Data from: Chapter 4: Carbon Stocks & Stock Changes in U.S. Forests. U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2018

The primary greenhouse gas (GHG) sources for agriculture are nitrous oxide (N2O) emissions from cropped and grazed soils, methane (CH4) emissions from ruminant livestock production and rice cultivation, and CH4 and N2O emissions from managed livestock waste. The management of cropped, grazed, and forestland has helped offset GHG emissions by promoting the biological uptake of carbon dioxide (CO2) through the incorporation of carbon into biomass, wood products, and soils, yielding a U.S. net emissions of 5,903 MMT CO2 eq (million metric tonnes of carbon dioxide equivalents). Net emissions equate to total greenhouse gas emissions minus CO2 sequestration in growing forests, wood products, and soils.

The report 'U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2018' serves to estimate U.S. GHG emissions for the agricultural sector, to quantify uncertainty in emission estimates, and to estimate the potential of agriculture to mitigate U.S. GHG emissions.

This dataset contains tabulated data from the figures and tables presented in Chapter 4, Carbon Stocks & Stock Changes in U.S. Forests, of the report. Data are presented for above and below-ground carbon stocks and stock changes. Please refer to the report for full descriptions of and notes on the data.

Resources in this dataset:
Resource Title: Table 4-1.
File Name: Table4_1.csv
Resource Description: Forest Land Remaining Forest Land Carbon Stock Change Estimates and Uncertainty Intervals for 2018 in MMT CO2 eq. (million metric tons carbon dioxide equivalent).

Resource Title: Table 4-2.
File Name: Table4_2.csv
Resource Description: Forest Land Remaining Forest Land Carbon Stock/Stock-change and Area. Carbon Stocks and stock change data in MMT CO2 eq. (million metric tons carbon dioxide equivalent). Area data is shown in thousands of hectares.

Resource Title: Table 4-3.
File Name: Table4_3.csv
Resource Description: Total Annualized Carbon Stock Change 1990-2018 in MMT CO2 eq (million metric tons carbon dioxide equivalent) per year.

Resource Title: Table 4-4.
File Name: Table4_4.csv
Resource Description: Total Annualized Forest Land 1990-2018 in thousands of hectares.

Resource Title: Table 4-5.
File Name: Table4_5.csv
Resource Description: Carbon Densities by Region, Ownership, and Carbon Pool, 2018. Carbon density and carbon pool data presented in Mg CO2 eq per ha (megagrams carbon dioxide equivalent per hectare) and forest area is presented in thousands of hectares.

Resource Title: Table 4-6.
File Name: Table4_6.csv
Resource Description: Total Forest Ecosystem Carbon Stocks by Region, Ownership, and Carbon Pool, 2018 in MMT CO2 eq. (million metric tons carbon dioxide equivalent).

Resource Title: Table 4-7.
File Name: Table4_7.csv
Resource Description: Net Annual Forest Ecosystem Carbon Stock Change by Region, Ownership and Carbon Pool, 2018 in MMT CO2 eq. (million metric tons carbon dioxide equivalentMMT CO2 eq. is million metric tons carbon dioxide equivalent).

Resource Title: Table 4-8.
File Name: Table4_8.csv
Resource Description: Net CO2 (carbon dioxide) Flux from Soil Carbon Stock Changes in Land Converted to Forest Land by Land Use Change Category, 2018. Data is presented in MMT CO2 eq. (million tons carbon dioxide equivalent). Negative values (shown in parentheses) indicate net carbon sequestration.

Resource Title: Table 4-9.
File Name: Table4_9.csv
Resource Description: State-level estimates of carbon stock changes by forest ecosystem pool, 2018. Carbon stock changes presented in MMT CO2 eq. (million tons carbon dioxide equivalent). Forest area in each state is displayed in thousands of hectares. Parentheses indicate net forest carbon sequestration.

Resource Title: Data for Figure 4-1a.
File Name: Figure4_1a.csv
Resource Description: Data for Figure 4-1a, Forest Ecosystem Carbon Stocks, 2018 in MMT CO2 eq. (million metric tons carbon dioxide equivalent).

Resource Title: Data for Figure 4-1b.
File Name: Figure4_1b.csv
Resource Description: Forest Ecosystem Average Stock Density, 2018. Carbon stock data is shown in Mg CO2 eq/ha (megagrams carbon dioxide equivalent per hectare).

Resource Title: Data for Figure 4-2.
File Name: Figure4_2.csv
Resource Description: Net Annual Forest Carbon Stock Change, 2018. Data is shown in Tg CO2 eq (teragrams carbon dioxide equivalent).

Resource Title: Appendix Table C-1.
File Name: AppendixC_1.csv
Resource Description: State-level estimates of carbon stock changes by forest ecosystem pool, 2018. Carbon stock changes shown in MMT CO2 eq (million metric tons carbon dioxide equivalent). Forest area in each state shown in thousands of hectares.

Resource Title: Chapter 4 tables, figures and appendices.
File Name: Chapter 4 data.zip

农业的主要温室气体（Greenhouse Gas, GHG）排放源包括耕地与放牧土壤产生的一氧化二氮（nitrous oxide, N₂O）排放、反刍家畜养殖与水稻种植产生的甲烷（methane, CH₄）排放，以及畜禽养殖废弃物处理产生的CH₄和N₂O排放。通过将碳固存于生物量、木材产品与土壤中，对耕地、牧地与林地的管理可抵消温室气体排放，使得美国温室气体净排放量达5903百万公吨二氧化碳当量（MMT CO₂ eq）。净排放量的定义为温室气体总排放量减去生长中森林、木材产品与土壤的碳汇量。

《美国农业与林业温室气体清单：1990-2018》报告旨在估算美国农业部门的温室气体排放量、量化排放估算的不确定性，并评估农业部门减缓美国温室气体排放的潜力。

本数据集包含该报告第4章“美国森林碳储量及其变化”中各图表与表格的制表数据，涵盖地上与地下碳储量及其变化量。有关数据的完整说明与注释，请参阅原报告。

本数据集包含的资源如下：
1. 资源标题：表4-1
文件名：Table4_1.csv
资源描述：2018年留存林地的碳储量变化估算与不确定区间，单位为百万公吨二氧化碳当量（MMT CO₂ eq）。
2. 资源标题：表4-2
文件名：Table4_2.csv
资源描述：留存林地的碳储量/碳储量变化与面积。其中碳储量与碳储量变化数据单位为百万公吨二氧化碳当量（MMT CO₂ eq），面积数据单位为千公顷。
3. 资源标题：表4-3
文件名：Table4_3.csv
资源描述：1990-2018年年度累计碳储量变化，单位为百万公吨二氧化碳当量（MMT CO₂ eq）/年。
4. 资源标题：表4-4
文件名：Table4_4.csv
资源描述：1990-2018年年度累计林地面积，单位为千公顷。
5. 资源标题：表4-5
文件名：Table4_5.csv
资源描述：2018年按区域、权属与碳库划分的碳密度。碳密度与碳库数据单位为兆克二氧化碳当量每公顷（Mg CO₂ eq/ha），森林面积单位为千公顷。
6. 资源标题：表4-6
文件名：Table4_6.csv
资源描述：2018年按区域、权属与碳库划分的森林生态系统总碳储量，单位为百万公吨二氧化碳当量（MMT CO₂ eq）。
7. 资源标题：表4-7
文件名：Table4_7.csv
资源描述：2018年按区域、权属与碳库划分的森林生态系统年度碳储量净变化，单位为百万公吨二氧化碳当量（MMT CO₂ eq，即百万公吨二氧化碳当量）。
8. 资源标题：表4-8
文件名：Table4_8.csv
资源描述：2018年按土地利用变化类别划分的、转为林地的土地因土壤碳储量变化产生的二氧化碳净通量，单位为百万公吨二氧化碳当量（MMT CO₂ eq）。负值（以括号标注）代表碳净固存。
9. 资源标题：表4-9
文件名：Table4_9.csv
资源描述：2018年按森林生态系统碳库划分的州级碳储量变化估算值。碳储量变化数据单位为百万公吨二氧化碳当量（MMT CO₂ eq），各州森林面积单位为千公顷。括号标注代表森林碳净固存。
10. 资源标题：图4-1a对应数据
文件名：Figure4_1a.csv
资源描述：图4-1a对应数据，即2018年森林生态系统碳储量，单位为百万公吨二氧化碳当量（MMT CO₂ eq）。
11. 资源标题：图4-1b对应数据
文件名：Figure4_1b.csv
资源描述：2018年森林生态系统平均碳储量密度。碳储量数据单位为兆克二氧化碳当量每公顷（Mg CO₂ eq/ha）。
12. 资源标题：图4-2对应数据
文件名：Figure4_2.csv
资源描述：2018年年度森林碳储量净变化，单位为太克二氧化碳当量（Tg CO₂ eq）。
13. 资源标题：附录表C-1
文件名：AppendixC_1.csv
资源描述：2018年按森林生态系统碳库划分的州级碳储量变化估算值。碳储量变化数据单位为百万公吨二氧化碳当量（MMT CO₂ eq），各州森林面积单位为千公顷。
14. 资源标题：第4章表格、图表与附录数据
文件名：Chapter4 data.zip
资源描述：第4章相关表格、图表与附录数据。