Increased biodiversity
generally enhances terrestrial ecosystem productivity. While niche-use
efficiency is thought to drive the biodiversity-productivity relationship, the
mechanisms within niche-use efficiency are not well understood. A potential
mechanism for niche-use efficiency is nutrient-use efficiency. To measure
nutrient-use efficiency, we calculated nitrogen-resorption efficiencies (NRE) because
nitrogen is an important growth limiting nutrient for forest productivity. We
used a plantation
implemented as a full factorial design that included two levels of competition,
implemented as different planting densities (one- and two-meter planting
densities), and three diversity levels (monocultures, two-, and three-species
plantings) that included three hardwood tree species (northern red oak (<i>Quercus
rubra</i>), black cherry (<i>Prunus serotin</i><i>a</i>), and American chestnut (<i>Castanea dentata</i>). For our
nitrogen-resorption efficiency data, we found that NRE increased as diversity
and planting density decreased, but the magnitude of the response varied among
species. This outcome suggests that while increased diversity likely provides a
release from intra-specific competition, different combinations of species will
play a critical role in shaping biodiversity-productivity relationships. Forest
nutrient cycling can also be influenced by herbivory. To address the effects of
forest diversity on herbivory rates, we monitored rates of foliar damage along
with foliar nitrogen content. To
measure foliar nitrogen content, we collected spectral data from early,
midseason, and late season foliar samples. To assess foliar damage, we
collected and imaged leaves from two canopy positions in order to measure late
season foliar area and estimate pre damaged foliar area. We found that
diversity and foliar nitrogen content have a positive relationship, and
diversity does influence canopy damage but the effects vary among species and
density. Upon further analysis, we found that foliar nitrogen content and
canopy damage are correlated. Meaning individual trees showed a release from
intraspecific competition, which lead to an increase in available nutrients and
higher canopy quality, showing that stands with higher canopy quality
experienced higher levels of damage.<br>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/14502180 |
| Date | 28 April 2021 |
| Creators | Taylor M Nelson (10716447) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/INFLUENCE_ON_BIODIVERSITY_ON_CANOPY_PROCESS_IN_A_HARDWOOD_PLANTATION_FOREST_ECOSYSTEM/14502180 |
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