Data from: Guidelines and considerations for designing field experiments simulating precipitation extremes in forest ecosystems

1. Context. Precipitation regimes are changing in response to climate
change, yet understanding of how forest ecosystems respond to extreme
droughts and pluvials remains incomplete. As future precipitation extremes
will likely fall outside the range of historical variability,
precipitation manipulation experiments (PMEs) are critical to advancing
knowledge about potential ecosystem responses. However, few PMEs have been
conducted in forests compared to short-statured ecosystems, and forest
PMEs have unique design requirements and constraints. Moreover, past
forest PMEs have lacked coordination, limiting cross-site comparisons.
Here, we review and synthesize approaches, challenges, and opportunities
for conducting PMEs in forests, with the goal of guiding design decisions,
while maximizing the potential for coordination. 2. Approach. We reviewed
63 forest PMEs at 70 sites worldwide. Workshops, meetings, and
communications with experimentalists were used to generate and build
consensus around approaches for addressing the key challenges and
enhancing coordination. 3. Results. Past forest PMEs employed a variety of
study designs related to treatment level, replication, plot and
infrastructure characteristics, and measurement approaches. Important
considerations for establishing new forest PMEs include: selecting
appropriate treatment levels to reach ecological thresholds; balancing
cost, logistical complexity, and effectiveness in infrastructure design;
and preventing unintended water subsidies. Response variables in forest
PMEs were organized into three broad tiers reflecting increasing
complexity and resource intensiveness, with the first tier representing a
recommended core set of common measurements. 4. Conclusions. Differences
in site conditions combined with unique research questions of
experimentalists necessitate careful adaptation of guidelines for forest
PMEs to balance local objectives with coordination among experiments. We
advocate adoption of a common framework for coordinating forest PME design
to enhance cross-site comparability and advance fundamental knowledge
about the response and sensitivity of diverse forest ecosystems to
precipitation extremes.