Composition and distribution of earthworms in khe ro natural reserve

JOURNAL OF SCIENCE OF HNUE Natural Sci., 2008, Vol. 53, N ◦ . 5, pp. 131-137 COMPOSITION AND DISTRIBUTION OF EARTHWORMS IN KHE RO NATURAL RESERVE Tran Thi Thanh Binh Hanoi National University of Education Ngo Van Nam Tien Du Gifted High School Abstract. This paper presented in composition and distribution of earth- worms in Khe Ro Natural Reserve. 25 species of earthworms have been found in Khe Ro. Among identified species, Pheretima truongsonensis is new recard from Northeastern Vietnam. Among 5 genera which we have found, there were 19 species of the genus Pheretima (76%, the most); 2 species of the genus Drawida (8%); 2 species of the genus Dichogaster (8%); 1 species of the genus Pontoscolex (4%) and 1 species of the genus Gordiodrilus (4%). In Khe Ro, there were 10 species with Ba Be National Park, 8 species with Cat Ba Island and 12 species with Tam ao National Park. The highest density of earthworms was found in bamboo forests (44.53 individual/m 2 ), then to shrub-plot (33.6 individual/m 2 ), house gardens (32.45 individual/m 2 ), perennial land on hill (27.66 individual/m 2 ), ever green broadleaf forests (21.2 individual/m 2 ). Earthworms were found low- est in short-day crops land (15.46 individual/m 2 ). The highest biomass of earthworms was found in shrub-plot (12.63 g/m 2 ), then to house garden (10.3 g/m 2 ), bamboo forest (9.9 g/m 2 ), short-day crops land (9.78 g/m 2 ), perennial land on hill (5.04 g/m 2 ) and was the lowest in ever green broadleaf forests (4.09 g/m 2 ). Generally, biomass and density of earthworms were the highest in A1 (0 - 10 cm) stratum, then to A2 (10 - 20 cm) stratum, and were the lowest in A0 stratum. In every biotope, biomass and density of earthworms were higher in the rainy season than in the dry season. In the rainy season, density of earthworms were the highest in A1 stratum, but earthworms tend to go down A2 stratum in the dry season. 1. Introduction Khe Ro Nature Reserve is located at An Lac Commune, the East of Son Dong District, Bac Giang Province with the area of 7,155 ha (including 1,480 ha of buffer region and 5,675 ha of Reserve). The Reserve is divided into two zones: strictly 131 Tran Thi Thanh Binh and Ngo Van Nam protected zone with an area of 2,920 ha and ecological restoring zone with an area of 2,755 ha. Among 5,675 ha of Reserve, there is 4,144.6 ha covering forest accounts for 81.5%. The rest of the Reserve with an area of 1,530.4 ha accounting for 18.5% is land for cultivation and other purposes [5]. Although there have been many promulgated documents about earthworms in Northeastern Vietnam, until now, there is not any documentation mentioning to earthworm at Khe Ro Nature Reserve. This research aims to discover species components and distributive features of earthworms, contributing to investigatations and reserve biological diversification at Khe Ro Nature Reserve. 2. Research method From December 2006 to August 2007, we collected quantitative and qualita- tive specimens of earthworms from regions of this Reserve, including: ever green broadleaf forest, Bamboo forest, shrub-plot, perennial land on hill, short-day crops land, and house gardens. We collected quantitative specimens following M.S. Ghil- iarov [3] specimen collecting method from lakes with the size of 50 cm x 50 cm. In each lake, earthworms were collected from stratum by stratum. Each stratum at a depth of 10 cm. Qualitative samples were collected in many different ways (such as digging, picking up, upturning stones, pulling up plants and pouring water). We also enlarged the region of collection in order that no species components of earth- worm would be missed. The total of collected specimens was 1,650 individuals from 152 quantitative holes and qualitative samples. We analyzed and defined species of earthworms basing on specific documents. We used the Stugren and Radulescu for- mula to examine species component relationships (R). All specimens were stored at the Zoology Department, Biology Faculty, Hanoi National University of Education. 