4. Southern deciduous forests

Territorial behaviour and hormones of pied flycatchers in optimal and suboptimal habitats

Dry deposition and canopy leaching rates in deciduous and coniferous forests of the Georgia Piedmont: an assessment of a regression model

The floristic composition and diversity of tropical dry deciduous and gallery forests were studied in Chacocente Wildlife Refuge, located on the Pacific coast in Nicaragua during 1994 and 2000. Density, dominance and frequency as well as species and family important values were computed to characterize the floristic composition. A variety of diversity measures were also calculated to examine heterogeneity in each forest community. A total of 29 families, 49 genera and 59 species were represented in 2 ha dry deciduous forest. In the gallery forest, the number of families, genera and species recorded in 2000 inventory was 33, 48 and 58, respectively and slightly higher than the 1994 inventory. The number of stems ≥10 cm dbh varied from 451 to 489 per hectare in the deciduous forest, and from 283 to 298 per hectare in the gallery forest. The basal area was much larger for species in the gallery than dry deciduous forest. Fabaceae, sub family Papilionoideae, was the most specious family in the deciduous forest while Meliaceae was the dominant family in the gallery forest. Similarity in species composition and abundance between deciduous and gallery forests was low. In terms of species diversity, the gallery forest was found more diverse than the deciduous forest using Fisher’s diversity index. Both forest communities were characterized by a typical inverse J shape. Therefore, emphasis should be given to the protection of rare species, i.e. as the forests are still under continued human pressure, an immediate action should be taken to conserve the remaining flora.

Atmospheric deposition and above-ground cycling of sulfur (S) were evaluated in adjacent deciduous and coniferous forests at the Panola Mountain Research Watershed (PMRW), Georgia, U.S.A. Total atmospheric S deposition (wet plus dry) was 12.9 and 12.7 kg ha-1 yr-1 for the deciduous and coniferous forests, respectively, from October 1987 through November 1989. Dry deposition contributes more than 40% to the total atmospheric S deposition, and SO2 is the major source (∼55%) of total dry S deposition. Dry deposition to these canopies is similar to regional estimates suggesting that 60-km proximity to emission sources does not noticeably impact dry deposition at PMRW. Below-canopy S fluxes (throughfall plus stemflow) in each forest are 37% higher annually in the deciduous forest than in the coniferous forest. An excess in below-canopy S flux in the deciduous forest is attributed to leaching and higher dry deposition than in the coniferous forest. Total S deposition to the forest floor by throughfall, stemflow and litterfall was 2.4 and 2.8 times higher in the deciduous and coniferous forests, respectively, than annual S growth requirement for foliage and wood. Although S deposition exceeds growth requirement, more than 95% of the total atmospheric S deposition was retained by the watershed in 1988 and 1989. The S retention at PMRW is primarily due to SO42- adsorption by iron oxides and hydroxides in watershed soils. The S content in white oak and loblolly pine boles have increased more than 200% in the last 20 yr, possibly reflecting increases in emissions.

In several areas in Northeast Thailand, evergreen and deciduous forests coexist under uniform terrain and climatic conditions. We compared depth and physical properties of soils between evergreen and deciduous forests in the Sakaerat Environmental Research Station to clarify what factor determines their distribution. The averaged soil depths were 79 ± 27 cm and 135 ± 58 cm in the deciduous and evergreen forests, respectively. The soils in the deciduous forests were relatively coarser in soil texture than those in the evergreen forests, particularly in the surface layers. The average available water capacity of the solum was lower in the deciduous forest soils (78 mm) than in the evergreen forest soils (123 mm). Compared with the evapotranspiration from the evergreen forest in the study area, the available water capacity of the evergreen forest soil was almost the same as the water deficit during the dry season (November–February), while that of the deciduous forest soil was lower and insufficient to maintain the evapotranspiration. These results suggest that the distribution of deciduous and evergreen forests in the study area was associated with soil water availability, which mainly depends on soil depth.

