Monitoring the Green Vegetation Period of Two Narcissus Taxa by Non-Destructive Analysis of Selected Physiological and Morphological Properties

In a pot experiment, an early-flowering Narcissus pseudonarcissus cv. ‘Dutch Master’ (DM) and late-flowering N. poeticus cultural form (PO) were examined. The photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs), photosynthetic water use efficiency (WUE), relative chlorophyll content (CCI) and chlorophyll fluorescence (F) were measured regularly. Leaf length, scape length and weight of the plant organs were also measured. The DM cultivar had higher gs and lower E values than the PO on most measuring dates (season average: gs: DM: 165.34, PO: 123.63; E: DM: 1.39, PO: 1.78 mmol H2O m−2s−1). The A curve was similar for the two taxa, except for the first measuring dates. The basic F values (F0, Fm, Fv) for DM were lower and CCI values were higher than for PO (season average of CCI: DM: 94.82, PO: 60.34). The Fm/F0, Fv/F0 and CCI curves were well described by a second order equation. The seasonal change of F and CCI values was the greatest for both taxa near the leaf tip. Bulb growth occurred in the two taxa in approximately the same calendar period, regardless of flowering time. A significant part of the leaf growth in DM occurred after flowering, while the leaves of PO reached their mature size by flowering.

Climate Resilience and Regeneration: How Precincts Can Adapt to and Mitigate Climate Change

Healthy urban ecosystems are increasingly recognised as important for resilient cities and need to be considered as part of GPR. Urban nature-based solutions (NBS) comprising green (vegetation) and blue (water) infrastructure need to be considered at multiple scales from the bioregions, through to catchments, neighbourhoods/precincts, blocks, streets, and buildings, including linkages through and in GPR areas. This chapter describes how climate change—particularly extreme urban heat—is expected to affect Australian cities, and how green and blue infrastructure can help GPR to be incorporated into urban adaptation and mitigation solutions. Topics covered include water-sensitive urban design, nature-based solutions, and urban cooling. The chapter outlines how nature-based solutions can be incorporated into higher-density regenerative urban redevelopment through new technologies and supported by planning models, many of which can be best designed and managed at precinct scale. The ‘additionality’ of green and blue nature-based solutions can offer residents of GPR areas increased liveability and enhanced resilience in both normal and extreme weather.

Loss and Recovery of Carbon in Repeatedly Burned Degraded Peatlands of Kalimantan, Indonesia

Although accurate estimates of biomass loss during peat fires, and recovery over time, are critical in understanding net peat ecosystem carbon balance, empirical data to inform carbon models are scarce. During the 2019 dry season, fires burned through 133,631 ha of degraded peatlands of Central Kalimantan. This study reports carbon loss from surface fuels and the top peat layer of 18.5 Mg C ha−1 (3.5 from surface fuels and 15.0 from root/peat layer), releasing an average of 2.5 Gg (range 1.8–3.1 Gg) carbon in these fires. Peat surface change measurements over one month, as the fires continued to smolder, indicated that about 20 cm of the surface was lost to combustion of peat and fern rhizomes, roots and recently incorporated organic residues that we sampled as the top peat layer. Time series analysis of live green vegetation (NDVI trend), combined with field observations of vegetation recovery two years after the fires, indicated that vegetation recovery equivalent to fire-released carbon is likely to occur around 3 years after fires.

Assessing Drought Vegetation Dynamics in Semiarid Grass- and Shrubland Using MESMA

Drought intensity and duration are expected to increase over the coming century in the semiarid western United States due to anthropogenic climate change. Historic data indicate that megadroughts in this region have resulted in widespread ecosystem transitions. Landscape-scale monitoring with remote sensing can help land managers to track these changes. However, special considerations are required: traditional vegetation indices such as NDVI often underestimate vegetation cover in semiarid systems due to short and multimodal green pulses, extremely variable rainfall, and high soil fractions. Multi-endmember spectral mixture analysis (MESMA) may be more suitable, as it accounts for both green and non-photosynthetic soil fractions. To determine the suitability of MESMA for assessing drought vegetation dynamics in the western US, we test multiple endmember selection and model parameters for optimizing the classification of fractional cover of green vegetation (GV), non-photosynthetic vegetation (NPV), and soil (S) in semiarid grass- and shrubland in central New Mexico. Field spectra of dominant vegetation species were collected at the Sevilleta National Wildlife Refuge over six field sessions from May–September 2019. Landsat Thematic Mapper imagery from 2009 (two years pre-drought), and Landsat Operational Land Imager imagery from 2014 (final year of drought), and 2019 (five years post-drought) was unmixed. The best fit model had high levels of agreement with reference plots for all three classes, with R2 values of 0.85 (NPV), 0.67 (GV), and 0.74 (S) respectively. Reductions in NPV and increases in GV and S were observed on the landscape after the drought event, that persisted five years after a return to normal rainfall. Results indicate that MESMA can be successfully applied for monitoring changes in relative vegetation fractions in semiarid grass and shrubland systems in New Mexico.

Evaluation of SWIR Crop Residue Bands for the Landsat Next Mission

This research reports the findings of a Landsat Next expert review panel that evaluated the use of narrow shortwave infrared (SWIR) reflectance bands to measure ligno-cellulose absorption features centered near 2100 and 2300 nm, with the objective of measuring and mapping non-photosynthetic vegetation (NPV), crop residue cover, and the adoption of conservation tillage practices within agricultural landscapes. Results could also apply to detection of NPV in pasture, grazing lands, and non-agricultural settings. Currently, there are no satellite data sources that provide narrowband or hyperspectral SWIR imagery at sufficient volume to map NPV at a regional scale. The Landsat Next mission, currently under design and expected to launch in the late 2020’s, provides the opportunity for achieving increased SWIR sampling and spectral resolution with the adoption of new sensor technology. This study employed hyperspectral data collected from 916 agricultural field locations with varying fractional NPV, fractional green vegetation, and surface moisture contents. These spectra were processed to generate narrow bands with centers at 2040, 2100, 2210, 2260, and 2230 nm, at various bandwidths, that were subsequently used to derive 13 NPV spectral indices from each spectrum. For crop residues with minimal green vegetation cover, two-band indices derived from 2210 and 2260 nm bands were top performers for measuring NPV (R2 = 0.81, RMSE = 0.13) using bandwidths of 30 to 50 nm, and the addition of a third band at 2100 nm increased resistance to atmospheric correction residuals and improved mission continuity with Landsat 8 Operational Land Imager Band 7. For prediction of NPV over a full range of green vegetation cover, the Cellulose Absorption Index, derived from 2040, 2100, and 2210 nm bands, was top performer (R2 = 0.77, RMSE = 0.17), but required a narrow (≤20 nm) bandwidth at 2040 nm to avoid interference from atmospheric carbon dioxide absorption. In comparison, broadband NPV indices utilizing Landsat 8 bands centered at 1610 and 2200 nm performed poorly in measuring fractional NPV (R2 = 0.44), with significantly increased interference from green vegetation.