Plant Species Diversity and Biomass in the Forests of Morang District, east Nepal
| dc.contributor.advisor | Dr. Chita Bahadur Baniya, Dr. Tej Narayan Mandal | |
| dc.contributor.author | Gachhadar, Pramila Kumari | |
| dc.date.accessioned | 2024-12-03T06:51:45Z | |
| dc.date.available | 2024-12-03T06:51:45Z | |
| dc.date.issued | 2024-08 | |
| dc.description.abstract | Tropical forest ecosystem is crucial for mitigating the effects of climate change, because it acts as a carbon sink. Additionally, forest is the home to a significant portion of world’s biodiversity. Species composition, diversity, and biomass thought to be changed along the increasing elevation. The objective of the present study was to determine the variation in soil characteristics and their effect on species composition, diversity, biomass, carbon and nutrient stocks in the forests located along elevation gradient in Morang district of east Nepal. Five forest sites located at different elevations were selected which are addressed here as Bhaunne (200 m), Raja-Rani (500 m), Murchungi (800 m), Adheri (1000 m) and Sagma (1200 m), which lie inside the five different community forests in Morang district. A total of 50 sampling plots, 10 from each forests were laid randomly. Sampling size for tree was 20 m x 20 m, for shrubs nested 5m x 5m and for herbs nested 1m x 1m. Soil was collected by soil monolith of 10 cm x 10 cm x 30 cm, which was also used for fine root collection and litter mass was collected by using 1 m x 1 m sampling size within the plots used for tree sampling. Trees (≥10 cm girth) biomass and shrubs biomass was estimated by girth: biomass allometric equation. Herb biomass was estimated by harvest method. The carbon content of each plant components were estimated by ash content method. The data were analyzed by MS excel and R-package. Plot wise generalized linear model up to first order showed that the total species richness, herbs species richness and shrub species richness statistically significantly inclined and tree species richness statistically significantly declined pattern with increasing elevation. Total biomass and tree biomass showed declined relationship with elevations. While, shrub biomass showed statistically not significant inclined pattern and herb biomass showed statistically significant inclined pattern with increasing elevation. Shorea robusta was a dominant tree species with the highest Important Value Index value in the four forests except Sagma. Schima wallichii was the dominant species with the highest IVI in Sagma. Sorensen’s similarity index of trees revealed 64% similarity between Murchungi and Adheri forests, while lower similarity (22%) was exhibited between Bhaunne (extreme lower elevation) and Sagma forest (extreme high elevation). Stand biomass (815.88 Mg ha-1) and carbon stock (333.63 Mg C ha-1) were maximum in lower elevation forest (Bhaunne), while minimum biomass (299.96 Mg ha-1) and carbon stock (140.19 Mg C ha-1) were found in higher elevation forest (Sagma). Litter mass ranged between 7.1 Mg ha-1 and 25.7 Mg ha-1 showing irregular trend even in carbon and nutrient stock (N, P, K) due to irregular variation in non–leaf (wood) component of litter mass. Leaf litter exhibited close C: N ratio than non-leaf (wood) litter indicating a fast decomposition and nutrient release in the ecosystem. Fine root biomass ranged from 7.14 Mg ha-1 to 16.0 Mg ha-1. Carbon and nutrient stocks in fine root followed the same trend as per the trend in biomass. Fine root of <2 mm diameter size contained higher biomass than 2-5 mm size. Further, C: N ratio in <2 mm size was narrow than 2-5 mm size which is expected to release more nutrients in the ecosystem. Soil moisture ranged between 8.48 % and 21.29 %, water holding capacity from 68.21 to 97.48%, pH from 5.06 to 5.68, organic carbon from 1.20% to 3.04%, total nitrogen from 0.12 to 0.26% in different forests located along the different elevations. The lower elevation forest (Bhaunne) contained maximum soil moisture, organic carbon and total nitrogen, representing a healthy condition for the ecosystem. The soil moisture and fine root biomass were the most significant