The ongoing climate change‐induced shifts in flowering phenology have emerged as a consequential force impacting biodiversity and ecosystems. Despite the globally recognized significance of flowering phenology as a key reproductive attribute, studies in subtropical regions have been relatively fewer, particularly in comparison to temperate and cold regions. Additionally, the nuanced response of deciduous and evergreen plants to climate change remains insufficiently explored. In addressing this gap, we built a phenological model and a generalized linear mixed effect model to assess the differential responses of key flowering phenological traits, that is, first flowering date (FFD), peak flowering date (PFD), end of flowering date (EFD), and flowering duration (FD), to climate factors (temperature and precipitation) between deciduous and evergreen plants. We observed distinct responses in flowering phenological traits to climate change between deciduous and evergreen plants. Specifically, the advancement of FFD, PFD, and EFD in deciduous in response to temperature rise exceeded that in evergreen plants. FD in evergreen plants exhibited a stronger extension to temperature increase compared to deciduous. Conversely, the phenological change of evergreen plants in response to decreasing precipitation was greater than that of deciduous ones. Since temperature is a decisive climatic factor in affecting phenological changes, climate change‐induced advances in flowering phenology of deciduous plants are still larger than evergreen plants. Projections from our phenological model under future climate scenarios (SSP 1‐2.6 and SSP 5‐8.5) indicate a continuous enlargement of difference in flowering phenology between deciduous and evergreen plants, with this trend escalating into the future (2100>2070>2050>2030). The larger extension in FD of evergreens to climate change suggests a potential increase in their proportion within subtropical forest communities relative to deciduous plants. These insights contribute significantly to our understanding of the intricate dynamics of climate‐induced changes in subtropical plant ecosystems.

Summary Neotropical deciduous forests are threatened by anthropogenic activities and only a small area is protected against exploitation. In contrast to other Neotropical forest types, not much is known about the effect of habitat disturbance on deciduous forest bird communities. In the present study, we examine the effects of human disturbance on a deciduous forest bird community in the Andean foothills of Bolivia. Bird community composition was determined by means of point count surveys in three forest types, i.e. undisturbed deciduous and semi-deciduous forest, and disturbed forest habitat. Habitat disturbance was estimated indirectly by measuring vegetation structure variables in these forests. The effect of habitat disturbance was subsequently examined at bird community level (species richness, species abundance and diversity indices) and functional group level (habitat preference categories and foraging guild). Differences in community composition and reduced species abundance could clearly be related to habitat disturbance. However, results also indicated that sensitivity to disturbance varied among functional groups. Humid forest specialists showed the strongest response to habitat disturbance, predominantly bark-gleaning insectivores, canopy insectivores, understorey insectivores and ground-dwelling species, whereas dry forest specialists were not affected by disturbance. The present study suggests that anthropogenic disturbance negatively influenced the forest bird community in the investigated deciduous forest in Bolivia. This may indicate that conservation of both deciduous and semi-deciduous forest remnants is relevant for a diverse montane bird community in South America. Because various bird species typical of deciduous forests may also be able to survive in partly disturbed forests, conservation strategies should not only be focussed on the protection of pristine remnants but should also include secondary forest edge zones.

Forest nitrogen use efficiency (NUE) values are often compared along N-availability gradients or between forest types, without adjustment for climate. In this study, NUE (leaf-fall mass/leaf-fall N) was examined with concurrent data on forest type, N expenditure (leaf-fall N), foliar life-span, and major climatic gradients. The hypotheses were that (1) NUE is negatively correlated with N expenditure, (2) NUE is positively correlated with climatic factors such as temperature and light availability, and (3) NUE differs between deciduous and evergreen forests. The data set included 76 deciduous broadleaf forests, 52 evergreen coniferous forests, and 6 mixed forests in North America. All three hypotheses are supported by best-fit models. NUE decreases by about 30% for each doubling of N expenditure for both deciduous and evergreen forests. It increases over 50% in deciduous forests and nearly triples in evergreen forests across the climate data range. Evergreen forests tend to have higher NUEs than deciduous forests only in areas with relatively high temperatures and light availability. This climate–forest type interaction is attributed to contrasts between the forest types in terms of growth period, and regional patterns of foliar N concentration and N resorption.

