Intensive Land Research Articles

Shrub facilitation promotes advancing of the Fagus sylvatica treeline across the Apennines (Italy)

AbstractQuestionsElevational treelines are expected to shift upwards in response to warming climate. However, worldwide upward shifts of treelines are inconsistent because local scale factors can affect the response to temperature. In this study, we explore the hypothesis that in the Apennines, where the current altitudinal treeline position is largely depressed because of past human activity, shrubs act as nurse plants promoting the upward migration of Fagus sylvatica.LocationA 500–km‐long latitudinal gradient in the Apennines, Italy.MethodsWe selected, along this gradient, nine treeline sites with different elevations, rock substrates, and physiognomic types including Juniperus communis, Pinus mugo, Vaccinium myrtillus shrublands, and grasslands. Here, in 68 transects we collected and analysed spatially fine‐scale distribution data of F. sylvatica individuals in relation to both their age and their position, associated or not with shrubs.ResultsFagus sylvatica regeneration is rare in open secondary grasslands at 1,600–2,100 m a.s.l., highlighting a bottleneck in the regeneration phase of this species. On the contrary, we systematically observed a strong association between shrubs and F. sylvatica individuals. Compared with the adjacent grassland, F. sylvatica regeneration was 58.3 times higher under Pinus mugo, 131.5 timeshigher under Juniperus communis and 102.4 times higher under Vaccinium myrtillus. The age structure of F. sylvatica population indicates that, in the last 50 years, recruitment under shrubs is continuous, while in grassland it is episodic.ConclusionsAbove the current treeline of the Apennines, F. sylvatica individuals develop only in the presence of shrubs, which act as nurse species. Shrubs are a necessary condition for F. sylvatica re‐colonization of the high‐altitude open areas affected, in the last centuries, by intense human land use.

Sustainable Soil Loss Management in Tropical Uplands: Impact on Maize-Chili Cropping Systems

Intensive land use with inappropriate land management is directly degrading South Asian uplands. A field trial was carried out on the uplands of Western Thailand with a 25% slope to examine the effect of land use management on soil loss for sustainable crop production during two consecutive years (2010–2011). Various cropping systems with soil conservation practices were compared to maize sole cropping (MSC). Results revealed that soil loss was at a minimum in the intercropping system of maize-chili-hedgerows with minimum tillage and fertilization that was 50% to 61% and 60% to 81% less than MSC and the bare soil plot during both years, respectively. Yield advantage was at its maximum, as indicated by the highest land equivalent ratios of 1.28 and 1.21 during 2010 and 2011, respectively, in maize-chili-hedgerows-intercropping with minimum tillage and fertilization. The highest economic returns (5925 and 1058 euros ha−1 during 2010 and 2011, respectively) were also obtained from maize-chili-hedgerows-intercropping with minimum tillage and fertilization. Chili fresh fruit yield was maximum in the chili alone plot during both years due to the greater area under cultivation compared with intercropping. Maize-chili-hedgerows with minimum tillage and fertilization reduced soil loss and increased land productivity and net returns, indicating its promising features for sustainable crop production on uplands.

Hydro-physical properties of agriculturally used peatlands in Liang Anggang Protected Forest, South Kalimantan, Indonesia

The utilization of peatlands as agricultural areas that do not pay attention to proper water management will result in peatland degradation. To restore the degraded peatlands, it is necessary to explore the peat’s hydrological and physical characteristics. Therefore this study investigates the hydro-physical peat characteristics in the peatlands that have been converted into agricultural use. The research was carried out in the Liang Anggang Protected Forest area, specifically in the area converted to agricultural land. Undisturbed peat samples were collected in both intensive and un-intensive agricultural sites. Peat characteristics were analysed in the laboratory include bulk density, particle density, porosity, total soil water content, and hydraulic conductivity variables. The result shows that peat characteristics in the intensive agricultural land significantly indicate higher bulk density and particle density with the values 0.30 g/cm3 and 0.91 g/cm3, respectively. Still, significantly lower values are found in porosity (66.87%), total soil water content (226.95%), and hydraulic conductivity (0.0025 cm/s). Degraded peatland restoration that functions as a protected forest must be carried out through rewetting activities and maintaining the water table depth. On the other side, the peatland whose function is designated as an agricultural area, wetland farming systems should be applied using adaptive crop species.

Early Holocene aeolian sediments in southwestern Crete\u2212preliminary results

The soilscapes along the southern and western coast of Crete (Greece) are dominated by coarse-grained reddish-brown slope sediments whose natural (pre-anthropogenic) configuration and properties are difficult to reconstruct due to the long history of intense land use. As a consequence, datable terrestrial sediment archives of pre-anthropogenic genesis are scarce. We present preliminary results of a study performed on an accumulation within an alluvial fan south of Stomio Bay in southwestern Crete. The studied profile is located in a small depression and is composed of a sequence of sandy to silty yellowish-brown calcareous sediments overlying coarse-grained slope sediments, including a fossil topsoil horizon. Based on macroscopic, micromorphological, geochemical, geophysical and mineralogical analysis, we interpret the fine-grained sediments to have a local aeolian origin. OSL dating indicates a final deposition phase during the early Holocene. Considering the scarcity of early Holocene terrestrial archives in Crete, the analysed profile provides valuable data for the reconstruction of landscape dynamics and paleoecological conditions as well as soil-sediment configurations during this time period. Additional research is needed to address the specific source area(s) as well as the ages of the deposition of slope sediments and formation of the fossil topsoil.

How to Perceive the Trade-Off of Economic and Ecological Intensity of Land Use in a City? A Functional Zones-Based Case Study of Tangshan, China

China, in a rapid urbanization process, is accompanied by the expansion of built-up land, population accumulation, and intensive land investment, while the improvement of the urban environment cannot keep up with the population and economic density growth. Therefore, the purpose of this paper is to discuss the balance between urban land use economic intensity (built-up area density, population density, land price) and ecological intensity (the depth, breadth, and integration of ecological spaces) in Tangshan. From the perspective of functional zones (FZs), the trade-off of economic and ecological intensity of different types of land use is detailed from the evaluation system. Finally, this paper explores a common intensive development model for different FZs to reach both reasonable economic and ecological purposes in Tangshan. The upshot indicates that the economic and ecological intensity of all FZs in Tangshan follows an opposite spatial distribution, and different types of FZ own their characteristics. The Gini index and Theil index for measuring the typical FZ indicate the unbalanced state between ecological spaces and population in residential areas. To sum up, a resource-based city, such as Tangshan, in the rapid development stage of urbanization tends to pay more attention to economic output and neglect ecological benefits.

Peatland subsidence enhances cultivated lowland flood risk

Peatlands worldwide are being threatened by intensive land use and drainage, which leads to soil subsidence. This has consequences for farming, especially on low-gradient cultivated peat-dominated lowlands with high flood risk. In this study, we combined historical soil elevation data and new lidar data to improve the estimation of subsidence and its consequences for lowland river systems. The results showed 202−349 mm subsidence within the last 24–51 years, with a mean rate of 5.15–9.47 mm y−1 for riparian peatland on the west coast of Finland. The subsidence rate was partly explained by the depth of the organic soil layer (R2 = 0.710, p > 0.05). The results also showed that increasing flooding of cultivated fields is mainly due to soil subsidence, not to increased flooding occurrence in river systems. The area flooded annually was found to increase by 101–194 % for the last 24–51 years, due to soil subsidence near rivers. Generalization of the results to catchment scale indicated an increase in the annual flood zone of 45 % in cultivated fields in one of two study catchments (Siikajoki river basin). These results demonstrate the value of using historical data to study soil subsidence and confirm that the risk of flooding increases in cultivated organic lowlands due to intensive drainage and subsidence. New management strategies, such as peatland rewetting, restoration, and paludiculture, should be considered in future land use plans to reduce subsidence and provide new income streams for farmers.

The resilience of Amazon tree cover to past and present drying

The Amazon forest is increasingly vulnerable to dieback and encroachment of grasslands and agricultural fields. Threats to these forested ecosystems include drying, deforestation, and fire, but feedbacks among these make it difficult to determine their relative importance. Here, we reconstruct the central and western Amazon tree cover response to aridity and fire in the mid-Holocene—a time of less intensive human land use and markedly drier conditions than today—to assess the resilience of tree cover to drying and the strength of vegetation-climate feedbacks. We use pollen, charcoal, and speleothem oxygen isotope proxy data to show that Amazon tree cover in the mid-Holocene was resilient to drying in excess of the driest bias-corrected future precipitation projections. Experiments with a dynamic global vegetation model (LPJ-GUESS) suggest tree cover resilience may be owed to weak feedbacks that act to amplify tree cover loss with drying. We also compare these results to observational data and find that, under limited human interference, modern tree cover is likely similarly resilient to mid-Holocene levels of aridification. Our results suggest human-driven fire and deforestation likely pose a greater threat to the future of Amazon ecosystems than drying alone.

