The most important mission of Shei-Pa National Park is to conserve the natural resources, especially the Formosan landlocked salmon in the basin of Chichiawan Stream of the Wulin area. In order to understand the dynamics of the Formosan salmon, it is necessary to construct the trophic model and to examine the interactions between communities and environmental factors in the area. However, as many other basins, the Wulin area is exploited intensively for agricultural activities. Here, a collaborative project is proposed to ecologically monitor and integrate hydrodynamics, physical habitats, water quality, organic detritus, periphyton, riparian plants, terrestrial and aquatic insects, other invertebrates, amphibians, reptiles, fish and birds. The aims of this ecosystem-scale project are: 1. Using ecological models to understand the ecological processes of the salmons and the food webs; 2. To demonstrate the relationships between environmental factors and communities and between communities within the food webs; 3. To search the driving forces on the the ecological processes of the salmons and the food webs; 4. To trace the sources of nitrate in the water column and its relationships with human impacts; 5. To relate abundance and composition of commnities to physical habitats; 6. To examine effects of floods on the communities and habitats and their recovery; 7. To develope scientific database; 8. To suggest items for long-term ecological monitoring and policy for sustainable management in the future.
Periphyton, detritus, data analysis, and ecosystem modeling
Hsing-Juh Lin, Yi-Chan Chang, Liang-Ching Lin, Ling-Hua Ke, Hui-Yu Hsu, Mei-Ling Liao
Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan, R.O.C.
One of the missions of Shei-Pa National Park is to conserve the natural resources, especially the Formosan landlocked salmon in the Chijiawan Stream basin of Wulin area. In order to understand the dynamics of the Formosan salmon, it is necessary to construct a stage-dependent population matrix model and a trophic model to examine the interactions with other communities.
Periphyton was sampled in the spring and summer of 2006. The results showed that the biomass was very low. Compared with the previous data, Yeaushen Stream has highest periphyton biomass. Riffle is the typical habitat type at all sites. No significant difference was found among sites and microhabitats. For the algal composition, there were in total seven algae genera. Algal diversity was highest in Yeaushen Stream. Taoshan West Stream and Dam 1 had fewer genera, including Achnanthes, Gomphonema and Cocconeis. The MDS analyses showed that the epilithic algae was structured by site rather than by microhabitat type.
Transport from upstream contributed most of detrital influx in the streams. The greatest value occurred in Kaoshan Stream. Annual Detrital influx could be significantly explained by coverage of riparian plants. Suspended organic matter was highest in April and in Taoshan North Stream, Taoshan West Stream and Kaoshan Stream. But the values declined after the floods induced by typhoons. Fine bottom organic matter was primarily in smaller sizes and peaked in February. The abundance of fine bottom organic matter could be explained by water velocity on the bottom, but that of coarse bottom organic matter could be explained by the coverage of riparian plants. Bottom organic matter mainly comprised of leaves, but the proportion of algae increased in Yeausheng Stream. Floods induced by typhoons resulted only in the decline of coarse and large fine bottom organic matter, but not small fine bottom organic matter.
The trophic models and the system statistics showed that the characteristics of the Wulin streams were similar. All sites processed a simple food web structure. The biomasses were concentrated in periphyton compartment, and primary consumers were the major consumers. Maximum trophic level ranged between 3.09 and 3.14. Yeaushen Stream had the highest total system throughput and followed by Dam 1, Breeding Center, Kaoshan Stream and Taoshan West Stream. At all sites, the net primary production (P)/respiration (R) ratios were > 1.0, indicating that the Wulin streams are autotrophic systems. The major system production was from primary producers, but because of fewer consumers, most of primary production was not used and flowed into the detrital pool. According to Lindeman spine analyses, geometric mean of trophic efficiencies in the Wulin Streams was low. Compared with other river systems, the Wulin streams were low-biomass, low-respiration, high P/R ratio, but the trophic efficiencies were low.
【Keywords】the Formosan salmon, the Chichiawan stream, periphyton, detritus, trophic model, ECOPATH.
The riparian insects survey
for the middle scale WLTERM carried out by various method and traps every
two month a year at the station 1, 2, 5, 8, 9 along the river Chichiawanshi.
Totally 150,403 individuals of insects were collected and identified as 22
orders, and there are 189 families were identified so far. The top four
orders in individual number are Diptera (60.9%), Collembola (22.3%),
Coleoptera (6.7%) and Hymenoptera (4.3%), therefore the insect indicator
group is DCmCpHy and include 93.3% of all individual number. There are
13,518 individuals collected by sweeping net from 4 transections which are
along the way from the mountain foot to the peak of Syue mountain by the
altitude of 2,500-2,900 m, 2,900-3,100m, 3,200-3,400m, 3500 m are 5,116,
4,165, 2,343 and 1,894 in individual respectively. The dominant orders are
Diptera (31.1%), Homoptera (29.8%), Collembola (14.8%) and Hymenoptera
(9.9%), the present insect indicator group is HmDCmHy and include 85.6% of
all individual number. According to the stomach analysis of the five fishes
of Oncorhychus masou formosamus, we found that the major groups of insect
prey are Ephemeroptera (44.2%), Diptera (14.2%) and Coleoptera (11.7%).
There are 33.6% of insect fragment belongs to the terrestrial insect which
were dropped into the water and purchased by the fish as the food resource
which is also important to the input of the river ecosystem.