IMPACT OF SELECTED SOIL AND WATER CONSERVATION TECHNOLOGIES ON TREE SEEDLING SURVIVALS: A CASE STUDY IN GERDUBA WATERSHED, BORANA ZONE, ETHIOPIA

Abstract

Establishing forest plantation on degraded rangelands play a key role in forest rehabilitation processes through afforestation or/and reforestation. In-situ rainwater harvesting has positive impact on seedling survivals at degraded rangelands. A quadrant of 10 m × 10 m of five times replication at three slope classes under area enclosure was used. Both survived seedlings and soil physical parameters were collected from three in situ structures and three soil depths profiles (0-10, 10-20 and 20-30 cm) and then analyzed using T-test procedures in which LSD is used for mean comparison. The data generated from soil attributes were analyzed as 3x3 factorial experiment using GLM procedure; the selected SWC practices and soil depths were used as the two factors with three slope classes each, respectively. Of the transplanted seedling to the area enclosure with selected SWC structures namely, in pits (66.53, 46.13, and 25.66%), half-moon (66.53, 41.80, and 20.40%), and soil bund embankment (55.46, 42.60, and 28.80%) were survived at bottom, middle and upper slope classes respectively. The interaction of structures on conserving and storing moisture was not significant except level soil bund embankments. Because, tree seedlings rose at nursery site transplanted to the level soil bund embankment structures, that was, on the dig out soils. The conserved soil moisture is far from transplanted seedling roots as a result needs more energy to absorb but weak and short rooting system. Infiltration pits and half-moon showed good performance than level soil bund embankments at bottom parts. Grass regeneration and maintaining around in-situ rainwater harvesting devices as well as transplanted tree seedlings stay alive are excellent indicators of moisture availability. This explains that almost all in-situ structures play a crucial role at flat land rather than middle and upper parts but highest bulk density achieved for the upper parts, which might be due to risks of soil erosion and only left with very compacted cobles. Therefore, slope gradient have implication on in-situ rainwater harvesting devices efficiencies in conserving moisture for tree seedling survival so as to establish good forest stands