Evergreen Forest Research Articles

Effects of Tiankeng topography on ecological strategy of karst evergreen and deciduous broad-leaved mixed forest

Tiankeng negative topography is a magnificent landscape located in karst evergreen and deciduous broad-leaved mixed forests. It has garnered increasing attention due to its geomorphological features, natural species refuge, and biodiversity conservation. Given its unique nature, it is likely that ecological strategy for resource allocation, key factors influencing species strategies, and underlying coexistence mechanisms of species in this habitat may differ from those found in general karst forests. Thus, we established three types of forest plots (The inside of Tiankeng forest, the fringe of Tiankeng forest and nearby typical karst forest) on two contrasting topographies (Tiankeng and mountain) and measured plant leaf functional traits and soil characteristics in a karst evergreen and deciduous broad-leaved mixed forest of southwest China. Based on measurements of leaf area, leaf dry matter content and specific leaf area in the “StrateFy” tool, we compared the effects of variations in ecological strategy by using Grime’s competitor (C), stress-tolerator (S), and ruderal (R) theory. The results showed that unique species in the inside of Tiankeng forests were 10.87% −17.98% higher than those in the nearby karst forests, and the soil phosphorus in the inside of Tiankeng forests was significantly higher than those in the nearby karst forests (P < 0.05). CSR strategies components were significantly different in the three forests. The component C and R in the inside of Tiankeng forests were higher than that in fringe of Tiankeng forests and nearby karst forests, indicating that the inside of Tiankeng forests can recruit more C- and R- selected species from the nearby forests. Furthermore, Tiankeng negative topography affected the distribution of species CSR strategy by altering soil characteristics, and the soil total phosphorus was the principal driver of species ecological strategy in the inside of Tiankeng forests. Our findings highlight the naturalness and specificity of Tiankeng species in evergreen and deciduous broad-leaved mixed forests, and differentiation in ecological strategy maybe one mechanism facilitates species coexistence. We suggest that the conservation of Tiankeng should not only focus on in-situ preservation of biodiversity but also consider the role of nearby karst forests in promoting sustainable development of Tiankeng.

Multi‐scale habitat overlap in two broad‐ranged sympatric Neotropical forest eagles reveals shared environmental space and habitat use

Quantifying resource partitioning between co‐occurring species can provide insight into processes facilitating coexistence by closely related species, a fundamental question in ecology. We tested whether the habitat requirements of two closely related Neotropical forest eagles, the Crested Eagle Morphnus guianensis and Harpy Eagle Harpia harpyja, differ at fine and coarse resolutions across their shared geographical range. Using landcover and topographical covariates, we quantified potential resource overlap first using higher resolution (30 arc‐s, ~ 1‐km2 data) generalized linear models (GLMs), and secondly using coarser‐grain (2.5 arc‐min, ~ 4.5‐km2 data) environmental ordination to capture the potential effect of scale on habitat overlap. The distribution of both eagles was largely explained by canopy tree species richness and canopy structural complexity, with peak suitability of 60–80% evergreen forest cover. Both eagles were negatively associated with mosaic forest and cultivated areas. From the GLMs, habitat overlap was &gt;93% in geographical space but was reduced to 73% when considering environmental space, a proxy for resource overlap. From ordination (principal component analysis), resource overlap was 67% in environmental space, with randomization tests supporting equivalent environmental space for both eagles. Our results suggest that at the continental scale, Crested and Harpy Eagles share identical environmental space when quantified at fine and broad scales, with little difference in distribution and habitat use. At the continental scale used here, both eagles can coexist, presumably with sufficient habitat heterogeneity for coexistence when they occur in close proximity. Therefore, further research is required at the local level to capture fully where coexistence at the local scale is facilitated more by fine‐scale habitat selection, or difference in diet between two species with indistinguishable habitat use.

