High Primary Productivity in Swamps and Marshes

Swamps and marshes are characterized by:

• Shallow water and nutrient-rich soils: These conditions support rapid plant growth and high rates of photosynthesis, leading to the creation of large quantities of organic matter27.

• Abundant food resources: The high productivity forms the base of complex food webs, supporting numerous invertebrates, fish, birds, and other wildlife2.

• Vital ecological functions: These wetlands play key roles in flood protection, nutrient cycling, and habitat provision for many species4.

Why Is Biodiversity Low Despite High Productivity?

The main reason for lower species biodiversity in swamps and marshes is the lack of diverse habitats8. Here’s why:

• Environmental Homogeneity: Many marshes and swamps are dominated by a few plant species that are highly adapted to saturated, low-oxygen soils. This creates a relatively uniform environment with limited microhabitat diversity, which restricts the number of different species that can establish and thrive68.

• Generalist Dominance: Wetland habitats often favor generalist species that can tolerate a wide range of hydrological conditions. As these species become more abundant, they outcompete specialists, further reducing overall species diversity8.

• Hydrological Constraints: The waterlogged conditions and fluctuating water levels can be stressful for many plants and animals, limiting the pool of species able to survive in such environments.

• Invasive Species: Disturbed wetlands are particularly vulnerable to invasion by non-native plants, which can further reduce native species diversity8.

Supporting Evidence

• Studies show that, while some marshes may have a moderate number of species, a small subset of dominant plants often makes up the majority of the biomass and observations56.

• Changes in flooding patterns or nutrient levels can favor a few highly adaptable species, leading to a loss of specialists and a decline in overall biodiversity8.

Other Factors Considered

• Energy Transfer: Energy is indeed efficiently transferred to higher trophic levels in these ecosystems, supporting rich food webs, but this does not directly translate to more species2.

• Decomposition and Predation: While decomposition rates and predation pressure can influence community structure, they are not the primary reasons for low species diversity in these highly productive wetlands.

Conclusion

Swamps and marshes are powerhouses of primary productivity but tend to have lower overall species biodiversity primarily due to the lack of diverse habitats. The environmental uniformity and dominance of generalist species limit the variety of plants and animals that can coexist. For wetland conservation, this means that protecting or enhancing habitat heterogeneity is key to supporting greater biodiversity in these vital ecosystems.

Correct answer:
(2) Due to lack of diverse habitats