Parana river basin has one of the major fragments of Decidual Seasonal Forest in Brazil. This vegetation is widely fragmented due to the selective wood exploitation and the growth of pasture areas, what justifies the development of studies in order to understand its dynamics and preserve its diversity. Thus, the present study aimed at defining a method for regional identification of the Deciduous Forest in the Parana river basin. The deciduous forest has a typical phenological cycle in comparison with other savanna physiognomies. Due these characteristics, a temporal series of normalized difference vegetation index (NDVI) images of the MODIS sensor was used for its detection. The adopted methodology may be subdivided into the following steps: (a) elaboration of the 3D cube of NDVI images, where the z profile corresponding to temporal signature or NDVI spectrum, (b) noise elimination using the Minimum Noise Fraction (MNF) transformation, and (c) NDVI temporal variability examination of deciduous forest vegetation, with the establishment of the best NDVI band applied in the vegetation index differencing method. The Deciduous Forest presents a typical NDVI spectral behaviour, with higher values in the raining season and lower values in the dry season, what makes this kind of vegetation different from others. The employment of a changing detection algorithm between two images: one for the dry season and the other for the raining season enhances the localization of the Decidual Seasonal Forest. So, the methodology has proved to be effective for regional delimitation of Deciduous Forests considering the MODIS sensor. Considering the changing detection method, Deciduous Forest region is characterized by presenting NDVI alteration values.

A study of alternative locality of botanic garden developments and flora explorations in deciduous monsoon forests based on forest type distribution in Nusa Tenggara has been carried out. The forest type distribution was allegedly obtained through overlay process of vegetation formation and satellite image of forest covering using software Arc-GIS versi 10.3. in Nusa Tenggara. A total of five forest types succeeded in mapping of Nusa Tenggara forests namely, evergreen rain forests (1008.77 km2), semi-evergreen rain forests (2944.98 km2), moist deciduous forests (6120.36 km2), dry deciduous forests (7955.18 km2) and thorn forests (93.07 km2). The existing forests in Nusa Tenggara reached 18122.36 km2 or 27.30%, in total. All of regencies/cities in Nusa Tenggara seemed appropriate to botanic garden developments, themed deciduous monsoon forests, based on habitat compatibility. At least each botanic garden developments covering an area of 10 ha consist of 500 species of potential trees collection. There are 58 coordinate point sites in which scattered in13 sub types of deciduous monsoon forests as a guide for exploration sites are recommended. It is about 487 species (trees, shrubs and woody plants) are potentially collected. Several large families are found such as Leguminosae (49 species), Malvaceae (28 species), Meliaceae (26 species), Moraceae (25 species), Rubiaceae and Rutaceae (23 species on each). A total of 59 species are listed in the IUCN red list, particularly four endangered species and 12 vulnerable species as put priority when conducting plant explorations.

Site requirements of the endangered rosewood Dalbergiaoliveri in a tropical deciduous forest in northern Thailand

Vegetation response to Holocene climate change in monsoon-influenced region of China

