川西亚高山流域水碳平衡研究

doi:10.17521/cjpe.2016.0020

摘要/Abstract

摘要：

森林生态系统的产水量与固碳效益之间存在着一种可交易的平衡关系。基于WaSSI-C水碳耦合模型和趋势分析, 研究了1982-2006年川西杂古脑河上游22个子流域内不同植被类型空间分布对水碳平衡的影响并分析了其水碳耦合关系, 发现: 1)针叶林主导的流域在生长季增加土壤水分入渗的功能明显高于其他植被类型, 但不足以补偿其高蒸散带来的水分消耗, 因而其年平均土壤含水量明显低于高山草甸和混交林类型; 且森林土壤含水量随着森林覆盖率的升高而降低。2) 25年的土壤水分蓄变量的平均值, 高山草甸流域为-44 mm, 混交林为-18 mm, 针叶林为-5 mm, 说明川西亚高山植被的整体维持稳定产水量及其潜力在下降, 其中高山草甸流域下降趋势尤为显著。3)流域产流量和净生态系统生产力具有显著负相关性, 且不同植被组成对固碳和产水效益的转化具有重要影响: 高山草甸主导的子流域具有较高的产水量和较低的固碳能力, 常绿针叶林主导的子流域具有较高固碳能力和较低产水量, 且森林覆盖率越高, 产水量越低。三种植被类型的净生态系统生产力在研究期间均呈现上升趋势, 且高山草甸的上升趋势显著。

关键词: 水碳平衡, 耦合, 水文响应单元, 土壤水分蓄变量, WaSSI-C水碳耦合模型

Abstract:

Aims There is increasing concern on the trade-off between carbon sequestration and water yield of forest ecosystems. Our objective was to explore the effects of vegetation composition on water and carbon trade-off in the sub-alpine watersheds of western Sichuan during 1982-2006.Methods The WaSSI-C, which is an eco-hydrological model with coupled water and carbon cycles, was employed to calculate the key components in water balance and carbon sequestration for the 22 sub-catchments in the upper reaches of Zagunao River. Spearman’s Rho trend analysis was used to examine the trends in runoff and net ecosystem productivity. Important findings Compared with either subalpine meadow or mixed forest dominated catchments, the conifer-dominated catchments had much higher water loss due to high evapotranspiration, and the loss was not offset by its higher soil water infiltration during the growing season. The change in soil water storage for subalpine meadow, mixed forest and coniferous forest are -44 mm, -18 mm and -5 mm, respectively, which indicated significant decline in soil water storage and thus water yield particularly in alpine meadow catchments. Significant negative relationship was found between runoff and net ecosystem productivity, the alpine meadow as the dominant vegetation type showed high water yield and low carbon sequestration, and the conifer-dominant and mixed forest vegetation showed low water yield and high carbon sequestration, moreover, the higher the forest coverage, the lower the water yield. Upward trends in net ecosystem productivity were observed in the three vegetation types during the study period and the alpine meadow type was significant.

Key words: water and carbon trade-off, coupling, hydrological response unit, change in soil water storage, WaSSI-C model

孙鹏森, 刘宁, 刘世荣, 孙阁. 川西亚高山流域水碳平衡研究. 植物生态学报, 2016, 40(10): 1037-1048. DOI: 10.17521/cjpe.2016.0020

Peng-Sen SUN, Ning LIU, Shi-Rong LIU, Ge SUN. Trade-offs between water yield and carbon sequestration for sub-alpine catchments in western Sichuan, China. Chinese Journal of Plant Ecology, 2016, 40(10): 1037-1048. DOI: 10.17521/cjpe.2016.0020

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2016.0020

https://www.plant-ecology.com/CN/Y2016/V40/I10/1037

图/表 9

图1 杂谷脑水文站月尺度水文过程观测与模拟数据的比较。

Fig. 1 A comparison of monthly runoffs (simulated vs observed) guaged by Zagunao Hydrology Station.

