Grassland Vegetation Changes and Nocturnal Global Warming

Global minimum temperatures (TMIN) are increasing faster than maximum temperatures, but the ecological consequences of this are largely unexplored. Long-term data sets from the shortgrass steppe were used to identify correlations between TMIN and several vegetation variables. This ecosystem is potentially sensitive to increases in TMIN. Most notably, increased spring TMIN was correlated with decreased net primary production by the dominant C4 grass (Bouteloua gracilis) and with increased abundance and production by exotic and native C3 forbs. Reductions in B. gracilis may make this system more vulnerable to invasion by exotic species and less tolerant of drought and grazing

Soil Moisture Enhancement Techniques Aid Shrub Transplant Success in an Arid Shrubland Restoration

In arid and semi-arid environments, where low and unpredictable rainfall is typical, establishment of perennial vegetation can be enhanced with modest increases in soil moisture. We evaluated methods for promoting shrub transplant establishment. We transplanted approximately 1 000 3-mo-old seedlings in April 2004, 2005, and 2006, using a full-factorial design with combinations of three treatments: addition of mycorrhizae spores to the root zone, addition of a hydrogel to the root zone, and placement of a wood obstruction south of the plant. We planted three shrubs: big sagebrush (Artemisia tridentata Nutt. ssp. tridentate), four wing saltbush (Atriplex canescens [Pursh] Nutt.), and rubber rabbitbrush (Ericameria nauseosa [Pall. ex Pursh] G.L. Nesom Baird ssp. nauseosa) in a 1.2-ha area. The summer months of 2004 and 2006 were dry, leading to low survivorship (<1%). With higher rainfall in summer 2005, transplant survivorship was <18%. For the 2005 transplants, A. tridentata had the highest survivorship after one growing season (31.0%), followed by A. canescens (20.6%) and E. nauseosa (6.9%). Placing a wood obstruction near the plant was significant in the statistical model to describe short-term overall transplant survival and survival of A. tridentata. Placing hydrogel in the root zone also explained short-term overall transplant survival, as well as survival of E. nauseosa. However, by 4.5 yr after transplanting, there was no significant treatment effect on survival. Thus, for transplanting shrub seedlings on arid or semi-arid sites, we recommend some form of resource enhancement technique to increase short-term survival. In this experiment, both the obstruction and hydrogel treatments were effective. We recommend the obstruction treatment since slash is often readily available onsite, has low labor requirements and cost, and it increased transplant survival of A. tridentata, a species of conservation concern; however, other treatments may be appropriate for individual species./En zonas áridas y semiáridas, donde las bajas precipitaciones y la lluvia impredecible son típicas, el establecimiento de la vegetación perenne puede ser mejorado con pequeños incrementos en la humedad del suelo. Se evaluaron métodos para promover el establecimiento de arbustos trasplantados. Se trasplantaron aproximadamente 1 000 plántulas de 3 meses en Abril de 2004,2005, y 2006, usando un diseño completamente factorial con combinaciones de tres tratamientos: adición de esporas de micorrizas en la zona de la raíz, adición de hidrogel en la zona de la raíz, y la colocación de una obstrucción de madera al sur de la planta. Se plantaron tres arbustos: big sagebrush (Artemisia tridentata Nutt. ssp. tridentata), four wing saltbush (Atriplex canescens [Pursh] Nutt.), and rubber rabbitbrush (Ericameria nauseosa [Pall. ex Pursh] G.L. Nesom & Baird ssp. nauseosa) en una área de 1.2 has. Los meses del verano de 2004 y 2006 fueron secos, dando como resultado una sobrevivencia baja (,1%). Con una mayor cantidad de lluvia en el verano del 2005 la sobrevivencia de los trasplantes fue,18%. Para los trasplantes de 2005 A. tridentate presentó la mayor sobrevivencia después de la época de crecimiento (31.0%) seguido por A. canescens (20.6%) y E. nauseosa (6.9%). La colocación de la obstrucción de madera cerca de la plantas fue significativa en el modelo estadístico para describir acorto plazo la supervivencia de los trasplantes en general y la sobrevivencia de A. tridentate. La colocación de hidrogel en la zona de la raíz también explicó a corto plazo la sobrevivencia de los trasplantes en general, así como la sobrevivencia de E. nauseosa. Sin embargo, cerca de 4 1/2 años después de los trasplantes, no hay efecto significativo en la sobrevivencia. Así para el trasplante de plántulas de arbustos en las zonas áridas y semiáridas se recomienda algún tipo de técnica para incrementar e hidrogel fueron efectivos. Se recomienda el tratamiento de obstrucción ya que la madera se puede conseguir fácilmente en estas áreas, tiene un bajo requerimiento de labor y costo, e incrementa la sobrevivencia de los trasplantes de A. tridentate, una especie de interés para la conservación; sin embargo otros tratamientos pueden ser apropiados para especies individuales.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Appendix A. Tables showing research site descriptions, weather station summaries, model parameters and statistics, and figures showing a map of study sites and weather stations and sampling protocol.

Tables showing research site descriptions, weather station summaries, model parameters and statistics, and figures showing a map of study sites and weather stations and sampling protocol

Comparative Assessment of UAV and Sentinel-2 NDVI and GNDVI for Preliminary Diagnosis of Habitat Conditions in Burunge Wildlife Management Area, Tanzania

Habitat condition is a vital ecological attribute in wildlife conservation and management in protected areas, including the Burunge wildlife management areas in Tanzania. Traditional techniques, including satellite remote sensing and ground-based techniques used to assess habitat condition, have limitations in terms of costs and low resolution of satellite platforms. The Normalized Difference Vegetation Index (NDVI) and Green NDVI (GNDVI) have potential for assessing habitat condition, e.g., forage quantity and quality, vegetation cover and degradation, soil erosion and salinization, fire, and pollution of vegetation cover. We, therefore, examined how the recently emerged Unmanned Aerial Vehicle (UAV) platform and the traditional Sentinel-2 differs in indications of habitat condition using NDVI and GNDVI. We assigned 13 survey plots to random locations in the major land cover types: three survey plots in grasslands, shrublands, and woodlands, and two in riverine and mosaics cover types. We used a UAV-mounted, multi-spectral sensor and obtained Sentinel-2 imagery between February and March 2020. We categorized NDVI and GNDVI values into habitat condition classes (very good, good, poor, and very poor). We analyzed data using descriptive statistics and linear regression model in R-software. The results revealed higher sensitivity and ability of UAV to provide the necessary preliminary diagnostic indications of habitat condition. The UAV-based NDVI and GNDVI maps showed more details of all classes of habitat conditions than the Sentinel-2 maps. The linear regressions results showed strong positive correlations between the two platforms (p &lt; 0.001). The differences were attributed primarily to spatial resolution and minor atmospheric effects. We recommend further studies to test other vegetation indices