Dry Forest Species Research Articles

Dry Forest Restoration and Unassisted Native Tree Seedling Recruitment at Auwahi, Maui

Efforts to restore highly degraded but biologically significant forests draw from a limited toolbox. With less than 10% of their former distribution remaining, Hawaiian dry forests, though critically endangered, remain impor- tant biological and cultural refugia. At restoration onset (1997), vegetation of restoration and control areas of degraded Auwahi dry forest, Maui Island, was similar, dominated by nonnative graminoids (restoration 78.3%; control 75.4%), especially Cenchrus ( Pennisetum) clandestinus. In 2012, unrestored control area vegetation was basically unchanged. In contrast, in the restoration area in 2012, native shrub cover increased from 3.1% to 81.9%, and cover of nonnative gram- inoids declined from 75.4% to 3.3%. In 2012, nonplanted seedlings of 14 of 22 native tree species and six of seven native shrub species were observed in restora- tion plots; the majority (99%) were five native (Dodonaea viscosa, Coprosma foliosa, Osteomeles anthyllidifolia, Chamaesyce celastoides, Nestegis sandwicensis) and one nonnative species (Bocconia frutescens). By 2012, stem counts of native woody plants had increased from 12.4 to 135.0/100 m 2 , and native species diversity increased from 2.4 to 6.6/100 m 2 . By 2012, seven rare dry forest tree species, Charpentiera obovata, Nothocestrum latifolium, Ochrosia haleakalae, Pleomele auwa- hiensis, Santalum ellipticum, S. haleakalae, and Streblus pendulinus, had established seedlings and/or saplings within the restoration site, especially notable because natural reproduction is largely lacking elsewhere. Without development and implementation of appropriate management strategies, remaining Hawaiian dry forest will likely disappear within the next century. Multicomponent restoration incorporating ungulate exclusion, weed control, and outplanting as described here offers one strategy to conserve and restore tracts of high-value but de- graded forests.

Leaf anatomical traits corroborate the leaf economic spectrum: a case study with deciduous forest tree species

Deciduous forests are seasonal systems that occur scattered throughout the Neotropics. Many aspects about these ecosystems have been studied. However, there is a lack of information about leaf structure and its possible functional and adaptive aspects. Here we examined leaf anatomy and specific leaf area (SLA) in 13 dominant tree species of dry forests in central Brazil, identifying structural patterns of these species. As the system is seasonal, with species presenting a deciduous behavior, we expect to find tree species with a set of mesomorphic leaf traits. The studied dry forest trees share similar leaf structure, with one-layered adaxial and abaxial epidermis and a well-developed mesophyll, high values of SLA, and the presence of calcium crystals and mucilaginous cells. Higher values of SLA and the high investment achieved in the mesophyll (especially in parenchyma tissue) are probably related to the accomplishment of a high performance of carbon and nutrients gain during the limited wet season.

A university campus in peri-urban Accra (Ghana) as a haven for dry-forest species

Valley View University (VVU) is a private university located within the dry forest zone of the Accra plains; an area strongly affected by urban sprawl. The campus covers approx. 105 ha. Considerable portions of it are yet undeveloped and covered with savannah thickets. In 2002, the university has committed itself to become Africa's first "ecological university". In the context of two projects, substantial improvements have been made in terms of sanitation, water supply, energy-saving buildings and organic agriculture. The further development of the campus was designed in a detailed "ecological masterplan". In this context, we carried out a floristic inventory of the savannah thickets and found more than 100 plant species; the majority of which represent the species pool of the unique mixture of dry forest and savannah thicket species, which is typical for the region. As the remainder of dry forests and savannah thickets in the Accra plains become increasingly threatened by urban sprawl and overgrazing, the VVU administration has agreed to preserve the species-rich thickets. This is a valuable contribution to a more sustainable development of the region.

