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Mechanisms of bush encroachment and its inter-connection with rangeland degradation in semi-arid African ecosystems:a review

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Journal of Arid Land 2017年第2期9卷 299-312页

作者： Anteneh BELAYNEH Zewdu K TESSEMA Department of Biology College of Natural and Computational Sciences Haramaya University Haramaya 282 Ethiopia rangeland ecology and Biodiversity Program School of Animal and Range Sciences College of Agriculture and Environmental Sciences Haramaya University Dire Dawa 138 Ethiopia

Many studies show that semi-arid rangelands throughout the world have been rapidly converted from a grassland state to a bush encroachment state during the past 50 years. Bush encroachment includes the spread of local woody species and/or incursion of woody species introduced from other ecosystems into semi-arid savannas and grassland ecosystems. rangeland degradation due to bush encroachment causes several challenges, affecting the production of livestock and pastoral people livelihoods in most parts of Africa. Scientists have long been attempting to develop schematic and mathematical theories to explain the observed phenomenon of bush encroachment, and several theories were proposed and developed. The well-regarded theories include：（1） Waiter＇s two-layer model, （2） Moir＇s one-layer model, （3） state-and-transition theory, （4） equilibrium theory, （5） disequilibrium theory, and （6） non-equilibrium theory. Within those theories, the most frequently-indicated driving factors that explain bush encroachment include over-grazing, availability of soil nutrient and moisture, elevated CO2 levels, frequency and intensity of fire, spread of seeds of woody species by livestock and wild animals. It should be stressed that couplings and interactions among diverse driving factors are more often at work in determining the condition of bush encroachment. To summarize, the effort in managing semi-arid ecosystems needs critical knowledge to understand the cause-effect relationships of underlying factors through integrated approach. Therefore, future research on encroachment of woody plants should be multi-discipline oriented and multi-partnership involved.

关键词： climate change exotic woody species indigenous woody species Moir's one-layer model rangelandtheories Walter's two-layer model

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The synergistic regulatory effect of PTP1B and PTK inhibitors on the development of Oedaleus decorus asiaticus Bei-Bienko

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Journal of Integrative Agriculture 2024年第8期23卷 2752-2763页

作者： Shuang Li Sibo Liu Chaomin Xu Shiqian Feng Xiongbing Tu Zehua Zhang State Key Laboratory for Biology of Plant Diseases and Insect Pests Institute of Plant ProtectionChinese Academy of Agricultural SciencesBeijing 100193China Chongqing Academy of Agricultural Sciences Chongqing 401329China Institute of Grassland Research Chinese Academy of Agricultural SciencesHohhot 010010China Inner Mongolia University Hohhot 010019China Scientific Observation and Experimental Station of Pests in Xilin Gol rangeland Institute of Plant ProtectionChinese Academy of Agricultural SciencesXilinhot 026000China

Tyrosine phosphorylation is crucial for controlling normal cell growth,survival,intercellular communication,gene transcription,immune responses,and other *** tyrosine phosphatase(PTP)and protein tyrosine kinases(PTK)can achieve this goal by regulating multiple signaling *** decorus asiaticus is an important pest that infests the Mongolian Plateau *** aimed to evaluate the survival rate,growth rate,overall performance,and ovarian developmental morphology of the 4th instar nymphs of *** asiaticus while inhibiting the activity of protein tyrosine phosphatase-1B(PTP1B)and *** addition,the expression and protein phosphorylation levels of key genes in the MAPK signaling pathway and antioxidant enzyme activity were *** results showed no significant differences in survival rate,growth rate,or overall performance between PTP1B inhibitor treatment and ***,after PTK inhibitor treatment,these indexes were significantly lower than those in the *** ovarian size of female larvae after 15 days of treatment with PTK inhibitors showed significantly slower development,while female larvae treated with PTP1B exhibited faster ovarian growth than the control *** comparison to controls and nymphs treated with PTK inhibitors,the expression and phosphorylation levels of key genes in the MAPK signaling pathway under PTP1B inhibitor treatments were significantly higher in 4th instar ***,reactiveoxygen(ROS)species levels and the activities of NADPH oxidase and other antioxidant enzymes were considerably reduced,although they were significantly greater in the PTK inhibitor *** results suggest that PTP1B and PTK feedback inhibition in the mitogen-activated-protein kinases(MAPK)signal transfer can regulate the physiological metabolism of the insect as well as its developmental *** findings can facilitate future uses of PTP1B and PTK inhibitors in controlling insect development to help contro

