When is a pond plant
Sometimes plants are just perceived to be a problem because they
interfere with a landowner's view of his pond or they make it difficult to access
the lake for boating or swimming. In fact, these pond plants may be healthy,
diverse and providing many benefits. However plants really become a problem
when excessive growth of one species clogs out all other species.
It is useful to understand a little bit about what controls the
growth of aquatic plants in order to manage them properly. The abundance, types
and species of aquatic plants are controlled by a complex suite of factors.
- Light: As with terrestrial plants, the main factor is the availability
of light. However, light rays do not move as far through water as they do
through air. Under clear water conditions, the specific wavelengths that plants
need to photosynthesize can travel to depths of tens of meters. However, suspended
sediment and phytoplankton can quickly cloud the water, decreasing light penetration
to just a few centimeters.
- Nutrients: Phosphorus, nitrogen, and other nutrients are essential
for plant growth. Frequently and excess of nutrients allow a few, more competitive
plant species, to crowd out other plants. The nutrients may be directly dissolved
in the water column, bound to the sediments, or draining into the lake along
groundwater seepage areas.
- Animals: Fish, waterfowl, aquatic insects and other animals will
eat many plant species, often to the point of controlling their abundance
- Substrates: Unusually rocky or mucky substrates may be too inhospitable
for some seeds to germinate and grow.
- Waves: Excessive wave action along some shorelines can severely impact
the ability of plants to get established and grow.
- Dispersal: Some plants may be absent from a lake or pond simply because
they haven't had the opportunity to get started there. However aquatic plants
have developed an amazing diversity of strategies for dispensing within and
among ponds. Fro example, many aquatic plants can successfully reproduce themselves
from small fragments of their leaves or roots.
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