图2 杂古脑河上游各子流域的土地覆盖类型分布图(图中数字表示子流域编号)。

Fig. 2 Land cover types for sub-catchments in upper reaches of Zagunao river (numbers in graph are serial numbers of sub-catchments).

表1 杂谷脑河流域上游各子流域的地形及植被组成

Table 1 Topography and vegetation composition for sub-catchments in upper reaches of Zagunao river

子流域编号 Serial number of sub-catchment	地形特征 Topography characteristics			植被组成 Vegetation composition
子流域编号 Serial number of sub-catchment	面积 Area (km²)	坡度 Slope (°)	平均海拔 Mean altitude (m)	针叶林覆盖率 Coniferous forest coverage (%)	森林覆盖率 Forest coverage (%)	高山草甸覆盖率 Alpine meadow coverage (%)	主导植被类型 Dominant vegetation type
3	20.0	51.5	4 077	91	99	0	针叶林 Coniferous forest
5	89.2	56.4	3 838	54	65	33
8	49.8	59.4	3 924	61	81	19
10	84.4	63.2	3 948	50	75	25
15	47.6	76.5	3 355	50	64	36
17	25.6	68.8	3 647	60	68	32
11	195.9	58.4	4 010	28	53	42	混交林 Mixed forest
12	127.9	69.3	3 322	28	6	38
18	171.2	65.9	3 937	18	5	44
19	59.6	71.6	3 866	24	76	23
21	112.5	66.7	4 017	39	58	34
22	66.0	59.1	3 543	22	48	43
1	251.5	49.4	4 004	27	48	51	高山草甸 Alpine meadow
2	146.2	54.9	3 995	25	47	50
4	221.7	58.9	3 371	21	41	55
6	82.5	59.3	3 672	33	52	49
7	132.7	61.3	3 446	30	47	51
9	149.1	60.9	3 628	37	43	57
13	139.8	73.6	3 348	32	43	55
14	87.9	69.6	3 998	33	45	51
16	81.2	70.6	3 348	36	51	50
20	96.9	66.6	4 016	29	43	54

图3 杂古脑河上游各子流域的年降水量(A)、年蒸散量(B)和年径流量(C)的空间分布(图中数字表示子流域编号)。

Fig. 3 Spatial patterns of mean annual precipitation (A), evapotranspiration (B) and runoff (C) of Zagunao upper reaches (numbers in graph are serial numbers of sub-catchments).

图4 杂古脑流域平均年总生态系统生产力(A)、生态系统呼吸(B)和净生态系统交换(C)的空间分布(图中数字表示子流域编号)。

Fig. 4 Spatial patterns of annual gross ecosystem productivity (A), net ecosystem exchange (B), respiration of ecosystem (C) of Zagunao upper reaches (numbers in graph are serial numbers of sub-catchments).

图5 不同主导植被类型下流域水量平衡要素的季节动态(平均值±标准误差)。

Fig. 5 Seasonal dynamics of water balance components under different dominating vegetation type (mean ± SE).

图6 土壤含水量(A)、土壤蓄水变量(B)与植被覆盖率之间的关系(图B中的数字为子流域编号, 圆圈内为水分流失严重的子流域)。

Fig. 6 The relationships between forest coverage and soil water content (A), and soil water storage change (B) (Numbers in Figure B denote sub-catchments and the severe water loss sub-catchments are inside circle).

图7 不同主导植被类型流域的生长季平均径流量与净生态系统生产力的变化趋势检验(Spearman’s Rho)。

Fig. 7 Spearman’s Rho trend analysis of runoff and net ecosystem productivity for different vegetation dominated catchments.

图8 杂谷脑河流域上游产水量与净生态系统生产力的关系(图中数值标志为子流域森林覆盖率)。

Fig. 8 Relationship between water yield and net ecosystem productivity in the upper reaches of Zagunao river (numerical values in plot denote forest coverage for sub-catchment).

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