关键词： PTP1B PTK inhibitor MAPK pathway Oedaleus decorus asiaticus development

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Influence of climatic conditions,topography and soil attributes on the spatial distribution of site productivity index of the species rich forests of Jalisco,Mexico

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Journal of Forestry Research 2014年第1期25卷 87-95页

作者： Adel Mohamed Robin M.Reich Raj Khosla C.Aguirre-Bravo Martin Mendoza Briseo Department of ecology and rangeland Stewardship Desert Research Center Department of Forest and rangeland Stewardship Colorado State University Department of Soil and Crop Sciences Colorado State University USDA Forest Service Colegio de Postgraduados

This paper presents an approach based on field data to model the spatial distribution of the site productivity index （SPI） of the diverse forest types in Jalisco, Mexico and the response in SPI to site and cli-matic conditions. A linear regression model was constructed to test the hypothesis that site and climate variables can be used to predict the SPI of the major forest types in Jalisco. SPI varied significantly with topog-raphy （elevation, aspect and slope）, soil attributes （pH, sand and silt）, climate （temperature and precipitation zones） and forest type. The most important variable in the model was forest type, which accounted for 35% of the variability in SPI. Temperature and precipitation accounted for 8 to 9% of the variability in SPI while the soil attributes accounted for less than 4% of the variability observed in SPI. No significant differences were detected between the observed and predicted SPI for the individual forest types. The linear regression model was used to develop maps of the spatial variability in predicted SPI for the individual forest types in the state. The spatial site productivity models developed in this study provides a basis for understanding the complex relationship that exists between forest productivity and site and climatic conditions in the state. Findings of this study will assist resource managers in making cost-effective decisions about the management of individual forest types in the state of Jalisco, Mexico.

关键词： Best management practices climate change spatial predic-tions tropical dry forests weighted least squares

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The effect of water spreading system on the functionality of rangeland ecosystems

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Journal of Arid Land 2012年第3期4卷 292-299页

作者： Mohammad Rahim FOROUZEH Mohsen SHARAFATMANDRAD PhD Student of rangeland Science Gorgan University of Agricultural Sciences and Natural Resources Gorgan 49138-15739 Iran

In recent decades, the control of floods is an efficient management practice for the rehabilitation of rangelands in most arid and semiarid areas. To evaluate the benefits, we used the Landscape Function Analysis （LFA） method to assess the function of patches and qualitative capability of a rangeland ecosystem in Gareh By- gone region, Fars province, southwestern Iran. Landscape functionality depends on soil, water and nutrient （col- lectively called ＂resources＂） conservation and use within a given ecosystem. Many landscapes are naturally het- erogeneous in terms of resource control and possess patches, where resources tend to accumulate, and in- ter-patches. Assessing rangeland health and function of landscape patches in response to environment and man- agement can give rise to correct management decisions for qualitative improvement of the ecosystem. Therefore, our study area was divided into two parts, i.e. water spreading and control parts, and sampling was done using LFA method in each part separately. Structural parameters, including the number, length and width of patches, and the mean length of inter-patches, were determined by the method to characterize the functional status of the monitoring sites. For each patch/inter-patch type identified in the transect organization log, we recorded its soil surface proper- ties classified according to the Soil Surface Assessment Method. The density, canopy cover and composition of plants were then assessed. The results showed that the number of ecological patches and their dimensions were significantly increased in the water spreading site. Soil stability and the values of nutrient cycling indices were in- creased but the infiltration values were decreased in the water spreading site. It could be related to the effect of suspended materials transported by floods to the soils in the study area. The improvement of ecological patches and rangeland ecosystem was achieved where water spreading systems were practiced. Theref