SEED ECOLOGY OF SOME SELECTED DRY FOREST SPECIES OF SRI LANKA

This study examines seed ecology of ten native dry zone forest species: Manilkarahexandra, Drypetes sepiaria, Salvadora persica, Bauhinia racemosa, Cassia fistula,Cassia siamea, Schlechera oleosa, Oroxylum indicum, Randia uliginosa, Dichrostachyscineria and in one alien invasive species: Prosopis juliflora.Seed samples were collected from the dry zone of Sri Lanka (in Anuradhapura,Polonnaruwa, Monaragala and Hambanthota districts). Morphology (colour, width,length of seeds) and the weight of 60 seeds per each species were recorded in threereplicates. Viability of seeds was tested using standard TIC test while the percentagegermination of seeds was recorded in moist petridishes laid according to RandomizeComplete Block Design. Rate of water absorption of seeds and seed coat widths were alsomeasured, while the presence of water-soluble growth inhibitors were examined througha bioassay using Brasica juncea seeds. Hot water treatments, Hot air treatments,Gibberalic acid treatments, Manual scarification and combinations of above treatmentswere tested to break the seed dormancy of these species. Seed and plant characteristicswere observed to determine the ecological state (Climax or Pioneer) of study species.Seed predation and dispersal mechanisms were observed during field visits.P.jutiflora and 0. indicum seeds are recalcitrant, while the remaining species showedseed dormancy. D.cineria Cfistula, Csiamea and B.racemosa seeds appeared to bedormant due to its water impermeable seed coat and the dormancy can be overcome bymanual-scarification. S.persica seeds contain underdeveloped embryo and hot watertreatment (at 45°C for 5 days) was found to be the best treatment to break the seeddormancy. D.sepiaria, S.oleosa and R.uliginosa seeds seem to be dormant due to thepresence Of a growth inhibitor and the hard seed coat. Manual scarification together withGibberalic acid (4000ppm) treatment was found to be suitable to break the seed dormancyof the species. M.hexandra seeds too have an undeveloped embryos and hard seed coats,which may cause seed dormancy, but seed germination can be improved by hot watertreatment (at 85°C for 15minutes) fallowed by manual scarification. o'indicum andR. uliginosa can be described as Pioneer species. Other 8 natural forest species can bedescribed as climax species, which mainly dispersed by animals. High seed predationcan be observed in these species. Especially insects including termites and several larvaeof insects attack the seeds of tbese species.

Seedling growth of five tropical dry forest tree species in relation to light and nitrogen gradients

Aims Increasing anthropogenic nitrogen (N) deposition has been claimed to induce changes in species composition and community dynamics. A greenhouse experiment was conducted to examine the effect of increased N availability on growth and functional attributes of seedlings of five tree species with different life history characteristics under varying irradiances. The following questions have been addressed: (i) how do the pioneer and non-pioneer species respond in absolute growth and relative growth rate (RGR) to the interaction of light and nitrogen? (ii) how does the interaction between irradiance and nitrogen availability modulate growth attributes (i.e. functional attributes)? (iii) is there any variation in growth responses between leguminous and non-leguminous species along the light and nitrogen gradients? Methods Seedlings of five tree species (Acacia catechu, Bridelia retusa, Dalbergia sissoo, Lagerstroemia parviflora and Terminalia arjuna) were subjected to twelve combinations of irradiance and N levels. Various growth traits, including height (HT), basal area (BA), whole plant dry biomass (MD), leaf mass per unit area (LMA), leaf area ratio (LAR), net assimilation rate (NAR), RGR, biomass fractions, root-toshoot ratio (R:S) and leaf nitrogen content, were studied to analyse intra- and inter-specific responses to interacting light and N gradients.

English

  Leaf phenology tree species of dry deciduous and evergreen forests of Bhadra Wildlife Sanctuary (13°25’ and 13°50’ N, 75°15’ and 75°50’ E) was studied during June 2004 to May 2006. Leaf fall starts in September and with a peak in December and January. Leaf initiation starts in February and with a peak in April before monsoon, while leaf expansion starts in February with a peak in May and July during monsoon in dry deciduous forest. In evergreen forest, leaf falling and leaf initiation was observed in one or the other species with a peak in January to February, leaf expansion too observed throughout the year with a peak in January and April before monsoon. Varying leaf phenology of these forest types is dependent on a regional rainfall pattern.   Key words: Bhadra Wildlife Sanctuary, dry deciduous forest, evergreen forest, leaf phenology, seasonality.

