1. Salt Spray and Salinity:
* Upper Beach: Plants in the upper beach are less exposed to salt spray and have more time to recover from it. The upper beach receives less direct saltwater spray, resulting in lower salt accumulation in the soil.
* Lower Beach: Plants in the lower beach are constantly exposed to salt spray and high salinity levels. The constant salt spray and saturated soil with high salinity make it challenging for plants to absorb water and nutrients.
2. Water Availability:
* Upper Beach: The upper beach receives occasional rainfall and experiences less frequent flooding, allowing plants to access freshwater.
* Lower Beach: The lower beach is frequently flooded by tides, leading to a constant supply of saltwater and hindering the access to freshwater.
3. Sand Movement and Instability:
* Upper Beach: The upper beach experiences less sand movement due to the lower tidal action, providing a more stable environment for root establishment.
* Lower Beach: Constant wave action and sand movement in the lower beach make it difficult for plants to establish roots and survive.
4. Sunlight Exposure:
* Upper Beach: Plants in the upper beach receive ample sunlight for photosynthesis.
* Lower Beach: The lower beach experiences more shade due to the presence of dunes and taller vegetation, limiting sunlight availability.
5. Nutrient Availability:
* Upper Beach: While the upper beach soil is generally poor in nutrients, the occasional rainfall and decomposition of organic matter contribute to some nutrient availability.
* Lower Beach: The constant washing away of nutrients by the tides makes it harder for plants to access essential nutrients for growth.
In summary, the upper beach offers a more suitable habitat for beach plants due to reduced salt stress, better water availability, greater stability, adequate sunlight, and some nutrient availability. These factors allow plants to establish and survive, while the harsh conditions of the lower beach make it a less hospitable environment.
