B. Papp szerk.: Studia Botanica Hungarica 38. 2007 (Budapest, 2007)

Rácz, István; Huyen, D. D.: Study of a low-elevation occurrence of Pinus dalatensis Ferré (Pinaceae) in Gia Lai province, Vietnam

montane habitats covered by subtropical evergreen forests. P. dalatensis drew the attention of researchers because it is among the threatened species of the Vietnam flora that occur in remnant primary forests, often affected by uncontrolled selective logging and loss of surrounding natural habitats. This is exemplified by the fact that at the type locality in the year 2000 only one tree of P. dalatensis remained of the five trees recorded in 1984 (NGHIA 2000). Until recently, the species was regarded as one of the endemic trees of Vietnam, although several references noted the possibility of its occurrence in the mountain ranges extending into Laos (RUNDEL 1999, Wu and RAVEN 1999, BUSINSKY 1999, LUU and THOMAS 2004). Its presence in Laos was confirmed in 2006 by the discovery of a population with over 200 trees occurring between 800-1,100 m in the Nakai Nam Theun conservation area (THOMAS et al. 2007). This new locality represents a significant extension of the northernmost limit of the species. In Vietnam, the Checklist of the plant species of Vietnam (LOC 2001) recorded P. dalatensis from Kon Tum, Dak Lak, Lam Dong, Khanh Hoa and Ninh Thuan provinces. More recent reviews of the conifer flora report additional occurrences in Gia Lai and Thua Thien-Hue provinces, but without giving further details (LUU and THOMAS 2004, NGUYEN et al. 2004). In his account of the distribution and morphology of the species, BUSINSKY ( 1999) also refers to a number of possible occurrences of P. dalatensis in the above provinces. A locality in the Mang Giang Forest Entrerprise area of Gia Lai is also mentioned in an overview of the threatened trees of Vietnam (NGHIA 2000). Its isolation (see Fig. 1 ) from other known locations made it a suitable subject for our investigations. The altitudinal range of Pinus dalatensis in NGUYEN and VlDAL (1996) was given as 1,500-2,400 m, in the Checklist of the plant species of Vietnam (LOC 2001) as 1,400-2,600 m and in LUU and THOMAS (2004) as (1,400-) 1,500-2,200 (-2,400) m. BUSINSKY (1999) refers to the location of P. dalatensis var. dalatensis near the city of Da Lat (1,470 m) as the lowest known occurrence. Based on the general descriptions and location data given by Businsky, and the localities of all of the specimens cited in his work, the species' altitudinal range in Vietnam appears to be as follows: — Pinus dalatensis subsp. dalatensis var. dalatensis - 1,470 to 2,442 m, — Pinus dalatensis subsp. dalatensis var. bidoupensis - 1,800 to 1,895 m,