Robert Zomer

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Papers by Robert Zomer

Building the Climate Change Resilience of Mongolia’s Blue Pearl: A Case Study of Khuvsgul Lake National Park

Global carbon sequestration potential of agroforestry and increased tree cover on agricultural land

Circular Agricultural Systems

Version 3 of the Global Aridity Index and Potential Evapotranspiration Database

Scientific Data

The “Global Aridity Index and Potential Evapotranspiration Database - Version 3” (Global-AI_PET_v... more The “Global Aridity Index and Potential Evapotranspiration Database - Version 3” (Global-AI_PET_v3) provides high-resolution (30 arc-seconds) global hydro-climatic data averaged (1970–2000) monthly and yearly, based upon the FAO Penman-Monteith Reference Evapotranspiration (ET0) equation. An overview of the methods used to implement the Penman-Monteith equation geospatially and a technical evaluation of the results is provided. Results were compared for technical validation with weather station data from the FAO “CLIMWAT 2.0 for CROPWAT” (ET0: r2 = 0.85; AI: r2 = 0.90) and the U.K. “Climate Research Unit: Time Series v 4.04” (ET0: r2 = 0.89; AI: r2 = 0.83), while showing significant differences to an earlier version of the database. The current version of the Global-AI_PET_v3 supersedes previous versions, showing a higher correlation to real world weather station data. Developed using the generally agreed upon standard methodology for estimation of reference ET0, this database and n...

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Baseline Report Yala and Nzoia River Basins - Western Kenya Integrated Ecosystem Management Project: Findings from the Baseline Surveys

International Centre for Research in Agroforestry, 2008

Ranjitkar et al_2016b.PDF

Global Aridity Index and Potential Evapotranspiration (ET0) Climate Database v2

The Global Aridity Index (Global-Aridity_ET0) and Global Reference Evapotranspiration (Global-ET0... more The Global Aridity Index (Global-Aridity_ET0) and Global Reference Evapotranspiration (Global-ET0) Version 2 dataset provides high-resolution (30 arc-seconds) global raster climate data for the 1970-2000 period, related to evapotranspiration processes and rainfall deficit for potential vegetative growth, based upon the implementation of a Penman Monteith Evapotranspiration equation for reference crop. The dataset follows the development and is based upon the WorldClim 2.0: http://worldclim.org/version2<br> Aridity Index represent the ratio between precipitation and ET0, thus rainfall over vegetation water demand (aggregated on annual basis). Under this formulation, Aridity Index values increase for more humid conditions, and decrease with more arid conditions. The Aridity Index values reported within the Global Aridity Index_ET0 geodataset have been multiplied by a factor of 10,000 to derive and distribute the data as integers (with 4 decimal accuracy). This multiplier has bee...

Published by the World Agroforestry Centre

and practices and stimulate feedback from the scientific community. Other publication series

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The Sustainability of Thailand’s Protected-Area System under Climate Change

Sustainability, 2021

Protected areas are the backbone of biodiversity conservation but vulnerable to climate change. T... more Protected areas are the backbone of biodiversity conservation but vulnerable to climate change. Thailand has a large and well-planned protected area system, covering most remaining natural vegetation. A statistically derived global environmental stratification (GEnS) was used to predict changes in bioclimatic conditions across the protected area system for 2050 and 2070, based on projections from three CMIP5 earth system models and two representative concentration pathways (RCPs). Five bioclimatic zones were identified composed of 28 strata. Substantial spatial reorganization of bioclimates is projected in the next 50 years, even under RCP2.6, while under RCP8.5 the average upward shift for all zones by 2070 is 328–483 m and the coolest zone disappears with two models. Overall, 7.9–31.0% of Thailand’s land area will change zone by 2070, and 31.7–90.2% will change stratum. The consequences for biodiversity are less clear, particularly in the lowlands where the existing vegetation mos...

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The role of soil carbon in natural climate solutions

