Understanding the effects of contour hedgerow and terracing hedgerow on soil and water conservation in the remote mountainous regions of Southwest China

ZHOU Ping, WEN Anbang, YAN Dongchun, SHI Zhonglin, LONG Yi

(Institute of Mountain Hazards and Environment, Chinese Academy of Sciences and Ministry of Water Resources, the Key Laboratory of Mountain Surface Processes and Ecological Regulation, 610041, Chengdu, Sichuan, China)

Understanding the effects of contour hedgerow and terracing hedgerow on soil and water conservation in the remote mountainous regions of Southwest China

ZHOU Ping, WEN Anbang?, YAN Dongchun, SHI Zhonglin, LONG Yi

(Institute of Mountain Hazards and Environment, Chinese Academy of Sciences and Ministry of Water Resources, the Key Laboratory of Mountain Surface Processes and Ecological Regulation, 610041, Chengdu, Sichuan, China)

[Background] Soil and water loss is a serious worldwide environmental problem, for example, soil loss from the sloping cultivated lands in the remote mountainous regions of Southwest China due to the abundant precipitation and steep sloping cultivated lands in these areas. Various soil protection techniques have been adopted to prevent soil loess, the local people did not admire the introduced contour hedgerow measurement from abroad; however, they have been actively accepted another traditional one, the terracing hedgerow. The purpose of this work is to understand the differences on soil and water conservation between contour hedgerow and terracing hedgerow. [Methods] The different structure between four treatments of contour hedgerow and terracing hedgerow were analysed. Meanwhile, three heights (0 cm, 10 cm, and 15 cm) of lynchet were set, and the soil erosion module, runoff efficiency, ratio of output and input, economic effects among the different treatments were compared. The soil anti-scourability was calculated using the equation, and analysis of variance (ANOVA) was performed with SPSS 11.5 and Microsoft Excel software. [Results] The obvious difference was that terracing hedgerow with a certain height of walkway was more convenient for farming activities and effectively reduced soil and water loss. The treatment of terracing hedgerow 2 (H15H) reduced runoff 55.56%±6.25% and reduced erosion modulus 79.26%±3.50% when compared to the sloping cultivated land plots with no lynchet and no hedgerow (CK). The contributions of the independent variables on runoff, soil erosion reduction and soil anti-scouring were in the following order: terracing hedgerow 2 (H15H) > terracing hedgerow 1 (H10H) > contour hedgerow (H0H) > non-hedgerow (CK). The value of ratio of output to input of H15H treatment was 1.52, which was the highest value among different treatments. [Conclusions] Although the treatment of terracing hedgerow 2 (H15H) needs more labour force, however, results in the higher hedgerow yield and ratio of output to input than other treatments as well as stronger anti-scourability. Thus, the traditional terracing hedgerow with 15 cm lynchet is recommended in the remote mountainous regions of Southwest China, even should be recommended often and used extensively in the similar climatic regions in other countries.

terracing hedgerow; structure; mechanism of the soil and water conservation; contour hedgerow

0 Introduction

Soil and water loss is a serious environmental issue worldwide. In China, nearly one third of the lands suffered from soil and water loss[1]. Especially serious soil and water loss problems occur in the remote mountainous regions of upper Yangtze River region of China mainly due to abundant precipitation and the characters of the soils. Additionally, soil erosion is the main cause of the loss of nutrient-rich topsoil and the declination of soil fertility, and thus is a potential threat to safety of the Three Gorges Dam. Soil degradation by erosion affects 1966 million hectares worldwide[2]. The total soil erosion in this region was about 11.98*107t/km2·a and the average modulus of soil erosion was 2.09 t/km2·a, depending on slope gradient and precipitation characteristics. Meanwhile, most of the population living in this region depends on agriculture for their livelihood; hence it is imperative to preserve soil to sustain crop yields in the Southwest China.

