Introduction to the Special Series "Environmental Monitoring on Global and Local Scales".

The ecosystems of Siberia provide valuable services to the human population and afford important climate feedback. However, they are subject to anthropogenic pressures leading to the transformation of ecosystem structure and functions such as deforestation; extraction and transportation of fossil hydrocarbons; mining, refining, and smelting industrial activities; damming of rivers by high-pressure hydroelectric plants, and other activities. The articles in this special series deal with the monitoring of natural ecosystems of Siberia that are located on vast areas of Eurasia, many of which are hard to reach and sparsely populated. The results and approaches of environmental monitoring presented in this special series offer new opportunities for developing the strategy of intelligent management and conservation of vulnerable Siberian ecosystems to meet the challenges of global climate change and unsustainable use of natural resources. Integr Environ Assess Manag 2023;19:970-971. © 2023 SETAC.

Untangling metabolic and spatial interactions of stress tolerance in plants. 1. Patterns of carbon metabolism within leaves.

The localization of the key photoreductive and oxidative processes and some stress-protective reactions within leaves of mesophytic C(3) plants were investigated. The role of light in determining the profile of Rubisco, glutamate oxaloacetate transaminase, catalase, fumarase, and cytochrome-c-oxidase across spinach leaves was examined by exposing leaves to illumination on either the adaxial or abaxial leaf surfaces. Oxygen evolution in fresh paradermal leaf sections and CO(2) gas exchange in whole leaves under adaxial or abaxial illumination was also examined. The results showed that the palisade mesophyll is responsible for the midday depression of photosynthesis in spinach leaves. The photosynthetic apparatus was more sensitive to the light environment than the respiratory apparatus. Additionally, examination of the paradermal leaf sections by optical microscopy allowed us to describe two new types of parenchyma in spinach-pirum mesophyll and pillow spongy mesophyll. A hypothesis that oxaloacetate may protect the upper leaf tissue from the destructive influence of active oxygen is presented. The application of mathematical modeling shows that the pattern of enzymatic distribution across leaves abides by the principle of maximal ecological utility. Light regulation of carbon metabolism across leaves is discussed.