Nutrient relations of the halophytic shrub, Sarcobatus vermiculatus, along a soil salinity gradient
Citation
James H Richards, Lisa A Donovan, and E Joy Schaber, Nutrient relations of the halophytic shrub, Sarcobatus vermiculatus, along a soil salinity gradient: .
Summary
Recent water level declines of a saline and alkaline lake (Mono Lake, California, USA) have exposed large areas of former lake bottom substrates that have been sparsely colonized by the halophytic shrub, Sarcobatus vermiculatus. To increase understanding of the interaction of salt and nutrient relations in halophytes we investigated spatial and seasonal patterns of leaf elemental composition and growth for Sarcobatus along an extreme salinity gradient using four sites varying in age since exposure. Soil and groundwater Na and EC increased from non-saline at the site farthest from the Lake to highly saline at the site closest to the Lake. Leaf and stem length growth declined along this same transect. In June, when shoot growth rates [...]
Summary
Recent water level declines of a saline and alkaline lake (Mono Lake, California, USA) have exposed large areas of former lake bottom substrates that have been sparsely colonized by the halophytic shrub, Sarcobatus vermiculatus. To increase understanding of the interaction of salt and nutrient relations in halophytes we investigated spatial and seasonal patterns of leaf elemental composition and growth for Sarcobatus along an extreme salinity gradient using four sites varying in age since exposure. Soil and groundwater Na and EC increased from non-saline at the site farthest from the Lake to highly saline at the site closest to the Lake. Leaf and stem length growth declined along this same transect. In June, when shoot growth rates were maximal, leaf Na paralleled substrate availability and reached a high of 130 g kg–1 leaf dry weight near the Lake. Through the remainder of the growing season, plants on the lower salinity site continued to accumulate increasing amounts of leaf Na, whereas plants at the highest salinity site reached a plateau earlier in the season. The similarity of high leaf Na at all sites by the end of the season indicates a dominance of Na nutrition over the entire gradient, and a possible upper bound of Na accumulation and tolerance for this species. In June, Sarcobatus leaf N, P were higher at sites further from the Lake and did not correspond to soil N (total) and P that were highest near the Lake. Leaf K, Ca, and Mg in June also did not match substrate availability, and were low enough to indicate marginal sufficiency for growth. However, the increasing substrate Na did not interfere with K, Ca and Mg uptake based on selectivity coefficients (e.g. (leaf K/leaf Na)/ (soil K/soil Na)) that did not decline with increasing substrate salinity. Uptake and transport to leaves, of K and Ca relative to Na, remained proportional to what was in the soil across the entire gradient of soil salinity. Uptake and transport of Mg relative to Na increased dramatically in inverse proportion to declining soil availability near the Lake, indicating that Mg may be a critical limiting factor for tolerance of high salinity sites. The key determinants of Sarcobatus growth and ecological dominance along this extreme salinity gradient (non-saline to highly saline) are the propensity to accumulate large amounts of leaf Na over the entire gradient, and the ability to maintain adequate uptake of N, P, K, Ca, and Mg under highly variable substrate combinations of nutrients and Na.
Published in Plant and Soil, volume 190, issue 1, on pages 105 - 117, in 1997.