Soils store the nutrients (essential elements) which are necessary for the plant growth. Plants uptake the nutrients adsorbed on the clay and humic substances (soil organic matters). The content of the clay and humic substances in the soil is an indication of the soil fertility. Humic substances are hardly decomposed by a microorganism. But, because they finally decompose and disappear, we furnish organic substances, and maintain the contents of humic substances in the soil. When large quantities of organic substances is given to soils for a long time, the content of humic substances becomes very excessive, and iron, cupper, and/or manganese are chelated (fixed) on humic substances, and plants can not uptake them any more. This leads to the crops with insufficient for essential elements of human being. When hazardous heavy metals and organic pollutants in the waste from homes and businesses are released in the environment, groundwater is polluted directly without an interaction between the soils and these hazardous materials. Cupper, lead, and cadmium are chelated (fixed) on humic substances in soils, and it is difficult to remove them. Most of the organic pollutants are hardly decomposed by micro-organisms and it is hydrophobic compounds which adsorbs on humic substances with hydrophobic interactions.

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Recent increase in green house gases, in particular the increase in carbon dioxide, resulted in the climatic change. The effect of global warming upon the phenological events of trees such as blooming of cherries was reviewed and the significance of the role of forests to absorb CO_2 was introduced. Achievements in leaf phenology and new models of the present author to estimate the gross primary production of forests by a single leaf's carbon gain was shown.

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A novel method to evaluate the gross primary production of forests first proposed by Kikuzawa & Lechowicz (2006) was applied and evaluated in a beech plantation. In this model, the product of average of maximum photosynthetic rate (A_<max>), mean labor time and leaf longevity gives the lifetime carbon gain by single leaves. The product of the lifetime carbon gain and average leaf litter production in the stand, in turn, will give the gross primary production of the stand. The maximum photosynthetic rate under given photon flux density (1500μmol m^<-2>s^<-1>) with ambient temperature conditions were repeatedly measured for arbitrarily chosen 28 leaves. A_<max> decreased significantly with time for the 28 leaves. From leaf longevity and the decrease in A_<max>, mean labor time of these leaves was estimated to be 1.5hr day^<-1>. Lifetime carbon gain by a single leaf was estimated, on an average, to be 3.0g g^<-1>, ranging from 1.8 to 5.7g g^<-1>. Annual leaf litter production was evaluated by 10 litter traps set on the forest floor. Average leaf litter production in this stand was estimated to be 363gm^<-2>yr^<-1>. Gross primary production of this stand was estimated to be 33 ton ha^<-1>yr^<-1>.

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In order to apply the idea to obtain a single leaf's lifetime carbon gain for the single leaf's lifetime transpiration, it is necessary to clarify the following two problems. 1. To obtain mean labor time (MLT) of transpiration from that of photosynthesis, 2. To obtain the relationship between the instantaneous respiration rate and the instantaneous photosynthetic rate, we hypothesize 1. transpirational MLT is proportional to the photosynthetic MLT and 2. instantaneous transpiration rate is also proportional to that of photosynthesis. We tested these two hypotheses by using leaves of Quercus serrata and Fagus crenata. Transpirational MLT in daytime was equivalent to photosynthetic MLT, but transpirational MLT throughout a day was 1.2 times longer than photosynthetic MLT. Instantaneous transpiration rate was proportional to that of photosynthetic rate. We conclude that the transpiration rate of a stand can be estimated by a single leaf's lifetime transpiration.

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