Spatiotemporal analysis of land use land cover changes and built-up expansion projection in predominantly dystric nitosol of Ebonyi state, Southeastern, Nigeria

During the past two decades, in post economic reforms and developmental policy push period, Ebonyi state and its surrounding thirteen administrative regions has attracted a large number of populations which led to the rapid transformation of its LULC pattern. Therefore, this study is determine to analyze the LULC changes during 1996 and 2018, to evaluate the growth and pattern of built-up expansion in relation to the population growth, to identify and generate LULC change spatial map and to identify hotspot areas and generate priority map for quantification, prioritization and for expert recommendations that are sensitive to achieving social and environmental goals. Our study applied remote sensing tools, Landsat images, geographical information system (GIS) and geospatial techniques to quantify LULC change, built-up expansion and hotspot areas in Ebonyi state. Five land Use Land Cover (LULC) types were classified; forest area, built-up area, bare land, farm land and water body. LULC analysis reviewed significant land conversation during1996 and 2018 with increases in built up area by +1461 km 2, bare land (+284 ha) and farm land (+349 km 2) at the expense of forest area that has significantly declined by −2094 km (28.1%). No variation or change detection was recorded in water body (0 km 2). The linear regression analysis in 1996 and 2018 confirmed increased in population in the study areas resulted in high/positive increase in built-up expansion with coefficient of determination (R 2) of 0.727 and 0.573 respectively. However, population and built-up expansion within the study periods were 73 and 57 times more related in 1996 and 2018 respectively. LULC change hotspot analysis reviewed that Abakaliki and Ezza North are most critical areas that has witnessed intense and robust land conversion over years. It is recommended that tree planting program should be designed and first priority be given to Abakaliki and Ezza North during reclamation project in Ebonyi state.

Analysis of the Spatio-Temporal Evolution of Land Intensive Use and Land Ecological Security in Tianjin from 1980 to 2019

The problem of land ecological security directly threatens the sustainable development of many regions, and exploring the spatio-temporal characteristics of land ecological security is helpful for analyzing the land ecological patterns between regions and over time. Based on the interpretation of remote sensing image data for Tianjin in 1980, 2000, 2010 and 2019, supported by software such as ArcGIS and GeoDa, the changes of land use in the study area are calculated by using the land use dynamic degree. Then, the land ecological security index and spatial autocorrelation analysis methods are used to study the spatial correlations and internal heterogeneity of land ecological security in each district in Tianjin. The results show that: (1) The land use of Tianjin has changed dramatically in the past 40 years: the building land has been expanding, while the farmland and barren have been shrinking continuously. (2) The overall level of land ecological security is in the high security area, and Jizhou District is the highest, while the Central areas and Binhai are low. (3) The spatial heterogeneity of land ecological security is not obvious, but the spatial agglomeration is strong.

Deterioration of groundwater quality along an increasing intensive land use pattern in a small catchment

Land use change has greatly influenced groundwater quality worldwide. Identifying the effects of different intensive land uses on the groundwater quality is the first step in taking proper action to solve the problem. In this study, we compared the effects of different intensive land uses (region A, natural vegetation; region B, cereal fields; region C, kiwifruit orchards) in the Yujiahe catchment between 2015 and 2017 in Shaanxi, China, on the major ions and stable isotopes of nitrate (δ15N–NO3– and δ18O–NO3–). The NO3- groundwater concentrations increased from region A to region B and region C; NO3- concentrations in shallow groundwater were higher than those of deep groundwater in region C (55.3 vs. 28.9 mg/L, respectively). The NO3- concentrations in region A and region B did not exceed the WHO standard of 50 mg/L. However, 56.3% and 22.2% of the shallow and deep groundwater samples have NO3- concentrations exceeding the standard in region C, respectively. The average electrical conductivity (EC) values of springs in region A and shallow groundwater in regions B and C were 438, 525, and 753 µs/cm, respectively. Concentrations of Ca2+, Mg2+, Na+, Cl-, and HCO3- ions and nitrogen isotope values increased from region A to region C, indicating that intensive land use change has modified groundwater hydrochemical composition, and deteriorated groundwater quality. This study has highlighted the significant effect of intensive land use of orchards at the small catchment scale on the groundwater quality.

