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vegetation was studied in summer 2012 using a transect method, estimating macrophyte speciescomposition and occurrence (on a five – point scale). In Dienvidu Garezers Lake and Vidējais GarezersLake 21 transects were set, but in ZiemeĜu Garezers Lake – 11 transects. To estimate biologicaldiversity of macrophyte vegetation species diversity indices were used. To assess ecological quality ofthe lakes, Polish Ecological State Macrophyte Index (ESMI), British Lake Macrophyte Nutrient Index(LMNI), and for Latvia adapted Estonian transect method with combination of phytolittoral mappingmethod, based on estimating abundance of macrophyte growth forms were used. Together in GarezeriLakes were recognized 36 macrophyte taxa. Highest number of taxa (27) was appointed in DienviduGarezers Lake. Species with highest occurrence in all lakes were Nuphar lutea, Phragmites australis,Carex acuta, Comarium palustre, Lythrum salicaria. Only in Dienvidu Garezers Lake was identified twoprotected and rare species - Lobelia dortmannaand Isoetes lacustris. In the Garezeri lakes helophytesdominate in amount of species and total occurrence. Highest number of species and total macrophyteoccurrence was estimated in the most shallow depth zone (0 – 1 m). Highest biological diversity is inZiemeĜu Garezers Lake, where is the highest Shannon index (H’ = 0,913) and the lowest Simpson’sindex (D = 0,135) values. In all three lakes existent species diversity and distribution equality is closeto maximum possible. According to ESMI and for Latvia adapted Estonian method ecological qualityof Garezeri Lakes is good. LMNI shows good ecological quality in Dienvidu and Vidējais GarezersLake, but moderate ecological quality in ZiemeĜu Garezers Lake.Vija FrīdaDaugavpils Universitys Parades street 1, Daugavpils,Latvia, vija.frida@gmail.comDENDROLOGY ANALYSIS IN NATURE RESERVE“PILSKALNES SIGULDIĥA”Nature Reserve „Pilskalnes SiguldiĦa” is a protected area with high biological diversity. The NatureReserve was created in 1999 and it is included in the Natura 2000 network, but its Natural resourcemanagement plan and Individual protection and use regulations have not been approved yet.In order to create these documents it is necessary to investigate natural values in the Nature Reserve.The aim of this paper is to make inventories of secular trees.Thirty-three secular trees of national significance and local significance have been investigated:circumference, height, crown projection, condition.As the results of the research nine secular oaks (circumference ≥4m), one secular spruce(circumference ≥3m) and one secular ash (circumference ≥3,5m) of national significance have beendiscovered. Only one of the investigated secular trees has already been under state protection – Senčusecular oak.AcknowledgementsResearch reported in this article was supported by the ESF project No.2011/0018/1DP/1.1.2.1.1/11/IPIA/VIAA/010 “Support of master’s studies in DaugavpilsUniversity”.~ 12 ~