The gully mountains are the main landscapes in the remote mountainous regions of Southwest China, with the high tillage index, overgrazing problem, severe soil erosion and fragile ecology. According to the results of agricultural and water conservation investigations, the main sediment source of Yangtze River was from the sloping cultivated land[3]. The broken terrain, complex geological construction, erosive topographic conditions, frequent landslide, debris flow hazards, serious soil loss, and water pollution have been the severe problems in this region, accelerating soil erosion on sloping lands[4], therefore, the soil erosion becomes a serious challenge for agricultural development in this region. On one hand, the sediments from the sloping cultivated land were the main sediment source of the rivers and lakes, and about 60%-78% of sediments of Yangtze River were from the sloping cultivated land[3]. On the other hand, the single land use pattern of sloping cultivated land, lower carry capacity, serious soil and fertilizer loss all lead to the thinner soil layer and lower land production. Also the vicious cycle of sloping cultivated land tillage - soil and water loss - production degraded - not meet people’s needs - reclaim the sloping cultivated land, which is the obstacle of the sustainable agriculture development of gully mountainous region of the Three Gorges Reservoir region at the upper reaches of Yangtze River[5].

The total area of the Three Gorges Reservoir region is 5.24*104km2with the complex topography and the hilly mountainous area is 94.1%, the percentage of sloping cultivated lands is 41.54% of the total cultivated lands, and mainly distributed in the inconvenient irrigation and steep slope degree mountain regions. And the percentage of sloping cultivated lands with more than 25 slope degree is 28%[6]. Meanwhile, the sloping cultivated lands had the more serious soil erosion with the total soil erosion yield of 9.45*107t/a[7], also the land productivity decreased and faced to the ecological environment restoration and the sustained economic development[8]. Agroforestry can greatly reduce some losses, especially on hill slopes, where soil evaporation, runoff and soil losses are important. The agroforestry ecosystem such as the contour hedgerow was first introduced to sloping farmlands as an effective soil-conservation strategy in this region. However, it didn’t play a significant role in reducing soil erosion, controlling non-point source pollution and increasing economic effects. Also the local people realized that the agroforestry ecosystem such as the contour hedgerow caused some problems. Meanwhile, the local people also think that there exist traditional hedges and the plants grow well on the hedgerow, why do not we adopt this traditional mode (terracing hedgerow) and why we abandoned this traditional soil and water conservation strategy and adopted the introduced new soil and water conservation (contour hedgerow) from abroad? The local people’s attitudes and suggestion let us reconsider the traditional strategy of soil and water conservation. Meanwhile, most researchers noted that hedgerows were effective in controlling soil erosion, but very few explained the structures and mechanism behind that effectiveness. Also the relationship of spatial and temporal of the terracing hedgerow and the long time location tests were all needed by the ecological theories and ecological landscape theories.

The objectives of this study are as follows: 1. comparing the conceptional differences between the contour hedgerow and the terracing hedgerow; 2. comparing the effects of soil and water conservation between the contour hedgerow and the terracing hedgerow.

1 Materials and methods

1.1 The concept of contour hedgerow

The concept of contour hedgerow is to use the narrow vegetative strips of trees, shrubs or grasses planted on the contour, often called ‘contour hedgerows’, is an experimental management practice with potential to reduce soil erosion on sloping lands in the humid tropics[9]. Food crops are planted in the alleys where the areas are between the hedgerows (Fig. 1). It is one of effective soil conservation strategies recommended for tropical and subtropical mountainous regions. The contour hedgerow effectively reduced soil loss, runoff and associated nutrient losses on sloping terrain[10].The contour hedgerow was used very widely in the agricultural lands and forestlands in the foreign countries[11-12]. From the 1970s, the contour hedgerow as one important way of agroforestry ecosystem was favored by the tropical and subtropical regions such as the South Africa, India and Philippines. In China, only some places implemented the contour hedgerow, but it was not popularized by the local farmers.

Fig.1 Composition and structure of a contour hedgerow

1.2 The concept of terracing hedgerow

The composition of terracing hedgerow includes the lynchet and the edge-of-field berms and the hedgerow (Fig.2). The “Lynchet” is an archeological term referring to the morphological response on a hill slope to the presence of field boundaries in filed berm. These edge-of-field berms may affect the rate and the distribution of runoff from the fields, as they may create temporary impoundments. If the soil is moving away from the boundary, soil loss occurs, otherwise accumulation occurs. The hedgerow may be planted on the lynchet, which has the effects to reinforce the lynchet and the edge-of-field berms to further control the soil and water loss on the sloping cultivated lands.

