Effects of afforestation with Eucalyptus grandis on soil physicochemical and microbiological properties

Abstract

It is generally believed that plantations of Eucalyptus bring about a decrease in soil fertility. Soil physicochemical and microbiological properties were measured across a range of E. grandis plantation ages (1–10 years) in south-western China to determine whether and how eucalypt afforestation of agricultural land affected the soil fertility. The results indicate that afforestation with E. grandis caused changes in soil properties with soil depth, and the changes were dependent on the stand age. Soil bulk density decreased significantly, but water-holding capacity increased significantly with time. Soil organic matter content, C : N ratio, and soil microbial biomass C and N concentrations showed an initial phase of decline and then increased significantly over time in the upper soil layers of E. grandis plantations aged from 1 to 4 or 5 years. Soil pH in E. grandis plantations did not change significantly with stand age or soil layer. Cation exchange capacity in the upper soil layer of E. grandis plantations increased significantly over time. Total exchangeable bases and base saturation in the soil decreased significantly with depth and with increasing plantation age. Furthermore, E. grandis afforestation of arable soils had no significant effects on total N, total P, and available P contents. The requirements of the trees, understory microenvironmental conditions, and allelopathic effects might play important roles in the dynamic changes of soil physicochemical and microbiological properties. The results demonstrate the progressive development of processes that lead to the restoration of soil fertility following E. grandis afforestation of arable soils. However, most of the properties measured for the afforested soils resembled the properties of arable soils and did not resemble those of the soil of control forests. Thus, reversion of soil properties in the study plantations is likely to require a considerable period of time. Long-term research is needed to understand changes in the soil properties resulting from afforestation with Eucalyptus and to predict future trends.

Soil Enzymatic Activity in Eucalyptus Grandis Plantations of Different Ages

“…In general, the results show that soil enzymatic activities reaches the values observed in the native forest after 3 years of plantation, indicating improvement of these properties with time of reforestation. The results obtained in our work and that of Zhang et al (2012) contrast with the general ideas about negative short-time effects of Eucalyptus plantation in the soil. In a more recent paper, Zhang et al (2015) observed that converting Pinus to Eucalyptus plantations produced a significant decrease in soil quality in the first and second generations, but the soil partially recovered in the following third and fourth generations.…”

“…The results obtained in our work and that of Zhang et al . () contrast with the general ideas about negative short‐time effects of Eucalyptus plantation in the soil. In a more recent paper, Zhang et al .…”

“…Possible changes in the soil caused by the establishment of Eucalyptus plantations have been investigated globally (Mendham et al, 2002;Behera & Sahani, 2003;Sicardi et al, 2004;Lemma et al, 2006;Turner & Lambert, 2008). Recent studies have also been conducted in Brazil and China but the results are inconclusive (Fialho & Zinn, 2012;Zhang et al, 2012;Wu et al, 2013) due perhaps to differences between the studied areas in terms of climate, soil properties, species of Eucalyptus and management practices (Zhang et al, 2015).…”

Plantation age, understory vegetation, and species‐specific traits of target seedlings alter the competition and facilitation role of Eucalyptus in South China

“…The microenvironment in a Eucalyptus plantation improves gradually with increasing age. Soil physical traits such as SBD and soil water content will be ameliorated (Zhang et al ; Wu et al ). The available N, P, K, and cation exchange capacity in the upper soil will be improved (Mohsin et al ; Zhang et al ), and the soil microbial biomass C and N concentrations will also increase accordingly (Zhang et al ), as well as the arbuscular mycorrhizae (Wu et al ).…”

Soil functions and ecosystem services research in the Chinese karst Critical Zone

“…The soil properties of former cropland in secondary forest are slowly modified towards conditions found in native forests because of a lack of intense cultivation (i.e. high fertilization rates, annual tillage, weed control) along with progressive vegetation succession (Zhang et al 2012). In the initial phase of regeneration, former cultivated land retains an increased N status as a legacy of former fertilization, which supports persistent, relatively increased rates of mineralization and nitrification (Jug et al 1999) but which is predicted to change over time as the source of N in soils switches from inorganic fertilisers to biological fixation.…”