青藏高原沙柳河流域自然径流驱动的流域生物信息流量化特征——以环境微生物为指标

物质流、能量流、信息流是生态系统过程研究中的三大主题。然而,在流域生态学研究中,有关信息流的研究一直缺位。为了推动流域信息流研究,从生物信息流切入,提出"流域生物信息流"概念,将其定义为"生物信息依托于流域生态系统过程在不同空间和系统之间进行传递、交流、作用、反馈的路径、过程与控制",并将其研究内容拟定为主要关注于水陆间、干支流间、上下游间、不同生态斑块间的流域生物信息流及其周期性节律和趋势性变迁,以及地貌、水文、人类活动等对这些生物信息流的影响等。然后,以青藏高原上青海湖重要入湖河流--沙柳河的河流水体微生物和岸带土壤微生物为研究对象,利用环境DNA技术,对沙柳河流域的自然径流驱动的流域生物信息流进行量化研究。结果表明（1）岸带土壤到水体的流域生物信息流主要由地表表面流、地下潜流等驱动,并受环境过滤效应影响,其输移效率降雨天约为62.76%、晴天约为44.16%,其中输移能力降雨天约为68.49%、晴天约为56.82%,环境过滤效应降雨天约为8.38%、晴天约为22.28%;（2）水体上游到下游的流域生物信息流主要由河川径流驱动,并受衰减效应影响,其基础综合输移效率约为97.41%/km,其中径流输移能力约为99.42%/km,无效流域生物信息流占比约为43.46%,无效流域生物信息流的半衰距离约为14.52 km;（3）降雨通过增加地表表面流等的冲蚀搬运能力并削弱环境过滤效应,促使岸带土壤到水体的流域生物信息流输移能力和输移效率增大;（4）流域生物信息流的输入在一定程度上增加了输入地的可检出生物多样性,但这种增加对于流水生态系统来讲是非累积的。

Watershed biological information flow driven by natural runoff in Shaliu River Basin on Qinghai-Tibet Plateau indicated by environmental microbes

The collection, transport and transformation of sediments, nutrients, organic matter, energy and information are key topics in the studies on ecosystem processes. However, there is no systematic literature on watershed information flow (WIF) in watershed ecology. To promote research on the WIF, we proposed the concept of watershed biological information flow (WBIF) by referencing the concept of biological information flow, and defined it as the path, processes and control of biological information transport, exchange, interaction and feedback among different spaces and systems along with watershed ecosystem processes. We proposed that the key of WBIF research should focus on 1) the WBIF between land and river, branch and main stream, upstream and downstream and different patches, 2) the periodical fluctuation and trending drift of the WBIF, and 3) the impacts of geomorphologic, hydrologic situations and human activities on WBIF. We conducted a case study on the WBIF in the Shaliu River basin indicated by the environmental microbes in riverine water and riparian soil using environmental DNA technology. Shaliu River is one of the main inflowing rivers of Qinghai Lake, which has a relative simple watershed ecosystem. In the river, there is a simple aquatic ecosystem with low biodiversity and a migratory fish Gymnocypris przewalskii which migration between river and lake. On the land, there are dominant grassland and limited human activities. To reveal the essential features of WBIF driven by natural runoff, we compared the bacterial community (indicated by operational taxonomic units (OTUs)) from upstream riverine water samples with from downstream riverine water samples and from riverine water samples with from adjacent riparian soil samples. Results showed that (1) the WBIF from riparian soil to riverine water was driven by surface flow and subsurface flow and filtrated by environment change. Its transport efficiency was 62.76% in rainy day and 44.16% in sunny day. Correspondingly, their transport capacity was 68.49% and 56.82%, respectively; their environmental filtration was 8.38% and 22.38%, respectively. (2) The WBIF from upstream to downstream was driven by river flow and attenuated in transport. Its basic integrated transport efficiency was 97.41% per kilometer, in which the transport capacity was 99.42% per kilometer, the proportion of noneffective WBIF was 43.46%, and half-life distance of noneffective WBIF was 14.52 kilometers. (3) As the transport efficiency of the WBIF was mainly constrained by transport capacity of WBIF, precipitation drove the arising of surface flow, then enhanced the power of erosion and transportation, and finally promoted the increase of WBIF transport capacity and efficiency. (4) The WBIF increased the detectable biodiversity of sink aquatic ecosystem, but the increase of detectable biodiversity is limited rather than accumulated along the river.