Emergy Estimation of the Main Forest Biomass in Shangri-La, Tibetan Area of Yunnan Province

2021-04-08YunLIU

Asian Agricultural Research 2021年2期

Yun LIU

Dazhou Middle School, Dazhou 635000, China

Abstract [Objectives] To calculate and study the biomass emergy of main forests in Shangri-La, Tibetan area of Yunnan Province. [Methods] Four main forest biomass values of P. likiangensis and A. georgei, P. densata, Q. aquifolioides and P. yunnanensis in Shangri-La, Yunnan were determined by emergy method. [Results] The energy of the four kinds of forests was 2 572 252.490 6×106 J, the emergy was 10 767.336 6×1020sej, and the economic value was 43 756.841 1×0.1 billion yuan. The total economic value was 41.56 times of GDP and 5 494.94 times of forestry output value in 2020; the emergy storage density was 9 271.795 9×1010 sej/m2, and the per capita emergy reserve was 741.220 2×1016 sej/person; the per capita macro value was 30.122 081 million yuan, which was 875.59 times that of the per capita GNP of 34 402 yuan in 2020. [Conclusions] The value of forest ecological assets was mainly distributed in P. likiangensis and A. georgei in four main forests and arborous layer in vertical layer. The value of forest biomass in Shangri-La is much higher than that of developing forestry economy, and it is a valuable and potential asset. We should strengthen the protection of forest ecological environment and maintain forest assets.

Key words Emergy, Forest, Shangri-La, Biomass, Estimation

1 Introduction

Forest is the most important type of vegetation on land, which plays an irreplaceable role in the regulation and control of terrestrial carbon cycle and balance. Forest vegetation and its dynamic changes are important factors affecting regional ecological process and quality. In order to further understand the function of forest ecosystem services, it is necessary to evaluate the economic value of forest systems. A comprehensive accounting method of environmental-economic system established by H. T. Odum, which takes emergy as the unit of measurement, has been widely used in the evaluation of ecological assets of various ecosystems. In recent years, people’s research is mainly focused on the functional value calculation of ecological services of forest ecosystem, but there are few studies on the emergy calculation of forest biomass, especially the forest system emergy research results in the western region of China are rarely reported.

2 General situation of the study area

Yunnan Province is an area of high ecological asset density in China, while northwest Yunnan is the most important forest area in Yunnan, with high forest coverage. The primary forest types are mainly boreal coniferous forest, cool coniferous forest and oak forest. Shangri-La (99°20′-100°19′ E, 26°52′-28°52′ N) is located in the Hengduan Mountains, the hinterland of the Hengduan Mountains on the southeastern margin of the Qinghai-Tibet Plateau, and the eastern part of Diqing Tibetan Autonomous Prefecture, covering an area of 11 613 km. By 2020, Shangri-La has jurisdiction over 4 towns, 7 townships, 6 neighborhood committees and 58 administrative villages. In addition to the Tibetan nationality, there are more than a dozen ethnic groups, such as Han, Naxi, Yi, and Bai, with a population density of 10 people per square kilometer. It is a typical Tibetan area in Yunnan.

The highest elevation in the city is 5 545 m, the lowest altitude is 1 503 m, the maximum altitude difference is 4 042 m, and the average elevation is 3 459 m. It is located in the transition zone from subtropical evergreen broad-leaved forest to alpine vegetation on the Qinghai-Tibet Plateau, so there is an obvious difference in vegetation distribution between north and south, and the vegetation vertically distributed in the mountains on the east, south and west around the city is complete and typical. In the vertical distribution, there is a snow line zone at an altitude of 4 500-4 700 m, with alpine meadow and shrub vegetation growing, and subalpine and alpine boreal coniferous forests at 3 000 m and warm coniferous forests below 3 000 m, are combined with many cool coniferous species and deciduous species to form a variety of complex forest types. On the edge of the Jinsha River, there are many types of shrubs formed in the dry and warm valley climate.

The forest coverage rate in China is 74.99%, and the forest greening rate is 81.23%, of which woodland coverage rate is 66.31%, shrub land coverage rate is 14.89%, and coverage rate of nearby forest is 0.03%. The main forests are divided into

georgei

Orr,

delavayi

Franch

likiangensis

(

Franch

Pritz

densata

aquifolioides

Rehd

Wils

yunnanensis

, L.

gmelinii

(

Rupr

Kuzen

dumosa

(

Don

)

Eichler

szechuanica

Schneid

., birch forest, maple forest, and so on. Among them,

aquifolioides

Rehd

Wils

yunnanensis

densata

and

likiangensis

and

georgei

account for 90.8% of Shangri-La arbor forests. The four kinds of forests have obvious layers in the vertical direction, which can be divided into arborous layer, shrub layer, herb layer and litter layer. Shangri-La’s ecosystem is fragile, and the changes in its forest ecosystem assets can reflect the characteristics of global change to some extent. The evaluation and estimation of forest potential social value by forest emergy measurement has important scientific significance and application prospect for improving local ecological environment construction and protection to support the macro decision-making of governments at all levels.

