A cost–benefit evaluation of direct seeding with and without protector for two native tree species in a tropical rainforest

Abstract

A priority in restoration research is to seek methods that reach high levels of plant establishment at the lowest possible cost. Here, we test how direct seeding works with and without a plastic protector that covers seeds and seedlings in an early-successional rainforest in Veracruz (Mexico). Two native species, Calophyllum brasiliense (barí) and Vochysia guatemalensis (corpo), at three topographic positions, were used. Germination rates with and without the protector were 84 versus 79% for C. brasiliense, and 98 versus 89% for V. guatemalensis, respectively. The protector significantly improved the germination only of V. guatemalensis. Plant survivorship of V. guatemalensis 27 months after seeding was significantly higher with the protector (78%) than without it (46%). For C. brasiliense, there were no differences in survivorship after 22 months with (61%) and without (54%) protector. In both species, the protector had no effect on height growth, which was significantly larger for seedlings located at the toeslope position. We developed a cost-benefit model that provides a threshold value at which the investment for protectors is justified by a resulting higher survivorship: If 27 months after seeding a treelet of V. guatemalensis is worth at least 0.83 USD on our sites, then the effect of the protector is worth the cost of its implementation (for C. brasiliense, survivorship was statistically undistinguishable with and without protector). We suggest that direct seeding with a plastic protector could be a promising alternative for forest restoration with suitable tree species. Implications for Practice• For direct seeding, the use of inexpensive plastic protectors for seeds and seedlings can enhance the germination and survivorship, without negatively affecting the height growth of the seedlings. • The employment of a simple cost-benefit model helps to evaluate the convenience of a given restoration strategy, even when benefits are not quantified in monetary terms.

Transplanting naturally regenerated tree seedlings for tropical forest restoration: a case study of Calophyllum brasiliense and Vochysia guatemalensis in Mexico

“…Specifically, our experimental plots were located at three topographic positions of one of those low hills (toeslope, backslope, and crest). A detailed study of soil properties is described in Prieto‐Rodao et al (2019): all plots had acid soils (with pH <5.5), loamy textures, and similar cation exchange capacity at the three topographic positions; the crest plots presented the highest acidity and exchangeable aluminum, whereas the toeslope had the highest available water holding capacity along the year.…”

“…A relatively inexpensive option for active forest restoration is direct seeding, which has been used in a number of tropical species (see, for instance Cole et al 2011; Bertacchi et al 2016). The success of this strategy is often limited by the low percentages of germination and survival (Ceccon et al 2016), though it may increase with the use of some kind of seed and seedling protector (García‐Orth & Martínez‐Ramos 2008; Prieto‐Rodao et al 2019). The plantation of nursery‐raised seedlings into degraded areas has been frequently used for forest restoration in the tropics, but the costs of this propagation method may be high (Douterlungne et al 2015; Atondo‐Bueno et al 2018).…”

“…Both species are abundant in the understory of old‐growth forests, and have been observed to produce dense carpets of seedlings after peaks of fruit production. We applied a cost–benefit model to compare the initial costs and subsequent survival of the transplantation strategy with the results obtained in Prieto‐Rodao et al (2019) for the same species with a direct seeding strategy. Specifically, first we aimed to evaluate the survival, growth, and damage by herbivores of transplanted naturally regenerated seedlings from old‐growth forest patches into a nearby secondary forest.…”

Avaliação de nucleários como técnica de restauração florestal em Mariana, MG, Brasil

“…Algumas técnicas alternativas têm sido utilizadas, como polímeros hidroretentores (hidrogel), valorizados por sua capacidade de absorver e armazenar água próximo à rizosfera (Navroski et al, 2014;Ahmed, 2015), o uso de formicidas, para controlar as populações de formigas cortadeiras e coroamentos manuais e roçadas mecânicas, para diminuir a matocompetição (Silveira et al, 2013;Santos et al, 2020). Contudo, ainda existe a necessidade de se aplicar técnicas sustentáveis e de baixo custo na manutenção das mudas durante o pós-plantio (Prieto-Rodão, 2018). Assim, a criação de novas tecnologias tem sido uma prioridade nas pesquisas de restauração.…”

Osmotic treatment, growth regulator and rooter in Tabebuia roseoalba (RIDL.) Sandwith seeds for direct sowing

“…Reforestation usually falls into three main categories: assisted natural regeneration, direct seeding, and planting seedlings by tubestock (Greening Australia Victoria, 2003). The choice between different restoration strategies depends in part on a compromise between effectiveness and cost (Prieto-Rodao et al, 2019). In recent years, direct seeding of native trees has been used as a low-cost alternative for restoration (Engel and Parrotta, 2001;Wallin et al, 2009;Ceccon et al, 2016).…”