**1. Introduction**

Most of the slope soils in the tropical region such as in Malaysia is arid and infertile due to lack of buffering capacity and low clay activities which resulted in soil acidity. In addition, high intensity rainfall and extreme conditions of slope such as transient drought and lack of nutrients have reduced the survival and growth of potential plants. Rain water percolation which leaches basic elements such as calcium, magnesium, potassium and sodium from the soil profile is also another factor which contributes to soil acidity.

Soil acidity has a huge negative impact on fertility, biological activities and plant produc‐ tivity. Fortunately, the use of vegetation and their association with microbes have great potential to alleviate soil acidity and erosion problems. Moreover, heavy metal-tolerant plants also play an important role in phytoremediation. Therefore, proper plantation and management of plants in polluted and acidic soil may significantly contribute to restoring the natural environment.

The practice of using vegetation, so-called "Bio-engineering" technique, combines an ecolog‐ ical, mechanical and hydrological concept which has been successfully applied to alleviate soil erosion in Malaysia [1]. The combined right choices of plants and planting technique confer numerous advantages such as producing a high biodiversity, low cost-maintenance, selfsustainability as well as environmental friendly slope [1]. Nonetheless, the interaction of vegetation and soil are complex as it is involved with, *inter alia*, varying soil properties, soil pollutants and different type of plant coverage. Therefore, in light of fast developmental land transformation and climate change, it is of a great challenge to integrate all plant-soil properties and its interaction with the whole ecosystem and environment.

© 2014 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

#### **1.1. Objectives of the chapter**

This book chapter will explore the attributions of vegetation to alleviate the most common slope problems in Malaysia; acidity and erosion. This chapter will also provide potential characteristics of plants to reinforce soil and the mechanism of Aluminium (Al) accumulator plant to alleviate soil acidity. The specific aims of this book chapter are to:

