Mapping Understory Vegetation using Phenological Characteristics Derived from Remotely Sensed Data

Remote Sensing of Environment, In Press, Available online 17 April 2010

Mao-Ning Tuanmu, Andrés Viña, Scott Bearer, Weihua Xu, Zhiyun Ouyang, Hemin Zhang, and Jianguo Liu

“Understory vegetation is an important component in forest ecosystems not only because of its contributions to forest structure, function and species composition, but also due to its essential role in supporting wildlife species and ecosystem services. Therefore, understanding the spatio-temporal dynamics of understory vegetation is essential for management and conservation. Nevertheless, detailed information on the distribution of understory vegetation across large spatial extents is usually unavailable, due to the interference of overstory canopy on the remote detection of understory vegetation. While many efforts have been made to overcome this challenge, mapping understory vegetation across large spatial extents is still limited due to a lack of generality of the developed methods and limited availability of required remotely sensed data. In this study, we used understory bamboo in Wolong Nature Reserve, China as a case study to develop and test an effective and practical remote sensing approach for mapping understory vegetation. Using phenology metrics generated from a time series of Moderate Resolution Imaging Spectroradiometer data, we characterized the phenological features of forests with understory bamboo. Using maximum entropy modeling together with these phenology metrics, we successfully mapped the spatial distribution of understory bamboo (kappa: 0.59; AUC: 0.85). In addition, by incorporating elevation information we further mapped the distribution of two individual bamboo species, Bashania faberi and Fargesia robusta (kappa: 0.68 and 0.70; AUC: 0.91 and 0.92, respectively). Due to its generality, flexibility and extensibility, this approach constitutes an improvement to the remote detection of understory vegetation, making it suitable for mapping different understory species in different geographic settings. Both biodiversity conservation and wildlife habitat management may benefit from the detailed information on understory vegetation across large areas through the applications of this approach.”

Assessment of Planetary Geologic Mapping Techniques for Mars using Terrestrial Analogs: The SP Mountain Area of the San Francisco Volcanic Field, Arizona

Planetary and Space Science, Volume 57, Issues 5-6, May 2009, Pages 510-532

Kenneth L. Tanaka, James A. Skinner Jr., Larry S. Crumpler, James M. Dohm

“We photogeologically mapped the SP Mountain region of the San Francisco Volcanic Field in northern Arizona, USA to evaluate and improve the fidelity of approaches used in geologic mapping of Mars. This test site, which was previously mapped in the field, is chiefly composed of Late Cenozoic cinder cones, lava flows, and alluvium perched on Permian limestone of the Kaibab Formation. Faulting and folding has deformed the older rocks and some of the volcanic materials, and fluvial erosion has carved drainage systems and deposited alluvium. These geologic materials and their formational and modificational histories are similar to those for regions of the Martian surface. We independently prepared four geologic maps using topographic and image data at resolutions that mimic those that are commonly used to map the geology of Mars (where consideration was included for the fact that Martian features such as lava flows are commonly much larger than their terrestrial counterparts). We primarily based our map units and stratigraphic relations on geomorphology, color contrasts, and cross-cutting relationships. Afterward, we compared our results with previously published field-based mapping results, including detailed analyses of the stratigraphy and of the spatial overlap and proximity of the field-based vs. remote-based (photogeologic) map units, contacts, and structures. Results of these analyses provide insights into how to optimize the photogeologic mapping of Mars (and, by extension, other remotely observed planetary surfaces). We recommend the following: (1) photogeologic mapping as an excellent approach to recovering the general geology of a region, along with examination of local, high-resolution datasets to gain insights into the complexity of the geology at outcrop scales; (2) delineating volcanic vents and lava-flow sequences conservatively and understanding that flow abutment and flow overlap are difficult to distinguish in remote data sets; (3) taking care to understand that surficial materials (such as alluvium and volcanic ash deposits) are likely to be under-mapped yet are important because they obscure underlying units and contacts; (4) where possible, mapping multiple contact and structure types based on their varying certainty and exposure that reflect the perceived accuracy of the linework; (5) reviewing the regional context and searching for evidence of geologic activity that may have affected the map area yet for which evidence within the map area may be absent; and (6) for multi-authored maps, collectively analyzing the mapping relations, approaches, and methods throughout the duration of the mapping project with the objective of achieving a solid, harmonious product.”

Video: Pedestrian Spatial Analysis

“Spatial Analysis can be used pre simulation to estimate areas of highest probability of conflict or most wear and tear in the pedestrian space. Space utilisation values can be queried using the Spatial Metrics Tool within the Urban Analytics Framework (UAF) during or after simulation to see the actual effect of the available free space on the movement of agents. This tool is used to highlight where excessive density or high spatial utilisation values indicate a potential for crushing and injury as the crowd moves through the model.”

Geostatistical Analysis of Surface Soil Texture from Zala County in Western Hungary

Proceedings of the International Symposium on Environment, Energy and Water in Nepal: Recent Researches and Direction for Future. 31 March – 01 April 2009, Hotel Himalaya, Kathmandu, Nepal

K. Adhikari, A. Guadagnini, G. Toth and T. Hermann. Pages 219 – 224

“Soil texture is one of the most important soil properties governing most of the physical, chemical and hydrological properties of soils. Variability in soil texture may contribute to the variation in nutrient storage and availability, water retention and transport and binding and stability of soil aggregates. It can directly or indirectly influence many other soil functions and soil threats such as soil erosion. Geostatistics has been extensively used for quantifying the spatial pattern of soil properties and Kriging techniques are proving sufficiently robust for estimating values at unsampled locations in most of the cases. In our study, we show the applicability of Ordinary Kriging techniques to characterize the spatial variation of soil texture i.e. sand and clay content on the basis of 100 samples collected over a forest mixed agriculture farming area covering about 250sq. km of Zala County in western Hungary. Our study supports the usefulness of geostatistical techniques to analyze the spatial distribution of soil texture content. The results (provided in terms of prediction maps and their associated variance) can be used as a source of information for the development and implementation of any further land management and soil and water conservation plans in the study area.”

