Litter Araneae as a Function of Varying Amounts of Deciduous Litterfall
Douglas M. Jenison
This experiment investigated and compared litter Araneae populations in varying
amounts of deciduous litterfall in both climax and successional forests during pre- and postlitterfall conditions.
The proposed hypothesis was that increased litter mass would harbor
increased diversity of Araneae, only further increasing after all the trees had shed their leaves.
Litter Araneae are very common in northeastern Ohio deciduous forests and represent the top of
the macroinvertebrate food chain.
The study was conducted at the John T. Huston-Dr. John D. Brumbaugh Nature Center
in Alliance, Ohio, due to it's unique characteristics as having both climax and successional forests
in close proximity to each other. There were three areas studied in each forest under both preand post-leaf fall conditions.
Each area was a 10m diameter circular plot, with all three
conditions per forest: 1.) Completely raked circle free of all litter 2.) A control circle with typical
amounts of litter, and 3.) A circle with double the normal amount of litter. These conditions were
measured over a five year period in each forest. Average transfers were 539 g.m-2yr-1 in the
maple stand and 839g.m-2yr-1in the beech stand. Each sample was 0.1m2 and taken randomly by
tossing the 0.1m2 grid over head and plotting where it landed. The samples were individually
packaged, labeled then processed via the "Berlese funnel method" over a 7 day period to ensure
maximum collection. Separation and identification was performed using a dissecting microscope.
The soil Araneae were separated into families by sample number and analyzed for density,
dominance, frequency and importance value. The results were analyzed using graphical imaging
to more easily recognize and compare the intra-forest Araneae communities not only by forest
type, but by season. The population numbers favored the September pre leaf fall period with the
double litter treatment most heavily. The diversity, calculated by means of the Shannon Wiener
Index, however, was higher in the successional forest. The top three dominant families were
analyzed in a comparative analysis to better show diversity and population trends between the
forests and seasons.
Two of the three dominant families were similar in both forests and
represented mobile hunting spiders. The third dominant family differed between the two forests
representing less mobile tendancies, and filling different niches provided by the varying habitat.
The data collected suggests varying amounts of litterfall, forest type, and seasonal changes have
an effect on litter Araneae populations and family composition among deciduous forests. The
data also suggests a strong correlation between hunting and web-weaving Araneae populations
and the litterfall in which they are found. This indicated the importance of litter volume and
Araneae population productivity amongst the macroinvertebrate community.