DEFINING RESTORATION Rehabilitation aims to revive important ecological

DEFINING RESTORATION • Rehabilitation aims to revive important ecological services, or to restore a natural dynamic to ecological communities. • Rehabilitation is used to regain some but not all of the original biodiversity of an area (WRI, 2003). • It might mean to regain agricultural value or to vegetate with species merely to have a natural system in place, (not necessarily an indigenous system). • Reclamation suggests bringing something back to its original condition. It includes any process promoting soil conservation and productive use of derelict land (Peterson and Etter, 1970). The best methods use vegetation cover that is self-renewing, attractive and long-term.

DEFINING RESTORATION • Restoration aims at facilitating natural processes in disturbed areas that will eventually lead to self-sustaining ecosystems similar to what was present before disturbance. • Most complete restoration is rarely realistic because determining the pre-disturbance state of most ecosystems is difficult, and because ecosystems continually change (WRI, 2003). • Goal: return a habitat to a more desirable condition involving a particular species composition, community structure, and/or set of ecosystem functions. • Revegetation means to establish a plant cover of any type (Mentis and Ellery, 1994).

RESTORATION ECOLOGY Benefits include: • • • http: //www. rioweb. org/ photogallery/boywithba rrow. jpeg • Restoration ecology aims to re-establish or rehabilitate damaged or lost plant or animal populations or species assemblages indigenous to the area of interest (Jordan et al, 1987). Relies on fundamental knowledge of the target species, but it also provides opportunities for testing basic ecological theories. Maintenance of diversity of plants and animals Improving wildlife habitats Creating more aesthetically pleasing surroundings Restoring natural communities Protecting locally rare species

THE PLANNING PROCESS • Setting realistic objectives is most NB step (Pastorok et al, 1997). • In a mountain catchment, the most NB function may be to supply clean water. Alien trees must be removed and indigenous cover must be there to prevent erosion (Holmes and Richardson, 1999). http: //www. cnpsyerbabuena. org/habitat_rest. html • Less transformed sites - reintroducing missing plant species

• More transformed sites - reintroduce soil biota before some species can establish (Holmes and Richardson, 1999). • Realistic objectives consider extent of damage (caused by IAS and the control or clearing of them), ecological potential, land-use goals and socio-economic constraints (available funds, time and trained staff). http: //ecology. ucdavis. edu/restoration/ec ological_restoration. htm • Landscape interactions must be considered.

MORE TO CONSIDER • Restoration of disturbance processes must include those to which the indigenous plants are adapted (e. g. natural flooding, herbivory, trampling). • Restoration may require reintroduction or management of the natural disturbance regime, elimination of a damaging anthropogenic disturbance regime, or introduction of a new disturbance regime (Pavlovic, 1994) http: //www. cnpsyerbabuena. org/habitat_rest. html • There is an important relationship between scale of disturbance and species abundance, distribution and persistence (Pavlovic, 1994)

REVEGETATION • Planned disturbances are often accompanied by revegetation plans. • Topsoil is frequently collected and stored, to be replaced at the surface during revegetation. This practice is important for restoring the indigenous seed bank and soil microbial community. • The longer the time that topsoil is stockpiled, the more likely it is that viable seeds of indigenous species will decline. Many harmful alien species have persistent seed banks. http: //www. eroresources. com/serv ices/Restore. htm

Ecosyste m condition Aim Example Actions Evaluation Most pristine Maintain or enhance local biodiversity Locally extirpated species Sow seed of desired species, or transplant seedlings, after disturbance Monitor establishment & survival of introduced species Vulnerable species As above Non-local indigenous species Remove planted indigenous species & their hybrids Monitor sites for non-local species & their hybrids Invasive alien species Remove alien species Monitor sites for alien species Young, dense stands of alien species Remove alien plants & burn Re-establish ecosystem diversity, structure and function Old, dense stands of alien species Monitor species recruitment i. t. o diversity, guild structure & Remove alien plants & burn; Monitor species canopy cover sow locally collected recruitment i. t. o indigenous species diversity, guild structure & canopy cover