Snow-corrected vegetation indices for improved gross primary productivity assessment in North American evergreen forests

North American evergreen forests cover large areas and influence the global carbon cycle. Satellite remote sensing has been used to track the phenology of ecosystem photosynthesis of these forests by detecting variation in vegetation optical properties associated with physiological and structural features, and most of these methods have been closely tied to vegetation greenness. However, in evergreens, the application of satellite data to monitor photosynthetic phenology is often limited by the lack of sensitivity of greenness-based indices. In this study, we identified 47 evergreen forest flux sites in North America that had MODIS observation overlapping with the flux tower records. We then calculated four vegetation indices using MODIS MAIAC data (MCD19A1), including NDVI, CCI, NIRv, and kNDVI, for the 47 flux sites and evaluated relationships between gross primary productivity (GPP) and vegetation indices across the North American evergreen forests. Our results showed that snow had substantial effects on the performance of all vegetation indices in tracking GPP phenology, particularly in the early spring when rapid changes occurred to both GPP and snow cover. Different vegetation indices were affected differently, indicating contradictory and confounding effects of snow on these indices. After correcting for the snow effects, both CCI and NIRv performed well in tracking GPP phenology, albeit for different reasons. CCI is sensitive to seasonal changes in the relative levels of chlorophyll and carotenoid pigments, which are closely tied to GPP phenology in evergreens. NIRv is sensitive to the absorbed photosynthetically active radiation and to the contribution of deciduous components to the overall optical properties. We also found that correlations between GPP and vegetation indices varied among ecoregions and climate classes. In general, regions with pronounced seasonal GPP patterns had stronger correlations between GPP and greenness-based indices than regions with weaker seasonal GPP patterns. These biome differences were less pronounced for CCI. The snow artifacts and complementary vegetation index effects reported here should be considered in any large-scale studies of GPP using reflectance-based indices from optical satellites.

Surface ozone risk to human health and vegetation in tropical region: The case of Thailand

Tropospheric ozone (O3) is a threat to vegetation and human health over the world, in particular in Asia. Knowledge on O3 impacts on tropical ecosystems is still very limited. An O3 risk assessment to crops, forests, and people from 25 monitoring stations across the tropical and subtropical Thailand during 2005–2018 showed that 44% of sites exceeded the critical levels (CLs) of SOMO35 (i.e., the annual Sum Of daily maximum 8-h Means Over 35 ppb) for human health protection. The concentration-based AOT40 CL (i.e., sum of the hourly exceedances above 40 ppb for daylight hours during the assumed growing season) was exceeded at 52% and 48% of the sites where the main crops rice and maize are present, respectively, and at 88% and 12% of the sites where evergreen or deciduous forests are present, respectively. The flux-based metric PODY (i.e., Phytotoxic Ozone Dose above a threshold Y of uptake) was calculated and was found to exceed the CLs at 1.0%, 1.5%, 20.0%, 1.5%, 0% and 68.0% of the sites where early rice, late rice, early maize, late maize, evergreen forests, and deciduous forests can grow, respectively. Trend analysis indicated that AOT40 increased over the study period (+5.9% year−1), while POD1 decreased (- 5.3% year−1), suggesting that the role of climate change in affecting the environmental factors that control stomatal uptake cannot be neglected. These results contribute novel knowledge on O3 threat to human health, forest productivity, and food security in tropical and subtropical areas.

Taxonomy and genesis of soils in contrasting ecosystems of Southern Western Ghats, India