Exploiting Geographic References of Documents in a Geographical Information Retrieval System using an Ontology-based Index

GeoInformatica, Volume 14, Number 3 / July, 2010

Nieves R. Brisaboa, Miguel R. Luaces, Ángeles S. Places and Diego Seco

“Both Geographic Information Systems and Information Retrieval have been very active research fields in the last decades. Lately, a new research field called Geographic Information Retrieval has appeared from the intersection of these two fields. The main goal of this field is to define index structures and techniques to efficiently store and retrieve documents using both the text and the geographic references contained within the text. We present in this paper two contributions to this research field. First, we propose a new index structure that combines an inverted index and a spatial index based on an ontology of geographic space. This structure improves the query capabilities of other proposals. Then, we describe the architecture of a system for geographic information retrieval that defines a workflow for the extraction of the geographic references in documents. The architecture also uses the index structure that we propose to solve pure spatial and textual queries as well as hybrid queries that combine both a textual and a spatial component. Furthermore, query expansion can be performed on geographic references because the index structure is based in an ontology.”

Clark Labs Releases New Global Monthly Data Archive for Image Time Series Analysis

Clark Labs is pleased to announce they have released a DVD archive of monthly global NDVI (Normalized Difference Vegetation Index) and EVI (Enhanced Vegetation Index) MODIS data. The MODIS data were processed by NASA Goddard from the Terra sensor projected on a 0.05 degree climate modeling grid. The DVD includes over 3 gigabytes of data from the MOD13C2 product, for the years 2000 – 2009, formatted and preprocessed for immediate input into the IDRISI GIS and Image Processing software. None of the original values were altered. The DVD is available for only $30 plus shipping and handling.

Historical data is crucial for the analysis of earth trends and dynamics, particularly for change detection and prediction and long-term image series analysis. Time series analysis is critical for exploring such global events as El Nino and related sea surface temperature anomalies and impacts. Although such data is a valuable resource for analysts, publicly available and typically free, a significant amount of effort must be invested before the data is ready for analysis. Files for each time period, typically at sizes of over 100 mb, must be downloaded individually. The data then needs to be imported and pre-processed. This archive allows analysts and researchers to bypass the tedious yet necessary data download and preparation process, freeing up more effort for a project’s analytical goals.

This data archive is a particularly significant resource as input for the Earth Trends Modeler application within the IDRISI software. Earth Trends Modeler, an application for the exploration and analysis of image time series data, includes a coordinated suite of data mining tools and a variety of techniques for the extraction of global trends and the impacts of climate change. The new data archive can immediately be used within Earth Trends Modeler.

The DVD also includes monthly atmospheric temperature data from Remote Sensing System (RSS), processed from the Microwave and Advanced Microwave Sounding Units on NOAA polar-orbiting platforms and in a 2.5 degree grid.

Learn more about the Global Monthly Data Archive Series.

[Source: Clark University press release]

Spatio-temporal Analysis of Forests under Different Management Regimes using Landsat and IRS Images

Institute for Social and Economic Change, Bangalore, Working paper 213, 2009

“Following the empirical study, cloud-free satellite data were used to study the forests in multi-temporal dimensions. Use of remote sensing data with visual observation/ground truth data is an advanced tool to study and understand the development patterns of the forests. Based on the vegetation index and land cover map a sound development has been observed in the community conserved forest (CCF) in comparison to other forests of the region. Community-based conservation would contribute to new conservation approaches that facilitate achieving the goal of sustainable landscape development in the mountains of the Indian Himalayan region.”

Evapotranspiration and Water Use Efficiency in a Chesapeake Bay Wetland under Carbon Dioxide Enrichment

Global Change Biology, Volume 16 Issue 1 , Pages 234-245 (January 2010)


“Wetlands evapotranspire more water than other ecosystems, including agricultural, forest and grassland ecosystems. However, the effects of elevated atmospheric carbon dioxide (CO2) concentration (Ca) on wetland evapotranspiration (ET) are largely unknown. Here, we present data on 12 years of measurements of ET, net ecosystem CO2 exchange (NEE), and ecosystem water use efficiency (EWUE, i.e. NEE/ET) at 13:00–15:00 hours in July and August for a Scirpus olneyi (C3 sedge) community and a Spartina patens (C4 grass) community exposed to ambient and elevated (ambient+340 μmol mol−1) Ca in a Chesapeake Bay wetland. Although a decrease in stomatal conductance at elevated Ca in the S. olneyi community was counteracted by an increase in leaf area index (LAI) to some extend, ET was still reduced by 19% on average over 12 years. In the S. patens community, LAI was not affected by elevated Ca and the reduction of ET was 34%, larger than in the S. olneyi community. For both communities, the relative reduction in ET by elevated Ca was directly proportional to precipitation due to a larger reduction in stomatal conductance in the control plants as precipitation decreased. NEE was stimulated about 36% at elevated Ca in the S. olneyi community but was not significantly affected by elevated Ca in S. patens community. A negative correlation between salinity and precipitation observed in the field indicated that precipitation affected ET through altered salinity and interacted with growth Ca. This proposed mechanism was supported by a greenhouse study that showed a greater Ca effect on ET in controlled low salinity conditions compared with high salinity. In spite of the differences between the two communities in their responses to elevated Ca, EWUE was increased about 83% by elevated Ca in both the S. olneyi and S. patens communities. These findings suggest that rising Ca could have significant impacts on the hydrologic cycles of coastal wetlands.”