3. Results and Discussion 3.1. Species component of earthworm at Khe Ro Nature Re- serve 1- The Table 1 introduces 25 species of earthworm collected from Khe Ro Nature Reserve. Among identified species, Pheretima truongsonensis is new record from Northeastern Vietnam. Among 5 genera which we have found, there were 19 species of the genus Pheretima (76%, the most); 2 species of the genus Drawida (8%); 2 species of the genus Dichogaster (8%); 1 species of the genus Pontoscolex (4%) and 1 species of the genus Gordiodrilus (4%). In Khe Ro Nature Reserve, there are three morpho-ecological group of earth- worms. 2 species are in the Humus group (accounting for 8%) including: Phere- tima hawayana, Ph. truongsonensis; 11 species in Land-humus group (accounting for 132 Composition and distribution of earthworms in Khe Ro Natural Reserve 44%) including: Pheretima arobusta, Ph. aspergillum, Ph. cupreae, Ph. leucocirca, Ph. robusta, Ph. zinkevichi, Pheretima sp.1, Pheretima sp.2, Pheretima sp.3, Phere- tima sp.4, Pheretima sp.6; 12 species in Land group (accounting for 48%) including: Pontoscolex corethrurus, Gordiodrilus elegans, Drawida beddardi, Drawida sp., Di- chogaster bolaui, Dich. modigliani, Pheretima adexilis, Ph. exilis, Ph. papulosa, Ph. socsonensis, Ph. wui, Pheretima sp.5. Among found earthworms in researching area, land and land-humus group are dominant (23 species, accounting for 92%). Humus groups are the lowest frequency (2 species, accounting for 8%). Table 1. Species components of earthworm in regions at Khe Ro Nature Reserve Order Species (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) 1 Pontoscolex corethru- rus x x x x x x ∗ x x x 2 Gordiodrilus elegans x x ∗ x 3 Drawida beddardi x x ∗ x x 4 Drawida sp. x x ∗ 5 Dichogaster bolaui x x ∗ x x x 6 Dich. modigliani x x x ∗ x x 7 Pheretima adexilis x ∗ 8 Ph. arobusta x x ∗∗ 9 Ph. aspergillum x x ∗∗ x x x 10 Ph. cuprea x ∗∗ x x 11 Ph. exilis x x x ∗ x x 12 Ph. hawayana x x ∗∗∗ x x 13 Ph. leucocirca x x ∗∗ x x 14 Ph. papulosa x ∗ x 15 Ph. robusta x x x ∗∗ x x x 16 Ph. socsonensis x ∗ 17 Ph. truongsonensis x ∗∗∗ 18 Ph. wui x x ∗ x x x 19 Ph. zenkevichi x ∗∗ x 20 Pheretima sp.1 x x x ∗∗ 21 Pheretima sp.2 x x ∗∗ 22 Pheretima sp.3 x ∗∗ 23 Pheretima sp.4 x ∗∗ 24 Pheretima sp.5 x ∗ 25 Pheretima sp.6 x ∗∗ Total 12 10 12 1 9 4 10 8 12 Note: * . Land group; **. Land-humus group; ***. Humus group (1). Ever green broadleaf forest; (2). Bamboo forests; (3). Shrub-plot; (4). Perennial land on hill; (5). Short-day crops land; (6). House garden; (7). Morpho- ecological group; (8). Ba Be National Park (26 species  According Huynh Thi 133 Tran Thi Thanh Binh and Ngo Van Nam Kim Hoi & associate, 2007 [4]); (9). Cat Ba Island (26 species - According Thai Tran Bai, Le Van Trien, 1992 [1] ); (10). Tam ao National Park (40 species - According Thai Tran Bai, Nguyen Van Canh, 2001 [2]). 2- There are differences regarding species components in different regions. They are more diverse in regions with high covering level and little effect from people. These regions include ever green broadleaf forests (12 species), shrub-plot (12 species), Bamboo forests (10 species). All regions such as regions with people's frequent effects, regions with high slope, little covering,. . . have fewer earthworms. In regions of short-day crops landsflat corn banks under shrub-plot (9 species). In house gardens - including perennial and short-day crops land around house in slope hills (4 species) and the lowest perennial land on hill with a lot of stones, hills growing litchi or nacre plants (only one species - Pont. corethrurus). 3- In comparison with contiguous regions having fauna of earthworm of the Northeastern, including Ba Be National Park, Tam Dao National Park and Cat Ba Island (Table 2), we can see that 12 species are similar to ones in Tam Dao National Park (accounting for 66.7% of total known earthworm species in research), 10 types are similar to ones in Ba Be National Park (accounting for 55.6%), and 8 species are similar to ones in Cat Ba Island (accounting for 30.8%). Earthworm systems at Khe Ro Nature Reserve is a little different from earth- worm systems at Ba Be National Park (R = 0.27), Cat Ba Island (R = 0.37) and Tam Dao National Park (R = 0.63). Closeness level of earthworm systems at Khe Ro Nature Reserve in comparison with contiguous zones is Ba Be National Park, Cat Ba Island, Tam Dao National Park. 3.2. Density and biomass distribution of earthworm at Khe Ro Nature Reserve 3.2.1. Regional basis Researching results about density (individual/m 2 ) and biomass (g/m 2 ) of earthworm in researched