Clay minerals formed during soil formation are imprints of ecosystem functioning and pedogenic processes in landscapes. The study evaluated the variations in taxonomy, soil weathering and pedogenic changes in contrasting forest soils in the Southern Western Ghats, India. Three different forest systems with comparable soil-forming factors vis-a-vis evergreen, moist deciduous and a man-made system (rubber plantation) were evaluated for physical, chemical, morphological, and pedogenic characteristics of the related soils. Soil profiles were dug up to 1.50 m in the selected ecosystems and horizon-wise soil samples were collected. All the pedons were classified in the soil order of Ultisols and subclassified as Ustic Palehumult (evergreen forest), Ustic Haplohumult (moist deciduous forest) and Typic Haplustult (rubber plantation), respectively. The soil pH was found to be acidic in all the ecosystems ranging from 4.6 to 5.8. Chlorite, hydroxyl interlayered vermiculite (HIV), mica, kaolinite, feldspars, gibbsite and quartz dominated the mineral assemblages in the clay fractions of soils of natural forest systems. The losses of SiO2 in the non-clay fraction and corresponding enrichment of the component in the clay-sized fraction in all horizons indicated an active continuous weathering process in all the systems of this region. Clay accumulation by way of formation and translocation was highest in the lower horizons of the soils of evergreen (Bt2 at a depth range of 28–57 cm) and moist deciduous (Bt3C at a depth range of 23–150 cm) forest, whereas it was highest at Bt1 at a depth range of 15–28 cm in the plantation soil. The depth variations in the clay formations in natural and manmade forest systems provide insights into ecosystems regulated profile development under natural and man-made systems in the humid tropics, a vital information gap hitherto in soil pedogenesis of the humid tropics. Such pedogenic assessments along with the factors responsible for such modifications would provide important inputs in developing soil health management strategies in the humid tropics.

Predicting the geographical distribution of Impatiens parasitica (Balsaminaceae), an epiphytic species endemic to the Southern Western Ghats, India

Impatiens parasitica Bedd. is an epiphytic balsam, endemic to the southern Western Ghats region of India. Maximum entropy distribution modelling (MaxEnt) was used for predicting the potential habitat suitability for this species. The Area Under the receiver operating characteristics Curve (AUC) value for training and test (0.95 and 0.817) is higher than 0.8, hence the model can be accepted. Jackknife test illustrates that temperature seasonality is the most contributed variable and Terrain Ruggedness Index (TRI) is the least contributed variable. The model predicted high suitability in the evergreen and semi-evergreen forests of the southern Western Ghats.

First Description of the Breeding Biology of the Spectacled Fulvetta (Fulvetta ruficapilla sordidior) in Southwest China.

The Spectacled Fulvetta (Fulvetta ruficapilla sordidior) is an endemic bird species to the southwest mountains of China, distributing from 1250 to 2500 m in the widespread broadleaved evergreen forest and occasionally in secondary scrubs. The present study describes its breeding biology for the first time. Fieldwork was conducted in the springs of 2017 and 2018 on Humashan Mountain, a hill mainly covered by secondary forest located at the eastern marginal of Kunming, the capital of Yunnan Province in Southwest China. This bird was found to initiate egg-laying mainly in March, and most nestlings fledged in late April and May. There were 16 nests found in total, which were located mainly in the dense shrubs at a height of 0.99 ± 0.40 m (n = 15). Of the 11 active nests, clutch size averaged 2.73 ± 0.45 (n = 11). Focal observations were made on nests; the incubation lasted for 13.67 ± 0.47 days (n = 3) with a notably high nest attendance, i.e., eggs were incubated 84.23% of the observation time. Nestlings fledged at 13.00 ± 0.71 days (n = 4), and parents feeding frequency increased as the nestlings grew. Overall, the cumulative hatching and fledgling rates were 71.43% and 35.71%, resulting in a nesting success rate of 45.45%.

