Effect of Different Moisture Harvesting Techniques on Seedling Survivals and Growth of Trees in Degraded Lands of Southern Tigray

Abstract

Tree planting on degraded lands play a key role in forest rehabilitation processes through afforestation and/or reforestation. Moisture harvesting structures (MHSs) has significant impact on seedling survivals at degraded lands. The objectives of this study were to investigate the impact of water harvesting techniques on seedling survival and growth performance of trees. Field experiments were conducted for two rainy seasons in southern Tigray, Atsela watershed. The experimental design followed was the split plot design. The MHSs as main plot used were eye-brow basins (EBs), micro trench (MTs), improved pit (IPs) and as control normal pit (NPs). The tree species grown as subplots were Eucalyptus camaldulensis, Grevillea robusta, Olea europaea and Cupressus lusitanica. The four tree species were planted by using seedlings. The tree survival rate, height, crown width (CW) and root collar diameter (RCD) of the four tree species were measured every six months after transplanting. The result shows that MHSs were significant in tree seedling height, CW and RCD but not in tree survival rate. Tree seedling height and CW grown in EBs were significantly higher than those grown in MTs, IPs and NP (P≤0.05). RCD of tree seedling was higher when grown in EBs than NP (control) (P≤0.05). The interaction of tree species seedlings and MHSs shows that those seedlings grown on MHSs were significantly thicker, taller and more survived than those grown on the NPs (control) (P≤0.05). So based on the experiments, it is concluded that MHSs particularly the eyebrow basin was considered as the most appropriate planting pit. Therefore, further demonstration of eyebrow basin tree planting should be carried out.

Effects of a Trench as a Moisture Harvesting Structure on the Biomass Production and Growth of Trees Planted to Restore Degraded Land, Southern Ethiopia

“…Although many rainwater harvesting structures are used to conserve soil and water in degraded lands, research findings have shown variability in their effectiveness for plant growth, biomass production, restoration of degraded lands, etc. [14,21,24,27]. This result shows that the extent to which different soil and water conservation structures influence plant growth and rehabilitation on severely degraded lands needs to be further investigated, as their effect could vary depending on the severity of the degraded land, precipitation pattern, and the type of planted species used for restoration.…”

“…Problems related to land degradation can be prevented by using various mechanisms and activities [13], such as maximizing vegetation cover in degraded lands which should be given a priority since this action can prevent erosion and replace soil nutrients removed by erosion [4,14,15]. However, to maximize vegetation cover through natural regeneration and artificial plantations, factors such as shortages in soil nutrients and limited available water during the dry season in degraded lands affect the restoration process [16,17].…”

“…This result shows that the extent to which different soil and water conservation structures influence plant growth and rehabilitation on severely degraded lands needs to be further investigated, as their effect could vary depending on the severity of the degraded land, precipitation pattern, and the type of planted species used for restoration. In addition to this, the different pieces of research conducted on the impacts of rainwater harvesting structures on the growth of trees were performed at a plot level [14,21,24,27], which is confined to a small space in an experimental area. However, findings on the impact of moisture harvesting structures on large scale degraded land restoration projects on the growth performance of trees are scant.…”

Evaluation of selected multipurpose tree species and moisture conservation structures for degraded dryland rehabilitation in Dugda Dawa District, Southern Ethiopia

“…The result contrasts with the study in dry areas of East Shoa zone where the survival percentages of four types of promising multipurpose trees that is, Azadirachta indica, Schinus molle, Acacia saligna and Parkinsonia aculeata were highest in semicircular bund and contour-bench and, least performed in infiltration pits (Abera and Fitih, 2015). In-situ rainwater harvesting devices are important in facilitating favorable conditions for plant growth as well as tree seedling survival in moisture-stress areas (Demisachew et al, 2018).…”

“…Successful tree seedling survival and growth depend on the soil condition and stored soil moisture available to ensure tree seedling survival dry season (Warren et al, 2005). In the degraded lands of Borana rangeland, pastoralists have been planting many tree seedlings species year after year (Demisachew et al, 2018). However, the survival of those seedlings is poor and variable as the area is mainly affected by moisture stress problems.…”