Fig. 1From: Prevalence of interspecific competition in a mixed poplar/black locust plantation under adverse climate conditionsSoil profiles for total N in the poplar (circles), black locust (diamonds), and mixed (triangles) plots before planting (open symbols) and 5 years later (closed symbols). Means ± standard errors, n = 2. Only soil depth was significant (**P ≤ 0.001)Back to article page