Nature Sustainability, 2020

Mitigating climate change requires clean energy and removing atmospheric carbon. Building soil ca... more Mitigating climate change requires clean energy and removing atmospheric carbon. Building soil carbon is an appealing way to increase carbon sinks and reduce emissions due to the associated benefits to agriculture. However, practical implementation of soil carbon climate strategies lag behind the potential, partly because we lack clarity around the magnitude of opportunity and how to capitalize on it. Here we quantify the role of soil carbon in natural (landbased) climate solutions (NCS), and review some of the project design mechanisms available to tap into the potential. We show that soil carbon represents 25% of the 23.8 GtCO2eyr-1 NCS potential of which 40% is protection of existing soil carbon and 60% is rebuilding depleted stocks. Soil carbon comprises 9% of the mitigation potential of forests, 72% for wetlands, and 47% for agriculture and grasslands. Soil carbon is important to land-based efforts to prevent carbon emissions, remove atmospheric carbon dioxide and deliver ecosystem services in addition to climate mitigation. Protecting and restoring soil organic matter delivers many benefits to people and nature 1,2. Globally, soils hold three times more carbon than the atmosphere 3 , and the role of soil organic matter as a regulator of climate has been recognized by scientists for decades 4. Recent work has highlighted the historical loss of carbon from this pool 3 , and the threat of future accelerated loss under warming scenarios 4,5. Soil organic carbon as a natural climate solution (NCS) thus has a role both through restoring a carbon sink and protecting against further CO 2 emissions in response to predicted land use change and climate change. This dual role for soil in the global carbon budget suggests climate benefits can be achieved through strategies that both conserve existing soil organic carbon stocks (avoid loss), and restore stocks in carbon-depleted soils 6. There are important additional benefits. Protecting and increasing soil carbon storage can (i) protect or increase soil fertility, (ii) maintain or increase resilience to climate change, (iii) reduce soil erosion, and where implemented through conservation of natural ecosystems iv) reduce habitat conversion, all in line with the United Nations Sustainable Development Goals (SDG's) 7 , the goals of the United Nationals Framework Convention on Climate Change (UNFCCC) and the United Nations Convention on Combating Desertification (UNCCD). As such, soil carbon is promoted as a common denominator amongst a variety of global and national initiatives 7. Although recent academic comment and perspective pieces point the way towards accelerated action on soils 8,9 , there remains much uncertainty around actionable pathways for achieving the global opportunity. Here we examine the scientific and policy context surrounding soil carbon projects, to aid prioritization and decision making.

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Global Tree Cover and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national carbon budgets

Scientific reports, Jan 20, 2016

Agroforestry systems and tree cover on agricultural land make an important contribution to climat... more Agroforestry systems and tree cover on agricultural land make an important contribution to climate change mitigation, but are not systematically accounted for in either global carbon budgets or national carbon accounting. This paper assesses the role of trees on agricultural land and their significance for carbon sequestration at a global level, along with recent change trends. Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover and that this has increased by 2% over the previous ten years. Combining geographically and bioclimatically stratified Intergovernmental Panel on Climate Change (IPCC) Tier 1 default estimates of carbon storage with this tree cover analysis, we estimated 45.3 PgC on agricultural land globally, with trees contributing >75%. Between 2000 and 2010 tree cover increased by 3.7%, resulting in an increase of >2 PgC (or 4.6%) of biomass carbon. On average, globally, biomass carbon increased from 20.4 to 21.4...

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Land Cover Change Along Tropical and Subtropical Riparian Corridors Within the Makalu Barun National Park and Conservation Area, Nepal

Mountain Research and Development, 2001

BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access t... more

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Land Area Eligible for Afforestation and Reforestation within the Clean Development Mechanism: A Global Analysis of the Impact of Forest Definition

Mitigation and Adaptation Strategies for Global Change, 2007

... Robert J. Zomer Æ Antonio Trabucco Æ Louis V. Verchot Æ Bart Muys ... Although at first sight... more ... Robert J. Zomer Æ Antonio Trabucco Æ Louis V. Verchot Æ Bart Muys ... Although at first sight the definition of forest may seem obvious, there are in fact many definitions of the term &amp;amp;amp;amp;amp;amp;#x27;&amp;amp;amp;amp;amp;amp;#x27;forest&amp;amp;amp;amp;amp;amp;#x27;&amp;amp;amp;amp;amp;amp;#x27; in use throughout the world (Lund 2002; Helms 2002). ...

Building spectral libraries for wetlands land cover classification and hyperspectral remote sensing

Journal of Environmental Management, 2009

Recent advances in remote sensing provide opportunities to map plant species and vegetation withi... more Recent advances in remote sensing provide opportunities to map plant species and vegetation within wetlands at management relevant scales and resolutions. Hyperspectral imagers, currently available on airborne platforms, provide increased spectral resolution over existing spacebased sensors that can document detailed information on the distribution of vegetation community types, and sometimes species. Development of spectral libraries of wetland species is a key component needed to facilitate advanced analytical techniques to monitor wetlands. Canopy and leaf spectra at five sites in California, Texas, and Mississippi were sampled to create a common spectral library for mapping wetlands from remotely sensed data. An extensive library of spectra (n ¼ 1336) for coastal wetland communities, across a range of bioclimatic, edaphic, and disturbance conditions were measured. The wetland spectral libraries were used to classify and delineate vegetation at a separate location, the Pacheco Creek wetland in the Sacramento Delta, California, using a PROBE-1 airborne hyperspectral data set (5 m pixel resolution, 128 bands). This study discusses sampling and collection methodologies for building libraries, and illustrates the potential of advanced sensors to map wetland composition. The importance of developing comprehensive wetland spectral libraries, across diverse ecosystems is highlighted. In tandem with improved analytical tools these libraries provide a physical basis for interpretation that is less subject to conditions of specific data sets. To facilitate a global approach to the application of hyperspectral imagers to mapping wetlands, we suggest that criteria for and compilation of wetland spectral libraries should proceed today in anticipation of the wider availability and eventual space-based deployment of advanced hyperspectral high spatial resolution sensors.