关键词： ecological patch landscape function analysis water spreading arid lands

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Perceptions of Bark Beetle Landscape Disturbance Effects on Natural Resources and Drinking Water: Assessing Communication and Knowledge Exchange in the Rocky Mountain Region, USA

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Open Journal of ecology 2024年第1期14卷 77-100页

作者： Stuart P. Cottrell Katherine Mattor Jana Raadik Cottrell Human Dimensions of Natural Resources Colorado State University Fort Collins CO USA Forest and rangeland Stewardship (FRS) Colorado State University Fort Collins CO USA University Honors Program Colorado State University Fort Collins CO USA Kuressaare College of Tallinn University of Technology Kuressaare Estonia

Widespread changes to forested watersheds affected by the mountain pine beetle (Dendroctonus ponderosae Hopkins) epidemic across western North America raised concerns about the effects of this climate-induced disturbance on drinking water and natural resources. Effective communication and knowledge exchange across scientists and stakeholders (i.e., drinking water managers) is essential for constructively responding to such landscape scale disturbances, providing improved adaptive capacity through knowledge sharing. An assessment of stakeholder knowledge levels, information needs, primary concerns, and suggested communication strategies were conducted via an online elicitation survey and World Science Café workshops. Knowledge levels, assessed via a survey of local water managers and experts, were relatively low with approximately half of the respondents reporting little to no knowledge of the effects of mountain pine beetle on drinking water quality and quantity, thereby indicating limited knowledge exchange between scientists and drinking water stakeholders. Increased accessibility and dissemination of research findings pertinent to the mountain pine beetle epidemic’s effects on drinking water quality and quantity is necessary for natural resource management. Recommendations for improved communication among scientists and drinking water stakeholders in particular and forest health in general include dispersal of non-academic research summaries, information exchange through existing media and community resources, demonstration projects, and information clearinghouses. This information provides a better understanding of the challenges, concerns, and first-hand experience of stakeholders of a landscape disturbance issue to apply this knowledge to enhance land management practice and how researchers on this overall project enhanced science communication efforts.

关键词： Adaptive Capacity Climate Change Forested Watersheds Water Quality Water Quantity

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Diversity and Structure of the Woody Stand in a Sudano-Sahelian Transition Zone in Senegal

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Open Journal of ecology 2024年第1期14卷 1-16页

作者： Oumar Sarr Moustapha B. Sagna Amy Bakhoum Sékouna Diatta Aliou Guissé UCAD/FST Laboratory of ecology and Ecohydrology Dakar Senegal Tessekere Human Environment Observatory (Senegal) IRL 3189 “Environment Health Society” Dakar Senegal

The main objective of the study was to investigate the diversity of the woody stratum of the vegetation in intercommunity rangelands in the department of Koungheul based on an ecological inventory using vegetation surveys. The results indicate a rich flora of 70 species divided into 54 genera and 27 families where Ceasalpiniaceae and Rubiaceae are dominant (5 genera each). They are followed by Combretaceae and Euphorbiacea (4 genera each) and by Capparaceae, Fabaceae and Mimosaceae (3 genera for each family). But at the specific level, it is the Combretaceae which dominates with 10 species and Rubiaceae (7 species). It is more representative at the level of the rural community of Lour Esacale. The different values of vegetation parameters from one site to another indicate variability in community rangeland management practices. The woody stand, dominated by small Combretaceae, shows a relatively stable level of organization with an average equitability of about 45% for the two rural communities studied. Species such as Cordyla pinnata, Sclerocarya birrea, Adansonia digitata and Sterculia setigera contributed strongly to the basal and aerial cover of the overall stand. The regeneration of the stand is very good (about 85% on average) but it represents very few species, especially of the Combretaceae family. This shows a tendency to a progressive loss of species richness in the woody stratum.

