Box 5.11 Post-fire restoration of native tree species: effects of wood shaving application M. Lallement, C. Tognetti, M.E. Gobbi Fires are the most devastating anthropogenic disturbances in forests of the A ndean-Patagonian region. They severely affect surface soil physical and chemical characteristics, as well as vegetation and fauna, thus inc reasing the risk of erosion. These forests are very import ant for the conservation of biodiversity, climate and watershed regulation, and soil stability. Therefore, it is relevant to implement strategies that favour ecological restoration after a disturbanc e has occurred. Reforestation with native species is one of the most used restoration strategies in t he Andean Patagonian forests. This strategy initially depends on the availability of plants, both in terms of quality and quality. The adequate growth and development of t hese plants will determine the success of a restoration project. Aspects such as the type of substrate used for seedling production and the strategies used to plant these seedlings in the field should be carefully considered when planning restoration projects. The general objective of the work carried out here was to evaluat e strategies that facilitate the recovery of burn ed forest areas of the Nahuel Huapi National Park (NW Patagonia), specifically by means of reforestation with native tree species. For this, we evaluated: I. The success of a reforestation project that included the aid of volunt eers to plant three native tree s pecies (Austrocedrus chilensis, Nothofagus pumilio and Lomatia hirsuta) in a postfire area of the Nahuel Huapi National Park. II. The effect of wood shavings, either applied as mulch or incorporated into t he soil, on the survival and growth of A. chilensis, N. pumilio y L. hirsuta: i) in a nursery, and ii) in the field. III. The effects of wood shavings, either applied as mulch or incorporated into the soil, on the water dynamic of a burned volcanic soil. The three tree species selected for this study are characteristic of the xeric forests in which most of the fires in the region occur. They have different life-forms and reproductive strategies (Table 1). Regarding L. hirsuta, there are no previous records of this species been used in restoration projects. The study was carried out in a post-fire shrubland in the Challhuaco Valley, where mean annual precipitation is 1,000 mm (mostly rain and snow in aut umn-wint er). Seedlings were obtained at local nurseries, and their ages varied as follows: 3 -5 years old (Objective I), 1 year old (A. chilensis and L. hirsuta, Objective II), and 3 years old (N. pumilio, Objective II). In the field study, seedlings were planted under shrubs (nurse plants). Growth and survival of plants in the reforestation aided by volunt eers (Fig. 1) was satisfactory; values obtained were within the range of those obtained in previous studies by experienced personnel and under similar climatic conditions. The highest survival aft er the first year was for A. chilensis (51% ), followed by L. hirsuta (43%), and N. pumilio (29% ). In conclusion, reforestation with the aid of volunteers proved to be a good strategy to recover degraded areas, and provided an opportunity to educate citizens regarding environmental problems. To evaluate the effects of wood shavings on the survi val and growt h of the three species, pine (Pseudotsuga menziesii) wood shavings were either incorporat ed into the soil at a 1:3 shavings to soil ratio (v/ v) or mulched over the soil forming a 2 cm deep layer. As controls, soil (burned for the field assay, unburned for the nursery assay) with no woods shavings was used. In the field, seedlings were only watered when they were planted, while in the nursery they were watered tree times a week. In the nursery assay, mixing wood shavings in with the soil increased survival of the three species and improved some of the growth indicators (Fig. 2). Apparently, this is a promising strategy to improve the nursery production of native species. However, mulching soil with wood shavings had no effects on survival or growth (Fig. 2). In the field assay, wood s havings had no effects on the measured parameter, regardless of whether it mulched or was incorporated int o the soil (Fig. 2). However, mulching did reduce and stabilize soil surface temperature. This is the first report of the use of L. hirsuta in restoration projects. The results outlined so far indicate that this species has good survival and growth rat es, and should be considered in future reforestations. For t he assays on the dynamic of soil water (assays without plants) surface soil from a burned shrubland was used. The soil was either mixed with wood shavings (at three soils to shavings rates ) or mulched with wood shavings (two mulch depths). In both cases, a burned soil without wood shavings was used as a contr ol. Mixing wood shavings into the soil increased water draining speed and field capacity; this effect was more marked as the proportion of wood shavings increased. Applying a layer of wood shaving mulch on the soil delayed evaporation, although final soil moisture values were not affected. The effects of wood shavings on the dynamics of soil water could prove to be positive for plants, provided that the water remains available near the root system. The application of new strategies aimed at increasing survi val and growth of native plants, especially those that use low cost and easily available resources, stimulates the development and undertaking of restoration projects. Ultimately, it accelerates t he succession process in deteriorated natural habitats, and improves recovery of degraded areas. Table 1. Characteristics of the three native tree species used in this work. Austrocedrus chilensis Nothofagus pumilio Lomathia hirsut a Family Cupresac eae Fagaceae Proteaceae Order Coniferales Fagales Proteales Ciprés Lenga Radal Perennial Caduca Perennial Tree Tree Shrub/Tree Resprouting ability No No Yes Masting No Yes No Common name Foliage Life-form Figure 1: Volunteers working in native plant ation in a post-fire area of the Nahuel Huapi National Park, Argentina. (Author´s photography ). HI (%) GI (%) 299 275 222 311 177 177 75 100 115 200 88 100 164 47 340 78 162 6 100 C I Survival (%) 80 M 60 40 20 0 A. chilensis N. pumilio L. hirsuta Native species Figure 2: Relative increase of height (HI) and growth (GI), and survival at the end of the nursery assay. Growth indicators were number of whorls (A. chilensis), number of branches (N. pumilio) and number of leaves (L. hirsuta). C: control, I: wood shavings incorporated into the soil; M: wood shavings applied as mulch. View publication stats