Forest Pattern, Fire, and Climatic Change in the Sierra Nevada

In the Sierra Nevada, distributions of forest tree species are largely controlled by the soil-moisture balance. Changes in temperature or precipitation as a result of increased greenhouse gas concentrations could lead to changes in species distributions. In addition, climatic change could increase the frequency and severity of wildfires. We used a forest gap model developed for Sierra Nevada forests to investigate the potential sensitivity of these forests to climatic change, including a changing fire regime. Fuel moisture influences the fire regime and couples fire to climate. Fires are also affected by fuel loads, which accumulate according to forest structure and composition. These model features were used to investigate the complex interactions between climate, fire, and forest dynamics. Eight hypothetical climate-change scenarios were simulated, including two general circulation model (GCM) predictions of a 2 × CO₂ world. The response of forest structure,species composition, and the fire regime to these changes in the climate were examined at four sites across an elevation gradient. Impacts on woody biomass and species composition as a result of climatic change were site specific and depended on the environmental constraints of a site and the environmental tolerances of the tree species simulated. Climatic change altered the fire regime both directly and indirectly. Fire frequency responded directly to climate's influence on fuel moisture, whereas fire extent was affected by changes that occurred in either woody biomass or species composition. The influence of species composition on fuel-bed bulk density was particularly important. Future fires in the Sierra Nevada could be both more frequent and of greater spatial extent if GCM predictions prove true. Received 5 May 1998; accepted 4 November 1998.     

Trends in Global Vegetation Activity and Climatic Drivers Indicate a Decoupled Response to Climate Change

Detailed understanding of a possible decoupling between climatic drivers of plant productivity and the response of ecosystems vegetation is required. We compared trends in six NDVI metrics (1982–2010) derived from the GIMMS3g dataset with modelled biomass productivity and assessed uncertainty in trend estimates. Annual total biomass weight (TBW) was calculated with the LINPAC model. Trends were determined using a simple linear regression, a Thiel-Sen medium slope and a piecewise regression (PWR) with two segments. Values of NDVI metrics were related to Net Primary Production (MODIS-NPP) and TBW per biome and land-use type. The simple linear and Thiel-Sen trends did not differ much whereas PWR increased the fraction of explained variation, depending on the NDVI metric considered. A positive trend in TBW indicating more favorable climatic conditions was found for 24% of pixels on land, and for 5% a negative trend. A decoupled trend, indicating positive TBW trends and monotonic negative or segmented and negative NDVI trends, was observed for 17–36% of all productive areas depending on the NDVI metric used. For only 1–2% of all pixels in productive areas, a diverging and greening trend was found despite a strong negative trend in TBW. The choice of NDVI metric used strongly affected outcomes on regional scales and differences in the fraction of explained variation in MODIS-NPP between biomes were large, and a combination of NDVI metrics is recommended for global studies. We have found an increasing difference between trends in climatic drivers and observed NDVI for large parts of the globe. Our findings suggest that future scenarios must consider impacts of constraints on plant growth such as extremes in weather and nutrient availability to predict changes in NPP and CO₂ sequestration capacity.     

Tree Community Change across 700 km of Lowland Amazonian Forest from the Andean Foothills to Brazil

We describe patterns of tree community change along a 700-km transect through terra firme forests of western Amazonia, running from the base of the Andes in Ecuador to the Peru–Brazil border. Our primary question is whether floristic variation at large scales arises from many gradual changes or a few abrupt ones. Data from 54 1-ha tree plots along the transect support the latter model, showing two sharp discontinuities in community structure at the genus level. One is located near the Ecuador–Peru border, where the suite of species that dominates large areas of Ecuadorean forest declines abruptly in importance to the east. This discontinuity is underlain by a subterranean paleoarch and congruent with a change in soil texture. A second discontinuity is associated with the shift from clay to white sand soils near Iquitos. We hypothesize that the first discontinuity is part of an edaphic boundary that runs along the Andean piedmont and causes a transition from tree communities preferring richer, younger soils near the base of the Andes to those preferring poorer, older soils farther east. Because the floristic changes observed at this discontinuity are conserved for large distances to the east and west of it, the discontinuity is potentially key for understanding floristic variation in western Amazonia. The significant floristic turnover at the Ecuador–Peru border suggests that the only large protected area in the region—Ecuador's Yasuní National Park—is not adequate protection for the very diverse tree communities that cover vast areas of northern Peru.     