Examining the Coupling Coordinated Relationship between Urban Industrial Co-Agglomeration and Intensive Land Use

Exploring the dynamic relationship and coupling coordination between urban industrial co-agglomeration and intensive land use is vital to ensure high-quality urban development. Based on an industrial co-agglomeration model, a revised intensive land use model, and a coupling coordination model, this paper comprehensively measured the urban industrial co-agglomeration and intensive land use coupling coordination in eight cities in the Chengdu metropolitan area from 2004 to 2018. It was found that despite the structural adjustment of the secondary and tertiary industries during the study period, the industrial co-agglomeration in the Chengdu metropolitan area fluctuated, the intensive urban land use had spatial characteristics that were decreasing from the center to the periphery, and while the general coupling coordination level was increasing, the increase rate in each city was different. The coupling coordination between the urban industry co-agglomeration and the intensive land use was found to have “low-high-low” spatial characteristics from the southwest to the northeast of the Chengdu metropolitan area, which revealed the core position of Chengdu. Suggestions are provided to improve the industrial co-agglomeration and intensive urban land use coupling coordination.

Colonial rainfed farming strategies in an extremely arid insular environment: Niche construction on Lanzarote, Canary Islands, Spain

The island of Lanzarote in the Canary Islands was first settled by people from northern Africa in the first millennium BC and then colonized by Spain in the late fifteenth century. This colonial legacy reflects an intensive land use driven by a European commodities market that experienced a series of boom-and-bust cycles. Although arid and seemingly resource limited, colonial farmers in the sixteenth to nineteenth centuries copied water capture techniques from the Indigenous population, were strategic in terms of field placement, and engaged in a range of niche construction techniques. An analysis of 420 soil samples for their chemical properties (e.g., pH, electrical conductivity, nutrients) has revealed that sixteenth to nineteenth agricultural infrastructure in the form of open fields, terraces, water capture basins, and mulched fields was constructed on the landscape avoiding areas of high soil salinity and placement was tailored to variations in terrain slope, elevation, and rainfall. These improvements fundamentally changed ecosystem relations resulting in increased agricultural productivity. A series of eolian and volcanic events in the eighteenth century resulted in environmental changes requiring counteractive responses and new processes of niche reconfiguration. Large tracts of land were initially removed from production, but processes of niche construction created new opportunities. These included constructing mulched pits for cultivating sweet potato and tephra mulching for enhanced moisture conservation and accelerated growth of cochineal insect (Dactylopius coccus) production on cactus host plants. Cochineal production lasted for a period of sixty years (ca. AD 1825–1885) before a collapse of the market caused by the invention of chemical substitutes.

Layout Methods for Integrated Energy Supply Service Stations from the Perspective of Combination Optimization

Integrated energy supply service stations (IES) are a new type of transportation energy infrastructure offering the advantages of comprehensive functions and intensive land use while providing more convenient and efficient energy supply services. Through the analysis of service station characteristics, this study regards the IES as a spatially superimposed combination of various energy supply services, proposes a layout method from the perspective of combination optimization, and establishes a station optimization model for energy supply stations. This method aims to further coordinate and optimize the combination of various energy supply stations to achieve global optimization of the energy supply service system. Finally, this study uses a hypothetical situation for example analysis to verify the validity and rationality of the method. The layout plan proposed in this study has important theoretical and practical significance for how to achieve the optimal layout of an IES.

