Peatland rehabilitation aims to repair ecosystem processes, productivity and services of the former peatland, but does not imply the reestablishment of the pre-existing biotic integrity in terms of species composition, community structure and ecosystem functions (Clarke and Rieley, 2010). Peatland restoration, i.e. the process of assisting the recovery of peatland that has been degraded or damaged to its original natural condition, goes one step further. Unlike the well-established studies of ecological restoration of temperate peatlands (Kozulin et al., 2010), knowledge of tropical peatland restoration is still in the early stage (Jauhianen et al., 2016; Jaenicke et al., 2010; Page et al., 2009).
In practice tropical peatland restoration trials have included activities on restoration of hydrology and restoration of vegetation (Jauhianen et al., 2016; Lampela et al., 2017).
Restoration of hydrology
Rizema et al. (2014) lists the first efforts to restore the hydrology in degraded peatlands:
Restoration of vegetation
Another major challenge for tropical peat restoration is establishment of vegetation. In the case of peat swamp forests where most of the vegetation is trees this means reforestation. When the trees are cut and burnt, there are very limited possibilities for natural regeneration (Graham & Page 2012, Blackham et al. 2013, 2014). Instead, there is a need for active reforestation.
Harsh conditions in the open degraded peatlands set several prerequisite for reforestation success. Firstly, when the sheltering canopy cover of a natural peat swamp forest is lost, the open degraded peatland becomes very hot in the daytime. Secondly, without regulating vegetation both flooding and drought are also more pronounced. Thirdly, most of the nutrients from the soil are lost when the fertilizing litter of a living canopy is removed, and soil surface layers containing most of the available nutrients for vegetation are first burnt and then leached with heavy rain to the watercourses. Lastly, wild fires form the main obstacle in successful return of trees on degraded peatlands.
The requirements for successful reforestation are:
Experimental demonstration plots on tropical peat reforestation have been made by scientists (CIMTROP, Saito et al. 2005, Morrogh-Bernard et al. 2011, Graham et al. 2013), and practical reforestation programs by governmental organizations and NGOs (Wetlands International, Indonesian government, Australian government KFCP, WWF, The Borneo Orangutan Survival Foundation). There is very little published information on the success of these experiments and programs. Many of the areas have been destroyed by fires and there is still very little information on tree species survival and growth potential that could be used in reforestation planning. Until now, there are more studies on natural regeneration conducted on degraded peat areas (Blackham et al. 2013, 2014) than active reforestation experimenting (Lampela et al. 2017).
Approaches for reforestation can include everything from small scale demonstration plots to seed sowing from helicopter to wide areas. One of the more systematic approaches, i.e. Buy a Living Tree System (BLTS), was implemented by CIMTROP.
During our STEM –project a practical reforestation experimenting was started in areas near the provincial capital (Palangka Raya) of Central Kalimantan. These areas were monitored until the wide-spread wild fires destroyed the site in 2015. Results from these experiments are in publication phase or published (i.e. Lampela et al. 2017) .
Aim of the study was to find suitable tree species for tropical peat swamp restoration. The first study site was clear-felled, drained and several times burnt deep peat area in the Kalampangan zone and the other was degraded shallow peat flooding area in the Natural laboratory area in the Sabangau National park.
We chose species which had potential for restoration purposes or importance for local communities. Seeds were collected from local sources and seedlings were grown in a field nursery for 6-11 months. The seedlings were planted in three blocks representing differing wetness conditions typical for the area. For species with already known potential for restoration, we performed management practices such as fertilizing, mounding and weeding to further study the possible practices for restoration. Mortality, diameter and height growth of the seedlings was monitored several times of the year. Environmental variables such as ground water table, soil temperature and chemistry were also monitored.