predictors for the tree species richness. Similarly, elevation, moisture, and non-leaf litter mass were significant for shrub species richness (Elev: p < 0.01, Moist1: p < 0.01, NLP: p < 0.05). The total nitrogen and leaf litter mass were important for herb species richness with p values; < 0.001 and < 0.01 respectively. In conclusion, variation in elevation has the effect on change in soil properties, plant density, plant diversity, biomass, carbon and nutrient stocks which accumulate in interdependent way. Findings of the present study may help to formulate a strategy for the management of productive forest to mitigate the carbon emission. उष्णकटिबंधीय वन पारिस्थितिक प्रणाली महत्त्वपूर्ण छ, किनभने यसले कार्बन भण्डारको रूपमा काम गर्दछ । प्रजाति संरचना, जैविक विविधता (Biodiversity), र जैविक पिण्ड (Biomass) बढ्दो उचाइसँगै परिवर्तन हुने गर्दछ । यो अध्ययनको उद्देश्य माटोको विशेषतामा हुने भिन्नता र वनमा रहेका प्रजातिहरूको संरचना, विविधता, जैविक पदार्थ, कार्बन र पोषक तत्वको भण्डारमा प्रभावको अध्ययन हो, जसको लागि मोरङ जिल्लामा भाउने (२०० मिटर), राजा-रानी (५०० मिटर), मुरचुङ्गी (८०० मिटर), अधेरी (१००० मि.) र साग्मा वन (१२०० मि.) गरी पाँच वटा वन छनोट गरिएको थियो, जुन सामुदायिक बन अन्तर्गत पर्दछ । ५० नमूना प्लटहरू, प्रत्येक वनबाट १० प्लटहरू अनियमित ढांचा अनुसार रूख (Trees) को लागि नमूना आकार २० मि. x २० मि., बुट्यानहरू (Shrubs) को लागि ५ मि.x ५ मि. र साना झाडीहरू (Herbs) को लागि १ मि.x १ मि. थियो । माटो १० से.मि. x १० से.मि. x ३० से.मि. को मोनोलिथद्वारा संकलन गरिएको थियो, जुन मसिना जरा सङ्कलनका लागि पनि प्रयोग गरिएको गरिएको थियो । कुल प्रजातिहरू, बुट्यान र साना झाडी प्रजातिहरू बढ्दो उचाइको साथ सांख्यिकीय रूपमा महत्त्वपूर्ण बढ्दो ढाँचा देखायो र रूख प्रजातिहरू बढ्दो उचाइसँगै गिरावट प्रवृत्ति देखाएको छ । कुल जैविक पिण्ड (Total stand biomass) र रूख जैविक पिण्ड (Tree biomass) ले सांख्यिकीय रूपमा महत्त्वपूर्ण रूपमा घटेको सम्बन्ध देखाएको छ, जबकि बुट्यान जैविक पिण्ड (Shrub biomass) र झाडी प्रजातिको जैविक पिण्ड (Herb biomass) ले बढेको ढाँचा देखायो । Important Value Index को आधारमा, साल (Shorea robusta) तलको चारवटा जंगलहरुमा र चिलाउने (Schima wallichii) साग्मा (माथिल्लो) वनमा प्रभुत्व छ । सोरेन्सेनको रुखको समानता सूचकाङ्कले मुरचुङ्गी (८०० मि.) र अधेरी जंगल (१००० मि.) बीच ६४ प्रतिशत समानता देखाएको छ । जबकि भाउन्ने (२०० मि.) र साग्मा वन (१२०० मि.) बीच कम समानता (२२%) प्रदर्शन गरिएको थियो । कूल वनस्पतिमा अधिकतम जैविक पिण्ड, ८१५.८८ Mg ha-1 र कार्बन स्टक, ३३३.६३ Mg C ha-1 भाउन्ने बनमा पाइयो भने न्यूनतम बायोमास, २९९.९६ Mgha-1 र कार्बन स्टक, १४०.१९ Mg C ha-1 साग्मा वनमा पाइयो । पातपतिंगर ७.१ Mg ha-1 र २५.७ Mgha-1 को बीचमा पाइयो । मसिनो जराको जैविक पिण्ड (Fine root biomass) ७.१४ Mg ha-1 देखि १६.० Mg ha-1 सम्म, भाउने जंगलमा न्यूनतम र मुर्चुङ्गी वनमा अधिकतम पाइयो । २ मि.मी. व्यास भएको जराले अधिकतम र २-५ मि.मी.ब्यास भएको जराले कम बायोमास देखायो । माटोको आर्द्रता ८.४८ % र २१.२९ %, पानी धारण क्षमता ६८.२१ देखि ९७.४८ %, pH ५.०६ देखि ५.६८ , जैविक कार्बन १.२० % देखि ३.०४ %, कुल नाइट्रोजन ०.१२ % देखि ०.२६ % सम्म पाइयो । भाउने वनमा अधिकतम माटोको आर्द्रता, जैविक कार्बन र कुल नाइट्रोजन रहेको थियो, जसले पारिस्थितिक प्रणालीको लागि स्वस्थ अवस्थालाई जनाउछ । माटोको आर्द्रता र मसिना जरा बायोमासले रूख प्रजातिहरूको वृद्धिको लागि सबैभन्दा महत्त्वपूर्ण रहेको पाइयो । त्यसैगरी, उचाइ, आर्द्रता, र गैर-पात लिटरमास झाडी प्रजातिहरूको लागि महत्त्वपूर्ण थियो। कुल नाइट्रोजन र पात लिटरमास झाडी प्रजातिहरूको लागि महत्त्वपूर्ण पाइयो । अन्तमा, उचाइको भिन्नताले माटोको गुण, बिरुवाको घनत्व, बिरुवाको विविधता, जैविक पिण्ड, कार्बन र पोषक तत्वको भण्डारमा प्रभाव पार्छ जुन एक अर्कामा निर्भर हुन्छ । वर्तमान अध्ययनका निष्कर्षहरूले कार्बन उत्सर्जनलाई न्यूनीकरण गर्न, उर्बर र उत्पादक वन व्यवस्थापनको रणनीति बनाउन मद्दत पुग्नेछ । | |
| dc.identifier.uri | https://hdl.handle.net/20.500.14540/23305 | |
| dc.language.iso | en | |
| dc.publisher | Institute of Science & Technology, TU | |
| dc.subject | Tropical forest | |
| dc.subject | Soil properties | |
| dc.subject | Species richness | |
| dc.subject | Litter mass | |
| dc.subject | Carbon stock | |
| dc.subject | Fine root | |
| dc.title | Plant Species Diversity and Biomass in the Forests of Morang District, east Nepal | |
| dc.type | Thesis | |
| local.academic.level | Ph.D. | |
| local.institute.title | Institute of Science & Technology |