Grazing impacts on ecosystem functions exceed those from mowing

Land use change due to the increasing anthropogenic activities is the most important driver leading to alteration of multiple ecosystem functions. Overgrazing is thought to be one of most pervasive and significant degrading processes in grasslands, but direct comparisons with other comparable drivers of land use intensification are lacking. Our results aimed to test how single land use practices (grazing, mowing), and combined land use practices (both grazing and mowing), influence biodiversity, soils and plant function, and the coupling of aboveground and belowground functions and properties in a Eurasian steppe grassland. We examined changes in individual functions associated with aboveground and belowground plant and soil compartments, and multiple combined functions (hereafter ‘multifunctionality’) at 317 sites along an extensive climatic gradient in Northern China. Further, we investigated the correlations (coupling) between aboveground and belowground processes under the three land use scenarios. We found a mixture of effects of grazing, mowing and mowing plus grazing. However, values of many aboveground and belowground attributes were lower when sites were grazed. Although grazed sites had lower values of soil carbon and nutrients, there were no grazing-induced changes in root carbon, nitrogen and phosphorus. More importantly, the most intense land use scenario (grazing combined with mowing) decoupled the correlations between belowground and aboveground functions compared with that of single land uses. Our study demonstrates that mowing is a better long-term management method than grazing for semi-natural grasslands in the Eurasian steppe are heavily grazed. Our results demonstrate that additional land use pressures imposed when mowing and grazing are applied together can decouple the positive associations between plant richness and functions. This knowledge is critical if we are to adopt strategies to maintain diverse grassland ecosystems and the important services and functions that they provide.

Genetic Diversity of Stratiotes aloides L. (Hydrocharitaceae) Stands across Europe.

Intense land use and river regulations have led to the destruction of wetland habitats in the past 150 years. One plant that is affected by the reduction in appropriate habitats is the macrophyte Stratiotes aloides which has become rare in several areas. The preservation of genetic diversity within a species is a prerequisite for survival under changing environmental conditions. To evaluate the level of genetic diversity within and among populations of Stratiotes aloides, we investigated samples from waterbodies across Europe using AFLP. Low genetic diversity among samples from the same population was found, proving that stands consist of few clones which propagate clonally. Nevertheless, most populations showed differences compared to other populations indicating that there is genetic diversity within the species. The analyzed samples formed two groups in STRUCTURE analyses. The two groups can be further subdivided and mainly follow the major river systems. For conserving the genetic diversity of Stratiotes aloides, it would thus be preferable to focus on conserving individuals from many different populations rather than conserving selected populations with a higher number of individuals per population. For reintroductions, samples from the same river system could serve as founder individuals.

Coordinated Development of Urban Land Use and Ecological Economics in China

To analyze the coordination between land use and the ecological economy in China, ecoefficiency and land use intensity were measured using the nonradial, nonoriented slacks-based measure (SBM) and the vertical and horizontal scatter degree method. The TOPSIS method was then used to comprehensively evaluate regional differences in coordination. Our research indicates that the level of coordinated development between intensive urban land use and the ecological economy in China showed an overall upward trend from 2006 to 2017. The level of coordination was high in Beijing, Shanghai, and Tianjin and was low in Gansu, Ningxia, and Xinjiang. Changes in ecoefficiency were not consistent with the degree of coordination, and intensive urban land use was positively correlated with the level of coordination, which showed a mutually reinforcing relationship. Improving ecoefficiency is necessary for intensive urban land use, and for ecological improvement, coordinated development between ecoefficiency and urban land use intensity is essential. The establishment of environmentally friendly land use patterns could promote urban land use.

Kebakaran Hutan dan Lahan di Pulau Rupat, Riau

Forest and land fires in Riau province generally occur on peatlands. This is due to the large area of ​​peatlands and intensive land conversion. Peat fires result in high PM 2.5 pollutant content, as happened on Rupat Island, Meranti Islands. Rupat Island has a history of repeated cases of forest and land fires in 2015 and 2019. This study aims to analyze the background of the causes of forest and land fires on Rupat Island, Riau Province. The research was carried out through several stages, namely data collection, data processing and data analysis. Forest fires on Rupat Island caused PM 2.5 content in February and March to have values ​​above the PM 2.5 content threshold. Based on the results of the study, it is known that the background causes of forest and land fires on Rupat Island, Riau, are caused by poor canal management, damaged peat conditions and the influence of the arrival of El Nino. This is the cause of the widespread forest and land fires on Rupat Island.
 Keywords: forest fires, peat land, Rupat island

