Throughfall exclusion and fertilization effects on tropical dry forest tree plantations, a large-scale experiment
<p>Across tropical ecosystems, global environmental change is causing drier climatic conditions and increased nutrient deposition. Such changes represent large uncertainties due to unknown interactions between drought and nutrient availability in controlling ecosystem net primary productivity...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-06-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/2143/2023/bg-20-2143-2023.pdf |
| Summary: | <p>Across tropical ecosystems, global environmental change is causing drier climatic conditions and increased nutrient deposition. Such changes represent large uncertainties due to unknown interactions between drought and nutrient availability in controlling ecosystem net primary
productivity (NPP). Using a large-scale manipulative experiment, we studied for 4 years whether nutrient availability affects the individual and integrated responses of aboveground and belowground ecosystem processes to throughfall exclusion in 30-year-old mixed plantations of tropical dry forest tree species in Guanacaste, Costa Rica. We used a factorial design with four treatments: control, fertilization (F), drought (D), and
drought <span class="inline-formula">+</span> fertilization (D <span class="inline-formula">+</span> F). While we found that a 13 %–15 % reduction in soil moisture only led to weak effects in the studied
ecosystem processes, NPP increased as a function of F and D <span class="inline-formula">+</span> F. The relative contribution of each biomass flux to NPP varied depending on the
treatment, with woody biomass being more important for F and root biomass for D <span class="inline-formula">+</span> F and D. Moreover, the F treatment showed modest increases in
maximum canopy cover. Plant functional type (i.e., <span class="inline-formula">N</span> fixation or deciduousness) and not the experimental manipulations was the main source of variation in tree growth. Belowground processes also responded to experimental treatments, as we found a decrease in nodulation for F plots and an
increase in microbial carbon use efficiency for F and D plots. Our results emphasize that nutrient availability, more so than modest reductions in
soil moisture, limits ecosystem processes in tropical dry forests and that soil fertility interactions with other aspects of drought intensity
(e.g., vapor pressure deficit) are yet to be explored.</p> |
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| ISSN: | 1726-4170 1726-4189 |