Life History Traits Reflect Changes in Mediterranean Butterfly Communities Due to Forest Encroachment

The biodiversity of the Southern Balkans, part of the Mediterranean global biodiversity hot-spot, is threatened by land use intensification and abandonment, the latter causing forest encroachment of formerly open habitats. We investigated the impact of forest encroachment on butterfly species richness, community species composition and the representation of life history traits by repeated seasonal visits of 150 one-hectare sites in five separate regions in three countries—Greece, Bulgaria, and the Republic of Macedonia (FYROM—the Former Yugoslav Republic of Macedonia)— 10 replicates for each habitat type of grasslands, open formations and scrub forest within each region. Grasslands and open formations sites hosted in average more species and more red-listed species than scrub forest, while no pattern was found for numbers of Mediterranean species. As shown by ordination analyses, each of the three habitat types hosted distinct butterfly communities, with Mediterranean species inclining either towards grasslands or open formations. Analysing the representation of life history traits revealed that successional development from grasslands and open formations towards scrub forest shifts the community composition towards species overwintering in earlier stages, having fewer generations per year, and inhabiting large European or Eurosiberian (e.g. northern) ranges; it decreases the representation of Mediterranean endemics. The loss of grasslands and semi-open formations due to forest encroachment thus threatens exactly the species that should be the focus of conservation attention in the Mediterranean region, and innovative conservation actions to prevent ongoing forest encroachment are badly needed.     

Upslope Range Shifts of Andean Dung Beetles in Response to Deforestation: Compounding and Confounding Effects of Microclimatic Change

Warmer, and sometimes drier, conditions associated with global climate change are driving many species to shift poleward and/or upslope. I hypothesized that microclimatic changes related to deforestation cause similar shifts for forest species persisting within degraded landscapes. This appears to be the first study to examine this novel hypothesis. I examined elevational distributions of dung beetle communities along parallel intact and disturbed elevational gradients from 290 to 3450 m asl in the Andes of southeastern Peru. Deforested sites were consistently warmer and drier than forested sites. To maintain the same ambient temperature as in forest, species in a deforested landscape would need to shift on average 489±59 m upslope. Dung beetle species showed a mean upslope range shift of 132±64 m (maximum=743 m) in the deforested landscape. Eight species occurred farther upslope in the degraded landscape, while none shifted downslope. In addition to upper range limit expansions, six species shifting upslope also showed range contractions or population declines at their lower range boundary. High elevation and disturbance‐tolerant species did not show range shifts. These findings suggest that land‐use change may both confound and compound the influence of global climate change on biodiversity. Synergies between habitat degradation and climate change could more than double previous range shift projections for this century, leading to unexpectedly rapid changes in biodiversity, especially for sensitive organisms such as tropical insects. On the other hand, range shifts caused by habitat degradation may be mistakenly attributed to global climate change. Abstract in Spanish is available in the online version of this article.     