Legacies of Nutrient Accumulation and Depletion in Residential Ecosystems

In residential ecosystems, land management can help regulate climate and improve water quality by promoting the accumulation of nutrients in the soil. We tested how varying intensity of residential land use and management altered nutrient (Ca, K, Mg, P, S) pools. We studied soils and vegetation across twelve land use-intensity gradients (yards-perennial old fields-forests) established 15–227 y. ago in the native ecosystems of temperate forests. We found that yard soils were enriched with nutrients relative to fields and forests, regardless of recent yard management intensity. Yard soils from 0- to 40-cm depth contained an average 72–93% more Ca, 11–22% more Mg and 18–50% more P than fields and forests. In the upper 20 cm of soil, where land-use effects were pronounced, 200-year-old yards contained 24% more soil P than one decade-old yards. Yards where managers exported grass clippings for forty years contained less soil K and Mg than yards managed similarly for ten years. Yard soil cation exchange capacity and C were not correlated, suggesting the importance of inorganic mechanisms of nutrient accumulation. With more intense land use, across yards-fields-forests and within yards, soil S and C tightly covaried indicating these nutrients may limit or stimulate organic nutrient cycling. Our research suggests residential land management can contribute to nutrient legacies that support resilient responses to global change.

Land-use intensity determines grassland Orthoptera assemblage composition across a moisture gradient

Two of the main principles of global and national conservation strategies consist in focusing on the most species-rich and most vulnerable ecosystems. In this study, we investigated the Orthoptera species assemblages of species-rich grasslands in the southern Black Forest, one of 30 German biodiversity hotspots. Across a moisture gradient, we considered the three dominant grassland types within the study area: (i) dry, (ii) mesic and (iii) wet grasslands. In order to analyze the drivers of biodiversity in a landscape of high conservation value, we related (i) differences in Orthoptera assemblage composition between the three grassland types and (ii) the relationship of Orthoptera assemblage composition within each grassland type to environmental conditions. In our study, we detected considerable variation in land-use intensity which dropped from high in mesic to low in dry and again to near-zero in wet grasslands. Land-use intensity was the only predictor of Orthoptera species richness in the multivariable Generalized Linear Mixed-effects Models. The mean number of both all and threatened species was highest in the grassland type with low land-use intensity, dry grasslands, differing from those of mesic (high land-use intensity) and wet (mostly abandoned) grasslands. Additionally, dry grasslands had the highest number of all, threatened and exclusive indicator species. Both (i) intensive land use in mesic grasslands and (ii) abandonment of land use in wet grasslands led to a homogenization of the habitat structures and the species assemblages. In contrast, dry grasslands with low land-use intensity and high habitat heterogeneity were hotspots of Orthoptera species richness.

Economic and environmental analyses of incorporating guar into the American southwest

CONTEXTPersistent drought is affecting the livelihood of American farmers in arid climates. Adopting drought-tolerant crops, such as guar (Cyamopsis tetragonoloba L.), is one potential solution for improving economic revenue and reducing the effect of drought on farms. Guar produces guar gum, which is a thickening and stabilizing agent in fluids used most recently in the hydraulic fracking of shale oil and gas recovery. OBJECTIVEThis study was performed to investigate the economic and environmental feasibility of cultivating guar in the American Southwest and transporting it to a domestic processing facility for the primary product of guar gum. METHODSAn integrated techno-economic (TEA) and life cycle analysis (LCA) was performed on the cradle-to-gate process of producing guar gum for domestic supply in the United States. TEA was performed to investigate the economic performance on the farm and downstream for the guar gum production facility. Similarly, the LCA investigated the environmental impact to the farm and the primary product of guar gum. RESULTS AND DISCUSSIONBaseline results indicate a minimum selling price of $1.44 per kg-guar gum, driven largely by irrigation, herbicides and associated equipment use. A best case economic scenario where irrigation and fertilizers were removed, low-cost herbicides were used and less intensive land management practices were adopted, highlights the feasibility of guar gum being produced for as low as $0.45 per kg-guar gum, which is lower than the five-year average U.S. import price of $0.99 per kg-guar gum. Environmental impacts of guar gum are largely attributed to irrigation and agricultural equipment use. The indicator, global warming potential, resulted in farm-level emissions of 1160 per hectare of guar grown. The combined farm, transportation and downstream processing production processes results in 2.67 kg CO2eq per kg-guar gum, or 806 kg CO2eq per hectare, which is lower than the farm emissions due to a co-product credit for animal feed. SIGNIFICANCEThe economic results indicate that guar gum can be produced for less than average U.S. import prices. The environmental impact results indicate that growing guar would lead to lower emissions than existing crops when cultivated in the American Southwest.