3 Research methods

Emergy method was founded in the 1980s by H.T.Odum, a famous American ecologist and pioneer of system energy analysis. With the application of emergy, a new disciplinary concept and measurement standard and its conversion unit-emergy conversion rate, different types of energy and substances flowing and stored in the eco-economic system can be converted into the same standard emergy for quantitative analysis. The theory and method can be widely used in the evaluation and utilization of forest natural resources.

The emergy value of main forest biomass is the product of energy and emergy conversion rate of main forest vegetation. In order to make the calculation results reflect the study area more accurately, the emergy conversion rate is calculated by the ratio of emergy input to energy storage per unit time, and the emergy conversion rate is localized. The main forest energy can be obtained by the product of main forest biomass and biomass-energy conversion rate.

3.1 Determination of emergy conversion rate

There are many methods to determine the emergy conversion rate, and most scholars calculate it through similar solar energy conversion rate in the study area. Although this method saves time, it reduces the accuracy of the results and does not fully represent the real situation of the study area. Therefore, this paper adopts the method of systematic energy flow and transformation analysis, and calculates the emergy conversion rate by analyzing the emergy input and energy output per unit time of four main forests in Shangri-La.

3.1.1

Energy output per unit time. Energy output per unit time is the primary productivity. The organic matter produced by photosynthesis in forest communities is called primary productivity. Productivity is usually expressed in terms of the amount of organic matter produced by plants per unit land area and per unit time, as well as carbon content or thermal energy. The primary productivity of the forest is closely related to the energy reserve of the forest system. The higher the primary productivity, the more the energy output. The lower the primary productivity, the less the energy output.Yue Cairong, Wang Jinliang

.have completed the forest biomass estimation of the main forest ecosystems in Shangri-La based on the 2008 and 2009 Landsat data TM as the information source, combined with the 2008 forest resources second-class survey data (Table 1).

Table 1 Biomass at different layers of four main forest types in Shangri-La

On this basis, Yue Cairong

.constructed an estimation model by using 2009 MODIS data as remote sensing information source, combined with Shangri-La basic geographical data and meteorological data of 119 meteorological stations in Yunnan Province. With the support of ArcEngine secondary development technology, the estimation of net primary productivity of vegetation in Shangri-La in 2009 is realized by using remote sensing technology and geographic information system technology. The net primary productivity of vegetation in Shangri-La in 2009 was 240 g/m.

On the basis of the research results and referring to the relevant data of type areas, the unit time biomass of four kinds of forests in this area in 2020 was measured. The unit time biomass of four kinds of forests is the product of the corresponding vegetation area and primary productivity (240 g/m) (Table 2).

Table 2 Biomass and energy produced per unit time of four kinds of forest vegetation in Shangri-La

3.1.2

Emergy input per unit time. Solar energy is the main energy of life, and other forms of energy are also transformed from solar energy. Therefore, the accumulation of forest vegetation biomass is actually a process of continuous conversion of solar energy. The formula of solar energy input is:

×(1-

)

(1)

where

is solar energy input,

is solar energy constant,

is number of sunshine hours,

is total area of four kinds of forests, and

is reflectivity.Among them, the solar constant=4.9×10, the annual average number of sunshine hours is 2 041.1, the reflectivity is 0.15, and the total area of the four kinds of forests is 740 513.27×10m. According to the existing materials, the total solar energy is calculated to be 6.321 5×10sej. According to the area data of the four main forests in Table 1, the area proportion of the four main forests is 40.51%, 22.69%, 13.28% and 23.52%, respectively. Then, the product of the area proportion of the four main forests and the solar emergy is calculated, and the solar energy input of the four main forests can be obtained respectively:

likiangensis

and

georgei

(255.192 3×10sej);

aquifolioides

(142.913 4×10sej);

yunnanensis

(53.687 9×10sej);

densata

(148.217 8×10sej).

3.1.3

Emergy conversion rate. The "principle of ten percent" of energy conversion by American ecologist Lindeman pointed out that when energy flows and converts along the ecosystem food chain, the energy flow decreases step by step, and the energy obtained by the latter nutrient level is about 10% of that of the previous one. H.T.Odum, an American ecologist, pointed out that in the ecosystem or eco-economic system, the energy flows and transforms from the level with large quantity but low energy quality to the level with small quantity but high energy quality. Those with higher level have high emergy conversion rate, and need more energy to maintain, with higher emergy and greater control ability, playing a central role in the system. Complex life, human services, scientific and technological information are high-level energy with high energy quality, high emergy conversion rate and high emergy. Forests can not only provide wood and forestry products, but also achieve the functions of water conservation, air purification and biodiversity protection. Therefore, the emergy conversion rate of forest vegetation biomass has a high energy quality and a high level, which plays an important role in the ecosystem.

Emergy conversion rate is a ratio, and the conversion rate of solar energy is actually applied, that is, how much solar energy converted is equivalent to each unit of certain energy (or substance). Different layers of vegetation are crossed and repeated in area, and the solar energy input into the same kind of forest is involved in the energy conversion and output at different layers. Therefore, the emergy conversion rates of different layers of vegetation can be obtained only by dividing the solar energy input of the four main forests in Table 3 by the corresponding vegetation energy output at different layers in Table 2 (Table 3).