Quantifying Components of Soil Respiration and Their Response to Abiotic Factors in Two Typical Subtropical Forest Stands,Southwest China

Separating the components of soil respiration and understanding the roles of abiotic factors at a temporal scale among different forest types are critical issues in forest ecosystem carbon cycling. This study quantified the proportions of autotrophic (R_A) and heterotrophic (R_H) in total soil (R_T) respiration using trenching and litter removal. Field studies were conducted in two typical subtropical forest stands (broadleaf and needle leaf mixed forest; bamboo forest) at Jinyun Mountain, near the Three Georges Reservoir in southwest China, during the growing season (Apr.–Sep.) from 2010 to 2012. The effects of air temperature (AT), soil temperature (ST) and soil moisture (SM) at 6cm depth, solar radiation (SR), pH on components of soil respiration were analyzed. Results show that: 1) SR, AT, and ST exhibited a similar temporal trend. The observed abiotic factors showed slight interannual variability for the two forest stands. 2) The contributions of R_H and R_A to R_T for broadleaf and needle leaf mixed forest were 73.25% and 26.75%, respectively, while those for bamboo forest were 89.02% and 10.98%, respectively; soil respiration peaked from June to July. In both stands, CO₂ released from the decomposition of soil organic matter (SOM), the strongest contributor to R_T, accounted for over 63% of R_H. 3) AT and ST were significantly positively correlated with R_T and its components (p<0.05), and were major factors affecting soil respiration. 4) Components of soil respiration were significantly different between two forest stands (p<0.05), indicating that vegetation types played a role in soil respiration and its components.     

Sentinel Nematodes of Land-Use Change and Restoration in Tallgrass Prairie

Changes in land use and the associated changes in land cover are recognized as the most important component of human-induced global change. Much attention has been focused on deforestation, but grasslands are among the most endangered ecosystems on Earth. The North American tallgrass prairie is a dramatic example, exhibiting a greater than 95% decline in historical area. Renewed interest in prairie conservation and restoration has highlighted the need for ecological indicators of disturbance and recovery in native systems, including the belowground component. The tallgrass prairie differs from the agricultural systems that have replaced it in having greater diversity and heterogeneity of resources, less physical soil disturbance (although other disturbances, such as fire and grazing, are prominent), and greater nitrogen limitation. Understanding the responses of nematode taxa to these characteristic differences is crucial to the development and improvement of community indices, but while knowledge of disturbance responses by individual taxa is accumulating, the level of necessary taxonomic resolution remains in question. Although nematode communities generally are better described for temperate grasslands than for other natural ecosystems, identification of sentinel taxa is further confounded by high levels of diversity, and both spatial and temporal heterogeneity.     

Altered Belowground Carbon Cycling Following Land-Use Change to Perennial Bioenergy Crops

Ecosystems - Belowground carbon (C) dynamics of terrestrial ecosystems play an important role in the global C cycle and thereby in climate regulation. Globally, land-use change is a major driver of...     

Effects of Land-Use Change on Carbon Stocks in Switzerland

We assessed how consequences of future land-use change may affect size and spatial shifts of C stocks under three potential trends in policy—(a) business-as-usual: continuation of land-use trends observed during the past 15 years; (b) extensification: full extensification of open-land; and (c) liberalization: full reforestation potential. The build-up times for the three scenarios are estimated at 30, 80 and 100 years, respectively. Potential C-stock change rates are derived from the literature. Whereas the business-as-usual scenario would cause marginal changes of 0.5%, liberalization would provoke a 13% increase in C stocks (+62 MtC). Gains of 24% would be expected for forests (+95 MtC), whereas open-land C stock would decrease 27% (−33 MtC). Extensification would lead to a C stock decrease of 3% (−12 MtC). Whereas forest C is expected to increase 12% (+36.5 MtC) at high elevations, stocks of open-land C would decline 38.5% (−48.5 MtC). Most affected are unfavorable grasslands, which increase in area (+59%) but contribute only 14.5% to the C stocks. C sinks would amount to 0.6 MtC y⁻¹ assuming a build-up time of 100 years for the liberalization scenario. C stocks on the current forest area are increasing by 1 MtC y⁻¹. The maximal total C sink of 1.6 MtC might thus suffice to compensate for agricultural greenhouse gases (2004: 1.4 Mt CO₂–C equivalents), but corresponds only to 11–13% of the anthropogenic greenhouse gas emission in Switzerland. Thus, even the largest of the expected terrestrial C stocks under liberalization will be small in comparison with current emissions of anthropogenic greenhouse gases.     

