DOI: 10.5061/dryad.vq83bk3pr
title: Data from: Magnitude and direction of stream-forest community interactions change with time scale

description: Networks of direct and indirect biotic interactions underpin the complex
 dynamics and stability of ecological systems, yet experimental and
 theoretical studies often yield conflicting evidence regarding the
 direction (positive or negative) or magnitude of these interactions. We
 revisited pioneering datasets collected at the deciduous forested Horonai
 Stream and conducted ecosystem-level syntheses to demonstrate that the
 direction of direct and indirect interactions can change depending on the
 timescale of observation. Prior experimental studies showed that
 terrestrial prey that enter the stream from the adjacent forest caused
 positive indirect effects on aquatic invertebrates during summer by
 diverting fish consumption. Seasonal and annual estimates of secondary
 production and organic matter flows along food web pathway demonstrate
 that this seasonal input of terrestrial invertebrate prey increases
 production of certain fish species, reversing the indirect effect on
 aquatic invertebrates from positive at the seasonal time scale to negative
 at the annual time scale. Even though terrestrial invertebrate prey
 contributed 54% of the annual organic matter flux to fishes, primarily
 during summer, fish still consumed 98% of the aquatic invertebrate annual
 production, leading to top-down control that is not revealed in short-term
 experiments and demonstrating that aquatic prey may be a limiting resource
 for fishes. Changes in the direction or magnitude of interactions may be a
 key factor creating non-linear or stabilizing feedbacks in complex
 systems, and these dynamics can be revealed by merging experimental and
 comparative approaches at different scales.
description: The study segment of Horonai Stream was located in the Tomakomai
 Experimental Forest (TOEF; 42 deg 43' N, 141 deg 36'E),
 Hokkaido, Japan. This small, spring-fed stream drains 15.4 square km in
 drainage area with an average discharge of 0.25 cubic m / sec over the
 study period.  The study site is described in additional detail by Nakano
 and Murakami 2001 PNAS 98:166-170 (https://doi.org/10.1073/pnas.98.1.166).
 The field work for this study was carried out during 14 months from May
 1997 to June 1998, over a full annual cycle of seasons in a stream
 draining a temperate deciduous forest.  Additional field work was
 completed to measure stream primary production and respiration during
 field campaigns led by Marcarelli in Oct 2008 during leaf fall and in
 March-April 2009 during snowmelt.  The dataset archived
 here includes new analyses and calculations completed for this paper
 (e.g., fish and invertebrate production, trophic basis of production), or
 time series of data that were not presented the same way in earlier papers
 (leaf litter, terrestrial prey flux, chlorophyll a).  It does not include
 the original data that was summarized from other publications - e.g., it
 does not include the full data from the organic matter budget, as most of
 that was taken directly from Shibata et al. 2001.  It also does not
 include fish density or biomass data or benthic macroinvertebrate data
 that are reported in full in Nakano and Murakami 2001.
 Detailed collection and analysis methods, including the location
 of samples, scale and extent of study reaches for each metric are all
 described in detail in the Ecology MS identified above, which is currently
 in production.
description: The first tab of this worksheet contains metadata, including the
 sources for any data that were previously published.  Each other tab
 contains a different dataset. If more appropriate, the first worksheet
 could be transoformed into a ReadMe file.   It's
 important for readers to know that although all of these data were
 collected from the same 1.2km study segment, they were not collected from
 the same reaches or with the same level of replication.  Detailed
 collection and analysis methods, including the location of samples, scale
 and extent of study reaches for each metric are all described in detail in
 the Ecology MS identified above, which is currently in
 production.