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Proceedings of the UNCCD First Scientific Conference, 22–24 September 2009
Rehabilitation and restoration to combat desertification in arid and semi-arid ecosystems of Patagonia DR Pérez 1, F Farinaccio 1, FM González 1, JL Lagos 1, A Rovere 2 and M Díaz 1 1 Laboratorio de Rehabilitación y Restauración de Ecosistemas Aridos y Semiáridos, Escuela Superior de Salud y Ambiente, Universidad Nacional del Comahue, Neuquén, Argentina –
[email protected] 2 Centro Regional Universitario Bariloche, Universidad Nacional del Comahue-CONICET Abstract: The following work summarizes experiences of rehabilitation in arid and semi-arid ecosystems with severe disturbance, where the recovery of the biodiversity at acceptable levels takes place over long periods of time. The study sites were located in the natural protected area Auca Mahuida and the area Aguada Pichana, in the Neuquén province, Patagonia Argentina. Seeds were collected in the degraded area to produce seedlings of the native species. Different experimental designs were applied using organic amendments, facilitation between species, and protection against herbivores, among others. The results show that the recovery in these ecosystems can be accelerated by means of technical ecological restoration. In Argentina this activity should be incorporated as tool to combat desertification in Patagonia. Keywords: desertification, rehabilitation, survival, native plants
Introduction The Neuquén province, located in Patagonia Argentina, has a high degradation level mainly due to overgrazing by cattle and extractive industries (Del Valle et al. 1995). The biological processes in these arid and semi-arid ecosystems are affected by the scarce and highly variable yearly rains, which determine a low primary productivity (Noy Meir 1973). Intervention through rehabilitation constitutes an alternative for the recovery of the vegetation of these ecosystems. This intervention requires investigation experiences in the field in order to contribute knowledge to institutions that combat desertification.
Body of work The Auca Mahuida area is characterized by a peculiar vegetation of great botanical interest due to its endemics. It can be considered an island located in the phytogeographic province of the Monte, with flora and vegetation of the Patagonian Steppe (district Payunia) and High-Andean species in higher areas (Cabrera 1976). The mountains reach 2,258 m and the precipitation ranges between 180 and 320 mm annually, according to the altitude. In the area Aguada Pichana, the vegetation corresponds to steppe with shrubs. Its climate is dry and cool, with scarce precipitation (around annual 120 mm). In both areas, decapitated and dismounted soils are found. The vegetation was evaluated both in the degraded area and the reference area ecosystems, in order to determine which species to incorporate. In Auca Mahuida we evaluated: (i) Survival of Senna arnottiana associated to Stipa speciosa var. speciosa. The treatments were: (1) S.arnottiana-S.speciosa with 1 l of polyacrylamyde powder; (2) S.arnottiana-S.speciosa with 1.5 l of polyacrylamyde powder; (3) isolated S.arnottiana with 1 l of polyacrylamyde powder; (4) isolated S.arnottiana with 1.5 l of polyacrylamyde powder. The results after two months of seeding show 60% of survival, and there are not significant differences between treatments.
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(ii) Survival of Prosopis denudans var. denudans, Grindelia chiloensis and Schinus johnstonii. The treatments were: (1) 0 l of polyacrylamyde powder; (2) 2 l of polyacrylamyde powder; (3) 2 l of polyacrylamyde powder + organic matter. The results after two months indicate that the contribution of organic matter and polyacrylamyde powder increase the survival of the species (in P. denudans var. denudans (1) 20%, (2) 90%, (3) 98% averages; in G. chiloensis (1) 35%, (2) 87%, (3) 83% averages; in S. johnstonii (1) 8%, (2) 62%, (3) 75% averages). (iii) Survival of Prosopis denudans var. denudans. The treatments were: (1) 0 l of polyacrylamyde powder, (2) 0.5 l of polyacrylamyde powder, (3) 1 l of polyacrylamyde powder. In each treatment, half of the plants were protected against the livestock. The results show that there are significant differences between treatments with polyacrylamyde powder, and without polyacrylamyde powder (95 and 2%) respectively. The mortality of treatments without protection was of 17% in the first 2 months of transplant. In Aguada Pichana we evaluated: (iv) Survival of Acantholippia seriphioides, Senecio filaginoides var filaginoides and Poa ligularis, through the transplant of mature plants with different volumes of polyacrylamyde powder (0, 2, and 3 liters). The results show that the survival of A. seriphioides was of 0% in all the treatments, for P. ligularis and S. filaginoides var. filaginoides were of 60% in all the treatments.
Conclusions It is necessary to consider the heterogeneity of the vegetation in the planning and implementation of the restoration projects. In arid and semi-arid environments of the north of Patagonia, the reintroduction of native plants for rehabilitation is an important strategy. The moisturizing gel polyacrylamyde powder usage, allowed a higher survival percentage of the different species. As regards pioneer species in the succession as S. arnottiana, facilitation is not a fundamental factor for survival. It is recommended to protect against herbivores during the first stage of development in those species that are consumed by the livestock.
Recommendations for decision-making A great vegetation heterogeneity is characteristic of the region, and is also found in small scale areas, and it is necessary to consider these differences previous to the rehabilitation works. The recovery of degraded areas with native species, moisturizing gel, or by the direct transplant of mature plants, is an alternative that offers a quick answer to degradation. It is fundamental to promote further investigations regarding restoration in Patagonia. It is important for the development of regional workshops to share with local people and technicians tools and knowledge that will enable them to incorporate the knowledge acquired in rehabilitation research.
References Cabrera AL. 1976. Regiones Fitogeográficas Argentinas. Enciclopedia Argentina de Agricultura y Jardinería. Del Valle HF, Elissalde NO, Gagliardini DA and Milovich J. Desertificación del Neuquén. Available at: www.inta.gov.ar/bariloche/nqn/recursos/m09.htm Noy-Meir I. 1973. Desert ecosystems: Environment and producers. Annual Review of Ecology, Evolution, and Systematics 4: 25–51. Available at: www.jstor.org/stable/2096803