关键词： Flora Woody Species Vegetation Surveys Regeneration Kaffrine Region

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Egg quality, fatty acid composition and immunoglobulin Y content in eggs from laying hens fed full fat camelina or flax seed

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Journal of Animal Science and Biotechnology 2016年第3期7卷 374-381页

作者： Gita Cherian Nathalie Quezada Department of Animal and rangeland Sciences Oregon State University

Background： The current study was conducted to evaluate egg quality and egg yolk fatty acids and immunoglobulin（Ig Y） content from laying hens fed full fat camelina or flax ***： A total of 75, 48-week-old Lohman brown hens were randomly allocated to 3 treatments, with 5replicates containing 5 laying hens each replicate. The hens were fed corn-soybean basal diet（Control）, or Control diet with 10 % of full fat camelina（Camelina） or flax seed（Flax） for a period of 16 wk. Hen production performance egg quality, egg yolk lipids, fatty acids and Ig Y were determined every 28 d during the experimental ***： Egg production was higher in hens fed Camelina and Flax than in Control hens（P 〈 0.05）. Egg weight and albumen weight was lowest in eggs from hens fed Camelina（P 〈 0.05）. Shell weight relative to egg weight（shell weight %）, and shell thickness was lowest in eggs from hens fed Flax（P 〈 0.05）. No difference was noted in Haugh unit, yolk：albumen ratio, and yolk weight. Significant increase in α-linolenic（18：3 n-3）, docosapentaenoic（22：5 n-3）and docoshexaenoic（22：6 n-3） acids were observed in egg yolk from hens fed Camelina and Flax. Total n-3 fatty acids constituted 1.19 % in Control eggs compared to 3.12 and 3.09 % in Camelina and Flax eggs, respectively（P 〈 0.05）. Eggs from hens fed Camelina and Flax had the higher Ig Y concentration than those hens fed Control diet when expressed on a mg/g of yolk basis（P 〈 0.05）. Although the egg weight was significantly lower in Camelina-fed hens, the total egg content of Ig Y was highest in eggs from hens fed Camelina（P 〈 0.05）.Conclusions： The egg n-3 fatty acid and Ig Y enhancing effect of dietary camelina seed warrants further attention into the potential of using camelina as a functional feed ingredient in poultry feeding.

关键词： Camelina seed Egg quality Flax seed Immunoglobulin Y n-3 fatty acids

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Germination pretreatment and storage behavior of Terminalia laxiflora seed

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Journal of Forestry Research 2019年第4期30卷 1337-1342页

作者： Befkadu Mewded Debissa Lemessa Hailu Negussie Abiyot Berhanu Forest and rangeland Biodiversity Directorate Ethiopian Biodiversity Institute

Terminalia laxiflora Engl.&*** an important indigenous and multi-purpose species in *** threatened due to low germination and its storage behavior is *** this study,we aimed to(1)test pretreatments for breaking the dormancy of *** seed and(2)determine its storage *** were subjected to four pretreatments such as soaking,scarification,high-temperature,and *** were done before storage and after 2 years of dry storage at cold temperature(-10℃)based on randomized design with four *** first round of experimental results showed that *** seeds with high temperature treatments at 78℃for 10 min showed significantly higher germination percentage(80%).In the second round experiment,high-temperature treatment at 78℃for15 min,cold water soaking,high-temperature treatment at78℃for 10 min,hot water soaking,and high-temperature treatment at 78℃for 5 min showed significantly higher germination percentage from the remaining treatments(75,64,58,56,and 53%,respectively).To break the dormancy of *** seed and attain good germination result,seeds should be pretreated with high-temperature at 78℃for 10 min to test the initial germination before storage and should be pretreated with high-temperature(at 78℃for15,10,or 5 min),soaked in cold,or hot water for 24 h to monitor the germination after *** two experiments show that *** produces orthodox seed.

