Functional plant traits
The MAP Project is dedicated to the collection of data on plant height, plus four traits representing the leaf economics spectrum (leaf area, specific leaf area, leaf nitrogen and leaf phosphorus). Together, these five traits provide good insight into the form and function of aquatic plants and their environment.
Below, we describe the ecological importance of of each of these five plant traits. For context and to demonstrate within trait variation, we include a photo of the species with the minimum and maximum value for each trait from the MAP Database.
Range of trait values
Subularia aquatica, height = 0.04 m
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Wolffia arrhiza, leaf area = 0.17 mm2
Ranunculus repens, SLA = 1.48 mm2/mg
Comarum paulstre, leaf N = 0.3 mg/g
Mentha aquatica, leaf P = 0.004 mg/g
Gynerium sagittatum, height = 10.36 m
Victoria amazonica, leaf area: 4340000 mm2
Potamogeton crispus, SLA = 1127.4 mm2/mg
Caltha palustris, leaf N = 97.18 mg/g
Spirodela punctata, leaf P = 28.4 mg/g
Plant Height
Plant height is the shortest distance (measured in metres) between the ground and the upper boundary of the main photosynthetic tissues (excluding inflorescences) on a mature plant. Plant height is related to growth form and position relative to light source, lifespan, and reproductive and competitive abilities and tendencies (e.g., fecundity, reproductive size, competitive vigour).
Leaf Area
Leaf area is the area of one-side of a fresh leaf, expressed in mm². Leaf area is related to climate, geology, altitude, and latitude, and generally declines in response to stress caused by heat, cold, drought, nutrient levels, and light. Leaf area is also associated with a number of allometric (e.g., plant size, number of leaves, shape and arrangement of leaves and other plant parts), ecological (e.g., responses to stress and other disturbances), and phylogenetic (e.g., divergence) factors.
Specific Leaf Area
Specific leaf area (SLA) is the area of one-side of a fresh leaf divided by its oven-dry mass and is expressed in mm²/mg. Specific leaf area generally shows a positive relationship with the relative growth rate of plants, photosynthetic rate, and leaf nitrogen content, and shows a negative relationship with leaf lifespan and the allocation of carbon toward the production of secondary metabolites, like lignin and tannins.
Leaf Nitrogen and Phosphorus Content
Leaf nitrogen (N) content is the total amount of N per unit of dry leaf mass and leaf phosphorus (P) content is the total amount of P per unit of dry leaf mass (both expressed in mg/g). Leaf N content and Leaf P content are generally correlated with one another and are both related to nutrient availability in the surrounding environment. Leaf N content and leaf P content can be taken together (N:P ratio) to determine which nutrient is a limiting factor for plant growth. Leaves with higher N and P content also provide more nutrients to consumers. Leaf N content is often associated with specific leaf area and maximum rates of photosynthesis (per unit mass), and nutrient availability in the surrounding environment.