Explanation:

Prairies are vast grasslands that are characterized by a lack of trees. However, there are a few tree species that are able to grow in the Prairie ecosystem. Among the given options, the tree that does not grow in Prairies is the Sal tree. Here is a detailed explanation of why the other tree species listed can grow in Prairies:

Alders:
- Alders are deciduous trees that are well-adapted to wetland environments.
- They are able to survive in areas with poorly drained soil, such as riverbanks and swamps.
- Alders have the ability to fix nitrogen in the soil, which improves the fertility and health of the surrounding ecosystem.
- They are able to withstand flooding and are often found in riparian zones along rivers and streams.
- Due to their adaptability to wet conditions, alders can grow in certain areas of the Prairie ecosystem where there is sufficient moisture.

Willow:
- Willows are also deciduous trees that are commonly found in wetland habitats.
- They have a high tolerance for standing water and can even survive in areas with periodic flooding.
- Willows have an extensive root system that allows them to absorb water from the soil and prevent erosion.
- They are often found near lakes, ponds, and marshes, where they provide important habitat and food sources for various organisms.
- Willows are able to grow in certain areas of the Prairie ecosystem where there is enough moisture for their survival.

Poplars:
- Poplars, or poplar trees, are another group of trees that can grow in the Prairie ecosystem.
- They are fast-growing and deciduous, making them well-suited to the open grassland environment.
- Poplars have deep root systems that enable them to access water from lower soil layers, allowing them to survive in drier conditions.
- These trees are often found along riverbanks and in areas with high water tables.
- The ability of poplars to adapt to a range of soil and moisture conditions makes them suitable for growth in certain parts of the Prairie ecosystem.

In summary, while alders, willows, and poplars are all able to grow in Prairies due to their adaptation to wetland or drier conditions, the Sal tree does not typically grow in this grassland habitat.

Sal is a tree which doesn't grows in Prairies.
As the requirements of Sal is not fulfilled in Prairies.