Subtropical–Tropical Urban Tree Water Relations and Drought Stress Response Strategies

Understanding native habitats of species successful as subtropical and tropical urban trees yield insights into how to minimize urban tree water deficit stress experienced during monsoonal dry periods. Equatorial and montane wet forest species rarely subject to drought are generally absent in subtropical and tropical cities with pronounced monsoonal dry seasons. Species native to monsoonal dry forests appear to have wide environmental tolerances, and are successful as urban trees in many tropical cities. Monsoonal dry forest species have a tendency to be deep rooted to avoid drought, with leaf habits falling along an avoidance to tolerance spectrum. Dry deciduous species, typically found on more fertile soils, maximize growth during the monsoonal wet season with high photosynthesis and transpiration rates, then defoliate to avoid stress during the dry season. Evergreen tree species, typically found on less fertile soils, have a higher carbon investment in leaves that photosynthesize and transpire less year-round than do dry deciduous species. Dry deciduous tree species are more common urban trees than dry evergreen species explicitly due to more ornamental floral displays, but also implicitly due to their ability to adjust timing and duration of defoliation in response to drought. An empirical study of three tropical species exhibiting a range of leaf habits showed isohydric behavior that moderates transpiration and conserves soil water during drying. However, dry evergreen species may be less adaptable to tropical urban conditions of pronounced drought, intense heat, and limited rooting volumes than dry deciduous species with malleable leaf habit.

Relations between water balance, wood traits and phenological behavior of tree species from a tropical dry forest in Costa Rica--a multifactorial study

Drought tolerance is a key factor for the establishment and survival of tree species in tropical ecosystems. Specific mechanisms of drought resistance can be grouped into four functional ecotypes based on differences in leaf fall behavior: deciduous, brevi-deciduous, stem succulent and evergreen. To identify the key factors influencing phenology and cambial activity and thus drought tolerance, we tested the stomatal conductance, leaf water potential and stable carbon isotopes in the leaves and wood of 12 species from a tropical dry forest in Costa Rica. With wood anatomical techniques, we further studied seasonal cambial activity and a suite of wood traits related to water transport for each of the functional ecotypes. Using a principal component analysis, we identified two groups of variables that can be related to (i) hydraulic conductivity and (ii) control of transpiration and water loss. Hydraulic conductivity is controlled by vessel size as the limiting variable, water potential as the driving force and wood density as the stabilizing factor of the anatomical structure of an effective water transport system. Stomatal control plays a major role in terms of water loss or saving and is the dominant factor for differences in phenological behavior. Stem succulent species in particular developed a rarely identified but highly effective strategy against drought stress, which makes it a successful pioneer species in tropical dry forests.

Source water, phenology and growth of two tropical dry forest tree species growing on shallow karst soils

Seasonally dry tropical forests are dominated by deciduous and evergreen tree species with a wide range of leaf phenology. We hypothesized that Piscidia piscipula is able to extend leaf senescence until later in the dry season due to deeper and more reliable water sources than Gymnopodium floribundum, which loses leaves earlier in the dry season. Physiological performance was assessed as timing of leaf production and loss, growth, leaf water potential, depth of water uptake determined by stable isotopes, and leaf stable isotopic composition of carbon (δ13C) and oxygen (δ18O). P. piscipula took water primarily from shallow sources, whereas G. floribundum took water from shallow and deep sources. The greatest variation in water sources occurred during the onset of the dry season, when G. floribundum was shedding old leaves and growing new leaves, but P. piscipula maintained its leaves from the previous wet season. P. piscipula showed greater relative growth rate, greater leaf expansion rates, and more negative predawn and midday water potentials than G. floribundum. P. piscipula also exhibited greater leaf organic δ13C and lower δ18O values, indicating that the decrease in photosynthetic carbon isotope discrimination was associated with greater stomatal conductance and greater photosynthesis. Our results indicate that the contrasting early and late dry season leaf loss phenology of these two species is not simply determined by rooting depth, but rather a more complicated suite of characteristics based on opportunistic use of dynamic water sources, maximizing carbon gain, and maintenance of water potential during the dry season.