Floral biology and pollinator captivating semiochemicals in Goniothalamus wynaadensis (Bedd.) Bedd. (Annonaceae) an endemic tree species of the Western Ghats

Goniothalamus wynaadensis (Bedd.) Bedd. (Family Annonaceae) is an endemic tree species growing in the evergreen forests of the Western Ghats up to 900m asl. The present study aims at understanding the functional floral traits and semiochemicals found in G. wynaadensis which support plant-pollinator interactions. The study revealed G. wynaadensis exhibits abbreviated anthesis (c.28hrs). Goniothalamus flowers exhibit unique features of cantharophily. The study indicated that outcrossing is promoted by protogyny, and pollination efficiency is enhanced by pollen aggregation, anthesis duration, and pollinator trapping which involves a close alignment between petal movements and the circadian rhythm of pollinators. Curculionidae and Nitidulidae beetles are effective pollinators of the plant. In beetle-pollinated flowers, floral scent is a crucial component for pollinator attraction. G. wynaadensis has a strong fruity aroma. The floral scent analysis performed using headspace solid- phase microextraction combined with GC-MS detected various semiochemicals that support plant-pollinator interactions. Ethyl butyrate, isobutyl acetate, 3 hydroxy 3 methyl 2 butanol, isopentyl acetate, and 3 methyl 1 butanol dominate the floral scent of G. wynaadensis.

Negative effects of the spatial clumping of thermal resources on lizard thermoregulation in a fragmented habitat

In ecosystems threatened by the expansion of croplands, habitat fragmentation and climate change, two of the main extinction drivers, may have thermoregulation-mediated interacting effects on demographic trends of terrestrial ectotherms. We studied the thermal biology of a metapopulation of the widespread Mediterranean lacertid Psammodromus algirus in ten fragments of evergreen or deciduous oak forests interspersed among cereal fields. We obtained thermoregulation statistics (selected temperature range, body and operative temperatures, thermal quality of the habitat, and precision, accuracy, and effectiveness of thermoregulation) that could be compared among fragments and with conspecific populations living in unfragmented habitat. We also measured the selection (use vs. availability) and spatial distribution of sunlit and shaded patches used for behavioral thermoregulation in fragments, and we estimated operative temperatures and thermal habitat quality in the agricultural matrix surrounding the fragments. Variation of the thermal environment was much larger within fragments than among them, and thermoregulation was accurate, precise, and efficient throughout the fragmented landscape; its effectiveness was similar to that of previously studied unfragmented populations. The average distance between sunlit and shaded patches was shorter in deciduous than in evergreen fragments, producing a more clumped distribution of the mosaic of thermal resources. Consequently, in evergreen habitat the cost of thermoregulation was higher, because lizards were more selective in their choice of sunlit sites (i.e. they used sunlit patches closer to shade and refuge than expected at random, and the extent of such selection was larger than at deciduous habitat). Temperatures available in croplands were too high to allow lizard dispersal, at least in the post-breeding season. This result confirms the role of croplands as a thermal barrier that promotes inbreeding and associated fitness losses in isolated fragments, and it forecasts a dark future for populations of forest lizards in agricultural landscapes under the combined effects of habitat fragmentation and global warming.

Abundance and distribution of plant derived leaf waxes (long chain n-alkanes & fatty acids) from lake surface sediments along the west coast of southern South America: Implications for environmental and climate reconstructions

Southern South America is the only large landmass that extends through the core of the Southern Westerly Winds (SWW), controlling hydrological and ecosystem variability in the region. In fact, the vegetation along the west coast changes from Temperate and Valdivian Rain Forest to the North Patagonian Evergreen Forest (ca. 42°S) due to the latitudinal influence of the SWW. Climate is an important driver of organic matter accumulation in lakes, hence changes in vegetation would be recorded in lacustrine sedimentary archives. This study evaluated leaf waxes contained in lake surface sediments as indicators of climate change along the west coast of southern South America, providing a biogeochemical dataset for ongoing and future (paleo)climate and environmental research. The fatty acid and n-alkane sediment leaf wax datasets are compared with latitudinal, orographic, and climatic (Mean Annual air Temperature [MAT] & Precipitation [MAP]) trends extracted from a monthly gridded reanalysis product of the Climate Forecast System Reanalysis. Fatty acids are more abundant than n-alkanes, with high abundances characterizing the transition between seasonal and year-round precipitation along the coast (ca. 42°S). The abundance of both leaf wax groups increases with MAP, suggesting precipitation as the main control on sedimentary leaf wax delivery to the lake sediments in the study area. The Carbon Preference Index (CPI) of the two groups show opposite trends, but both highlight the climate transition at ca. 42°S, and have a linear relationship with MAP. The opposite significant trends between n-alkane CPI and fatty acid CPI with MAP are interpreted as higher n-alkane production at much higher precipitation because leaf wax fatty acids are the precursors of n-alkanes. Hence, past periods during which these leaf waxes show opposite trends in CPI might be interpreted as a precipitation change, especially if additional information such as pollen, diatoms, chironomids and stable isotopes is available.

