Recent Observation Of A Proliferation Of Ranunculus Trichophyllus Chaix. In High-Altitude Lakes Of The Mount Everest Region: Comment

The record altitudes at which organisms have been found are widely dispersed in the literature. Because of their anecdotal nature—a record altitude is often discovered by chance, rarely by specifically looking for it—such records often go unpublished, or are buried within publications dealing with wider subjects. However, the distributional limits at which organisms grow (maximum or minimum altitudes as well as other limits) are critical to our understanding of numerous basic biogeographic, ecological and physiological issues (Korner, 1999). With current awareness of global warming, records of maximum altitudes for organisms have taken on an even more pressing importance: variations in the actual maximum altitudes may indicate species responses to warming (Gottfried et al., 2002; Pauli et al., 2001; Parmesan and Yohe, 2003), and fragility of life at maximum altitudes has important management consequences (Halloy, 1989; Korner, 2000). We therefore welcome Lacoul and Freedman’s (2006) observations on Ranunculus trichophyllus at a maximum altitude of 4760 m (4750 m and 4780 m are also specified in the publication) in the Nepal Himalaya, which they quote as the highest altitude from which an aquatic angiosperm has been recorded. The authors consider this to represent a range expansion likely facilitated by climatic warming, given previous record altitudes quoted for the area of only around 4000 m. However, it is worth complementing this information. The recorded altitude is considerably lower than those routinely surpassed by several vascular plants in numerous lakes in the South American Andes from latitudes 13uS to 27uS, and probably elsewhere along the cordillera, too. A few examples from above 4800 m are given here from our own experience and the literature to place the Ranunculus trichophyllus record from Nepal in perspective. Vouchers for the species cited are at LIL herbarium, Tucuman, Argentina; LPB herbarium, La Paz, Bolivia; and CUZ herbarium, Cuzco, Peru. N Cerro Condor, Argentina, 5350–5400 m. On the border between Tucuman and Catamarca province, this lake harbors a dense population of Zanichellia sp. despite being partly ice covered, even in mid-summer (Halloy, 1981, 1983; Kuhn and Rohmeder, 1943). As far as we are aware, this is the highest published record for an aquatic vascular plant. N Lago Sibinacocha, Peru, 4880 m. This large high-altitude lake harbors diverse submerged communities, including Potamogeton, Myriophyllum, Isoetes, and Nitella (an algae but with an almost vascular plant-like life form). Being largely unexplored, it is likely to harbor a number of other species known from lower lakes such as Titicaca. Upward range expansion in this area is being documented for diverse organisms from amphibians to plants (Halloy et al., 2005; Seimon et al., 2007). N High Andean pools and tarns often linked to peat bogs harbor a variety of submerged vascular plants, e.g. Callitriche (4800 m, Sajama, Bolivia), Myriophyllum cf. elatinoides (4600–5244 m), Potamotegon cf. pectinatus (4600–5244 m), and Isoetes spp. (4400–5030 m); the latter three are in the Sibinacocha lake region, Peru. A large number of semi-aquatic vascular plants also characterize these communities (Carex spp., Distichia muscoides, Oxychloe andina, and many more) throughout the Andes, often reaching well above 5200 m. Previously recognized altitudinal limits for other organisms (e.g. clams, amphibians) are also being breached in the Sibinacocha area (Krajick and Peter, 2006; Seimon et al., 2007).