlings) has great potential as a restoration tool as it involves the use of acclimatized individuals and preservation of local and endemic genotypes. When successfully used, this technique has the added benefits of increasing structural and compositional diversity, preserving local and endemic genotypes, and reducing ecological restoration costs. In wetland ecosystems, flooding is an abiotic filter that may hinder success of restoration efforts. We hypothesized that transplanting “ecologically toughened” wildlings from low-lying, flooded areas into restoration areas of higher relief and lower frequency of flooding, would be a successful strategy. In this study, we transplanted wildlings from periodically flooded areas upslope to test the effect of topographic position (where they were collected and outplanted), and protection against herbivory on seedling survival and growth. The experimental design included two collection times and planting areas (high and low topography), two seedling height, use of protection against mammalian herbivory, and four species that represent different functional types. We also evaluated the costs involved. The best experimental outcome for the four study species (most abundance floodplain species) was found with small seedlings (10–39 cm) collected at low relief and outplanted to higher elevations, with protection against herbivory. Even under unusually extreme flood events (high flooding over 7 months) the tree legume Inga vera has emerged with the highest survival rate. The costs of transplantation are lower (USD 739 ha−1) than those found in previous studies and the use of protection against herbivory was also considerably low (USD 2484 ha−1). That said, these estimated costs are on an experimental scale and do not represent large-scale operations, which could reduce and improve cost-benefits significantly. In remote places such as the Pantanal, the lack of nursery infrastructure, high associated costs of seedling production and vulnerability to herbivory are the main challenges for restoration. Hence, wildling collection can be a useful strategy to overcome such obstacles.