Effectiveness of Erythrina gall wasp biocontrol and implications for the recovery of threatened Wiliwili trees (Fabaceae: Erythrina sandwicensis)1

Abstract Wiliwili (Erythrina sandwicensis), an endemic Hawaiian dry forest tree species, is threatened by an invasive gall-forming wasp (Quadrastichus erythrinae) first detected in Hawai‘i in 2005. Eurytoma erythrinae, a predator of Q. erythrinae from Tanzania, was selected as a biological control agent and was released at sites throughout the Hawaiian Islands. To assess the effectiveness of this biocontrol release, we measured the extent of damage attributable to Q. erythrinae wasps in 124 E. sandwicensis trees at the Waikoloa Village Dry Forest Recovery Project before (January, 2009) and after (January, 2011) the release of the parasitoid wasp at this site. Because host spatial distribution has important consequences for the establishment and success of natural enemies such as parasitoids, we took a spatially explicit approach to account for the potential spatial heterogeneity in E. sandwicensis. We observed an increase in galling damage across the population and 21 trees became completely defoliated be...

Rediscovering an extraordinary vanishing bug: Llaveia axin axin

The “aje” (Llaveia axin axin) is a parasitic hemipteran of various tree species in tropical dry forests of Mexico and Guatemala. Females produce fatty extracts used since pre-hispanic times (i.e., traditional medicine and as raw material to produce handcrafts). However, very little is known about its biology and conservation status. In Michoacán and Guerrero States (Mexico), fifteen localities with historical reports of “aje” were visited 4 times (2006-2007). The incidence, seasonal abundance and distribution, host species, tree size and section preference, were determined. Only 3 populations in 2 localities were found at low altitudes (< 300m asl), close to water sources, with only 1 host tree, Acacia cochliacantha. Females were mostly found at the base of the trunk, but showed no preference for any tree size. July (2007) was the month with greater abundance. The “aje” seems highly threatened with local extinction, due to their fragmented relict populations and rapid destruction of its habitat and host species, which is considered as a weed. More basic information on its biology and population dynamics is urgently needed to implement any conservation strategy. In addition, the management of the “aje” should take into consideration biological, pharmacological and cultural connotations.

Performance of established native seedlings in relation to invasive Lantana camara, rainfall and species’ habitat preferences in a seasonally dry tropical forest

Native species' response to the presence of invasive species is context specific. This response cannot be studied in isolation from the prevailing environmental stresses in invaded habitats such as seasonal drought. We investigated the combined effects of an invasive shrub Lantana camara L. (lantana), seasonal rainfall and species' microsite preferences on the growth and survival of 1,105 naturally established seedlings of native trees and shrubs in a seasonally dry tropical forest. Individuals were followed from April 2008 to February 2010, and growth and survival measured in relation to lantana density, seasonality of rainfall and species characteristics in a 50-ha permanent forest plot located in Mudumalai, southern India. We used a mixed effects modelling approach to examine seedling growth and generalized linear models to examine seedling survival. The overall relative height growth rate of established seedlings was found to be very low irrespective of the presence or absence of dense lantana. 22-month growth rate of dry forest species was lower under dense lantana while moist forest species were not affected by the presence of lantana thickets. 4-month growth rates of all species increased with increasing inter-census rainfall. Community results may be influenced by responses of the most abundant species, Catunaregam spinosa, whose growth rates were always lower under dense lantana. Overall seedling survival was high, increased with increasing rainfall and was higher for species with dry forest preference than for species with moist forest preference. The high survival rates of naturally established seedlings combined with their basal sprouting ability in this forest could enable the persistence of woody species in the face of invasive species.

Modelling the potential distribution of endangered, endemic Hibiscus brackenridgei on Oahu to assess the impacts of climate change and prioritize conservation efforts.

