Multiple resources limit plant growth and function in a saline‐alkaline desert community

Abstract

Summary 1We investigated resource limitations in a saltbrush scrub community along a salinityalkalinity gradient in the Mojave Desert of North America. Previous studies have shown that, as productivity declines with increasing soil stress, there are parallel declines in leaf Ca and Mg, suggesting availability of these resources may limit growth in addition to water, N and P limitations expected in deserts. 2 To determine which soil resources limited growth of the dominant shrub, Atriplex parryi , and whether this differed along the soil stress gradient or among life stages, water and nutrients were applied in combination at different rates to plants at high-and low-stress sites. We developed and applied a conceptual model to identify resource limitations from this experiment. We also investigated how those limitations interacted to influence A. parryi growth and physiological function at the high-stress site. 3 Availability of soil N and P limited growth at the low-stress site and N, P and Mg limited growth at the high-stress site for both adult and juvenile life stages. There was no evidence that availability of water alone or K, Ca or other nutrients, or increasing soil Na and B, limited growth along the soil stress gradient. 4 When N, P, Mg and water were supplied in combination, plant growth increased more than 16-fold. Supply of these resources interacted to influence both plant growth and function. Because of the high demand for N relative to other resources, N supply rate was the major driver of these interactions, influencing the magnitude by which P and Mg affected growth. The major mechanism behind these growth responses was an increase in allocation to leaves relative to fine roots, rather than nutrient or water effects on water relations, photosynthesis or water use efficiency. 5 Multiple, interacting resources limit the growth and distribution of A. parryi on a saline, alkaline Mojave Desert site. Similar interactions between multiple limiting resources are likely to be instrumental in shaping community and species distributions along other abiotic stress gradients.

Effects of drought stress and N supply on the growth, biomass partitioning and water-use efficiency of Sophora davidii seedlings

“…The results from this study indicated that both drought and N limited the growth of S. davidii seedlings and their biomass production, which was in agreement with the findings of the previous study for this dry valley (Wang et al, 2003) and many other arid ecosystems (Hooper and Johnson, 1999;Corkidi et al, 2002;James et al, 2005). Regardless of N supply levels, drought stress dramatically reduced the seedlings growth and biomass production.…”

“…The ratio of leaf to fine root biomass (L/FR) is a sensitive measure of functional allocation because it quantifies the amount of resource dedicated to instantaneous leaf photosynthetic rate relative to nutrient and water absorption in these perennial shrubs (James et al, 2005). Although no statistical effects of either drought stress or N supply were observed on L/FR, seedlings with Nl treatment showed higher L/FR under severe drought stress, while seedlings with Nh treatment displayed the similar case under well-watered and medium drought conditions.…”

“…How to improve the efficiency of using finite resources and restore the degraded vegetation is always the problem facing ecosystem managers. James et al (2005) suggested that the change of finite nutrient availability would have the largest impact in altering community and ecosystem properties rather than changes in water availability or efficiency of water utilization. Fertilization increases the availability of limited nutrient, and then could alter system properties, which might be a potentially practical way to stimulate plant growth, enhance stress tolerance, and improve the efficiency in using finite resources in infertile and dry environment (Baligar et al, 2001;Singh et al, 2005;Dang et al, 2006).…”

Distribution patterns of shrubby N‐fixers and non‐N fixers in an arid valley in Southwest China: implications for ecological restoration

“…Water, N and P limitations to shrub distribution and growth in arid lands have been demonstrated (Marschner 1995;Drenovsky and Richards 2004;James et al 2005). Similar to other arid systems, the combination of a low, unpredictable water supply and nutrient status limited seedling establishment and plant growth in the arid valley.…”

Species specific plant-soil interactions influence plant distribution on serpentine soils

“…2). In single or factorial nutrient addition studies, increases in biomass that accompany increases in foliar concentration of a particular element with fertilization are interpreted as evidence of limitation by that element for that species in the unfertilized soil (James et al 2005; model in Fig. 2).…”