Knowledge Resource Center for Ecological Environment in Arid Area
| Dynamics of Bio-Elements in Soils Along a Land-Use Gradient in the Tropical Mountain Rain Forest of Southern Ecuador | |
| Burneo Valdivieso;Juan Ignacio | |
| 出版年 | 2014 |
| 学位授予单位 | Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden |
| 英文摘要 | The tropical montane forest of Ecuador is one of the ‘hot spots’ of species diversity. Despite this great species diversity, there are forests in our study area, namely in the Zamora-Chinchipe province in southern Ecuador, which are being depleted at an alarming rate. For example, large areas are being permanently deforested for use as ‘pastureland ’. This development is typically characterized by intensive slash and burn activities for vegetation clearance. After clear cut and slash burning, pasture species are planted of which Setaria sphacelata and Melinis minutiflora, are the most common. However, forest clearing by slash burn for pasture production occurs in the region simultaneously with subsequent invasion of bracken fern (Pteridium arachnoideum) and re-colonization of secondary succession vegetation on abandoned pasture land. In this study, we will examine the effects that the above phenomena have on ecosystems, namely the effects associated with the conversion of natural forestland to pasture land, and the succession that occurs as a result. We will also examine how land use change affects the nutrient status of the soil. This study focuses specifically on the area called the ‘San Francisco Valley’, (3°58’ 30”S latitude, 79°4’ 25”W longitude), which lies between Loja and the Zamora-Chinchipe provinces in Ecuador. Field work for this study was carried out at 1,798 and 2,226 m a.s.l in the following sites: 1) the San Francisco Natural Forest (this area refers to the eastern part of Podocarpus National Park); 2) active pastures Type I (this area refers to the pastureland in front of the San Francisco Scientific Station ECSF, and are pastures that have existed for 50 years or more); 3) active pastures Type II (this area refers to the pastureland in Sabanilla sites, and are pastures that have existed for approximately 17 years); and 4) abandoned pastureland (affected by succession over a period of at least twenty years). Each land-use type consists of five plots of approximately 20 x 20m2. Five points in each plot were then chosen and later sampled (two sub-samples) according to the defined horizons and depth units, namely the organic layer and mineral top soil horizons. Organic layer (only on forest and succession sampling plots) were designated as LOf1, Of2/Oh1 and mineral top soil was sampled to a depth of a 0-10, 10-20, 20-30 cm. To quantify the effects of the impact that land use change has on the chemical characteristics of soil in the selected areas, we analyzed the following bio-elements: the pH value, soil organic carbon (SOC), the total nitrogen (TN), the effective cation exchange capacity (ECEC), as well as stocks of total and available macronutrients. In addition, we examined the biological characteristics such as carbon and nitrogen microbial biomass (MBC, MBN), basal respiration (BR), and nitrogen mineralization (Nmin) in organic layers and top mineral soils (0-30 cm) of the following: the San Francisco Natural Forest, ECSF pastureland, Sabanilla pastureland, and abandoned pastures affected by succession. The main results of this study can be summarised as follows: The soil pH value increased after forest-to-pasture conversion and tended to decrease with soil depth. Moreover, pastureland in the study that was fifty years or more, showed evidence of a decrease in pH values. This decrease in pH value of the soil can be attributed to the reduction in exchangeable cations . However, they still remained higher than the pH values for the forest sites in the study. After the abandonment of pastureland, we observed a re-acidification in the soil of succession sites. This resulted in a decrease of base saturation . On the other hand, the total exchangeable base cation stocks were significantly higher for pasture soils compared with forest and succession soils. This was because of the addition of basic cations by ‘slash and burn activity ’. In this study, we observed that the greater values of soil organic carbon stock |
| 英文关键词 | Tropischer Bergwald Landnutzungs?nderungen N?hrstoffkreislauf Tropical montane forest Land use change Nutrient cycle Ddc:630 Rvk:ZC 73588 |
| 语种 | 英语 |
| URL | http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-144002 |
| 来源机构 | Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/248757 |
| 推荐引用方式 GB/T 7714 | Burneo Valdivieso;Juan Ignacio. Dynamics of Bio-Elements in Soils Along a Land-Use Gradient in the Tropical Mountain Rain Forest of Southern Ecuador[D]. Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden,2014. |
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