| To increase wetland area and biodiversity, agencies constructed >220 depressional wetlands throughout Delaware. During wetland construction, they included amendments thought to increase wetland diversity [coarse woody debris (CWD), microtopography, and organic matter]. Because the efficacy of amendments is unknown, I investigated their effects on anuran, avian, macroinvertebrate, and vegetative communities. I also investigated the effects of landscape variables within 1,000 m and 5,000 m of wetlands on each community. I selected 20 standardized wetlands in which 5 contained CWD and microtopography amendments, 5 had neither, 5 had CWD but no microtopography, and 5 had microtopography but no CWD. Additionally, 12 wetlands received organic matter amendments. CWD increased insect biomass (P = 0.046), total plant richness (P = 0.038), and obligate wetland plant richness (P = 0.015). Microtopography increased total (P = 0.035) and facultative wetland ( P = 0.034) plant richness, and bird richness (P = 0.023). Although organic matter amendments did not result in greater percent soil organic matter, they increased insect richness (P = 0.020) and diversity (P = 0.033), and macroinvertebrate biomass (P = 0.024). Additionally, bird abundance (P = 0.045, r2 = 0.10), insect richness (P = 0.010, r2 = 0.16), and insect (P = 0.023, r2 = 0.13), Ephemeroptera (P = 0.027, r 2 = 0.12), and Odonata biomass (P = 0.046, r 2 = 0.10) increased with CWD volume. Green frog (Rana clamitans ) relative abundance increased with microtopographic variation ( P = 0.001, r2 = 0.26). Green frog abundance ( P = 0.029, r2 = 0.12), bird richness (P < 0.001, r2 = 0.34), bird abundance (P = 0.008, r2 = 0.17), and total (P = 0.027, r2 = 0.12), native (P = 0.036, r2 = 0.11), and FACW (P = 0.001, r2 = 0.24) plant richness increased with percent soil organic matter. I detected negative relationships with distance to nearest forest and anuran richness (P = 0.025), bird richness (P = 0.004), bird diversity ( P < 0.001), total plant richness (P = 0.003), facultative wetland plant cover (P = 0.038), and native ( P = 0.008; P = 0.023), exotic (P = 0.043; P = 0.022), and obligate wetland (P = 0.001; P = 0.024) plant richness and cover. Furthermore, bird richness (P = 0.029) and diversity (P = 0.001) increased with forest area within 1,000 m and bird diversity increased with forest area within 5,000 m (P = 0.001). To optimize wetland biodiversity, future constructed wetlands in Delaware should contain CWD, microtopography, and organic matter amendments and should be located near forests. |
