Browsing by Author "Seltzer, Carrie E."
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Item In Search of Sustainable Seed Harvest: Seed Removal and Establishment of an Endemic African Rainforest Tree(2012-08) Seltzer, Carrie E.; Kremer, Colin T.; Ndangalasi, Henry J.; Cordeiro, Norbert J.Background/Question/Methods Harvest of non-timber forest products such as seeds requires assessment to determine if it is sustainable. Allanblackia stuhlmannii (Clusiaceae) is a rainforest tree with seeds that are harvested for an emerging commercial market. Seeds that are not collected by humans are mostly scatterhoarded by giant pouched rats (Cricetomys gambianus). Two simultaneous experiments were conducted in twelve 50x50m plots within the Amani Nature Reserve: a seed tagging experiment that followed fates of 1152 seeds (in two rounds of 576 seeds each), and a seed planting experiment that followed fates (until disappearance) for 960 seeds (in two rounds). We recorded fruit abundance in each plot throughout the fruiting season and followed seed fate for approximately one year. This presentation will address the goal of determining how seed removal and fate vary with background seed abundance for experimentally planted seeds. We use generalized additive models to investigate the relationship between the persistence of seeds in their original locations and covariates such as fruit abundance, seed weight, and rodent activity. This allows us to estimate the persistence and germination probabilities of Allanblackia seeds under different conditions. Results/Conclusions We observed rapid removal of experimentally planted seeds within the first twelve days, followed by low levels of removal over several weeks. During the first five months of the experiment, fruit abundance within a plot affected the proportion of seeds that persisted in a non-linear way. Comparison between general additive models including seed weight and both logistic and lowess relationships with fruit abundance indicated that seed persistence was depressed at intermediate fruit abundances. A second intense period of seed removal occurred between the fifth and sixth months, after the Allanblackia fruiting season, after which all plots had similar proportions of seeds remaining. Seed removal during this second event was unrelated to fruit abundance, and may correspond to a period of low resource availability for rodents. Interestingly, seed weight did not have consistent or significant effects on seed persistence over time. Ultimately, approximately 5% of the seeds germinated where they were planted in the first ten months of the experiment. Seeds removed from the planting experiment were likely either consumed or scatterhoarded and could have germinated elsewhere. Consequently, understanding the fates of removed seeds will depend on results from the seed tagging experiment.Item Plants, Rats, and People: Seed Dispersal of an Economically Important Rainforest Tree In Tanzania(2011-08) Seltzer, Carrie E.; Kremer, Colin T.; Ndangalasi, Henry J.; Cordeiro, Norbert J.enus Allanblackia. Allanblackia stuhlmannii (Clusiaceae) is a canopy tree endemic to the Eastern Arc Mountains of Tanzania. Recently, humans have begun heavily collecting seeds throughout the Amani Nature Reserve (ANR) in spite of its prohibition, and there is concern that illegal seed harvest will diminish the regeneration of Allanblackia over the long term. The objective of this project was to determine how Allanblackia seed fate and dispersal varies under different levels of seed availability. Twelve 50 by 50 m plots containing at least 4 fruit-bearing trees were established in ANR. Seed addition within plots was recorded by counting the number of fresh fruits during each visit to the plot. Within each plot, removal trials were conducted at seed stations containing 16 seeds each. Each seed was weighed and marked with a wire, flag, and thread bobbin to aid in the post-dispersal recovery. Seeds were checked after 4, 8, 12, and 28 days and monthly thereafter. The location, dispersal distance, and condition of seeds was recorded at each visit. Each plot had one camera to identify seed dispersers at a subset of seed stations. Results/Conclusions Preliminary analyses show that increasing fruit abundance decreased the probability of seed removal and increased the time to seed predation/disappearance, but did not affect the distance seeds were moved. Seed weight did not influence the probability of being removed from a seed station but the distance moved increased with seed weight. Giant pouched rats (Cricetomys gambianus) were the most common seed dispersers (79% of 1514 photos). Seeds were broken off of the wires for nearly half of the seeds at some point in the experiment meaning the ultimate fate is unknown because it could have been re-cached or eaten. Monthly monitoring continues to follow seed fate of the remaining seeds. From these results we conclude that reduced seed availability, potentially due to human harvesting, alters Allanblackia seed predation and dispersal in ways that mayItem Seed Dispersal in the Dark: Shedding Light on the Role of Fruit Bats in Africa(Wiley, 2013-06) Seltzer, Carrie E.; Ndangalasi, Henry J.; Cordeiro, Norbert J.In spite of their recognized importance as seed dispersers in other parts of the tropics, seed dispersal by fruit bats has received scant research attention in Africa. To evaluate the role of African fruit bats in seed dispersal, we studied fruits and seeds below 480 bat feeding roosts in the East Usambara Mountains of Tanzania. We compared these findings to those reported in other African localities to place our results in a broader context. We found 49 plant species dispersed by bats: 28 species, 18 genera, and one family are novel reports of bat dispersal in Africa. Approximately 20 percent of the submontane tree flora of the East Usambaras is bat-dispersed, including both widespread and endemic trees. African fruit bats are important seed dispersers at our study site because they move seeds of dozens of species tens or hundreds of meters, even seeds that are too large to ingest (greater than 5 mm in length). Fruit bats are likely important seed dispersers in other Afrotropical forests, as bats elsewhere in Africa are known to consume 20 genera and 16 species of plants reported here. Insights from studying remains under bat feeding roosts offer a simple method to further document and substantially increase our understanding of the role of African fruit bats in seed dispersal.Item Seed Harvesting of A Threatened African Tree Dispersed by Rodents: Is Enrichment Planting A Solution(Elsevier, 2015-03) Seltzer, Carrie E.; Kremer, Colin T.; Ndangalasi, Henry J.; Cordeiro, Norbert J.Non-timber forest products (NTFPs) provide income to local communities with less ecological harm than timber extraction. Yet overharvesting can still influence the regeneration and sustainability of these resources. Developing sustainable harvesting practices for emerging NTFPs depends on the biology of the NTFP species, the ecological context in which management occurs, and its cost in terms of effort and resources. Allanblackia stuhlmannii (Clusiaceae) is a canopy tree species whose seeds are a source of vegetable oil and an important food for rodents. In an experiment within the Amani Nature Reserve (Tanzania), we studied how enrichment planting of A. stuhlmannii seeds affected germination and establishment rates under varying local levels of seed abundance and rodent activity. Overall, germination and establishment rates were high (4.8% and 2.2%, respectively, after 11 months), while local ecological conditions had a short lived (1–2 weeks) and unexpectedly small influence on the persistence of planted seeds. Given these rates, we estimate a cost of approximately US$0.14 per seedling. Enrichment planting of seeds, across a range of local ecological conditions, appears to be a viable and cost effective management strategy for increasing A. stuhlmannii recruitment in harvested areas.