FOREST ECOSYSTEM SERVICES AND THEIR VALUATION IN MIZORAM, THE EASTERN EXTENSION OF THE HIMALAYA

This paper examines forest ecosystem services and their valuation in Mizoram, the eastern extension of the Himalaya. This study was conducted by applying two approaches – qualitative and quantitative. The data were mainly gathered from secondary sources – the State of Environment Report of Mizoram, Aizawl, and the Ministry of Environment, Forests, and Climate Change, Aizawl, Mizoram. Data on wetlands within the forest areas were also gathered from the Forest Survey of India 2019. Field observation was conducted to verify the data on the ground. The author visited several national parks and wildlife sanctuaries and observed the rich forest ecosystem services. Mizoram obtains a rich floral diversity ranging from tropical wet forests to sub-temperate wet and dry forests and montane evergreen forests. About 86% of the total geographical area is covered by forest. Of which, 50% forest area is covered by bamboo forests. Here, bamboo has 27 species. The valuation of forest ecosystem services – tangible and intangible was carried out and benefits from different forest products were calculated. The study reveals that Mizoram has a very high value in ecosystem services. The annual valuation of tangible ecosystem services was noted from fuelwood, followed by timber, small wood, and poles. In terms of annual valuation of intangible ecosystem services, the highest was from pollination, followed by food and livelihood security, and prevention of soil erosion, and landslides. However, the use of ecosystem services is just negligible. Most of the services are unused. Even, tourism, mainly natural and eco-tourism has high potential but it is not developed yet. If the ecosystem services are used sustainably, the rural poor can enhance their livelihood, and the state government can earn sufficient revenue.

Uncovering the diversity of rodents and shrews in the Chebera Churchura National Park, Ethiopia

Abstract The recently established Chebera Churchura National Park represents a mosaic of savanna and montane evergreen forest. A report on small mammals (2013) showed their relatively high diversity, but species identification was based only on external morphology. We conducted a new field survey and genetic analyses to shed light on diversity and biogeographical affinities of small mammals in this under-explored national park. Based on results of mitochondrial DNA barcoding, 14 species of rodents and two species of shrews, including Crocidura turba (new to the Ethiopian fauna), were identified. Moreover, a new taxon of gerbils – presumably representing a new species – of the genus Gerbilliscus was discovered. We show that forest and savanna species often inhabit the same localities, which can be explained by the mosaic nature of biotopes. These results document the uniqueness of Chebera Churchura NP, especially in comparison with other Ethiopian national parks, and argue for its protection and further development.

Where do the Tropical Owls Roost: Multiscale Habitat Variables Explain Roost Site Selection by Two Sympatric Otus Species in the Andaman Archipelago, India

