How Fern and Fern Allies Respond to Heterogeneous Habitat--- A Case in
Yuanjiang Dry-Hot Valley
Abstract
The Yuanjiang dry-hot valley features hot and dry climate, low
vegetation and soil degradation. It had lush vegetation in the past, but
has become degraded in recent decades. Understanding the
interrelationship between species and the habitat is necessary to
explain this change. In this study, a link between fern and fern allies
- a group that is hypersensitive to environmental factors and their
circumstances is constructed. Intensive transects and plots were
designed to be proxies for extant fern and fern allies, and their
habitats. Fifty years of meteorological records of precipitation and
temperature along altitude and river running direction (latitudinal)
were employed. Alpha and beta diversity are used to access diversity.
Species_estimated, Singletons, Uniques, ACE, ICE, and Chao2, which
associate to abundance and rarity, are subscribed to the correlation
between fern and fern allies, and their ecosystem. Eight species,
Selaginella pseudopaleifera, Aleuritopteris squamosa, Adiantum
malesianum, Pteris vittata, Davallia trichomanoides, Sinephropteris
delavayi, Selaginella jugorum, and Lygodium japonicum are used as
indicators of a typical xeric and sun-drying habitat. The results
indicate (1) accompanied by dramatically shrinking habitats, fern and
fern allies are in very low diversity and abundance, whereas the rarity
is relatively high; (2) for fern and fern allies, environmental factors
are positive when altitude goes up; and (3) eight indicator species are
latitudinally correlated with fern and fern allies along the river
running direction.