Growth and survival of rainforest seedlings in reforestation in lowland Costa Rica Nina Schnetzer1 , Daniel Jenking2, Anton Weissenhofer3, Peter Hietz1 email: [email protected] 1 Institute of Botany, Universität für Bodenkultur Wien, Gregor Mendel Str. 33, 1180 Vienna, Austria 2 La Gamba Biological Research Station, La Gamba, Costa Rica Universität für Bodenkultur Wien 3 Department of Tropical Ecology and Animal Biodiversity, Universität Wien, Rennweg 14, 1030 Vienna, Austria Department für Integrative Biologie Reforestation of a former pasture Slope at La Bolsa Calophyllum Schizolobium with bordering brasiliense grows parahyba grorw fast secondary forest well in partial shade but with a mortality of c. 40%) Height by light levels (S1: canopy closure < 10%, S2: <30%, S3: <70%, S4: >70%) Light conditions affected growth in many species with significant light x species interactions, i.e. species performance depends on their light preferences. We classified species based on growth, survival and the effect of shading, into groups suitable for reforestation under different conditions (table below). Study area in La Gamba, Costa Dicranopteris Growth is often poor Competing grasses Table: Species performance related to light conditions and mean height Rica, Golfo Dulce Region (map from invades eroded soil on ridges and upper have to be cut during Category Species with survival > 80% mean height [m] Weissenhofer et al., 2008, modified) on sun-exposed sites slopes the first years and recommendation for reforestation + SD A: require not shading Aspidosperma spruceanum 0.7 ± 0.4 planted in open reforestation sites, could Buchenavia costaricense 2.1 ± 1.6 At the border of the Piedras Blancas National Results & discussion serve as nurse trees. Inga spp. 2.5 ± 1.5 Park, close to the „Tropical Station La Gamba”, Ochroma pyramidale 8.0 ± 3.4 Average survival of 31 species with each the project “Biological Corridor La Gamba” Zygia longifolia 1.9 ± 1.0 >19 individuals (n= 3693 trees) was 83.3%, (COBIGA) aims to enhance connectivity B: initial shading preferable i.) Vitex cooperi 1.6 ± 0.9 which is a similar result as in a reforestation (sorted by light demand i(much)> ii > iii) ii.) Calophyllum brasiliense 1.3 ± 0.8 between montane and lowland forests outside to be used in (semi-)open reforestation Platymiscium spp. 1.3 ± 0.7 project in Panama (Breugel et al. 2011). the Piedras Blancas National Park, close to sites. Will grow also without shade, but Terminalia amazonia 1.9 ± 1.2 Average height ranged between 8m for slower and with reduced quality. iii.) Anacardium excelsum 1.4 ± 0.9 the „Tropical Station La Gamba” by re- Ochroma pyramidale to 37cm for Elaeoluma Vochysia ferruginea 1.7 ± 0.8 foresting some agricultural areas. In 2010 the Vochysia allenii 1.3 ± 0.5 glabrescens. former pasture of Finca La Bolsa (13 ha) was Brosimum utile 0.8 ± 0.3 C: initial shading necessary Perrottetia sessiliflora 0.8 ± 0.4 reforested by planting c. 4700 seedlings of 83 not recommended for open sites Carapa guianensis 1.1 ± 0.7 native species that had been pre-grown in a Pseudobombax septenatum 3.2 ± 1.2 nursery from seeds and seedlings collected D: no clear preference Symphonia globulifera 0.7 ± 0.3 from the local forest. no specific recommendation Peltogyne purpurea 0.7 ± 0.4 Rollinia pittieri 0.8 ± 0.4 Objectives of research were the initial Species with survival < 80% performance of plants and reforestation suc- B: initial shading preferable i) Virola sebifera 0.9 ± 0.5 cess. Tree survival and size were evaluated to Ocotea spp. 1.0 ± 0.7 ii) Cedrela odorata 1.5 ± 0.9 identify suitable species for reforestation. Spondias mombin 1.1 ± 0.7 Micro-environmental factors such as light and C: initial shading necessary Trichilia septentrionalis 1.3 ± 0.8 topography were taken into consideration to Qualea paraensis 0.8 ± 0.6 Virola koschnyi 0.8 ± 0.6 determine the conditions that may have Ruptiliocarpon caracolito 0.8 ± 0.4 supported or reduced seedling survival and Sterculia recordiana 1.1 ± 0.6 growth. Influence of Topography on growth The highest mortality was recorded Site conditions on ridges (25%) and in ditches (20%). Mean annual precipitation is 5836 mm. La Most trees observed in very good Bolsa is a small valley with very hetero- quality were situated in flat areas geneous terrain, from flat areas to slopes (82%) and slope bottom (80%). While (inclinatons up to 60°) and dry ridges. Soils are most species grow worse on ridges and upper slopes with poorer soil also heterogeneous, generally acid with low T1 = ditch Q1 = very good cond. nutrient availability. As predominant soil types T2 = flat area Q2 = good condition conditions, species with high toleran- T3 = lower slope Q3 = bad condition ce for conditions at unfavourable sites Typic Hapuldult and Andic Dystrudept were T4 = middle slope Q0 = dead identified where plant growth can be limited by T5 = upper slope include Vochysia ferruginea, high aluminium-saturations (Pamperl, 2001). T6 = ridge Symphonia globulifera, Light conditions range from full sun to shaded and Aspidospema spruceanum (also Health: naturally occurring on ridges in the similar to closed forests. dead bad area). good Method very good Two years after planting, tree health and size Conclusions (height, diameter at 0.5 m and in 1.3 m) were Evaluating performance under field conditions permitted us to identify References assessed and evaluated in combination with Weissenhofer, A. (2008). " Natural and cultural history of the Golfo Dulce region, Costa Rica". suitable species and their micro-site preferences. In addition to species [Ausstellung: Der Pfad des Jaguars. Tropenstation La Gamba, Costa Rica ; Biologiezentrum der Oberösterreichischen Landesmuseen, Linz, 10. Oktober 2008 bis 22. März 2009]. Linz, Land Oberösterreich performance, the final choice of species will also depend on other the semi-qualitative factors light (~ canopy ,Oberösterr. Landesmuseen. closure), topography, slope, herbivory and Pamperl, S. (2001). "Der Boden als Standortfaktor eines baumartenreichen Tieflandregenwaldes in Costa Rica." objectives including diversity, protecting endangered species or Diplomarbeit ,Uni versität Wien competing neighbouring plants. Significance ecosystem functions. Breugel, M. V., J. S. Hall, D. J. Craven, T. G. Gregoire, A. Park, D. H. Dent, M. H. Wishnie, E. Mariscal, J. Deago, D. Ibarra, N. Cedeño and M. S. Ashton (2011). "Early growth and survival of 49 tropical tree species across sites of factors was tested with one-way ANOVAs. differing in soil fertility and rainfall in Panama." Forest Ecology and Management 261(10): 1580-1589. University of Natural Resources and Applied Life Sciences, Vienna Department of Integrative Biology .