Foliar Amino Acid Accumulation as an Indicator of Ecosystem Stress for First‐Year Sugar Maple Seedlings

Abstract

AbstractAccumulation of certain plant foliar amino acids (arginine, glutamine, and proline) can be used as indicators of anthropogenic and natural stressors, such as atmospheric deposition and mineral nutritional imbalances, which result in decreased plant growth. In this study a number of factors were evaluated to assess the use of foliar amino acid accumulation as indicators of sugar maple seedling stress at two sugar maple dominated forests in Michigan. These factors were: (i) first‐year sugar maple (Acer saccharum Marshall) seedling growth, (ii) N and P nutrition, (iii) soluble foliar and root total amino acid concentrations, and (iv) concentrations of foliar arginine, glutamine, and proline. The most southern site (Wellston), which was exposed to high atmospheric deposition and had high available soil P and seedling foliar P, had greater seedling growth. Foliar glutamine, arginine, and proline were greater at the most northern site (Alberta), which received lesser amounts of atmospheric deposition, but also had lower levels of available soil phosphorus, seedling foliar phosphorus, less seedling growth, and greater canopy closure. These results suggest that since atmospheric deposition is high in nitrogen, even the low levels of deposition at Alberta may be interacting with ecological variables such as, available soil phosphorus, light, or moisture to result in N/P imbalances and consequently higher arginine and glutamine concentrations in seedling foliage.