From in situ measured woody cover we develop a phenology driven model to estimate the canopy cover of woody species in the Sahelian drylands at 1km scale. The model estimates the total canopy cover of all woody phanerophytes and the concept is based on the significant difference in phenophases of dryland trees, shrubs and bushes as compared to that of the herbaceous plants. Whereas annual herbaceo

Monitoring long-term biomass dynamics in drylands is of great importance for many environmental applications including land degradation and global carbon cycle modeling. Biomass has extensively been estimated based on the normalized difference vegetation index (NDVI) as a measure of the vegetation greenness. The vegetation optical depth (VOD) derived from satellite passive microwave observations i

Woody plants play a major role for the resilience of drylands and in peoples' livelihoods. However, due to their scattered distribution, quantifying and monitoring woody cover over space and time is challenging. We develop a phenology driven model and train/validate MODIS (MCD43A4, 500 m) derived metrics with 178 ground observations from Niger, Senegal and Mali to estimate woody cover trends from

Aim: To evaluate trend analysis of earth observation (EO) dense time series as a new way of describing and mapping changes in ecosystem functioning at regional to global scales. Spatio-temporal patterns of change covering 1982-2011 are discussed in the context of changes in land use and land cover (LULCC). Location: Global. Methods: This study takes advantage of the different phenological cycles o

This chapter summarizes approaches to the detection of dryland vegetation change and methods for observing spatio-temporal trends from space. An overview of suitable long-term Earth Observation (EO) based datasets for assessment of global dryland vegetation trends is provided and a status map of contemporary greening and browning trends for global drylands is presented. The vegetation metrics suit

This chapter summarizes methods of inferring information about drivers of global dryland vegetation changes observed from remote sensing time series data covering from the 1980s until present time. Earth observation (EO) based time series of vegetation metrics, sea surface temperature (SST) (both from the AVHRR (Advanced Very High Resolution Radiometer) series of instruments) and precipitation dat

The co-existence of trees and grasses is a defining feature of savannah ecosystems and landscapes. During recent decades, the combined effect of climate change and increased demographic pressure has led to complex vegetation changes in these ecosystems. A number of recent Earth observation (EO)-based studies reported positive changes in biological productivity in the Sahelian region in relation to

This paper presents the Dahra field spectrometer system (DAFIS) sited in Senegal, West Africa. DAFIS is a unique system that automatically measures the spectro-directional reflectance properties of a semi-arid savanna in the spectral range of 350-1800. nm, daily from sunrise to sunset. The instrumental setup allows studying surface anisotropy for different phenological phases. First data retrieved

As a way to understand vegetation changes, trend analysis on NDVI (normalized difference vegetation index) time series data have been widely performed at regional to global scales. However, most long-term NDVI datasets are based upon multiple sensor systems and unsuccessful corrections related to sensor shifts potentially introduce substantial uncertainties and artifacts in the analysis of trends.

Numerous coal fires burn underneath the Datong coalfield because of indiscriminate mining. Landsat TM/ETM, unmanned aerial vehicle (UAV), and infrared thermal imager were employed to monitor underground coal fires in the Majiliang mining area. The thermal field distributions of this area in 2000, 2002, 2006, 2007, and 2009 were obtained using Landsat TM/ETM. The changes in the distribution were th

The impact of human activities via land use/cover changes on NDVI trends is critical for an improved understanding of satellite-observed changes in vegetation productivity in drylands. The dominance of positive NDVI trends in the Sahel, the so-called re-greening, is sometimes interpreted as a combined effect of an increase in rainfall and cropland expansion or agricultural intensification. Yet, th

Woody vegetation in global tropical drylands is of significant importance for both the interannual variability of the carbon cycle and local livelihoods. Satellite observations over the past decades provide a unique way to assess the vegetation long-term dynamics across biomes worldwide. Yet, the actual changes in the woody vegetation are always hidden by interannual fluctuations of the leaf densi

A limitation of current LoRa networks is their single-hop nature. This causes difficulties in areas with poor Internet access, such as remote rural areas, or challenging radio environments, for example in metropolitan areas, as the LoRa gateway must be placed at a location with backhaul access to the network server, but must nonetheless be reachable by all end devices. To facilitate these applicatA limitation of current LoRa networks is their single-hop nature. This causes difficulties in areas with poor Internet access, such as remote rural areas, or challenging radio environments, for example in metropolitan areas, as the LoRa gateway must be placed at a location with backhaul access to the network server, but must nonetheless be reachable by all end devices. To facilitate these applicat

The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products, which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody vegetation. There is thus an incomplete understanding of how woody vegetation responds to socio-economic

Woody vegetation in farmland acts as a carbon sink and provides ecosystem services for local people, but no macroscale assessments of the impact of management and climate on woody cover exist for drylands. Here we make use of very high spatial resolution satellite imagery to derive wall-to-wall woody cover patterns in tropical West African drylands. Our study reveals that mean woody cover in farml

Adverse weather conditions can cause deterioration of wireless channels, leading to reduced link capacities. Unlike in other types of networks, in radio-based wireless mesh networks, the link capacities depend not only on the prevailing conditions, but also on interfering transmissions, as well as the transmission power and modulation and coding schemes used. This leads to increased difficulty in Adverse weather conditions can cause deterioration of wireless channels, leading to reduced link capacities. Unlike in other types of networks, in radio-based wireless mesh networks, the link capacities depend not only on the prevailing conditions, but also on interfering transmissions, as well as the transmission power and modulation and coding schemes used. This leads to increased difficulty in

Understanding the relationships between snow and vegetation is important for interpretation of the responses of alpine ecosystems to climate changes. The Qinghai-Tibetan Plateau is regarded as an ideal area due to its undisturbed features with low population and relatively high snow cover. We used 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) datasets during 2001–2010 to examine the

Vegetation is an important part of the environment but may be subjected to disturbance in areas close to coal mines. This results in a slowing of the rate of biomass growth, which is caused by fading of vegetation. Simultaneously, carbon stored in vegetation is constantly released, weakening vegetation ability to act as a carbon sink. Indirect release of carbon during coal mining processes is diff