Remote sensing technology applications in forestry and REDD+

Advances in close-range and remote sensing technologies are driving innovations in forest resource assessments and monitoring on varying scales. Data acquired with airborne and spaceborne platforms provide high(er) spatial resolution, more frequent coverage, and more spectral information. Recent developments in ground-based sensors have advanced 3D measurements, low-cost permanent systems, and community-based monitoring of forests. The UNFCCC REDD+ mechanism has advanced the remote sensing community and the development of forest geospatial products that can be used by countries for the international reporting and national forest monitoring. However, an urgent need remains to better understand the options and limitations of remote and close-range sensing techniques in the field of forest degradation and forest change. Therefore, we invite scientists working on remote sensing technologies, close-range sensing, and field data to contribute to this Special Issue. Topics of interest include: (1) novel remote sensing applications that can meet the needs of forest resource information and REDD+ MRV, (2) case studies of applying remote sensing data for REDD+ MRV, (3) timeseries algorithms and methodologies for forest resource assessment on different spatial scales varying from the tree to the national level, and (4) novel close-range sensing applications that can support sustainable forestry and REDD+ MRV. We particularly welcome submissions on data fusion

Integrating Participatory Methods and Remote Sensing to Enhance Understanding of Ecosystem Service Dynamics Across Scales

The value of Traditional Ecological Knowledge (TEK) for informing resource management has long been recognized; however, its incorporation into ecosystem services (ES) assessments remains uncommon. Often “top-down” approaches are utilized, depending on “expert knowledge”, that are not relevant to local resource users. Here we propose an approach for combining participatory methods with remote sensing to provide a more holistic understanding of ES change. Participatory mapping in focus group discussions identified TEK regarding what ES were present, where, and their value to communities. TEK was then integrated with satellite imagery to extrapolate to the landscape-scale. We demonstrate our method for Nyangatom communities in the Lower Omo Valley, Ethiopia, showing for the first time the ES impacts of regional environmental change, including the Gibe III dam, for communities in the Omo River basin. Results confirmed the collapse of flood-retreat cultivation associated with the loss of the annual Omo flood. Communities reported declines in many other provisioning ES, and these results were supported by satellite mapping, which showed substantial reductions in land covers with high ES value (shrubland and wetland), leading to consequent ES declines. Our mixed-methods approach has potential to be applied in other regions to generate locally relevant information for evaluating ES dynamics and improving management of natural resources

The Changing Matrix: Reforestation and Connectivity in a Tropical Habitat Corridor

