Assessing Sustainability of Nontimber Forest Product Extractions: How Fire Affects Sustainability

Abstract

Sustainable use of nontimber forest products (NTFPs) can be affected by levels of extractions as well as by other anthropogenic influences such as fire and grazing. We examined the effects of fire on the demography of Phyllanthus emblica, an important NTFP in the forests of Biligiri Rangan Hills, India. We then assessed demographic responses to the combined effects of fire and current fruit harvesting patterns. Fruits of Phyllanthus are commercially harvested by an indigenous forest dwelling people. Using matrix population models, we compared demographic indices across a chronosequence of time since last fire. Population growth rates (k) ranged from 0.7692 to 1.1443 across the five times since last fire. k was the lowest at times since last fire of 2 and 3 yr. Frequent fires increased time to maturity by altering growth and survival rates, thereby causing a demographic shift from growth to regressions or negative growth. Elasticity analysis revealed that stasis of adults makes the biggest contribution to k. Simulations of periodic and stochastic fire regimes suggest that higher k and population persistence can be achieved at firereturn intervals of ‡7 and ‡9 yr, respectively. These fire-return intervals became longer when the simulations included harvesting and fire. Extinction probabilities under the current fire regimes (every 2-3 yr) suggest that populations will decline to lower densities. Our findings provide critical information for developing guidelines for sustainable use and management of NTFPs in Biligiri Rangan Hills, and demonstrate the need to incorporate various human-generated physical regimes in assessing sustainability of NTFPs.

Evaluation of a Participatory Resource Monitoring System for Nontimber Forest Products: the Case of Amla (Phyllanthus spp.) Fruit Harvest by Soligas in South India

“…Many other tree species harvested for their fruits are also tolerant of high levels of fruit extraction (Ticktin 2004). However, sustainable harvesting is contingent on harvesting without branch cutting; when the latter occurs, even lower levels of harvesting can be unsustainable Bawa 2002, Sinha andBrault 2005). Similarly, frequent high-intensity fires decrease the quantity of amla fruits that can be harvested sustainably (Sinha and Brault 2005).…”

“…However, sustainable harvesting is contingent on harvesting without branch cutting; when the latter occurs, even lower levels of harvesting can be unsustainable Bawa 2002, Sinha andBrault 2005). Similarly, frequent high-intensity fires decrease the quantity of amla fruits that can be harvested sustainably (Sinha and Brault 2005). Therefore, improving PRM protocols to reincorporate estimates of annual levels of branch cutting as well as to record the frequency of high-intensity fires could provide still better insights on sustainability.…”

Regional Variation in Non-Timber Forest Product Harvest Strategies, Trade, and Ecological Impacts: the Case of Black Dammar (Canarium strictum Roxb.) Use and Conservation in the Nilgiri Biosphere Reserve, India

“…Indeed, despite the dependence of millions of people on the collection of NTFP species in India, and of the wide diversity of species harvested, to date there is still little research on harvest patterns and trade of Indian NTFP and their ecological impacts. The few studies that have been done have illustrated that some types of harvest have negatively affected the structure and dynamics of populations (Murali et al 1996, Kala 2000, Sinha and Bawa 2002, Sinha and Brault 2005, Muraleedharan et al 2005) and led to changes in plant communities (Murali et al 1996, Ganeshaiah et al 1998. These findings point to the great need for more work in this area, especially for those wild-harvested NTFP such as C. strictum, whose populations are reported to be declining.…”

Sensitivity analysis of periodic matrix population models

“…Periodic interannual variability. Periodic models based on sequences of annual observations (e.g., Mandujano et al 2001 for a cactus, Golubov et al 1999 for a shrub), variations in rainfall (Mondragon et al 2004 for an epiphyte, Vega and Montana 2004 for a grass), fire intervals (Gross et al 1998, Hoffmann 1999, Caswell and Kaye 2001, Sinha and Brault 2005, Stokes et al 2004, snowfall variation (Griffith et al 2010), ENSO effects (Awkerman et al 2006), pond levels (Ripley et al 2004), and food availability (Gervais et al 2006). …”