关键词： Dormancy breaking Dry storage High-temperature Soaking Storage behavior

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Scales of snow depth variability in high elevation rangeland sagebrush

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Frontiers of Earth Science 2017年第3期11卷 469-481页

作者： Molly E. TEDESCHE Steven R. FASSNACHT Paul J. MEIMAN Watershed Science Department of Ecosystem Science and Sustainability Colorado State University Fort Collins CO 80523-1476 USA Intemational Arctic Research Center Water & Environmental Research Center Institute of Northern Engineering University of Alaska Fairbanks Fairbanks AK 99775 USA Cooperative Institute for Research in the Atmosphere Fort Collins CO 80523-1375 USA Natural Resources ecology Laboratory Fort Collins CO 80523-1499 USA Abt. Kartographie GIS & Femerkundung Geographisches Institut Georg-August-Universitat Gottingen 37077 Gottingen Germany rangeland Ecosystem Science Department of Forest and Rangeland Stewardship Colorado State University Fort Collins CO 80523 USA

In high elevation semi-arid rangelands, sage- brush and other shrubs can affect transport and deposition of wind-blown snow, enabling the formation of snowdrifts. Datasets from three field experiments were used to investigate the scales of spatial variability of snow depth around big mountain sagebrush （Artemisia tridentata Nutt.） at a high elevation plateau rangeland in North Park, Colorado, during the winters of 2002, 2003, and 2008. Data were collected at multiple resolutions （0.05 to 25 m） and extents （2 to 1000 m）. Finer scale data were collected specifically for this study to examine the correlation between snow depth; sagebrush microtopogra- phy, the ground surface, and the snow surface, as well as the temporal consistency of snow depth patterns. Vario- grams were used to identify the spatial structure and the Moran＇s I statistic was used to determine the spatial correlation. Results show some temporal consistency in snow depth at several scales. Plot scale snow depth variability is partly a function of the nature of individual shrubs, as there is some correlation between the spatial structure of snow depth and sagebrush, as well as between the ground and snow depth. The optimal sampling resolution appears to be 25-cm, but over a large area, this would require a multitude of samples, and thus a random stratified approach is recommended with a fine measurement resolution of 5-cm.

关键词： snow hydrology high elevation rangelands,spatial statistics variograms snow pack spatial variability,snow drifts

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Inhibiting soil loss and runoff from small plots induced by an individual freeze-thaw cycle using three rangeland species

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International Soil and Water Conservation Research 2020年第3期8卷 228-236页

作者： Milad Hatefi Seyed Hamidreza Sadeghi Reza Erfanzadeh Morteza Behzadfar Department of Watershed Management Engineering Faculty of Natural ResourcesTarbiat Modares UniversityIran Department of rangeland Management Faculty of Natural ResourcesTarbiat Modares UniversityNoorIran

This study investigated the role of three rangeland species *** trichophorum,Medicago sativa,and Lolium prenne on mitigating of effects of a freeze-thaw(FT)cycle on runoff generation and soil loss from small experimental *** plots(0.5×0.5m)were prepared in three replicates for control(i.e.,under a FT cycle only)and treatments(i.e.,individually planted with the study species and subject to a FT cycle).The treated plots were then placed at a slope of 20%and subjected to simulated rainfall with intensity of 70 mm h-1 and 30 min *** results of the study showed a significant effect(P<0.05)of the plants on controlling runoff and soil loss after a FT ***,the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the *** to runoff increased by 54,111 and 10%,runoff volume decreased by 27,68 and 0.4%and soil loss changed by-34,-62,and+6.5%in the plots planted with ***,*** and ***,*** results of the current study indicated that *** had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.

关键词： Biological measures Frosted soil Plant binding effects Soil hydrology

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