In the last two decades, export-oriented crops and timber and fruit plantations have joined small-scale cultivation and pasture as important causes of tropical deforestation. Widespread conversion of tropical forest to agriculture threatens to isolate protected areas, which has led to efforts to maintain functional connectivity in landscapes between protected areas. Relatively few "landscape conservation" efforts have been assessed for their effect on deforestation, but advances in remote sensing now permit detailed monitoring of tropical land uses over time, including mapping of tree crops and plantations. This dissertation evaluates the long-term impact of forest conservation and reforestation policies on tropical forests in a habitat corridor. The following chapters test the capability of remote sensing to monitor tropical conservation efforts and assess whether landscape conservation policies can maintain forest cover and connectivity in the face of rapid agricultural expansion. Costa Rica has one of the most comprehensive landscape conservation policies in the tropics: a 1996 Forest Law banned deforestation and expanded payments for environmental services (PES) to protect forests and plant trees, prioritizing designated habitat corridors between protected areas. The long-term effect of the program on land-use transitions is not well known. To take advantage of this regional policy experiment, I used a time-series of five moderate-resolution Landsat images to track land-use change from 1986 to 2011in the oldest habitat corridor, the San Juan-La Selva Biological Corridor (SJLSBC). Forest conservation policies were associated with a 40% decline in deforestation after 1996 despite a doubling in the area of cropland in the last decade. The proportion of cropland derived from mature forest dropped from 16.4% to 1.9% after 1996, while one fifth of pasture expansion continued to be derived from mature forest. These results suggest that forest conservation policies can successfully lower deforestation, and that they can be more effective with large export producers than small-scale cattle producers. Tree plantations are an important component of Costa Rican PES, but knowledge of their distribution and contribution to connectivity in the corridor region is poor. After reviewing the remote sensing literature, I employed a novel integration of hyperspectral images and a Landsat time-series to create the first regional map of tropical tree plantation species. Including multitemporal data significantly improved overall hyperspectral map accuracy to 91%; the six tree plantation species were classified with 83% mean producer's accuracy. Non-native species made up 89% of tree plantations, and they were cleared more rapidly than native tree plantations and secondary forests. I combined existing land cover maps, field behavioral experiments, and a graph connectivity model to estimate whether landscape conservation policies increased connectivity for understory insectivorous birds, a representative forest-dependent group. The field playback experiments indicated both native and exotic tree plantations with a dense shrubby understory were acceptable dispersal habitat for all species, and that birds traveled readily near secondary forest edges but rarely into forested pasture. Graph model parameters were informed by these results. For all of these bird species, functional connectivity declined by 14-21% with only a 4.9% decline in forest area over time, implying that conservation policies have not caused a net increase in functional connectivity in the SJLSBC region. Despite making up 2% of the region, tree plantations had little effect on regional connectivity because of their placement in the landscape; we demonstrate that spatially-targeted reforestation of 0.1% of the region could increase connectivity by 1.8%. Collectively, the results presented in these chapters underline the potential and limitations of landscape conservation policies and corridor plans in the tropics; combining regulations and PES can lower deforestation over the medium-term, but increased enforcement, improved monitoring with remote sensing, and targeted conservation effort is needed to combat illegal deforestation and restore functional connectivity. Given numerous new tropical corridor and PES programs and the qualified successes of landscape conservation policies in Costa Rica and other tropical countries, our approach to the analysis can be applied to monitor and evaluate connectivity across the tropics

Modelling spatial variability of coffee (Coffea Arabica L.) crop condition with multispectral remote sensing data.

Doctor of Philosophy in Environmental Science. University of KwaZulu-Natal, Pietermaritzburg, 2017.Abstract available in PDF file

Measuring and modelling carbon stocks in rubber (Hevea brasiliensis) dominated landscapes in Subtropical China