Abstract. The annual carbon and water dynamics of two eastern North American temperate forests were compared over a 6-year period from 2012 to 2017. The geographic location, forest age, soil, and climate were similar between the two stands; however, stand composition varied in terms of tree leaf-retention and shape strategy: one stand was a deciduous broadleaf forest, while the other was an evergreen needleleaf forest. The 6-year mean annual net ecosystem productivity (NEP) of the coniferous forest was slightly higher and more variable (218±109 g C m−2 yr−1) compared to that of the deciduous forest NEP (200±83 g C m−2 yr−1). Similarly, the 6-year mean annual evapotranspiration (ET) of the coniferous forest was higher (442±33 mm yr−1) than that of the deciduous forest (388±34 mm yr−1), but with similar interannual variability. Summer meteorology greatly impacted the carbon and water fluxes in both stands; however, the degree of response varied among the two stands. In general, warm temperatures caused higher ecosystem respiration (RE), resulting in reduced annual NEP values – an impact that was more pronounced at the deciduous broadleaf forest compared to the evergreen needleleaf forest. However, during warm and dry years, the evergreen forest had largely reduced annual NEP values compared to the deciduous forest. Variability in annual ET at both forests was related most to the variability in annual air temperature (Ta), with the largest annual ET observed in the warmest years in the deciduous forest. Additionally, ET was sensitive to prolonged dry periods that reduced ET at both stands, although the reduction at the coniferous forest was relatively larger than that of the deciduous forest. If prolonged periods (weeks to months) of increased Ta and reduced precipitation are to be expected under future climates during summer months in the study region, our findings suggest that the deciduous broadleaf forest will likely remain an annual carbon sink, while the carbon sink–source status of the coniferous forest remains uncertain.

Forest ecosystems play a critical role in maintaining key ecosystem services and functions. However, the impacts of climate change have become apparent in recent years. Long-term forest observation data suggest that deciduous forests are being replaced by evergreen tree species, potentially as a result of climate change. Detecting such ecosystem changes at an early stage is crucial for assessing the impacts of climate change and implementing effective management. In this study, we aim to develop a method for identifying evergreen trees in deciduous broadleaf forests where the effects of climate change are becoming apparent. Specifically, we employed cost-effective and efficient UAV-LiDAR technology. By focusing on the deciduous season, we effectively enhanced the detection of evergreen trees, as their presence becomes more distinguishable during this period.The study was conducted in a 6-hectare plot within the deciduous broadleaf forests of the Ogawa Forest Reserve in Japan, a site where long-term forest monitoring has been conducted. This site harbors Pieris japonica subsp. japonica (hereafter, PJ), an evergreen shrub that has shown an increase in recent years. Other species that retain green leaves during the deciduous season, such as dwarf bamboo (Sasa) and epiphytic plants, are also present. To ensure effective detection of PJ, we first stratified the acquired LiDAR data into different canopy layers (upper canopy trees and multiple understory layers). We then determined the required point density for rational segmentation of PJ. Using RGB data, we extracted "green" points for each canopy layer. This method effectively excluded dwarf bamboo and epiphytic plants, enabling the accurate extraction of PJ. The study demonstrated that combining UAV-LiDAR with RGB data is highly effective for identifying understory evergreen trees. This approach facilitates the extraction of "green" objects by canopy layer in deciduous forests during the deciduous season. This method would be not only efficient for detecting forest changes but also applicable to identifying invasive species and enhancing forest management practices.

We examined differences in the responses of deciduous and evergreen broadleaved trees to fluvial disturbance and light environment near a river-facing forest edge in order to identify the factors limiting the distribution of deciduous trees, which are important components of warm-temperate mountainous riparian forests. Deciduous trees tended to be distributed on lower terraces of less than 2-m relative elevation from the water level, which corresponded with sites suffering from strong bank erosion due to high flood frequency. On the other hand, evergreen trees showed an opposite trend of distribution, indicating that high flood frequency associated with strong erosion-dominated soil disturbances might be a constraint for their establishment and/or survival. Furthermore, crowns of deciduous trees tended to be in the canopy layer at the forest edge, with fewer individuals observed beneath the canopy of evergreen trees, even at the forest edge. In contrast, evergreen trees were concentrated in the understory of the forest interior. These observations suggested that the light environment is the predominant factor affecting the establishment and survival of deciduous trees in warm-temperate mountainous riparian forests; however, the river-facing forest edge beneath the evergreen canopy is not a suitable habitat for deciduous trees. We concluded that erosion-dominated soil disturbance on lower terraces provides suitable habitats for deciduous trees by facilitating their reaching the canopy layer by limiting the establishment and/or survival of evergreen trees.