Understanding the niche differentiation between sympatric species that permit species to coexist and partition resource is the central concept in ecology. In this context, we evaluated the differences in roost site resources between two sympatric Otus species — Andaman Scops-owl Otus balli and Oriental Scops-owl Otus sunia in the Andaman Islands using a multi-scale approach. We measured variables that influence roost site use by owls at three different scales (tree, patch and macro). A total of 38 and 69 independent roost locations of O. balli and O. sunia respectively were recorded. We found that both species showed a high preference for Arecaceae plants at tree scale, possibly for their spiny structures that could offer protection. But both species showed different selection patterns at the patch and macro scales. At the patch scale, O. balli selected roosting sites in patches with relatively mature tree stands (characterised by higher tree height, girth at breast height and canopy cover) with thick understory cover (understory cover, height, and herbaceous elements). In contrast, O. sunia was found to select trees in secondary or highly disturbed forests. Land use and land cover types distinguish both species from their habitat preferences at a macro scale with a very low predicted overlap. The area of potential roost sites is very low for O. balli when compared to O. sunia. Our findings suggest that the two sympatric species' preferences for roost sites are shaped by the characteristics of evergreen forests of the Andaman Islands. Hence, any further changes to this forest type may have adverse effects on the endemic O. balli.

Paleofires and vegetation in a Late Pleistocene paleolake (&gt;43 ka bp) of the savannas of central Brazil

ABSTRACTThis study investigates paleoenvironmental changes at the Paleolagoa Seca site, an Upper Quaternary locality of lacustrine origin in central Brazil. We present charcoal and pollen analyses of this sedimentary sequence, and assess how they compare with previously published fossil macroflora and paleoclimatic reconstructions of the same site and adjacent localities. We identified a mosaic of savannas, forests and flooded environments before 43 ka bp with the presence of evergreen forest formations. For this period, we found charcoal particles resulting from natural fires that represent the oldest Quaternary record of fire in the Cerrado. By conducting a morphological analysis of charcoal particles, we were able to identify that the primary constituents of fire fuel were grasses, which suggests that surface fires were prevalent. During this Pleistocene wet phase, fire probably played a vital role in preserving areas of open vegetation. In contrast, at ~43 ka bp, an open landscape and a drier‐than‐present climate characterized the Paleolagoa Seca site.

Spatial patterns of China's carbon sinks estimated from the fusion of remote sensing and field-observed net primary productivity and heterotrophic respiration

Accurately assessing the carbon sink and spatial distribution pattern of China's terrestrial ecosystems is of great significance to the implementation of climate change and carbon neutrality strategy. However, the views of various studies are still very controversial due to the differences in carbon sink estimation methods and data sources. In this study, vegetation net primary productivity (NPP) and ecosystem heterotrophic respiration (Rh) estimation models were constructed based on machine learning methods by fusing multisource data, such as remote sensing and ground observation data. The magnitude and spatial pattern of carbon sink in China from 2000 to 2018 were then revealed, and the carbon sink capacity of various ecosystems was quantitatively assessed. The main conclusions include the following: (1) The use of scale-matched carbon input and output data can help reduce the system error in carbon sink estimation. (2) China's terrestrial ecosystem carbon sink since the twenty-first century is approximately 0.458 Pg C/yr, which is equivalent to 22.72% of China's anthropogenic carbon emissions. (3) Deciduous forest has a higher carbon sink capacity than evergreen forest, while coniferous forest has a more stable carbon sink capacity than broad-leaved forest. The magnitude and spatial distribution of carbon sink in China reported in this study provides a scientific reference for achieving carbon neutrality and sustainable development.

Using normalised difference infrared index patterns to constrain semi-distributed rainfall–runoff models in tropical nested catchments