3.2 Total biological energy of four kinds of forest vegetation

Forest biomass is the most basic quantitative feature of forest ecosystem. It is usually expressed in terms of dry matter mass or energy accumulated per unit area or per unit time, which is the result of the accumulation of forest ecosystem in the process of long-term production and metabolism. Forest biomass is the energy basis and material source for the operation of the whole forest ecosystem, and it is the basis for the study of forest vegetation productivity and net primary productivity. The total biomass energy of four forest types in Shangri-La is sorted out from Table 2 (Table 4).

Table 3 Emergy conversion rates of different layers of vegetation in four main forest types 109 sej/J

Table 4 Total biomass energy of four forest types 106 J

3.3 Total emergy

The basic expression for converting matter or energy into solar energy is:

(2)

where

is solar emergy,

is emergy conversion rate, and

is available energy.

4 Results and analysis

The total emergy of different layers of vegetation in four kinds of forests can be obtained by the product of the emergy conversion rate of different layers for four kinds of forests in Table 3 and the corresponding biomass energy in Table 4, and the corresponding economic value can be obtained by the product of emergy and emergy-money conversion rate (Table 5).

Table 5 Total emergy and economic value of four kinds of forest vegetation at different layers

The total emergy of four kinds of forests (Table 6) and the total emergy at different layers (Table 7) were sorted out from Table 5.

Table 6 Energy, emergy and economic value in four kinds of forest

Table 7 Energy, emergy and economic value in vegetation at four layers

4.1 Energy and emergy of 4 kinds of forests

It can be seen from Table 6 that the energy of the four kinds of forests is 2 572 252.490 6×10J, the total emergy is 10 767.336 6×10sej, and the total value is 43 756.841 1×0.1 billion yuan. And the energy accounts for 58.58%, 13.88%, 12.17% and 15.38%, respectively; the emergy accounts for 56.75%, 13.77%, 17.24% and 12.24%, respectively; the economic value accounts for 56.75%, 13.77%, 17.24% and 12.24%, respectively. Thus it can be seen that the energy, emergy and economic value of the four kinds of forest vegetation are mainly distributed in

likiangensis

and

georgei

, while there is little difference in the energy, emergy and economic value among

aquifolioides

yunnanensis

and

densata

, only about 20% of that of

likiangensis

and

georgei

4.2 Energy, emergy and economic value of four kinds of vertically distributed vegetation

As can be seen from Table 7, the energy, emergy and economic value of the arborous layer account for the largest proportion, which is 86.59%, 98.60% and 98.60%, respectively; the proportion of the energy, emergy and economic value in herbs is the smallest, which is 1.28%, 0.03% and 0.03%, respectively; the proportion of the energy, emergy and economic value in shrubs and litter accounts for 7.04%, 1.01%, 1.01% and 5.09%, 0.36%, 0.36%, respectively. Therefore, the energy, emergy and economic value of the forest system are mainly distributed in the arborous layer.

4.3 Socio-economic indicators

The emergy economic value of the four kinds of forests is 2 483.161 5×0.1 billion yuan when converted into RMB. Compared with the regional GDP (5.975 57 billion yuan) and the total forestry output value (45.19 million yuan) of Shangri-La in 2020, the emergy economic value of the four kinds of forests is 41.56 times of the regional GDP and 5 494.94 times of the total forestry output value. The emergy storage density is 9 271.795 9×10sej/m, the per capita emergy reserve is 741.220 2×10sej/person, and the per capita macro value is 30.122 081 million yuan, which is 875.590 9 times of the per capita GNP of 34 402 yuan in 2020. This shows that Shangri-La forest resources have great economic value, and the maintenance and proper development and utilization of forest resources will produce more far-reaching economic benefits.

5 Conclusion

Emergy theory and its research method are a hot issue in the current ecological economics research, which is regarded as the bridge between ecology and economics, and is of great theoretical and practical significance. It provides a bridge between economy and ecosystem, makes up for the defect that money can not objectively evaluate non-market inputs, and the irrationality caused by the direct addition of different energies in traditional energy measurement, and provides an ecology-centered evaluation method. With the unity of dimensions, all resources of different qualities can be compared on an equal basis. Therefore, it can provide a more comprehensive analysis scheme for many current environment-related decision-making methods.

Emergy method is an important application field to analyze forest value and ecosystem service function. Through the calculation, the forest emergy in Shangri-La is mainly distributed in

likiangensis

and

georgei

in the four kinds of forest and the arborous layer at the four layers. In addition, the arborous layer emergy of

likiangensis

and

georgei

accounts for the largest proportion at about 56.34%, becoming a high energy-intensive area. From the perspective of social and economic indicators, the economic value of forest ecological assets is huge, which is a valuable wealth. The study only estimates the total emergy and macro value of biomass. Shangri-La is a big tourist city, and the forest also plays the function of ecological service. The forest has great potential economic value, and the macro value of forest ecosystem is much higher than this value.

Asian Agricultural Research

2021年2期