Fig.2 Composition and structure of a terracing hedgerow

1.3 The studied area

Experiments were conducted at the soil and water conservation station in Zhongxian county (30°24′53″N, 108°10′25″E), Chongqing municipality city, which is located in the Three Gorges Reservoir region of the upper reach of Yangtze River in the Southwest China. The experimental station belongs to the Institute of Mountain Hazard and Environment, Chinese Academic of Sciences. With the mean annual rainfall of 1 150 mm, about 70% falls is from April to October. Soil is mainly purple soil (Orthic Entisols in the Chinese soil taxonomic system, Regosols in FAO taxonomy or Entisols in USDA taxonomy)[13]of fast weathering products of the Jurassic rocks of the Shaximiao Group (J2s). The character of purple soil in this area is shown in Tab.1.

1.4 Experimental design and methods

The experiment included 4 treatments with 3 replicates of each. The plots were designed as 3 m width, 15 m length down slopes. The experimental hedgerow was a kind of grazing grass (Cichoriumintybus) with the slope gradient of the plots all 15° (Tab. 2). The lynchet heights of the terracing hedgerow were set 0 cm, 10 cm, 15 cm and double rows of the grazing hedgerow were planted (0.1 m inter-row and 0.2 m among the row spacing). The hedgerow distance was 4.5 m between each plot. The details of experimental treatments and farming practice in the experimental plots are shown in Tab.3.

Tab.1 Characters of purple soil at the soil and water conservation station in the Three Gorges Reservoir

Tab.2 Designed treatments in the experimental plots

Tab.3 Details of experimental treatments and farming practice in the experimental plots

The initial soil water content and the bulk density were measured before the experiment. The runoff and soil erosion were monitored after a big precipitation with 96.4 mm during a whole day. Soil loss and runoff were collected after each natural rainfall event using collecting tanks with a volume of 1 m3. These tanks were connected indirectly to the erosion plots via one of 9 outlets of a divisor box placed between erosion plot and tank. The amount of runoff water and the soil loss were collected from collecting channels at the lower end of each plot and weighed. Meanwhile, crops and stover were harvested from each plot respectively. Then the grains and stover were oven dried at 70 ℃ until constant weight reached.

The represented sites were selected for soil sampling. The soils were collected using soil hand auger (diameter 5 cm) at 10 cm soil depth intervals. The sampling soil depth ranged from 0 to 0.6 m. Three duplicates for each sampling site were taken to evaluate the enrichment ratio of the runoff sediments. The soil samples were air-dried, gently grounded with a mortar and pestle, homogenized, and divided into two parts. One part of the soil samples was sieved to pass through a 2 mm mesh for analyzing the particle size distribution. After the removal of organic matter with hydrogen peroxide, the particle fractions were determined in duplicate with the laser diffraction technique, i.e., using the MS2000 Laser particle size analyzer (Malvern Instruments, Malvern, England) to analyze the content of clay, silt and sandy. Another part of the soil samples was sieved to pass through a 0.25 mm mesh for analyzing the soil chemical character.

1.5 Calculation and statistical analysis

For each hedgerow mode, the soil anti-scourability was calculated using the equation:

M=Q/(G1-G2)

WhereMis the modulus of the anti-scouring (L/g),Qis the water weight during the scouring experiment, andG1,G2are the weights of the soil before and after scouring experiments.

All results are recorded as means ± standard deviations. Analysis of variance (ANOVA) was performed with SPSS 11.5 and Microsoft Excel software. The significance level was set asP<0.05.

2 Results

2.1 Compositions and structures of the contour hedgerow and the terracing hedgerow

The hill slopes with gradients less than 25° are more commonly used for farming in the Three Gorges Reservoirs region of the upper reach of Yangtze River. The terracing hedgerows are used commonly in this region. The composition and structures of the terracing hedgerow and the contour hedgerow were shown in Fig. 1 and Fig. 2. The configuration mode and the spatial distribution of the contour hedgerow and terracing hedgerow were different as the geographical condition and the local peoples’ demands[14]. The single and double rows of hedgerows with the same hedgerow type or the different hedgerow types are very common.

