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Abstract Forests sequester a substantial portion of anthropogenic carbon emissions. Many open questions concern how. We address two of these questions. Has leaf and fine litter production changed? And what is the contribution of old‐growth forests? We address these questions with long‐term records (≥10 years) of total, reproductive, and especially foliar fine litter production from 32 old‐growth forests. We expect increases in forest productivity associated with rising atmospheric carbon dioxide concentrations and, in cold climates, with rising temperatures. We evaluate the statistical power of our analysis using simulations of known temporal trends parameterized with sample sizes (in number of years) and levels of interannual variation observed for each record. Statistical power is inadequate to detect biologically plausible trends for records lasting less than 20 years. Modest interannual variation characterizes fine litter production, and more variable phenomena will require even longer records to evaluate global change responses with sufficient statistical power. Just four old‐growth forests have records of fine litter production lasting longer than 20 years, and these four provide no evidence for increases. Three of the four forests are in central Panama, also have long‐term records of wood production, and both components of aboveground production are unchanged over 21–38 years. The possibility that recent increases in forest productivity are limited for old‐growth forests deserves more attention.
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This content will become publicly available on December 1, 2025
Getting better with age: Lessons from the Kenya Long‐term Exclosure Experiment
Abstract The Kenya long‐term exclosure experiment (KLEE) was established in 1995 in semi‐arid savanna rangeland to examine the separate and combined effects of livestock, wildlife and megaherbivores on their shared environment. The long‐term nature of this experiment has allowed us to measure these effects and address questions of stability and resilience in the context of multiple drought‐rainy cycles. Here we outline lessons learned over the last 29 years, and how these inform a fundamental tension in long‐term studies: how to balance the need for question‐driven research with the intangible conviction that long‐term data will yield valuable findings. We highlight the value of (1) identifying experimental effects that take many years to manifest, (2) quantifying the effects of different years (including droughts) and (3) capturing the signatures of anthropogenic change. We also highlight the potential for long‐term studies to create a collaborative community of scientists that brings new questions and motivates continued long‐term study.
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- Award ID(s):
- 1931224
- PAR ID:
- 10574380
- Publisher / Repository:
- Ecology Letters
- Date Published:
- Journal Name:
- Ecology Letters
- Volume:
- 27
- Issue:
- 12
- ISSN:
- 1461-023X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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