Designing mixed-species plantation systems for smallholder and community forestry in the tropics
Lead reviewer: Dr. John Herbohn, University of the Sunshine Coast
Collaborating institutions: The University of Queensland, Queensland University of Technology, Southern Cross University, University of Melbourne
Systematic map protocol: Environmental Evidence 2015, 4:15 (link to http://www.environmentalevidencejournal.org/content/4/1/15)
Over the past two decades there has been an increasing interest in the establishment of mixed-species plantations in the tropics. Despite this interest, the proportion of new plantings that are mixtures of species is low relative to the area of monoculture plantations established. Monocultures offer significant economic benefits and have been preferred in large-scale ‘industrial’ plantation development in the tropics. However, there has been a shift to smallholder and community forestry in many parts of the tropics, along with a requirement of many national reforestation programs to use mixtures, especially involving combinations of native species for which there is often little information. Mixed-species plantings offer a number of benefits to smallholder and community forestry. Potentially, mixed-species systems can lead to greater productivity, offer greater financial benefits and provide risk diversification by offering multiple products, thus reducing the impact of a catastrophic loss of any one species through poor performance, pest attack and or decline in economic value.
Piotta (2006) undertook the most comprehensive review of factors affecting the performance of species within mixtures, however, the study only considered a limited number of factors. In addition, since that time a number of studies have been published that may shed further light. As such, the first objective of this systematic map will be to:
- Review past studies reporting growth of species within mixtures to better understand the factors that affect species performance, so as to identify principles that can be used to design species combinations.
Compared to the literature on the growth of mixed-species plantations, much less is known on the specific social and economic factors that are important in the design of mixed-species systems. While Le et al.’s (2012) review is possibly the most comprehensive in regards to social factors affecting the success of reforestation in general, it does not discuss in detail the differences between mixed-species and monocultures, nor between smallholder and community forestry across different levels of social and political organization (e.g. people’s organizations and municipal councils). In recognition of these critical factors, the second part of our map will:
- Identify the key socio-economic factors to be considered when designing mixed-species plantation systems.