2.2 The function of the terracing hedgerow

The roots of the terracing hedgerow better enhanced the soil physical and chemical characters, increased the soil infiltration and the soil porosity capillary, also reduced the bulk density and the soil texture[15], and therefore enhanced the soil conservation and the potential soil productivity.

The hedgerow was periodically mowed to 0.5 m height each time by two or three months. And the mowed stems and leaves were returned to the sloping cultivated land to increase the soil organic matter and soil fertilizers[16]. Many studies were carried out on the decomposition of the mowed hedgerows. Lupwayi[17]used the exponential model to simulate the decomposition process of the organic matter ofLeucaenaleucocephala. Bross et al[18]compared the influence of decomposition of coverage of branches and leaves of locust and clover underground and aboveground condition, and analyzed the decomposition effects of the lignin of locust and clover.

As growingly horizontal terraces were constructed in the Three Gorges Reservoir region of the upper Yangtze River, the areas of the terrace reached 12% of the whole areas of the sloping cultivated lands. New lynchets of the terraces reached 3.2*104hm2each year. More and more people paid attention to the concret function of the lynchets and the edge of field berms. The roots of the terracing hedgerow enhanced the stability of the lynchets and the edge-of-field berms, also prolonged the longevity of the lynchet and field berms. Hedgerow also played an obvious part in reducing the soil loss and soil erosion modulus. There were three functional approaches to influence the moving process of sediment and weaken soil erosion from the sloping cultivated lands. Firstly, the precipitation was intercepted and the energy of rain drops was reduced by the hedgerows. Also the soil scourability of the sloping cultivated land was reduced by the aboveground of the hedgerow. Secondly, the function of the hedgerow roots in the soil further increased the soil infiltration and reinforced the lynchets, and the edge-of-field berms enhanced the anti-scourability of the soils. The results of Wu’s[19]showed that the soil anti-scourability reduced by the roots of the hedgerow was nearly equal to that by the whole plant. The runoff and sediment yield time of the sloping cultivated lands were delayed and shortened by the roots of the hedgerows. The third function was that the aboveground of the terracing hedgerow had the direct function to intercept the runoff and sediment, prolonged the infiltration time and reduced the soil fertilizer loss. All these three functions together reduced the soil and water conservation and enhanced the soil fertilizer of the sloping cultivated lands.

The hydraulic characters of the runoff of terracing hedgerow were changed. The velocity of the runoff reduced in the upper position of the terracing hedgerow and the sediment taken by the runoff reduced, which led to the sediment deposit in these places. However, the velocity of the runoff increased in the lower position of the terracing hedgerow, and the sediment taken by the runoff also increased, which led to the aggravation of the sediment erosion in these places. All the two processes of the upper position and lower position of the terracing hedgerow reduced the slope gradient and terracing the sloping cultivated lands. Shen et al[20]showed that the hedgerow reduced the slope degree from 30°-34° to 15°-18° in 9 years. And the soil organic matter also increased from 0.9% to 1.61%. The hedgerows all grew on the lynchets and the edge-of-field berms of the sloping cultivated lands formed the alley for farmer to walk while doing some farming activities. It reduced the trample of the cropping lands and reduced the touch of field crops to influence the field yields. Finally, economic factors play a role in determining whether farmers will adopt or not such technology. The hedgerow systems had the disadvantage of providing only limited early returns on investment[21]. Farmers repeatedly complain about the fact that improved yield response only comes in several years after hedgerow establishment[22].

