SPAC Soil Plant Atmosphere Continuous Monitoring System

1 Systembackground

SPAC (Soil Plant Atmosphere Continuum) refers to the soil plant atmosphere continuum. Water reaches the plant roots through the soil, is absorbed by the roots, transported by cells, enters the plant stems, reaches the leaves from the woody parts of the plant, diffuses through the leaf stomata to the static air layer, and then participates in the turbulent transformation of the atmosphere, forming a unified, dynamic, and feedback continuous system, namely the SAPC system.

In 1966, Philip, an outstanding Australian hydrologist and soil physicist, proposed the concept of Soil Plant Atmosphere Continuum (SPAC). The main content is that water reaches the plant root system through the soil, enters the root system, is transported through cells into the xylem, reaches the leaves from the plant's xylem, diffuses into the atmosphere through stomata, and then participates in turbulent exchange in the atmosphere, forming a unified and dynamic mutual feedback continuous system, namely the Soil Plant Atmosphere Continuum (SPAC) system. In this continuum, there exists the transmission and exchange of matter, energy, and information. Soil, plants, and atmosphere are the objects of our research, and the transmission of water in soil, plants, and atmosphere is the core content of our research.

2 System principles

The SPAC Soil Plant Atmosphere Continuous Monitoring System integrates various monitoring factors of soil plant atmosphere on the same monitoring platform to obtain continuous monitoring data, and processes these data uniformly to obtain the following key information

Systematic study of groundwater-Water Movement in Soil Plant Atmosphere Continuum (SPAC)

Systematic study of plants-Interface processes between atmosphere, soil atmosphere, soil root system, soil water groundwater, etc

Long term monitoring of meteorological indicators, plant physiological indicators, soil moisture indicators, and groundwater indicators

The measurement results can be used to guide fields such as irrigation, agricultural water conservation, and agricultural and forestry meteorological forecasting

Systematically serving fields such as agricultural hydrology and water resources, forest ecological hydrology, and environmental hydrology

3 measurement metrics

1) Meteorological indicators

Total radiation, photosynthetically active radiation, net radiation, ultraviolet radiationCO2、 Wind speed, wind direction, temperature, humidity, air pressure, rainfall, evaporation, etc.

2) Plant indicators

Leaf temperature, leaf humidity, stem flow, stem and stem changes, fruit changes, leaf water potential, stem and stem water potential, chlorophyll content, gas exchange parameters (net photosynthetic rate, transpiration rate, stomatal conductance, water pressure saturation deficit, etc.), chlorophyll fluorescence parameters（Fv/Fm, DF/Fm ¢, qL, qP, qN, NPQ, Y (NO), Y (NPQ), ETR, etc.), leaf area index, vegetation index, canopy parameters, plant height, root water potential, root length, root mass, root surface area, root volume, root angle, root depth, root distribution in soil, etc.

3) Soil indicators

Soil moisture, soil water potential, soil temperature, soil salinity, soil heat flux, soil evapotranspiration, soil compaction, soil particle size, soil hydraulic conductivity, etc.

4) Groundwater indicators

Water level, water temperaturepH、 Conductivity, dissolved oxygen, turbidity, etc.

4 System Composition

The SPAC physiological and ecological environment monitoring system is a set of instruments developed for this research, which can monitor plant physiological and ecological parameters, meteorological factors, and soil parameters. The system consists of data collectors, sensors, bus modules, network modules, power supply modules, etc., to achieve long-term monitoring without human supervision in the field, and the network module realizes remote data management.

1) Data collector，2) Bus module，3) Network module，4) Intelligent sensors，5) Power supply module，6）Platform software