Functional-trait based restoration alters nutrient cycling and invasion rates in Hawaiian lowland wet forest

Many degraded ecosystems have altered nutrient dynamics, due to invaders possessing a suite of traits that allow them to both outcompete native species and alter the environment. In ecosystems where invasive species have increased nutrient turnover rates, it can be difficult to reduce nutrient availability. This study examined whether a functional-trait-based restoration approach, involving the planting of species with conservative nutrient-use traits, can slow rates of nutrient cycling and consequently reduce rates of invasion. We examined a functional trait restoration initiative in a heavily-invaded lowland wet forest site in Hilo, Hawai'i. Native and introduced species were chosen to create four experimental hybrid forest communities, in comparison to the invaded forest, with a factorial design in which communities varied in rates of carbon turnover (slow or moderate [SLOW, MOD]), and in the relationship of species in trait space (redundant or complementary [RED, COMP]). After the f..., Nutrient cycling metrics
Litterfall was measured as an index of productivity. Litter screens (40 cm x 40 cm, 1 mm mesh size) were placed in the plots along diagonal and crossed transect lines (n=20 per plot). Litter was collected monthly, bulked per plot, dried at 70°C for at least 48 hours, and then weighed. Starting in 2016, we separated out litter from the outplant species and sorted and weighed each species in order to calculate species-specific productivity and overall outplant contribution to the plots. Nutrients in the litterfall of outplant species were determined by grinding material in a Wiley mill (40 mesh), and then processing samples with a Costech CE Elemental Analyzer (Costech ECS 4010; Valencia, CA) to obtain the concentration of carbon (C) and nitrogen (N), and a Varian inductively coupled plasma spectrometer (Varian Vista-MPX inductively coupled plasma-optical emission spectrometry; Palo Alto, CA) to obtain the concentration of P. All nutrient analyses were conducted a..., ExcelÂ