2.3 Comparing the effects between contour hedgerow and terracing hedgerow

2.3.1 Effects of soil and water conservation between the contour hedgerow and the terracing hedgerow

The measured soil erosion modulus, runoff and runoff coefficient of the different strategies are shown in Fig. 3. The CK consistently had the highest runoffs, followed by the H0H,then was H10H. The H15H had the lowest runoff. The H15H reduced runoff 55.56%±6.25% when compared to CK, and it reduced runoff 21.11%±1.36% when compared to the H10H. In addition, the H15H reduced erosion modulus 79.26%±3.50% when compared to the CK, and it reduced erosion modulus 58.64%±5.87% when compared to the H10H. The H10H reduced soil erosion modulus by 49.85%±5.50% and the H10H reduced runoff by 43.66%±4.45% when compared to the CK. According to ANOVA, the differences in runoffs of the different treatments were not significant for the H0H (F=2.36,P=0.15), H10H (F=1.85,P=0.21) and H15H (F=1.63,P=0.27). Difference in soil erosion moduli of the different treatments were not significant for the HOH (F=1.36,P=0.16), H10H (F=1.55,P=0.21), but was significant for the H15H (F=1.73,P=0.05). The results showed that the H15H had better soil and water conservation effects than the other two types of hedgerow. And the terracing hedgerow showed more effects on control soil erosion of the sloping cultivated lands than reducing the runoff.

Different letters on the data dots in figure caption are statistically significant (P<0.05).Fig.3 Characters of soil erosion modulus, runoff, and runoff coefficient among the different lynchet heights of terracing hedgerow and the contour hedgerow on the sloping cultivated plots

2.3.2 Economic effects between the contour hedgerow and the terracing hedgerow

When compared the contour hedgerow and the terracing hedgerows with different lynchet height to CK, the contour hedgerow and the terracing hedgerow needed more labor force to sustain the normal farming activities (Tab.4), however, the less crop seeds, fertilizer and pesticides than the CK, only about 89%-93% of the latter. Although the input of the labor force was more in the mode of terracing hedgerow than that in the contour hedgerow, the output efficiency of the terracing hedgerow was higher than the latter (Tab.4), because the hedges such as the soybean, maize, peanut and so on were planted in the lynchet of the terracing hedgerow and intercepted the soil nutrients into the field lands.

The ratio of the output to input of the CK was lower than the hedgerow mode. The contour hedgerow was of 96% when compared to the terracing hedgerow. The H15H had higher ratio of output to input than that of the H10H. As to avoide the competition of sunlight, water and fertilizer with the crops in the field, the hedgerows were cutting down to 0.5 m for two to three month (Tab.5). The cutting parts were returned to the cropping field and to the edge of lynchet to increase the soil nutrients. Also in some places, the farmers planted the valuable hedgerow such as the grazing grass, medical materials and the flowers or plants to increase the incomes. The hedgerow of these kinds had the higher economic effects (Tab.5). The farmers obtained the additional gains to enhance their incomes from different hedgerows.

Tab.4 Output and input of the contour hedgerow and the terracing hedgerow

Note: The data in the above Table showed as mean values ± standard deviation. Values followed by the same letters in the same column are not significantly different (P<0.05). The same below.

Tab.5 Economic effects of different types of hedgerow

Tab.6 Characters of soil anti-scourability and soil particle composition among different hedgerow modes

Note: * refers toP<0.05, ** refers toP<0.01, *** refers toP<0.001

The H15H had the highest anti-scourability when compared to the contour hedgerow and the traditional non-hedgerow. It enhanced 29.67% of the anti-scourability as compared with other hedgerow modes. Meanwhile, the content of sand reduced 4.41% and the content of silt and clay increased 2.9% and 12.26%, respectively. The soil aggregates became better and the hedgerow with the higher lynchet played more obvious part in soil and water conservation (Tab.6).