Rubber plantation has been rapidly expanded in Montane Mainland South East Asia in past decades. Limited by long-term monitoring data availability, the impacts of environmental change on rubber trees carbon stock development still not fully understood. Against global warming background, in order to better facilitate regional forest management, we applied synergetic approach combining field survey and modelling tools to improve predictions of dynamic carbon stock changes. The trade-off analysis regarding to rubber carbon stock and latex production optimization was further discussed in view of sustainable rubber cultivation. The first study explored the impact of regional land-use changes on landscape carbon balances. The Naban River Watershed National Nature Reserve (NRWNNR), Xishuangbanna, China, was selected as a case study location. Carbon stocks were evaluated using the Rapid Carbon Stock Appraisal (RaCSA) method based on tree, plot, land use and landscape level assessments of carbon stocks, integrating field sampling with remote sensing and GIS technology. The results showed that rubber plantations had larger time-averaged carbon stocks than non-forest land use types (agricultural crops, bush and grassland) but much lower than natural forest. During 23 years (1989-2012), the whole landscape of the nature reserve (26574 ha) gained 0.644 Tg C. Despite rubber expansion, the reforestation activities conducted in NRWNNR were able to enhance the carbon stocks. Regional evaluation of the carbon sequestration potential of rubber trees depends largely on the selection of suitable allometric equations and the biomass-to-carbon conversion factor. The second study developed generic allometric equations for rubber trees, covering rotation lengths of 4-35 years, within elevation gradient of 621-1,127 m, and locally used rubber tree clones (GT1, PRIM600, Yunyan77-4) in mountainous South Western China. Allometric equations for aboveground biomass (AGB) estimations considering diameter at breast height (DBH), tree height, and wood density were superior to other equations. We also tested goodness of fit for the recently proposed pan-tropical forest model. The results displayed that prediction of AGB by the model calibrated with the harvested rubber tree biomass and wood density was more accurate than the results produced by the pan-tropical forest model adjusted to local conditions. The relationships between DBH and height and between DBH and biomass were influenced by tapping, therefore biomass and C stock calculations for rubber have to be done using species-specific allometric equations. Based on the analysis of environmental factors acting at the landscape level, we noticed that above- and belowground carbon stocks were mostly affected by stand age, soil clay content, aspect, and planting density. The results of this study provide reference for reliable carbon accounting in other rubber-cultivated regions. In the last study, we explored how rubber trees growth and production response to climate change and regional management strategies (cultivation elevation, planting density). We applied the process-based Land Use Change Impact Assessment tool (LUCIA) calibrated with detailed ground survey data to model tree biomass development and latex yield in rubber plantations at the tree, plot and landscape level. Model simulation showed that during a 40-year rotation, lowland rubber plantations (< 900m) grew quicker and had larger latex yield than highland rubber (&#8807;900m). High planting density rubber plantations showed 5% higher above ground biomass than those at low- and medium-planting density. The mean total biomass and cumulative latex yield per tree over 40 years increased by 28% and 48%, respectively, when climate change scenarios were modelled from baseline to highest CO2 emission scenario (RCP 8.5). The same trend of biomass and latex yield increase with climate change was observed at plot level. Denser plantations had larger biomass, but the cumulative latex production decreased dramatically. The spatially explicit output maps produced during modelling could help maximize carbon stock and latex production of regional rubber plantations. Overall, rubber-based system required for appropriate monitoring scale in both temporal aspect (daily-, monthly-, and yearly-level) and in spatial aspect (pixel-, land use-, watershed-, and landscape- level). The findings from present study highlighted the important application of ecological modelling tools in nature resources management. The lessons learned here could be applicable for other rubber-cultivated regions, by updating with site-specific environmental variables. The significant role of rubber tree not limited in its nature latex production, it also lies in its great carbon sequestration potential. Our results here provided entry point for future developing comprehensive climate change adaption and mitigation strategies in South East Asia. By making use of interdisplinary cooperation, the sustainable rubber cultivation in Great Mekong Regions could be well realized.In den vergangenen Jahrzehnten wurde der Kautschukanbau in den Bergregionen des südostasiatischen Festlandes rasch ausgebaut. Die Auswirkungen von Umweltveränderungen auf die Entwicklung des Kohlenstoffbestandes von Kautschukbäumen sind durch die eingeschränkte Verfügbarkeit von Langzeit-Monitoring-Daten noch nicht vollständig geklärt. Vor dem Hintergrund der globalen Erwärmung und um die regionale Waldbewirtschaftung zu unterstützen, haben wir einen