In the Hawaiian dry forest, 45% of all tropical dry forest trees and shrubs are on the federal threatened and endangered species list. Research is needed to understand the current range of these endangered species, the factors that affect their current and future distributions, and ultimately, identify areas where the most successful restoration can be undertaken. This research uses species distribution modelling to predict the potential range of Hibiscus brackenridgei, the state flower of Hawaii and a federally endangered species found on Oahu. We used presence data and the modelling algorithm Maxent to model the current potential distribution of H. brackenridgei, identify climate and environmental variables that influence the species’ distribution, and model the species’ predicted future distribution based on a range of projected climate change scenarios. Statistical analysis suggests that the Maxent models accurately predict the species’ distribution, and therefore, may be useful for conservation management. Comparing the current model with the future models of changes for 2060-2089, changes in the potential niche of H. brackenridgei only range by -4% to 14%. This suggests that the predicted changes in climate, under both low (B2a) and high (A2a) SRES (Special Report on Emissions Scenarios) global emissions scenarios, may not significantly impact the future distribution of H. brackenridgei on Oahu. We identified a total of 115 km2 of very highly (≥ 0.70) and highly (≥ 0.50) suitable habitat which represents potential areas where restoration projects could be implemented. This research suggests that threats like habitat loss, fire, invasive species, and grazing may be more important than climate for the future conservation of Hawaiian dry forest species.

Resprouting Ability of Dry Forest Tree Species after Disturbance Does Not Relate to Propagation Possibility by Stem and Root Cuttings

AbstractTropical dry forest tree species are recognized for their high resprouting ability after disturbance. We tested whether species that commonly produce root and stem suckers can be propagated by large stem and root cuttings, a useful method for landscape restoration programs. We performed four experiments: (1) In a greenhouse, we tested the propagation of six species using large stem cuttings collected from early successional sites. We used the following treatments: (i) dry season collection and planting; (ii) dry season collection, storage in humid soil, and wet season planting; (iii) wet season collection and planting; and (iv) wet season collection and planting after treatment with commercial NAA auxin. (2) Stem cuttings of Myracrodruon urundeuva were planted in a pasture during the rainy season after either NAA, IBA, or no auxin treatment. (3) As a control experiment, we also planted cuttings of Spondias mombin, a species known for successfully regenerating from cuttings. (4) Root cuttings of six species were collected in recently plowed pastures and planted in the greenhouse with and without treatment with NAA auxin. No root cuttings rooted. Only M. urundeuva and Astronium fraxinifolium stem cuttings rooted. Maximum success was obtained for stem cuttings collected and planted in the dry season (23%). Only 13% of M. urundeuva had sprouted by the 15th month of the field experiment. As a result, large cuttings are not recommended for propagation of the studied species. Future studies should include development of suitable methods of root harvesting and prospection of traditional knowledge for species selection.

Use of 3S technology as a tool for endangered vegetation area assessment in Togo

The main objective of research was to use 3S technology coupled to traditional method of vegetation sampling to assess the vegetation dynamic in Northern Togo. The remote sensed data of three different years (1987, 2000 and 2007) were used to evaluate the land use change by employing the normalized difference vegetation index (NDVI) algorithm, Iso-Data unsupervised classification and change detection method set by Winne. The vegetation sampling followed the Braun-Blanquet concept and was carried in riparian forest. The analysis and interpretation of the map of land cover change dynamic show that the rate of forest harvest is higher than it regrowth. The vegetation which has not been subjected to physical structure modification is localized along the river and is displayed in white color on the map, but around this type of vegetation, it is evolved in the regrowth stage displayed in cyan. From the 62 forest samples, 61 plants species were listed. A large number of these species belong to Combretaceae, Rubiaceae, Mimosaceae and Caesalpiniaceae families. The cluster analysis of the samples allows the identification three riparian forest grouping. Their distributions follow a latitudinal position; the grouping of Pterocarpus santaloides and Cola laurifolia (Rp1) is found in low latitude while P.santaloides and Eugenia kerstingii (Rp2) is presented in high latitude. The third group is mainly constituted of adjacent dry forest species which grow in flooded plain around the rivers and streams. These basic information in spite of their insufficiency, could be useful management purposes of land resources. Key words: Land use change, land resources, Riparian forest, normalized difference vegetation index (NDVI), biodiversity.