Sixty-Seven Years of Land-Use Change in Southern Costa Rica

Habitat loss and fragmentation of forests are among the biggest threats to biodiversity and associated ecosystem services in tropical landscapes. We use the vicinity of the Las Cruces Biological Station in southern Costa Rica as a regional case study to document seven decades of land-use change in one of the most intensively studied sites in the Neotropics. Though the premontane wet forest was largely intact in 1947, a wave of immigration in 1952 initiated rapid changes over a short period. Overall forest cover was reduced during each time interval analyzed (1947–1960, 1960–1980, 1980–1997, 1997–2014), although the vast majority of forest loss (>90%) occurred during the first two time intervals (1947–1960, 1960–1980) with an annual deforestation rate of 2.14% and 3.86%, respectively. The rate dropped to <2% thereafter and has been offset by forest recovery in fallow areas more recently, but overall forest cover has continued to decline. Approximately 27.9% of the study area is forested currently. Concomitantly, the region shifted from a single contiguous forest to a series of progressively smaller forest fragments with each successive survey. A strong reduction in the amount of core habitat was paralleled by an increased proportion of edge habitat, due to the irregular shape of many forest fragments. Structural connectivity, however, remains high, with an expansive network of >100 km of linear strips of vegetation within a 3 km radius of the station, which may facilitate landscape-level movement for some species. Despite the extent of forest loss, a substantial number of regional landscape-level studies over the past two decades have demonstrated the persistence of many groups of organisms such as birds and mammals. Nonetheless, the continued decline in the quantity and quality of remaining habitat (~30% of remaining forest is secondary), as well as the threat of an extinction debt (or time lag in species loss), may result in the extirpation of additional species if more proactive conservation measures are not taken to reverse current trends–a pattern that reflects many other tropical regions the world over.     

Simulated Small Scale Disturbances Increase Decomposition Rates and Facilitates Invasive Species Encroachment in a High Elevation Tropical Andean Peatland

Tropical alpine peatlands are important carbon reservoirs and are a critical component of local hydrological cycles. In high elevation peatlands slow decomposition rates result from a nutrient‐poor substrate resistant to decay. The responses of páramo peatland ecosystems to increased nutrient additions and physical disturbance due to agricultural activities are unknown. Here, we conducted a two‐year fertilization and physical disturbance experiment in a Sphagnum—dominated peatland in the Central Andes of Colombia. We hypothesized that fertilization and physical disturbance will diminish the ability of the peat to store organic matter by increasing decomposition and that vascular plants will displace Sphagnum as the dominant plant group. We simulated cattle activity by adding manure as a fertilizer and physical disturbance as a proxy for cattle trampling. Species composition varied in proportion to the intensity of disturbance. Sphagnum cover was reduced under any disturbance treatment. Non‐native grasses usually found in cattle pastures invaded treatments with fertilizer additions or physical disturbance. Overall aboveground plant biomass doubled in fertilized treatments, suggesting that plant biomass production was nutrient limited. Decomposition rates tripled in disturbed treatments as compared to controls. This reduces the ability of the peatland to store organic matter. Andean peatlands are prized ecological assets; however, our results show that the El Morro páramo peatland experienced increased decomposition rates over short time periods after small‐scale disturbances. This created profound consequences for the ecological services offered by these peatlands.     