synergetischen Ansatz angewandt, der Feldmessungen und Modellierungswerkzeuge kombiniert, um die Vorhersage dynamischer Veränderungen der Kohlenstoffbestände zu verbessern. Die Kosten-Nutzen Abwägung für einen nachhaltigen Kautschukanbau bezüglich der Kautschuk-Kohlenstoffvorräte und der Optimierung der Latexproduktion wird im Weiteren diskutiert. Die erste Studie untersuchte die Auswirkungen regionaler Landnutzungsänderungen auf die Kohlenstoffbilanz der Landschaft. Das Naban River Watershed National Nature Reserve (NRWNNNR), Xishuangbanna, China, wurde als Fallstudienstandort ausgewählt. Die Bewertung der Kohlenstoffvorräte erfolgte mit der Rapid Carbon Stock Appraisal (RaCSA)-Methode. Diese basiert auf der Bewertung von Kohlenstoffvorräten auf dem Niveau von Bäumen, Grundstücken, Landnutzung und Landschaft, mit Einbindung von Feldprobennahme verbunden mit Fernerkundung und GIS-Technologie. Die Ergebnisse zeigten, dass Kautschukplantagen einen größeren zeitgemittelten Kohlenstoffvorrat hatten als nicht-forstliche Landnutzungsarten (Ackerland, Busch- und Grünland), aber viel weniger als natürliche Wälder. Während 23 Jahren (1989-2012) gewann das gesamte Gebiet des Naturschutzgebietes (26574 ha) 0,644 Tg C hinzu. Trotz Ausdehnung der Kautschukanbauflächen konnten die Aufforstungsaktivitäten in NRWNNR die Kohlenstoffvorräte erhöhen. Die regionale Bewertung des Kohlenstoffsequestrierungspotenzials von Kautschukbäumen hängt wesentlich von der Auswahl geeigneter allometrischer Gleichungen und des Biomasse-Kohlenstoff-Umwandlungsfaktors ab. Die zweite Studie entwickelte allgemeine allometrische Gleichungen für Kautschukbäume, basierend auf Daten aus Kautschukplantagen mit Umtriebszeiten von 4-35 Jahren, Höhenlagen von 621-1.127 m und lokal verwendeten Kautschukbaumklonen (GT1, PRIM600, Yunyan77-4) im bergigen Südwesten Chinas. Allometrische Gleichungen zur Berechnung der oberirdischen Biomasse (AGB), welche den Durchmesser in Brusthöhe (DBH), Baumhöhe und Holzdichte berücksichtigten, waren anderen Gleichungen überlegen. Wir haben auch die Anpassungsgüte des kürzlich vorgeschlagene pan-tropische Waldmodell getestet. Die Ergebnisse zeigten, dass die Vorhersage der AGB durch das mit der destruktiv bestimmten Biomasse und der Holzdichte kalibrierte Modell genauer war als die Ergebnisse des pan-tropischen Waldmodells, das an die lokalen Bedingungen angepasst wurde. Die Beziehungen zwischen DBH und Höhe, und DBH und Biomasse wurden durch die Anzapfung der Bäume beeinflusst. Aufgrund dessen müssen Biomasse- und C-Bestandsberechnungen für Kautschuk mit artspezifischen allometrischen Gleichungen durchgeführt werden. Basierend auf der Analyse von Umweltfaktoren, die auf Landschaftsebene wirken, stellten wir fest, dass die ober- und unterirdischen Kohlenstoffvorräte vor allem durch das Bestandsalter, den Tongehalt des Bodens, die Hanglage und die Pflanzdichte beeinflusst wurden. Die Ergebnisse dieser Studie liefern Anhaltspunkte für eine zuverlässige Kohlenstoffbilanzierung in anderen Kautschukanbaugebieten. In der letzten Studie haben wir untersucht, wie Kautschukbäume auf den Klimawandel und regionalen Managementstrategien (Anbauhöhe, Pflanzdichte) reagieren. Wir setzten das prozessbasierte Land Use Change Impact Assessment Tool (LUCIA) ein, das mit detaillierten Bodenuntersuchungsdaten kalibriert wurde, um die Entwicklung der Baumbiomasse und den Latexertrag in Kautschukplantagen auf Baum-, Parzelle- und Landschaftsebene zu modellieren. Die Modellsimulation zeigte, dass während einer 40-jährigen Rotationzeit die Flachland-Kautschukplantagen (< 900m) schneller wuchsen und eine höhere Latexausbeute hatten als die Hochland-Kautschukplantagen (&#8807;900m). Kautschukplantagen mit hoher Pflanzdichte zeigten eine um 5% höhere oberirdische Biomasse als solche mit niedriger und mittlerer Pflanzdichte. Der durchschnittliche Gesamtertrag an Biomasse und der kumulative Latexertrag pro Baum stieg in 40 Jahren um 28% bzw. 48%, wenn die Klimaszenarien vom Basisszenario bis zum höchsten CO2-Emissionsszenario (RCP 8. 5) durchsimuliert wurden. Dieser Trend der Zunahme der Biomasse- und Latexausbeute mit verstärktem Klimawandel wurde auch auf der Ebene der Parzelle beobachtet. Dichtere Plantagen hatten eine größere Biomasse, aber die kumulative Latexproduktion ging drastisch zurück. Die während der Modellierung erstellten räumlich expliziten Output-Karten könnten helfen, die Kohlenstoffvorräte und die Latexproduktion regionaler Kautschukplantagen zu maximieren. Allgemein ist für ein angemessenes Monitoring ein Kautschuk-basiertes System erforderlich, das sowohl in zeitlicher Hinsicht (Tages-, Monats- und Jahresebene) als auch in räumlicher Hinsicht (Pixel-, Landnutzungs-, Wassereinzugs- und Landschaftsebene) geeignet ist. Die Ergebnisse der vorliegenden Studie verdeutlichen die Bedeutung ökologischer Modellierungswerkzeuge im Naturressourcenmanagement. Die hier gemachten Erfahrungen könnten auch auf andere Kautschukanbaugebiete übertragen werden, indem sie mit standortspezifischen Umweltvariablen aktualisiert werden. Die bedeutende Rolle des Kautschukbaums ist nicht nur auf dieHerstellung von Naturlatex beschränkt, sondern liegt auch in seinem großen Potenzial zur Kohlenstoffbindung. Unsere Ergebnisse lieferen den Ausgangspunkt für die künftige Entwicklung umfassender Strategien zur Anpassung an den Klimawandel und zur Eindämmung des Klimawandels in Südostasien. Durch interdisziplinäre Zusammenarbeit könnte der nachhaltige Kautschukanbau in den Großen Mekong-Regionen realisiert werden