A coupled phylogeographical and species distribution modelling approach recovers the demographical history of a Neotropical seasonally dry forest tree species

We investigated here the demographical history of Tabebuia impetiginosa (Bignoniaceae) to understand the dynamics of the disjunct geographical distribution of South American seasonally dry forests (SDFs), based on coupling an ensemble approach encompassing hindcasting species distribution modelling and statistical phylogeographical analysis. We sampled 17 populations (280 individuals) in central Brazil and analysed the polymorphisms at chloroplast (trnS-trnG, psbA-trnH, and ycf6-trnC intergenic spacers) and nuclear (ITS nrDNA) genomes. Phylogenetic analyses based on median-joining network showed no haplotype sharing among population but strong evidence of incomplete lineage sorting. Coalescent analyses showed historical constant populations size, negligible gene flow among populations, and an ancient time to most recent common ancestor dated from ~4.7±1.1MyrBP. Most divergences dated from the Lower Pleistocene, and no signal of important population size reduction was found in coalescent tree and tests of demographical expansion. Demographical scenarios were built based on past geographical range dynamic models, using two a priori biogeographical hypotheses ('Pleistocene Arc' and 'Amazonian SDF expansion') and on two additional hypotheses suggested by the palaeodistribution modelling built with several algorithms for distribution modelling and palaeoclimatic data. The simulation of these demographical scenarios showed that the pattern of diversity found so far for T.impetiginosa is in consonance with a palaeodistribution expansion during the last glacial maximum (LGM, 21kyrBP), strongly suggesting that the current disjunct distribution of T.impetiginosa in SDFs may represent a climatic relict of a once more wide distribution.

Growth of tree seedlings in a tropical dry forest in relation to soil moisture and leaf traits

Aims The growth of plant species in tropical dry forest (TDF) is expected to be largely governed by the availability of soil moisture. In this study we attempt to identify mechanisms by which seedlings of dry tropical trees cope with water stress by adjusting their leaf characteristics to water availability and micro environments, and address following questions: How are leaf traits and relative growth rate (RGR) of the dominant seedling species of TDF affected by seasonal changes in soil moisture content (SMC)? What is the relationship of functional traits with each other? Can leaf traits singly or in combination predict the growth rate of seedling species of TDF? The study was conducted in situ on four sites (viz., Hathinala, Gaighat, Harnakachar and Ranitali, listed in order of decreasing SMC) within the tropical dry deciduous forest in northern India. Methods Five leaf traits viz., specific leaf area (SLA), leaf dry matter content (LDMC), concentrations of leaf nitrogen (leaf N), phosphorus (leaf P) and chlorophyll (Chl) and two physiological processes, viz., stomatal conductance (Gsnet) and photosynthetic rate (Anet), and RGR, of four dominant tree seedling species of a TDF (viz., Buchanania lanzan, Diospyros melanoxylon, Shorea robusta and Terminalia tomentosa) on four sites were analysed for species, site and season effects over a 2-year period. Step-wise multiple regression was performed to predict RGR from mean values of SMC, leaf traits and physiological processes. Principal component analysis (PCA) was performed to observe the extent of intra- vs. inter-specific variability in the leaf traits and physiological rates. Important Findings All the traits and physiological rates were interrelated and showed significant positive relationship with RGR except for the correlation of LDMC with RGR which was not significant. Further, relationships of SMC with all leaf traits, physiological rates and RGR were significant, except for that between SMC and SLA for B. lanzan and D. melanoxylon. The slope of seedling trait:SMC relationship, a measure of phenotypic plasticity in response to soil moisture gradient, varied among species. Among the four species, T. tomentosa was the most plastic and S. robusta the least. In conclusion, leaf traits and physiological processes were strongly related to soil water availability on the one hand and seedling growth on the other. Gsnet is the most important variable which accounted for the greatest amount of variability (62%) in RGR, emphasizing the role of stomatal conductance in shaping growth patterns across spatial and temporal gradients of soil water availability. Gsnet and SMC together explained 64% variability in RGR, indicating that other traits/factors, not studied by us are also impor tant in modulating the growth of tropical tree seedlings.

