Earthworm as Bioindicator for Soil Fertility within Land Cover Types in Bogor Dramaga

Abstract

Rapid population growth accompanied by improved quality of life for the better cause of human dependence on natural resources increases. In a natural resource ecosystems, plants have an important role in maintaining the ecological functions of ecosystems natural resources through its ability to regulate micro-climate conditions, water management and soil fertility. Soil fertility is the ability of the soil provides nutrients for plant growth. In this case, the earthworm is one of the terrestrial ecosystem biotic factors that served to increase soil fertility. The role of earthworms are very important for the process of decomposition of soil organic matter significantly affect the soil fertility. Research aims: (1) determine the type of land cover in Dramaga, (2) identify and analyze the various types of plants on land cover, (3) analyzing the fertility of the soil on the following types of land cover history management, (4) identify the type and abundance suspect earthworms as indicators of soil fertility, and (5) examine the relationship of the abundance of earthworms in soil fertility and plant abundance. Research activities carried out in Dramaga, West Bogor District, West Java. The research lasted for 3 (three) months, from February to April 2013. At the study site was the interpretation of Landsat imagery to identify and interpret the land cover type (landuse) at the study site. Then on each type of land cover is an inventory / treatise against three research objects that is plants, earthworms and soil fertility. Sampling design of the study using a two stage sampling. Primary sampling units in the form of squares measuring 20 m x 20 m three units per land cover type plants to the minutes of the tree level. As for the minutes of the level of regeneration is made smaller squares by three squares units each measuring 2 m x 2 m for seedlings, 5 m x 5 m for sapling and 10 m x 10 m for the pole in each primary sampling unit. Being for the benefit of earthworms treatise made secondary sampling unit size of 1 m x 1 m by one unit per primary sampling unit. In this study the identification or interpretation of land cover types is done using ArcGIS 9 software on Landsat imagery in 2012. The analysis of vegetation data (density, frequency, dominance, importance value index) using analysis of vegetation (Misra, 1974) and species diversity are analyzed according to the Shannon-Wiener formula (Krebs, 1978), soil fertility by the Research and Development of the Agriculture Department of Agriculture, 2005 and estimate the abundance of earthworms in each land cover type calculation procedures used by two stage sampling design. Based on the results of processing of Landsat imagery in the study site using ArcGIS 9 software, there are five types of land cover that bare ground, grasses, shrubs, forest plantations, and mixed forest. Results of data acquisition fifth land cover types dominated by species of different plants, namely: Digitaria sanguinalis (L.) in grasses, Waltheria indica (L.) in the bush, in Tectona grandis plantations, as well as Mimosa pudica (undergrowth), Hopea bancana (sapling), Baccaurea racemosa (pole), and Eugenia cymosa (trees) in the mixed forest. Further diversity in land cover types of grasses, shrubs, and forest crops is low, while the mixed forest land cover types are medium. Based on a rough identification (morphology) found one species of earthworms that live on the three cover types in the study site Pheretima aspergillum, that is shrubs, teak plantation and mixed forest. Pheretima aspergillum species morphologically characterized by brownish red, clitelum layout on segments 14-16, from total 122-153 segments and the number of segments ranging from 2-11 cm body length reached. Soil analysis results are taken from the study site indicate that the type of soil on the five land cover types is latosols brownish red. The content is highest pH in mixed forest of 5.4 category includes land with acid. In this condition turns earthworms live and reproduce more because the soil acidity (pH), pH approached the environmental conditions that favor earthworms ranged from pH 6.5 to 8.3. C-organic soil fertility is an indicator that consists of various bond C (carbon), the analysis shows the value of Corganic content was highest in the mixed forest land by 3.90%. The value of the basis states better soil fertility. Highest nitrogen content by 0.41% in the mixed forest land. The content of nitrogen (N) levels categorized as fertile soil N needed by plants in large quantities. Potassium (K) was highest in the mixed forest land cover types by 0.42% and 0.33% of forest plants. In both categories of land cover types have fertile soil because potassium is a catalyst in the formation of proteins, helping the development of plant roots, as well as increase the meristem tissue growth. Soil with a high CEC is able to provide nutrients better than soil with a low CEC. Phosphorus (P) is a chemical element that is necessary soil on plant growth. Phosphorus is most readily absorbed by the plant at a pH of about 6-7. Results of saturation analysis bases (KB) exhibit very high values > 100% in the teak forests and mixed forest by 92%. These results indicate that both types of land cover is a fertile soil. From these results it can be concluded that there is a significant positive relationship between earthworms variable with a value of C-organic soil fertility and phosphorus. Evidence of organic matter plays an important role improve soil physical, chemical and biological factors that further increase the productivity of the soil and plants which are arise in the abundance of earthworm which are inhabit in landcover types of shrubs, teak plantation and mixed forest.