Integrated Analyses of PALSAR and Landsat Imagery Reveal More Agroforests in a Typical Agricultural Production Region, North China Plain

As the largest among terrestrial ecosystems, forests are vital to maintaining ecosystem services and regulating regional climate. The area and spatial distribution of trees in densely forested areas have been focused on in the past few decades, while sparse forests in agricultural zones, so-called agroforests or trees outside forests (TOF), have usually been ignored or missed in existing forest mapping efforts, despite their important role in regulating agricultural ecosystems. We combined Landsat and PALSAR data to map forests in a typical agricultural zone in the North China Plain. The resultant map, based on PALSAR and Landsat (PL) data, was also compared with five existing medium resolution (30&ndash;100 m) forest maps from PALSAR (JAXA forest map) and Landsat: NLCD-China, GlobeLand30, ChinaCover, and FROM-GLC. The results show that the PL-based forest map has the highest accuracy (overall accuracy of 95 &plusmn; 1% with a 95% confidence interval, and Kappa coefficient of 0.86) compared to those forest maps based on single Landsat or PALSAR data in the North China Plain (overall accuracy ranging from 85 &plusmn; 2% to 92 &plusmn; 1%). All forest maps revealed higher accuracy in densely forested mountainous areas, while the PL-based and JAXA forest maps showed higher accuracy in the plain, as the higher omission errors existed in only the Landsat-based forest maps. Moreover, we found that the PL-based forest map can capture more patched forest information in low forest density areas. This means that the radar data have advantages in capturing forests in the typical agricultural zones, which tend to be missing in published Landsat-based only forest maps. Given the significance of agroforests in regulating ecosystem services of the agricultural ecosystem and improving carbon stock estimation, this study implies that the integration of PALSAR and Landsat data can provide promising agroforest estimates in future forest inventory efforts, targeting a comprehensive understanding of ecosystem services of agroforests and a more accurate carbon budget inventory

Dipterocarps protected by Jering local wisdom in Jering Menduyung Nature Recreational Park, Bangka Island, Indonesia

Apart of the oil palm plantation expansion, the Jering Menduyung Nature Recreational Park has relatively diverse plants. The 3,538 ha park is located at the north west of Bangka Island, Indonesia. The minimum species-area curve was 0.82 ha which is just below Dalil conservation forest that is 1.2 ha, but it is much higher than measurements of several secondary forests in the Island that are 0.2 ha. The plot is inhabited by more than 50 plant species. Of 22 tree species, there are 40 individual poles with the average diameter of 15.3 cm, and 64 individual trees with the average diameter of 48.9 cm. The density of Dipterocarpus grandiflorus (Blanco) Blanco or kruing, is 20.7 individual/ha with the diameter ranges of 12.1 – 212.7 cm or with the average diameter of 69.0 cm. The relatively intact park is supported by the local wisdom of Jering tribe, one of indigenous tribes in the island. People has regulated in cutting trees especially in the cape. The conservation agency designates the park as one of the kruing propagules sources in the province. The growing oil palm plantation and the less adoption of local wisdom among the youth is a challenge to forest conservation in the province where tin mining activities have been the economic driver for decades. More socialization from the conservation agency and the involvement of university students in raising environmental awareness is important to be done