Species Composition And Distribution Of Diatoms At Huoditang Forest Region In Qin Ling Mountains

Huoditang forest region located on the middle part of south hillside of Qinling mountains.In this area, there are eleven great channels, characterized by mountain stream water. Thisforest region have complicated physiognomy, diversiform entironment and various species.There are many researches about advanced plant resources and a small quantity of studiesabout insects and fungi, but the researches about algae flora is a vacancy till now.In order to make definite that the species composition and the ecological habitats of thediatoms from huoditang forest region of Qinling mountains,23samples which were collectedfrom Huoditang forest region of Qinling mountains were acidized before being observed andidentified by light microscope, part of the samples were identified by scanning electronicmicroscope(SEM). This thesis listed the primary research results of the diatoms of Huoditangforest region, and made a particular description of the species that had been observed. At thesame time, the species composition, dominant species and the ecological habitats of all thediatom species have been studied preliminarily. Otherwise, the pollute situation of the forestregion has been brief analyzed.After the identification of the samples, a total of161taxa were discoveried, including2classes,6orders,10families,32genera,112species,42varieties and7forms.125taxa arethe new records of Shaanxi province, including84species,35varieties and6forms.4taxa ofPennatae were dominated in this region, including Diatoma hiemale var. mesodon (Ehr.)Grun., Cymbella ventricosa Ag., Cocconeis placentula Ehr. and Cocconeis placentula var.euglypta (Ehr.) Grun..The characteristic of ecological distribution of the diatoms from Huoditang forest regionlisted as follows: 1. From the view of the life style of the diatoms, the diatoms from Huoditang forestregion have three classes, including planktonic diatoms, benthic diatoms and epiphyticdiatoms.2. From the view of the microhabitat of the diatoms, the habitat of epiphytic float grass issuitable for the diatoms from Huoditang forest region. From the view of the whole watercondition, the lenitic condition is more suitable for the growth and the reproduction of thediatoms.3. From the view of the pH and the salt content of the waters, most species of thediatoms from Huoditang forest region belong to the neutral pH, freshwater species. A fewspecies belongs to between freshwater to brackish water and between freshwater to mildlybrackish water. Very few species belongs to the other species.4. From the view of some typical habitats, there are many high mountain cold waterspecies and the general widespread species, including21and20taxa. On the other side, thereare2tropical species.5. Many of the diatom species of Huoditang forest region are more comfortable to higherheight. There are the most species between1743-2340m of the range of variation of thesample points. But the distribution of the maximum diatom density relatived to the heights isnot obvious.In addition, by the experiment analysis, there are mild pollutions of two places thatpeople often come in and go out. The two places are the penstock by the roadside of new roadban and the hillside towards the station of the forest region. In order to avoid the pollution tobecome more serious, some protection measures would be advised to the relevant department.