Land-Use History and Forest Regeneration in the Cayey Mountains, Puerto Rico

Although deforestation continues to be a major threat to tropical biodiversity, abandonment of agricultural land in Puerto Rico provides an opportunity to study long-term patterns of secondary forest regeneration. Using aerial photographs from 1937, 1967, and 1995, we determined land-use history for 2443 ha in the Cayey Mountains. Pastures were the dominant land cover in 1937 and <20% of the area was classified as forest. Between 1937 and 1995, forest cover increased to 62% due to widespread abandonment of agriculture. To examine the effect of historic land use on current forest structure and species composition, we sampled secondary forests in 24 abandoned pastures, 9 abandoned coffee plantations and 4 old-growth forest sites. Sites were located on two soil types along an elevational gradient (125–710 m) and included a chronosequence from 4 to over 80 years old. After 25–30 years, basal area and species richness in secondary forest sites derived from abandoned pastures and coffee plantations were similar to old-growth forest sites. The species composition of secondary forests derived from abandoned pastures and coffee plantations remained distinct from old-growth forest. In addition to historic land use, age and elevation were important environmental variables explaining variation in secondary forest species composition. Non-indigenous species were common in recently abandoned pastures and coffee plantations, but their importance declined in the older sites. This study demonstrates that secondary forests on private land can be an important component of the conservation of tropical tree biodiversity. Received 16 June 1999; Accepted 8 October 1999.     

无样地法在亚热带常绿阔叶林调查中的应用

 The toxicity of N-503 on wheat appears evidently in the seedling stage and becomes gradually less and little from the jointing stage to the mature stage. However, the symptom of damage is based upon the concentration of N-503 used. The concentration is better to keep below 50ppm. The effect of N-503 on rice is similarly to wheat, but the amount of residue in rice is more apparently than that in wheat. Chlorobenzene in the mixed sewage is also shown some damage symptom to rice.     

Public Health Risk Assessment Linked to Climatic and Ecological Change

Disturbances of climatic and ecological systems can present risks to human health, which are becoming more evident from health studies linked to climate variability, landuse change and global climate change. Waterborne disease agents, such as Giardia cysts and Cryposporidium oocysts have been positively correlated with rainfall. El Niño-related extreme weather conditions can have a significant impact on vector- and water-borne diseases. The linkages between weather, terrestrial ecology and human health have been discovered for some diseases, such as rodent-borne hantavirus. Marine ecology also plays a role in determining human health risks, such as from cholera, and other enteric pathogens. Deforestation and ensuing changes in landuse, human settlement, commercial development, road construction, and water control systems singly, and in combination have been accompanied by increases in or emergence of diseases like malaria and schistosomiasis in some regions of the world. Long-term climate change may increase the frequency of heat waves and potentially air pollution episodes, increase the number of extreme weather events, cause coastal flooding and salination of fresh water aquifers, and displace coastal settlements. Ultimately, a two-pronged approach (empirical and modeling studies) is required to better understand these linkages between climato-logical and ecological change as determinants of disease.     

广东石门台亚热带典型常绿阔叶林和亚热带山顶矮林群落特征

为了研究亚热带典型常绿阔叶林和亚热带山顶矮林的物种组成和群落结构,在广东石门台国家自然保护区内分别建立了1 hm2亚热带典型常绿阔叶林样地和1 hm2亚热带山顶矮林样地,以样地内所有胸径（DBH）≥1 cm的乔木、灌木和藤本为研究对象,分析两种森林类型的物种组成、密度、径级和株高结构。结果显示：（1）两种森林的Srensen物种相似性指数为0.41,优势种不同,但优势科却较相似;其中,茶科和杜鹃花科在两种森林中所占比例较高;（2）亚热带典型常绿阔叶林的幼苗（1 cm≤DBH〈2.5 cm）和幼树（2.5 cm≤DBH〈12.5 cm）密度都显著小于亚热带山顶矮林,但两种森林的小树（12.5 cm≤DBH〈25 cm）和大树（DBH≥25 cm）密度均无显著差异;亚热带典型常绿阔叶林幼苗和大树的平均胸径都显著大于亚热带山顶矮林,而幼树的平均胸径则显著小于亚热带山顶矮林,小树的平均胸径无显著差异;亚热带典型常绿阔叶林中小树和大树的平均高度都显著大于亚热带山顶矮林,而幼苗的平均高度显著小于亚热带山顶矮林,幼树的平均高度无显著差异。综合分析表明,亚热带典型常绿阔叶林和亚热带山顶矮林的物种组成、密度、胸径和高度结构差异较大,亚热带典型常绿阔叶林群落稳定性强于亚热带山顶矮林。     