3 Discussions

Contour hedgerows, defined as dense, erect, vegetative barriers made of stiff-stemmed grass that slow-down runoff and reduce erosion[23-24], potentially reduce runoff and soil loss by up to 60% and 80%[25-26], respectively, by filtration, deposition, and infiltration[27-28]. Nevertheless, the effects of contour hedgerows reduced runoff a soil loss only 50.04%±5.12% and 70.01%±2.87% in the present study. The main reason was that the planting density of the contour hedgerow was less in this region than that in the foreign countries, also the degree of the sloping cultivated lands is steeper in this region. And the effects of the contour hedgerow depended mostly on slope gradient, runoff volume and flow rate, size and density of sediment particles, grass species, density, interval and width of grass strips, underlying soil properties, and rainfall intensity and duration[29-30]. In previous research tests, vetiver grass (Chrysopogonzizanioides), switchgrass (Panicumvirgatum), tall fescue (Festucaarundinacea), and achnathemps pendens (Achnatherumextremiorientale) were very effective in reducing soil and water loss[31-32]. Among these grasses, vetiver grass has often been suggested in the tropical and subtropical regions due to its unique characteristics, including fast growth, deep and penetrating root systems, and high tolerance to adverse conditions. However, vetiver is not favored by the farmers in the Three Gorges Reservoir region for its poor economic value. In this region, the grazing grass was more popularily planted. Thus, one kind of grazing grass (Cichoriumintybus) was chosen to analyze its ecological and economic effectiveness in this study.

Due to high amount of precipitation, fragmentized sloping cultivated land and steep slope and severely soil erosion, annual averaged soil erosion amount was 19 364.71*104t/a, and the mean soil erosion modulus was 2 741.48 t/km2·a in the Three Gorges Reservoir region of the Southwest China[33]. Our results clearly supported the hypothesis that the lynchet of the terracing hedgerow had the positive effects on soil and water conservation, also was suitable for applying on the sloping cultivated lands in this region. In this study, the terracing hedgerow significantly reduced the erosion modulus and the runoff than the contour hedgerow and non-hedgerow. The lynchet height of 15 cm of the terracing hedgerow was recommended in this region.

The lynchet of the terracing hedgerow also significantly reduced the soil and water loss from the sloping cultivated land and nutrients loss. The hedge planted on the lynchet effectively reduced the runoff velocity, increased the soil infiltration and soil capillary porosity to further reduce the loss of runoff. The similar results of the grass hedges and micro-basins on reducing soil and water loss were showed by the Xiao and alley cropping for managing soil erosion of hilly lands in the Philippines[28]. The results of Long[33]showed that the erosion modulus of contour hedgerow (Boehmerianivea) averaged 802.50 t/km2·a and the nearby sloping cultivated lands with on hedgerow reached 20 299.70 t/km2·a. The efficiency of the soil erosion reduction was 65.1%. As to the soil erosion, most of the sediments were intercepted by the stems and leaves of the hedge. For a longer time, the slope degree became gentle and the soil and water loss were effectively controlled.

The distance of the hedgerow played important part in reducing the erosion. However, the present study was mainly concentrated on the qualitative analysis of the mechanism of the soil erosion and runoff reduction, and more researches need. The typical study results showed that there existed the exponent relationship between the hedgerow coverage and the concentration of the runoff in the mode of the contour hedgerow. Nevertheless, it was nearly no research on the lynchet height of the terracing hedgerow. The study on the hedgerow showed the diversified trends, and the related basic theory should be strengthened[34].

4 Conclusions

The structures and the mechanism of soil and water conservation of the contour hedgerow and terracing hedgerow were studied in subtropical regions of Southwest China. The conclusions are as following:

1) The obvious difference existed between the terracing hedgerow with a certain height of lynchet and the contour hedgerow. And the function of the lynchet was for farmers to walk on it in conducting the farming activities at more convenience, and effectively reduced the soil and water loss.

2) The comparative results showed that the traditional non-hedgerow CK control plots consistently had the highest runoff, followed by the H0H (Contour hedgerow), and then was H10H (Terracing hedgerow 1 with 10 cm lynchet). The H15H (Terracing hedgerow 2 with 15 cm lynchet) had the lowest runoff. The H15H reduced runoff 55.56%±6.25%, reduced runoff coefficient 21.11% ±1.36% and reduced erosion modulus 79.26%±3.50% when compared to CK. These results indicated that the terracing hedgerow with 15 cm lynchet presented better soil and water conservation effects than the other two kinds of hedgerow in the Three Gorges Reservoir region.

