N and p are often the limiting nutrients The limiting nutrient is the least available element in relation to its required abundance N is abundant in the form of N2, but N2 can only be utilized througl gh N2-fixing bacteria In waters where N2-fixing algal species are common, N is not usually limiting In regions where N2-fixing species are less abundant especially the oceans, N maybe the limiting nutrient This leaves P as the limiting element to plant growth This shortage keeps the spread of vegetation under controlN and P are often the limiting nutrients • The limiting nutrient is the least available element in relation to its required abundance. • N is abundant in the form of N2, but N2 can only be utilized through N2-fixing bacteria. • In waters where N2-fixing algal species are common, N is not usually limiting. – In regions where N2-fixing species are less abundant, especially the oceans, N maybe the limiting nutrient. • This leaves P as the limiting element to plant growth. • This shortage keeps the spread of vegetation under control