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Environmental stratifications as the basis for national, European and global ecological monitoring

Ecological Indicators, 2013

There is growing urgency for integration and coordination of global environmental and ecological ... more There is growing urgency for integration and coordination of global environmental and ecological data and indicators required to respond to the 'grand challenges' the planet is facing, including climate change and biodiversity decline. A consistent stratification of land into relatively homogenous strata provides a valuable spatial framework for comparison and analysis of ecological and environmental data across large heterogeneous areas. We discuss how statistical stratification can be used to design national, European and global biodiversity observation networks. The value of strategic ecological survey based on stratified samples is first illustrated using the United Kingdom (UK) Countryside Survey, a national monitoring programme that has measured ecological change in the UK countryside for the last 35 years. We then present a design for a European-wide sampling design for monitoring common habitats, and discuss ways of extending these approaches globally, supported by the recently developed Global Environmental Stratification. The latter provides a robust spatial analytical framework for the identification of gaps in current monitoring efforts, and systematic design of new complementary monitoring and research. Examples from Portugal and the transboundary Kailash Sacred Landscape in the Himalayas illustrate the potential use of this stratification, which has been identified as a focal geospatial dataset within the Group on Earth Observation Biodiversity Observation Network (GEO BON).

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Implications of Country-Level Decisions on the Specification of Crown Cover in the Definition of Forests for Land Area Eligible for Afforestation and Reforestation Activities in the CDM

Climatic Change, 2007

Within the Kyoto Protocol, countries have significant latitude to define a forest. The most impor... more Within the Kyoto Protocol, countries have significant latitude to define a forest. The most important parameter affecting area designated as forest is the minimum crown density which can be set between 10 and 30 percent. The choice will have implications for the amount of land available in a country for afforestation and reforestation (A/R) activities within the Clean Development Mechanism (CDM). In this paper, we used GIS analysis to look at four case studies from countries involved in the EU-funded ENCOFOR project: Bolivia, Ecuador, Uganda and Kenya. We also looked at the effects of other factors that would exclude land from eligibility for A/R projects. A low threshold of 10 percent crown cover resulted in exclusion of 70 to 90 percent of the land area of all countries except Kenya, which differed from the other countries by its large dryland areas. Much less area was excluded when higher thresholds were used. The spatial analyses showed not only the effects of the choice of the crown cover criterion, but also where the land was available for CDM activities within each country at different thresholds. This is the first time that the effect of the crown cover element of the Kyoto forest definition on land availability and distribution for CDM A/R activities has been quantified. While there are a number of reasons to choose different thresholds, this analysis suggests that countries that are considering using CDM finance for rural development might want to select the higher minimum threshold for crown cover in order to maximize their participation and flexibility.

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Climate change mitigation: A spatial analysis of global land suitability for clean development mechanism afforestation and reforestation

Agriculture, Ecosystems & Environment, 2008

This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

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Trees on farm: analysis of global extent and geographical patterns of Agroforestry ICRAF Working Paper no. 89

Agroforestry, the inclusion of woody perennials within farming systems, has been both a tradition... more Agroforestry, the inclusion of woody perennials within farming systems, has been both a traditional landuse approach developed by subsistence farmers throughout the tropics, and a livelihood option promoted by landuse managers and international development efforts. Agroforestry systems range from subsistence livestock and pastoral systems to home gardens, alley intercropping, and biomass plantations with a wide diversity of biophysical conditions and socio-ecological characteristics. The extent of its practice has never been quantified leading to widely varied estimates about its importance. This paper is the first attempt to quantify the extent of agroforestry at the global level. A geospatial analysis of remote sensing derived global datasets investigated the correspondence and relationship of tree cover, population density and climatic conditions within agricultural land at 1 km resolution. Among the key results are that agroforestry is a significant feature of agriculture in all regions, that its extent varies significantly across different regions (e.g. more significant in Central America and less in East Asia), that tree cover is strongly positively related to humidity, and that there are mixed relationships between tree cover and population density depending on the region. This first analysis suggests that patterns of tree cover are influenced by a range of factors we were not able to examine at the global scale and a number of follow up analyses are recommended.

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Global High-Resolution Soil-Water Balance

The Global High-Resolution Soil-Water Balance dataset provides hydrological raster data describin... more

Ranjitkar et al_2016b.PDF

Climate change mitigation through afforestation/reforestation: A global analysis of hydrologic impacts with four case studies

Agriculture, Ecosystems & Environment, 2008

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