Change in Bacterial Community Structure in Response to Disturbance of Natural Hardwood and Secondary Coniferous Forest Soils in Central Taiwan

Forest management often results in changes in the soil and its microbial communities. In the present study, differences in the soil bacterial community caused by forest management practices were characterized using small subunit (SSU) ribosomal RNA (rRNA) gene clone libraries. The communities were from a native hardwood forest (HWD) and two adjacent conifer plantations in a low-elevation montane, subtropical experimental forest at the Lienhuachi Experimental Forest (LHCEF) in central Taiwan. At this locality, the elevation ranges from 600 to 950 m, the mean annual precipitation is 2,200 mm, the mean annual temperature is 20.8°C, and the soil pH is 4. The conifer forests included a Cunninghamia konishii Hay (CNH) plantation of 40 years and an old growth Calocedrus formosana (Florin) Florin (CLC) forest of 80 years. A total of 476 clones were sequenced and assigned into 12 phylogenetic groups. Proteobacteria-affiliated clones (53%) predominated in the library from HWD soils. In contrast, Acidobacteria was the most abundant phylum and comprised 39% and 57% in the CLC and CNH libraries, respectively. Similarly, the most abundant OTUs in HWD soils were greatly reduced or absent in the CLC and CNH soils. Based on several diversity indices, the numbers of abundant OTUs and singletons, and rarefaction curves, the diversity of the HWD community (0.95 in evenness and Shannon diversity indices) was somewhat less than that in the CNH soils (0.97 in evenness and Shannon diversity indices). The diversity of the community in CLC soils was intermediate. The differences in diversity among the three communities may also reflect changes in abundances of a few OTUs. The CNH forest soil community may be still in a successional phase that is only partially stabilized after 40 years. Analysis of molecular variance also revealed that the bacterial community composition of HWD soils was significantly different from CLC and CNH soils (p = 0.001). These results suggest that the disturbance of forest conversion and tree species composition are important factors influencing the soil bacterial community among three forest ecosystems in the same climate.     

Typhoon Disturbance and Forest Dynamics: Lessons from a Northwest Pacific Subtropical Forest

Strong tropical storms are known to affect forest structure, composition, and nutrient cycles in both tropical and temperate regions, although our understanding of these effects disproportionally comes from regions experiencing much lower cyclone frequency than many forests in the Northwest Pacific. We summarized the effects of typhoons on forest dynamics at Fushan Experimental Forest (FEF) in northeastern Taiwan, which averages 0.49 major typhoons annually, and compared their resistance and resilience to those of forests in other regions. Typhoons cause remarkably few tree falls at FEF; multiple typhoons in 1994 felled only 1.4% of canopy trees, demonstrating high structural resistance. The most important effect of typhoons in this ecosystem is defoliation, which maintains high understory light levels and enhances heterogeneity, sustaining diversity without large canopy gaps. The vulnerability of taller trees to being blown down has resulted in the short-stature FEF (mean canopy height is 10.2 m). As the FEF is P-limited and a large fraction of total annual P export occurs during typhoons, these storms may have the effect of reducing productivity over time. DIN and K⁺ export only remain elevated for days at FEF, in contrast to the several years observed in Puerto Rico. High resilience is also evident in the rapid recovery of leaf area following typhoons. Heavy defoliation and slow decomposition are among the processes responsible for the high resistance and resilience of FEF to typhoon disturbance. These key structural features may emerge in other forest ecosystems if the frequency of major storms increases with climate change.     