regions are shown in Figure 1. Figure 1. The number of species and density, biomass distribution of earthworm in researching area 134 Composition and distribution of earthworms in Khe Ro Natural Reserve The research also shows that the highest density of earthworms were found in bamboo forests (44.53 individual/m 2 ), then to shrub-plot (33.6 individual/m 2 ), house garden (32.45 individual/m 2 ), perennial land on hill (27.66 individual/m 2 ), ever green broadleaf forest (21.2 individual/m 2 ). Earthworms were found lowest in short-day crops land (15.46 individual/m 2 ). The highest biomass of earthworms was found in shrub-plot (12.63 g/m 2 ), then to house garden (10.30 g/m 2 ), bamboo forest (9.90 g/m 2 ), short-day crops land (9.78 g/m 2 ), perennial land on hill (5.04 g/m 2 ) and was the lowest in ever green broadleaf forest (4.09 g/m 2 ). Like this, Biomass is not completely in direct ratio with density because they depend on size and quantity of each species. In regions having large earthworms, though their density is small, their biomass is still high. Although there is only one type on hills for growing perennial plants, their density is relatively high (27.66 individual/m 2 ). It means that this type has a good ability to adapt. 3.2.2. Seasonal basis In general, in each area, density and biomass of the earthworm in the rainy sea- son are always higher than in dry season (Figure 2). This is suitable and reasonable because earthworms suffer greatly from the effects of humidity and temperature. In dry seasons, the weather is cold and dry. It is not suitable for development of earthworm. 3.2.3. Deep basis Results of reseal on density (individual/m 2 ) and biomass (g/m 2 ) of earthworm in researched regions following deep basis are shown in Figure 3. Earthworms are distributed mainly in 2 stratums A1 and A2 (0 - 10 cm and 10 - 20 cm). They are also distributed at A0 stratum in and bamboo forests. Generally, A1 is stratum which has highest density of earthworm, lower is A2 stratum and lowest is A0. Among of them, at all regions, A1 has density of earthworm higher in the rainy season rather than in dry season. However, in A2 stratum at ever green broadleaf forest, bamboo forests, Perennial land on hill and short-day crops land, density of earthworm in dry season is higher than in rainy season. So, in researched zones earthworm density is high in rainy season at A1 stratum but earthworms tend to go down A2 stratum in the dry season. Thai Tran Bai (1992) said that in Cat Ba Island forests, earthworms have a tendency to distribute deeper in rainy season than in dry season [1]. It is different from our results. This shows that we need to research more regarding the density of earthworms in rainy and dry seasons in order to have more data. 135 Tran Thi Thanh Binh and Ngo Van Nam Density Biomass E v e r g r e e n b r o a d l e a f f o r e s t B a m b o o f o r e s t s S h r u b - p l o t P e r e n n i a l l a n d o n h i l l S h o r t - d a y c r o p s l a n d H o u s e g a r d e n Figure 2. Density and biomass distribution of earthworm following seasonal basis 136 Composition and distribution of earthworms in Khe Ro Natural Reserve Figure 3. Density and biomass distribution of earthworm following deep basis 1. Ever green broadleaf forest; 2. Bamboo forests; 3. Shrub-plot; 4. Perennial land on hill; 5. Short-day; 6. crops land House garden REFERENCES [1] Thai Tran Ba, Le Van Trien, 1992. Composition and distribution of earth- worms in Cat Ba Island (Hai Phong). Information of Science of Hanoi National University of Education, N ◦ . 4, pp. 14-23, (in Vietnamese). [2] Thai Tran Bai, Nguyen Van Canh, 2001. Diversification of earthworms species at Tam Dao National Park. Journal of Biology, Vol. 23, N ◦ . 3b, pp. 3-10, (in Vietnamese). [3] M.S Ghiliarov, 1976. Method for studying on Mesofauna. Moscow Science Publishing House, Rusia, (in Russian). [4] Huynh Thi Kim Hoi, Vuong Tan Tu, Nguyen Canh Tien Trinh, 2007. Composition, quantity, distribution of earthworms at Ba Be National Park (Bac Can Province). Science Report on Ecology and Biological Resoures, Agriculture Publishing House, Ha Noi, pp. 323-326, (in Vietnamese). [5] Bac Giang Department of Forestry, 1994. Theoretical factual foundations on Civil Engineering - Economics of Khe Ro Nature Reserve. Documentation of Bac Giang Province. 137