Final answer:
The correct answer is b. The statement that species diversity is lower in an ecotone than in the bordering ecosystems is not true. Ecotones often have greater species diversity due to the presence of species from both surrounding ecosystems and unique species that thrive in transitional areas.
Step-by-step explanation:
An ecotone is a transition area between two biomes or ecosystems and is a zone of junction where two communities meet and integrate. It often includes a variety of species from the adjacent ecosystems and might also include species unique to that zone. Ecotones are important for biodiversity, and scientists often study these areas to understand the ecological relationships and transitions between ecosystems.
Regarding the specific question asked, which of the following is not true of an ecotone:
a. Population density for some species is higher than in either of the bordering ecosystems.
b. Species diversity is lower than in either of the bordering ecosystems.
c. They are studied as environmental indicators of change.
d. Properties such as soil moisture, temperature, or sunlight may vary significantly from those of either bordering ecosystem.
The correct option is b. Species diversity is not lower in ecotones; it is often greater than in either of the bordering ecosystems. This is because ecotones can contain species from both bordering ecosystems as well as species that prefer the transitional area, leading to increased diversity.