Abstract. A parsimonious semi-distributed rainfall–runoff model has been developed for flow prediction. In distribution, attention is paid to both the timing of the runoff and the heterogeneity of moisture storage capacities within sub-catchments. This model is based on the lumped FLEXL model structure, which has proven its value in a wide range of catchments. To test the value of distribution, the gauged upper Ping catchment in Thailand has been divided into 32 sub-catchments, which can be grouped into five gauged sub-catchments at which internal performance is evaluated. To test the effect of timing, first the excess rainfall was calculated for each sub-catchment, using the model structure of FLEXL. The excess rainfall was then routed to its outlet using the lag time from the storm to peak flow (TlagF) and the lag time of recharge from the root zone to the groundwater (TlagS), as a function of catchment size. Subsequently, the Muskingum equation was used to route sub-catchment runoff to the downstream sub-catchment, with the delay time parameter of the Muskingum equation being a function of channel length. Other model parameters of this semi-distributed FLEX-SD model were kept the same as in the calibrated FLEXL model of the entire upper Ping River basin (UPRB), controlled by station P.1 located at the centre of Chiang Mai province. The outcome of FLEX-SD was compared to the (1) observations at the internal stations, (2) calibrated FLEXL model, and (3) the semi-distributed URBS model – another established semi-distributed rainfall–runoff model. FLEX-SD showed better or similar performance during calibration and especially in validation. Subsequently, we tried to distribute the moisture storage capacity by constraining FLEX-SD on patterns of the NDII (normalised difference infrared index). The readily available NDII appears to be a good proxy for moisture stress in the root zone during dry periods. The maximum moisture-holding capacity in the root zone is assumed to be a function of the maximum seasonal range of NDII values and the annual average NDII values to construct two alternative models, namely FLEX-SD-NDIIMaxMin and FLEX-SD-NDIIAvg. The additional constraint on the moisture-holding capacity (Sumax) by NDII, particularly in FLEX-SD-NDIIAvg, improved both the model performance and the realism of its distribution across the UPRB, which corresponds linearly to the percentage of evergreen forests (R2=0.69). To check how well the models represents simulated root zone soil moisture (Sui), the performance of the FLEX-SD-NDII models was compared to the time series of the soil water index (SWI). The correlation between the Sui and the daily SWI appeared to be very good and was even better than the correlation with the NDII, which does not provide good estimates during wet periods. The SWI, which is model-based, was not used for calibration but appeared to be an appropriate index for validation.

The relationship between forest fire and deforestation in the southeast Atlantic rainforest.

Given the scarcity of studies relating fire to deforestation in the Atlantic Forest and great economic and ecological importances of this biome, this work aimed to investigate this relationship in the Atlantic Forest of the State of São Paulo, trying to answer whether deforestation is related to fire events in up to three years, if there are regions most affected by this relationship and what land use and land cover predominates after fire and deforestation in these areas. The study was carried out in Evergreen Forest and Semideciduous Seasonal, along the time series from 2000 to 2019 using the MapBiomas Project database to survey deforested and burned sites with moderate to high severity fires. Burning positively influenced deforestation in EGF in eight of 19 years studied (2001, 2004, 2005, 2007, 2008 and 2009, 2013 and 2015), while only for three years in the SSF. Burning followed by deforestation corresponded to only 3.2% of the total deforestation, located mainly in the eastern region of the state with the highest density in the EGF. Most of these areas have been converted to agriculture. This study provides the first indication that, generally, fire is not a driver of deforestation in the southeast Atlantic Forest.

Mapping Eucalyptus plantation in Guangxi, China by using knowledge-based algorithms and PALSAR-2, Sentinel-2, and Landsat images in 2020

Eucalyptus plantations promote the economic development of forestry in southern China, but many studies have reported their negative environmental impacts, such as high water resource usage of certain species of Eucalyptus plants and losses in biodiversity. To date, annual maps of Eucalyptus plantations at large scales with high spatial resolutions are not yet available. Here, we investigated the spectral properties of Eucalyptus plantations and developed a knowledge-based Eucalyptus plantation mapping algorithm. We produced annual maps of Eucalyptus plantation at 10-m spatial resolution in the Guangxi Zhuang Autonomous Region (Guangxi), China, using our proposed algorithm and images of ALOS PALSAR-2, Sentinel-2, and Landsat (ETM+/OLI) in a single year. First, we generated annual evergreen forest maps using PALSAR-2 and Landsat/Sentinel-2-based vegetation index time series data. Second, we distinguished Eucalyptus plantations from the evergreen forest layer using the unique biophysical features of Eucalyptus plantations, the Sentinel-2 red edge bands, and Landsat/Sentinel-2-based enhanced vegetation index (EVI). Our resultant 2020 Eucalyptus plantation map had high producer's, user's, and overall accuracies of 0.85, 0.89, and 0.96, respectively. There were 3.10 × 106 ha of Eucalyptus plantation in Guangxi in 2020. Among the 14 administrative units, Wuzhou City had the largest Eucalyptus plantation area in Guangxi, followed by Nanning, Baise, and Chongzuo cities. We demonstrated the potential of knowledge-based mapping approaches for identifying evergreen forest and Eucalyptus plantations in complex and fragmented landscapes where cloud cover is frequent. Our 10-m Eucalyptus plantation map is the most current dataset available and can be used to assist the sustainable production of Eucalyptus, ecological assessments, and conservation.