Disentangling the effects of multiple anthropogenic drivers on the decline of two tropical dry forest trees

Summary1. Tropical plant populations are often subject to multiple types of anthropogenic disturbance. Effective management requires disentangling the effects of these disturbances and prioritizing interventions for the driver(s) most responsible for population decline. However, the effects of multiple drivers on plant population dynamics are rarely examined.2. We assessed the independent and combined effects of common anthropogenic disturbances on the transient and long‐term population dynamics of two economically important, declining tree species in an Indian dry forest. Specifically, we drew on 10 years of demographic monitoring to assess the effects of non‐timber forest product (NTFP) harvest and two invasive species (an understorey shrub Lantana camara and a mistletoe Taxillus tomentosus) on amla (Phyllanthus emblica and Phyllanthus indofischeri) populations.3. Although fruit harvest has been blamed for declining amla populations, the current policy and management strategies implemented to restrict it have little effect on long‐term stochastic growth rates (λs) of amla both with and without invasive species. In contrast, mistletoes significantly decreased λs of both species.4. Lantana had both direct and indirect effects on P. emblica, causing a regeneration bottleneck. Lantana had a direct negative effect on seeding and sapling growth, whereas populations without lantana experienced higher levels of grazing by wild animals. Over 10 years, P. emblica populations dropped to 16% of their original size in areas with invasive species.5. Synthesis and applications. Our results illustrate that mistletoe and lantana, not fruit harvest, are the main drivers of amla decline, and these species are likely to be driving the decline of other Indian dry forest tree species. Management directed only at limiting fruit harvest will be ineffective. Instead, control of both invasive species combined with temporary protection from grazing is urgently needed. The ban on fruit harvest in Indian protected areas is not an effective conservation policy for these species. Harvest is not necessarily the main cause of decline for NTFP species. Management plans for NTFP and other at‐risk species must consider the relative effects of different drivers of decline, including direct and indirect effects of invasive species.

Distribution ofLeprariain Latvia in Relation to Tree Substratum and Deciduous Forest Type

The aim of the study was to evaluate the distribution of Lepraria lichen species in dry deciduous forests, in relation to tree substratum and forest characteristics. In total, 34 localities with 1020 trees (13 tree species) were studied in different parts of Latvia. Lepraria spp. were found on 642 trees: L. eburnea on 8 trees, L. incana on 80 trees, and L. lobificans on 568 trees. Lepraria eburnea was recorded for the first time in Latvia. Tree species, tree bark crevice depth, inclination, pH and forest type were the most important variables explaining the presence of Lepraria species. Lepraria incana was associated with Quercus robur and Tilia cordata, while L. lobificans was associated with Betula pendula. The occurrence probability of L. lobificans increased with tree inclination and tree bark pH, and that of L. incana with bark crevice depth and tree bark pH.

Variation in habitat use of coexisting rodent species in a tropical dry deciduous forest

Use of habitat is a critical component related to structure of small-mammal communities, with partitioning occurring primarily along dimensions of microhabitat, although use of microhabitat often does not explain fully use at a macrohabitat level. Through grid studies of small mammals in coastal Colima, Mexico (during January 2003–2005), we appraised influence of available habitat, species richness, abundance, and cumulative abundance of other small mammals on variation in habitat used by species. We evaluated 14 habitat variables (reflecting ground cover, slope, canopy, and vegetation density on vertical and horizontal axes) and developed a composite variable (principal component 1) reflecting general openness of habitat through which we addressed habitat use. For the four most common mammalian species (Sigmodon mascotensis, Heteromys pictus, Baiomys musculus, and Oryzomys couesi), two measures of variation in habitat used were employed to estimate niche breadth, one of which assessed variation in habitat use relative to variation present on a grid. Sigmodon mascotensis and B. musculus preferred areas that were more open, and H. pictus and O. couesi occupied less-open areas; breadth of habitat use did not differ interspecifically. Habitat use was more variable on grids with more variability in habitat, although not greater than chance expectations. Findings do not lend support to the resource-breadth hypothesis as an explanation for population densities of species at a local level or the habitat-heterogeneity hypothesis as a predictor of species richness. Variation in habitat used by S. mascotensis did not proportionally increase when diverse habitat was available but was greater when the species was more abundant. For H. pictus, when cumulative abundance of other small mammals was greater, breadth of habitat used was greater. Intraspecific density-dependent habitat selection may result in S. mascotensis selecting a greater variety of habitats, while greater interspecific abundance is related to a greater range in use of habitats by H. pictus. Baiomys musculus used a higher proportion of habitat relative to that available when more species were present on a grid. Variation in habitat used by O. couesi was unrelated to any factor examined. Overall, the four species responded in notably different ways with respect to availability of habitat, abundance, and presence of other species.