Introduction: Forest restoration in temperate and boreal zones

The role of different plantation tree species in soil nutrient cycling is of great importance for the restoration of degraded lands. The objective of the present study was to evaluate the potential of N-fixing and non-N-fixing tree species to recuperate degraded land in southern China. The soil properties and N transformations in six forest types (two N-fixing plantations, three non-N-fixing plantations and a secondary shrubland) established in 1984 were compared. The N-fixing forests had 40-50% higher soil organic matter and 20-50% higher total nitrogen concentration in the 0-5 cm soils than the non-N-fixing forests. Soil inorganic N was highest under the secondary shrubland. The N-fixing Acacia auriculiformis plantation had the highest soil available P. There were no significant differences in soil N mineralization and nitrification among the forest types, but seasonal variation in these N processes was highly significant. In the rainy season, the rates of N mineralization (7.41-11.3 kg N ha )1 month )1) were similar to values found in regional climax forests, indicating that soil N availability has been well recovered in these forest types. These results suggest that N-fixing species, particularly Acacia mangium, are more efficient in re-establishing the C and N cycling processes in degraded land in southern China. Moreover, the N-fixing species A. auriculiformis performed better than other species in improving soil P availability.

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“…2005). Thus, restoration at both regional and global scales is critical for the sustainability of the earth’s ecosystem (Gardiner et al. 2003).…”

Section: Introductionmentioning

confidence: 99%

“…However, millions of hectares of subtropical and tropical forests are being deforested or degraded as a result of human activities (Lamb et al 2005). Thus, restoration at both regional and global scales is critical for the sustainability of the earth's ecosystem (Gardiner et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Effects of nitrogen-fixing and non-nitrogen-fixing tree species on soil properties and nitrogen transformation during forest restoration in southern China

Wang

Hong

et al. 2010

Soil Science and Plant Nutrition

141

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“…Human activities have greatly changed land‐use patterns worldwide, with millions of hectares of land being deforested or degraded (Vitousek 1994). Thus, restoration at a global scale is critical for the sustainability of the earth ecosystem and the long‐term well‐being of humanity (Gardiner et al 2003). Afforestation of former agricultural land, rehabilitation of degraded natural ecosystems and conversion of single‐species to mixed‐species plantations are among the major types of restoration practices currently being implemented throughout the world (Lamb 1998).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen Mineralization and Leaching in the Early Stages of a Subtropical Reforestation in Southern China

Wang

Zhu

Hong

et al. 2010

Restoration Ecology

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Nitrogen cycling is a critical component in plantations, yet the spatial and temporal variations of N transformations in different stages of reforestation are often poorly known. Here we report the seasonal variation of soil in situ net N mineralization, net nitrification and N leaching in five young plantations (two monocultures of exotic species: Eucalyptus urophylla and Acacia crassicarpa; a native species monoculture; a 10-species mixture and a 30-species mixture) and a shrubland (without experimental planting) in subtropical southern China. Our results show that net N mineralization and nitrification rates in the E. urophylla monoculture (13.5 and 9.98 kg N ha −1 yr −1 , respectively) were the lowest among six planting treatments, less than 1/3 of those in the 10-species and 30-species mixtures. Two exotic fast-growing monocultures had 10-60% lower soil extractable nitrate concentrations than the native plantations and shrubland and had the lowest nitrogen leaching losses. The leguminous A. crassicarpa monoculture did not have higher soil N availability in comparison with non-leguminous species. Both N mineralization and nitrification varied seasonally; soil moisture seemed to be important in controlling these temporal variations. This study highlights that in the early stages of reforestaion, a better understanding of plant species effects on soil N cycling would be beneficial to forest management decisions and could provide a critical foundation for advancing restoration practices.

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