Ecosystem condition Aim Re-establish indigenous plant cover Improve remnant connectivity Highly degraded Establish plant cover Example Actions Evaluation Old, dense alien stands with evidence of soil damage Remove alien plants & burn; stabilize slopes against further soil erosion; sow locally collected indigenous species Monitor species recruitment & soil erosion Denuded & eroding footpaths Reconstruct footpath & stabilize surrounding slopes; plant denuded areas with local seedling material in winter; sow with locally collected species after disturbance As above Revegetation following mining or other short-term construction operations Replace topsoil; sow with suitable seed mix Monitor indigenous plant cover & alien species Grassy road verges with potential to become indigenous vegetation corridors Remove non-indigenous cover (herbicide as last resort); sow or plant with suitable indigenous species As above Creation of indigenous vegetation corridors in agricultural land As above Stabilise slopes after road construction If little topsoil is available, add mulch & sow with fast-growing noninvasive alien annuals; oversow with indigenous seed Monitor plant cover & alien species

ROLE OF IAS IN RESTORATION (D’Antonio and Meyerson, 2002) • IAS may be part of the reason or need for restoration • IAS may be the first to re-colonize after disturbances associated with vegetation removal (unplanned or “natural” disturbance) • IAS may be the first to colonize after a planned disturbance, even if they were not present in the pre-disturbance community, and may interfere with restoration efforts • IAS may leave behind a legacy after removal that makes long-term restoration difficult (e. g. seed bank, chemical or physical alteration of the habitat) • Alien spp. may be used in restoration to restore particular functions if indigenous spp. aren’t suitable or available

LONG-TERM EFFECTS OF IAS • Myrica faya has colonized young volcanic soils in Hawaii, where fixes nitrogen at a rate four times as high as all other sources of fixation combined. When it is killed, it leaves a legacy of high soil nitrogen. Introduced grasses appear to benefit from this dieoff, complicating restoration efforts (Adler et al, 1998). http: //www. omv arldsbilder. se/2 002/020207. ht ml • Invasive alien species often have very large persistent seed banks. They often maintain a much larger seed bank in their new habitat. Species with buried seed banks or extensive and persistent rhizomatous networks require repeated follow-up treatments (D’Antonio and Meyerson, 2002).

LONG-TERM EFFECTS OF IAS cont. • In South African riverbanks, erosion has been accelerated by many introduced species (Acacia and Pinus spp. ). • Restoration of sites degraded by alien species and soil erosion pose a particular challenge. • The topography may no longer resemble the pre-invasion conditions, and removal of the aliens may cause further erosion. • Highly degraded sites may no longer be able to support the desired species assemblages. Under these conditions it may be necessary to stabilise the soil using synthetic or biodegradable materials or establish indigenous vegetation before alien removal (D’Antonio and Meyerson, 2002).

THE ROLE OF IAS IN RESTORATION • In some degraded sites it may be necessary to introduce an alien species to assist with the restoration process. • Where soil erosion or the potential for it is severe, many practitioners use fast-growing but sterile alien grasses to quickly establish cover. These grasses do not seed and presumably give way to indigenous species (D’Antonio and Meyerson, 2002). • Introduced species used in restoration must be monitored over time, and only used if no other options. • Introduced species do sometimes have a role to play in restoring functional aspects of ecosystems, but this must be related to the overall goal of restoration and the context within which restoration is carried out (Hobbs and Mooney, 1993).

Chapter 1 Definitions Chapter 2 History, globalisation and GMOs Chapter 3 The human dimension Chapter 4 Pathways of introduction Chapter 5 Characteristics of invasive alien species Chapter 6 The ecology of biological invasions Chapter 7 Impacts of invasive alien species Chapter 8 Invasive species management Chapter 9 Predicting invasive spp. occurrence and spread Chapter 10 Ecological restoration Next Chapter 11 International perspective Chapter 12 South African perspective I hope that you found chapter 10 fun to do and that you will enjoy the next chapter in this course.