Ten-Year Growth of Woody Species Planted in Reclaimed Mined Banks with Different Slopes

Abstract

In landscape reconstruction in an opencast coal mine, a gradient of slopes can be obtained. The slope gradient can affect different processes, such as plant growth, especially in semi-arid conditions. On the other hand, to favor the heterogeneity of habitats and ensure long-term restoration, late successional woody species have been planted but with heterogeneous results. In this study, the effect of a slope gradient (from 11.4 to 15.5 degrees) on the growth and survival of five Mediterranean woody species 10 years after the reconstruction of mining banks was evaluated. Slope gradient reduced height growth significantly from 10 cm degree⁻¹ (lentish) to 25 cm degree⁻¹ (pine) in 10-year-old woody species. This gradient also reduced basal diameter growth from 0.22 mm degree ⁻¹ (juniper) to 0.58 mm degree⁻¹ (pine). Survival and slope were not significantly correlated. Growth and survival of the 10-year-old woody species were equal to or higher than those of the same species in other afforestations in semi-arid conditions. This outcome demonstrates the adequacy of species and applied techniques of restoration that allow a long-term reliability of reclaimed mine slopes.

Keywords:

• northeast Spain
• opencast mine reclamation
• seedling survival
• woodland restoration (pine, oak, lentish, juniper)

Authors wish to express their thanks to the reviewers and Professors J. Cortina, A. M. Felicísimo, J. M. Nicolau, and J. Peñuelas.

Notes

Data in the same column followed by different letters are significantly different according to least significance differences test (P ≤ 0.05); mean ± standard deviation.

R ² = determination coefficient.

P = probability.

∗∗P < 0.01.

∗P < 0.05.

^a Height growth rate = (height at time 10 − height at time 0)/time 0.

Data in the same column followed by different letters are significantly different according to least significance differences test (P ≤ 0.05); mean ± standard deviation.

R ² = determination coefficient.

P = probability.

∗∗P < 0.01.

∗P < 0.05.

n.s.: not significant.

^a Diameter growth rate (DGR) = (diameter at time 10 − diameter at time 0)/time 0.

^a Runoff calculated by the Frevert method, considering 391 mm yr⁻¹ of rainfall.

^b Effective rainfall, Er = (rainfall − surface runoff).

^c Water deficit = ETP − effective rainfall.