3) The contributions of the independent variables to runoff were in the following order: H15H>H10H>CK>H0H. Similarly, the contributions to soil loss and the soil anti-scouring were in the following order: H15H > H10H > H0H > CK. Therefore, these traditional terracing hedgerow practices should be recommended often and used extensively in similar climatic regions.

4) Although the input of the labor force was more in the mode of terracing hedgerow than that in the contour hedgerow, the output efficiency of the terracing hedgerow was higher than the latter. Meanwhile, the farmers planted the high valuable hedgerows such as the grazing grass, medical materials and the flowers or plants to increase their incomes in some places of Southwest China.

Acknowledgements

The authors wish to thank the Foundation of STS Program of the CAS (KFJ-SW-STS-175) and the National Natural Science Foundation of China (41671286). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Also we would like to thank the anonymous reviewers and editors for constructive comments and English corrections on the manuscript.

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2016-08-19

2017-04-14

S152.2

A

2096-2673(2017)02-0025-06

西南山區(qū)等高植物籬和植物固結(jié)地埂的水土保持功能的理解

周萍， 文安邦， 嚴(yán)冬春， 史忠林， 龍翼

(中國(guó)科學(xué)院水利部成都山地災(zāi)害與環(huán)境研究所，山地表生過(guò)程與生態(tài)調(diào)控重點(diǎn)實(shí)驗(yàn)室， 610041, 成都)

水土流失是個(gè)世界范圍的嚴(yán)重環(huán)境問(wèn)題，比如由于豐沛的降雨和陡坡耕作，造成的中國(guó)西南部偏僻山區(qū)的坡耕地水土流失。這些區(qū)域采取了多種保持土壤措施減少土壤流失，可當(dāng)?shù)剞r(nóng)民并不接受引進(jìn)的等高植物籬措施；而植物固結(jié)地埂是一項(xiàng)傳統(tǒng)的且當(dāng)?shù)剞r(nóng)民樂(lè)意接受的水土保持措施。本文比較了等高植物籬和植物固結(jié)地埂的結(jié)構(gòu)，設(shè)置3種植物固結(jié)地埂高度0 (CK)、10 cm (H10H)、 和15 cm (H15H), 分析了等高植物籬(H0H)和上述3種地埂高度的植物固結(jié)地埂對(duì)徑流、侵蝕量的影響及產(chǎn)投比和經(jīng)濟(jì)效益，旨在理解當(dāng)?shù)剞r(nóng)民的選擇。研究結(jié)果顯示最明顯的區(qū)別是植物固結(jié)地埂具有一定高度的地埂能夠方便農(nóng)事活動(dòng)并且有效減少水土流失。植物固結(jié)地埂的第2個(gè)處理(H15H)比無(wú)地埂無(wú)植物籬的坡耕地處理(CK)減少?gòu)搅?5.56%±6.25% ，減少侵蝕量79.26%±3.50%。不同處理的徑流量、土壤侵蝕減少量和土壤抗蝕性變化順序?yàn)椋?H15H > H10H > H0H > CK。H15H的產(chǎn)投比最高為1.52.與其他試驗(yàn)處理相比，雖然H15H措施需要的勞動(dòng)力更多，但它具有較高的植物籬收獲量和產(chǎn)投比以及較強(qiáng)的抗沖蝕性。因此，西南地區(qū)坡耕地上推薦具有15 cm地埂高度的植物固結(jié)地埂措施(H15H) ，甚至該項(xiàng)水土保持措施可適用于與西南地區(qū)氣候相似的其它區(qū)域或是其它國(guó)家。

植物固結(jié)地??； 結(jié)構(gòu)； 水土保持機(jī)理； 等高植物籬

ZHOU Ping (1981-)，female， associate professor. Main research interests: soil and water conservation. E-mail: zp09@imde.ac.cn

?Corresponding author: WEN Anbang (1964-), male, professor. Main research interests: soil erosion. E-mail: wabang@imde.ac.cn.

10.16843/j.sswc.2017.02.004

Funded： the STS Program of the CAS (KFJ-SW-STS-175); the National Natural Foundation (41671286); State’s Key Project of Research and Development Plan (2016YFC0402301); 973 Project (2015CB452704).