Improved Vegetation Photosynthetic Phenology Monitoring in the Northern Ecosystems Using Total Canopy Solar‐Induced Chlorophyll Fluorescence Derived From TROPOMI

AbstractSolar‐Induced chlorophyll Fluorescence (SIF) from the TROPOspheric Monitoring Instrument (TROPOMI) with substantially improved spatiotemporal resolutions provides a new potential to improve satellite‐based phenology monitoring. The performance of TROPOMI SIF for tracking vegetation photosynthetic phenology, and how it compares to conventional vegetation indices (VIs)‐based approaches, however, have not been adequately assessed. Total canopy SIF, as a better proxy of Gross Primary Productivity (GPP) than original directional SIF, is a new SIF to estimate phenology while its performance has not been investigated. This study assesses the capability of TROPOMI SIF before and after canopy correction for phenology monitoring and improves our understanding of these questions. Benchmarked by tower‐based GPP, TROPOMI SIF generally performed better than VIs, especially for capturing the End Of Season (EOS) of vegetation photosynthetic activity at deciduous broadleaf forest (DBF), evergreen forest (ENF), and croplands (CRO) sites, but not for Start Of Season (SOS). This suggested that the advantage of SIF over VIs depended on phenological metrics. The total canopy SIF emission obtained through canopy correction generally performed better than the original SIF retrievals, especially in estimating the EOS of forest sites (DBF, MF, ENF), but soil correction did not further improve the accuracy of phenological monitoring. When comparing SIF‐ and VI‐based phenological metrics over northern terrestrial ecosystems, SIF showed earlier senescence date widely, while the differences in onset date were region dependent. These results indicate the necessity of canopy correction to convert directional SIF to canopy total SIF when using satellite SIF products to estimate phenological metrics.

Microbial P limitation in tropical forest soils could be overestimated: Insight from a sorption experiment and a meta-analysis

The prevailing paradigm for soil microbial activity in tropical forests is that microbial activity is limited by phosphorus (P) availability, and thus exogenous P addition stimulates organic matter decomposition. This idea has been testified by studies demonstrating that experimental P addition accelerates soil respiration. Contrary to this conventional view, we hypothesize that the increased rates of soil microbial respiration could be due to the release of organic material from the surface of soil minerals when P is added, because P competes with organic C for binding sites in soil particles. Here we performed a sorption experiment in a tropical evergreen forest in southern China, where P addition had previously been reported to stimulate soil respiration but suppressed leaf litter decomposition. P addition to soils significantly increased dissolved organic carbon (DOC) content, which was extracted immediately after P addition and under a cold temperature where microbial activity was suppressed. This result can explain why P addition stimulated soil respiration but not litter decomposition in our study site. Namely, P addition abiotically elevated microbially-available C through the release of organic matter from the soil mineral surface. We also conducted a meta-analysis using data obtained in forest ecosystems, demonstrating that previous studies have consistently reported that P addition led to higher response ratios of soil microbial respiration than litter decomposition. Our findings suggest that the prevailing paradigm (i.e., soil microbial activity in tropical forests is limited by P availability) might require re-evaluation.