Selection of shade trees in forest restoration plantings should not be based on crown tree architecture alone

Abstract

The planting of tree seedlings is a common restoration technique in the tropics, and using large-crowned, fast-growing shade species is recommended to suppress invasive grasses and accelerate forest succession. We analyzed the effectiveness of shade species in shading the forest floor during the rainy and dry seasons at young forest restoration sites, whether shade changes according to site for a given species, and whether crown architecture can predict the shade level. We measured the photosynthetically active radiation (PAR) intercepted by the tree crowns of 14 species in two 3-year-old restoration plantings. The ability to predict shade based on crown architecture traits was evaluated using multiple linear regressions. The interception of PAR varied according to species, site, and season for seven species and was generally higher during the rainy season. Low values of tree and first branch height and high values of trunk diameter and mean area of a leaf predicted greater light interception. For the dry season, the ability to predict PAR interception was weaker than that for the rainy season and affected by a shorter tree height and a greater crown area. The crown architecture of shade species did not completely predict their shading ability, and the preselection of shade species for forest restoration purposes based only on crown architecture traits is not effective. Therefore, it is important to consider other factors, such as how long trees retain their leaves throughout the year and the soil and management conditions of the sites undergoing restoration, during the selection of species.

Large canopy and animal‐dispersed species facilitate natural regeneration in tropical forest restoration

“…Species traits are also a better predictor of the microclimatic conditions under the canopy, e.g. tree height and height of branching are closely related light interception, as observed by Almeida and Viani (2019). Animal-dispersed species attract fauna that will bring other animal-dispersed seeds to restoration sites, creating a positive feedback that contributes to forest persistence (Lameira et al 2019).…”

“…While other studies have separately approached the role of dispersal syndrome (e.g. Viani et al 2015), deciduousness (Gandolfi et al 2009), and canopy size and light interception (Almeida & Viani 2019) and species composition (G omez-Aparicio et al 2005), our study is one of the few in identifying their simultaneous role in facilitating natural regeneration. Canopy cover had an additive effect with animal dispersal and deciduousness for facilitating regenerating seedlings, but it is a poor predictor by itself (e.g.…”

“…Species in which the mean value for a given indicator falls within 1 SE interval for the best-ranked species for that indicator belong to the first group; the first species in which the mean falls outside the standard error interval of the first ranked species will serve as the baseline for group 2, and so forth. characteristics, such as tree height and crown format (Almeida & Viani 2019), as well as species traits, such as leaf specific area, deciduousness, and leaf area index (Gandolfi et al 2009). The shading of evergreen trees may favor the development of more diverse taxa under their canopy, probably reducing water stress compared to deciduous trees that lose leaves during the dry season (Gandolfi et al 2009).…”

“…Alternatively, other drivers of restoration fate, such as planted species composition and traits, can be more easily manipulated in restoration projects and influence restoration success (Fink et al 2009; Martínez‐Garza et al 2013; Schweizer et al 2015; Holl et al 2020). Planted species' traits affect light interception (Almeida & Viani 2019), native tree recruitment and development (De Pena‐Domene et al 2016; Galindo et al 2017; Li et al 2018), seed dispersal visitation (Fink et al 2009), and community resilience (Timpane‐Padgham et al 2017). In other words, the differential structure and resources provided by the diverse species planted will affect the dispersal limitation, composition, abundance, and diversity of the natural regeneration (Li et al 2018; Camargo et al 2020), which in turn will affect ecological processes (Lanuza et al 2018) and future forest composition.…”

Framework Species Approach Proves Robust in Restoring Forest on Fire Prone Invasive Grass: A Case Study from Panama

“…As a case study, the individual species that were planted for successful restoration are not the most important conclusion of this study as the species that can achieve the desired framework-role will be very different across areas (de Almeida & Viani, 2019). It is the way of approaching the selection of species for similar reforestation projects that was shown to work: even though the business-as-usual approach seems to perform well, including important framework species can markedly improve restoration success.…”