Responses of N<Subscript>2</Subscript>O Flux from Forest Soils to Land Use Change in Subtropical China

To evaluate the effect of land use change from a natural broadleaf evergreen forest to Moso bamboo plantations and their management practices on soil N₂O efflux in a subtropical region of China, N₂O efflux was measured during June 2008 and May 2009 using static closed chamber method. The observed mean N₂O fluxes were 0.230, 0.102 and 0.093 mg N₂O/m²/h from the intensively managed bamboo forest (IM), conventionally managed bamboo forest (CM), and broadleaf evergreen forest (BL), respectively, and calculated annual cumulative N₂O were 15.8, 8.7 and 7.2 kg N₂O/ha, respectively. Soil temperature had significant influence on N₂O flux. Whereas there was no correlation between N₂O flux and soil water content. Conversion of the natural subtropical broadleaf evergreen forest to Moso bamboo did not increase soil N₂O efflux, but intensive management practices such as regular tillage and fertiliser application, significantly increased soil N₂O emission from bamboo soil.     

Biodiversity Promotes Tree Growth during Succession in Subtropical Forest

Losses of plant species diversity can affect ecosystem functioning, with decreased primary productivity being the most frequently reported effect in experimental plant assemblages, including tree plantations. Less is known about the role of biodiversity in natural ecosystems, including forests, despite their importance for global biogeochemical cycling and climate. In general, experimental manipulations of tree diversity will take decades to yield final results. To date, biodiversity effects in natural forests therefore have only been reported from sample surveys or meta-analyses with plots not initially selected for diversity. We studied biomass and growth of subtropical forests stands in southeastern China. Taking advantage of variation in species recruitment during secondary succession, we adopted a comparative study design selecting forest plots to span a gradient in species richness. We repeatedly censored the stem diameter of two tree size cohorts, comprising 93 species belonging to 57 genera and 33 families. Tree size and growth were analyzed in dependence of species richness, the functional diversity of growth-related traits, and phylogenetic diversity, using both general linear and structural equation modeling. Successional age covaried with diversity, but differently so in the two size cohorts. Plot-level stem basal area and growth were positively related with species richness, while growth was negatively related to successional age. The productivity increase in species-rich, functionally and phylogenetically diverse plots was driven by both larger mean sizes and larger numbers of trees. The biodiversity effects we report exceed those from experimental studies, sample surveys and meta-analyses, suggesting that subtropical tree diversity is an important driver of forest productivity and re-growth after disturbance that supports the provision of ecological services by these ecosystems.     

Flowering and Fruiting Patterns in a Subtropical Rain Forest,Taiwan

Reproductive patterns of tropical and temperate plants are usually associated with climatic seasonality, such as rainfall or temperature, and with their phylogeny. It is still unclear, however, whether plant reproductive phenology is influenced by climatic factors and/or phylogeny in aseasonal subtropical regions. The plant reproductive phenology of a subtropical rain forest in northern Taiwan (24°45′ N, 121°35′ E) was monitored at weekly intervals during a 7‐yr period (2002–2009). The flowering patterns of 46 taxa and fruiting patterns of 26 taxa were examined and evaluated in relation to climatic seasonality, phylogenetic constraints, and different phenophases. Our results indicated that most of the studied species reproduced annually. Additionally, both community‐wide flowering and fruiting patterns exhibited distinct annual rhythms and varied little among years. The community flowering peak matched seasonal changes in day length, temperature, and irradiance; while the community fruiting peak coincided with an increase in bird richness and the diet‐switching of resident omnivorous birds. In addition, phylogenetically closely related species tended to reproduce during the same periods of a year. Neither the mean flowering dates nor seasonal variation in solar radiation, however, was related to the fruit development times. Our results indicate the importance of abiotic, biotic, and evolutionary factors in determining the reproductive phenology in this subtropical forest.