Dataset on light measuments in the understory of a Tropical forest restoration submitted to four thinning intensities through chemical management

The lack of information on the management of light in tropical forests causes a technical constraint for timber production in restoration sites, especially given the light restrictions for timber production. This issue could be amended with the development of methods to easily manage and estimate light availability, targeting  practices that balance restoration success and productivity. We conducted the study that gathered this data in an area within the Atlantic Forest, Brazil, where we tested the efficiency of chemical thinning fast-growing species to increase light availability in the understory of a five-year-old restoration planting. Our goal was to increase the growth rates of desirable timber species in the understory of the restoration site. Moreover, we tested the viability of using hemispherical photography taken with a smartphone to assess light incidence and assist restoration management practices. We calculated the percentage of photosynthetically active radiation (PAR) using a ceptometer in four different thinning intensities and compared them to the smartphone measures using correlation analysis and generalized mixed models. Chemical thinning increased light incidence in the understory Light management through PAR and canopy opening were highly correlated overall, especially after three months of management and above 60% of the basal area thinned. Data demonstrates the potential of chemical thinning as a management practice to enhance light availability in the understory of tropical forest restoration sites and highlights the value of using smartphones and fisheye clips for the indirect assessment of light conditions.